Add docker practice

.drone.yml

@@ -0,0 +1,9 @@
+kind: pipeline
+type: docker
+name: default
+
+steps:
+- name: test
+  image: nixos/nix:master
+  commands:
+  - echo 522

04/README.md

@@ -1,6 +1,6 @@
 ### Что здесь лежит?
 
 В файле [git instruction](./git_instruction.md) лежат
-инструкции что нужно проделать в качестве первичной практики
+инструкции, которые нужно проделать в качестве первичной практики
 по **git**.
 

04/git_instruction.md

@@ -1,35 +1,44 @@
-## Что делать?
+## Что нужно сделать?
 
-1. Зайти на сайт: cs-sh.xyz;
+0. Зайти на сайт: [cs-sh.xyz].
-2. Зарегистрироваться, если ещё не;
+1. Зарегистрироваться, если ещё не.
-3. Создать репозиторий, называть можно как угодно;
+2. Создать репозиторий, называть можно как угодно.
-4. Взять HTTPS ссылку к репозиторию (далее `<url>`);
+3. Взять HTTPS ссылку к репозиторию (далее `<url>`).
-4. Склонировать репозиторий к себе на машину по этой ссылке;
+4. Склонировать репозиторий к себе на машину по этой ссылке:
 ```ssh
 git clone <url>
 ```
-5. Изменить файл `README.md`, наполнить каким-нибудь содержимым;
+5. Открыть склонированный репозиторий как обычную директорию _любым_ привычным
+способом:
+  - в терминале с помощью команды `cd`, `pwd` также может помочь;
+  - в Windows с помощью File Explorer, в других ОС -- с помощью его аналогов;
 
-6. Создать коммит с **содержательным** сообщением;
+6. Создать файл `README.md`, если он ещё не был создан.
-Сначала добавляем файлы в Staging:
+
+7. Изменить файл `README.md`, наполнить каким-нибудь содержимым.
+
+8. Создать коммит с **содержательным** сообщением.
+
+Для этого добавить файлы в Staging:
 ```ssh
 git add README.md
 ```
-и коммитим:
+и создать коммит:
 ```
 # git commit -m "some mess"
 # лучше
 git commit
 ```
-7. Запушить содержимое ветки в ветку `main`;
+9. Запушить содержимое ветки в ветку `main`.
 ```sh
 git push origin main
 ```
-8. "Отпочковать" новую ветку:
+10. "Отпочковать" новую ветку:
 ```
 git checkout -b name_of_branch
 ```
-9. Изменить или добавить какие-нибудь файлы, создать коммит;
+11. Изменить или добавить какие-нибудь файлы, создать коммит.
-10. Запушить изменения на cs-sh.xyz в ветку `name_of_branch`;
+12. Запушить изменения на [cs-sh.xyz] в **свой** (не в данный!) репозиторий в ветку `name_of_branch`.
-11. Создать Pull Request (Запрос на слияние) в **СВОЙ**
+13. Создать Pull Request (Запрос на слияние) в **СВОЙ** репозиторий.
-репозиторий;
+
+[cs-sh.xyz]: https://cs-sh.xyz

04/testfile

@@ -1,6 +1,3 @@
 1
 2
 3
-4
-5
-6

05/README.md

@@ -0,0 +1,6 @@
+### Что здесь лежит?
+
+В файле [sh instruction](./sh_instruction.md) лежат
+инструкции, которые нужно проделать в качестве первичной практики
+по **shell**.
+

05/sh_instruction.md

@@ -0,0 +1,43 @@
+## Что делать?
+
+1. Открыть терминал.
+
+2. Открыть и полистать man-pages:
+  - `man`
+  - `pwd`
+  - `cd`
+  - `ls`
+  - `mkdir`
+  - `rm`
+  - `rmdir`
+  - `cat`
+  - `bash`
+  - `grep`
+
+Что делать, если **no manual entry found**
+```bash
+$ sudo apt update
+$ sudo apt install manpages-posix
+```
+
+3. Не забывайте, что `man` откроет пагинатор вроде `less` (или `most`, как у меня);
+убедитесь, что понимаете как им пользоваться:
+  - вызовите помощь с помощью клавиши `h`;
+  - найдите какое-нибудь вхождение с помощью `/`,`?` и клавиш `n`/`N`;
+  - поймите как пролистывать целый экран/половину экрана вверх-вниз;
+  - выясните как перейти в начало/конец файла;
+
+4. ознакомиться с утилитой `help`, начать можно с вызова `help` без аргументов,
+далее -- повызывать `help` для различных встроенных команд, например,
+`help set`.
+
+5. Открыть `info coreutils`
+
+Попробовать попользоваться:
+  - потыкать клавиши вниз-вверх;
+  - потыкать клавиши `[`,`]`,`p`,`n`;
+  - понять, какие действия они делают;
+  - научиться вызывать помощь;
+
+Обязательно офигеть, закрыть, открыть info-страницы в браузере по ссылке с
+cscwiki.

06/README.md

@@ -0,0 +1,27 @@
+### Что здесь лежит?
+
+Только README.md, больше ничего
+
+### Задания на практику
+
+#### 1. Удваиватель
+
+Написать команду, копирующую содержимое файла `data` в конец этого же файла.
+
+Примечания:
+ * решение на полный балл не должно использовать временные файлы;
+ * файл может содержать бинарные данные;
+ * проверьте, что если изначальный размер файла был n байт, то размер результирующего файла -- 2 * n байт
+ * проверьте свое решение на больших (> 1 MB) файлах;
+ 
+#### 2. Числа Фибоначчи
+
+Определим числа Фибоначчи следующим образом:
+
+![fibonacci](https://wikimedia.org/api/rest_v1/media/math/render/svg/caa1e3b2e9c19fe638fc0b3d6548718bfe5119e2)
+
+Вам нужно написать скрипт, который будет считывать из `stdin`
+число `n` и выводить в `stdout` `n`-ое число Фибоначчи.
+
+Примечания:
+* Время работы функции -- `O(n)`.

07_haskell/Main.hs

@@ -0,0 +1,37 @@
+data A = True' | False'
+  deriving Show
+
+foo :: A -> Integer
+foo True'  = 1
+foo False' = 0
+
+data P3 = P Bool A -- P (Bool x A)
+
+data BigP = P1 Bool A | P2 Integer
+  deriving Show
+
+bar :: BigP -> Integer
+bar (P1 _ _) = 1
+bar (P2 _) = 2
+
+int_plus_3 :: Integer -> Integer
+int_plus_3 n = n + 3
+
+-- examples
+comp :: BigP -> Integer
+comp = int_plus_3 . bar
+-- same as: int_plus_3 $ bar $ P2 10
+
+double_arg :: Integer -> Integer -> Integer
+double_arg a b = a + b
+
+partially_applied :: Integer -> Integer
+partially_applied = double_arg 7
+
+
+func_arg :: (Integer -> Integer) -> Integer -> Integer
+func_arg f b = f b
+
+
+main :: IO ()
+main = putStrLn "Hello world"

07_haskell/Second.hs

@@ -0,0 +1,35 @@
+
+type Name = String
+type Table = [ (Name, Name) ]
+
+fathers :: Table
+fathers = [
+  ("a", "d"),
+  ("b", "r")
+  ]
+
+head' :: [a] -> a
+head' (x:xs) = x
+
+
+helper :: Integer -> [a] -> Integer
+helper acc (x:xs) = helper (acc + 1) xs
+helper acc ([]) = acc
+
+len' :: [a] -> Integer
+len' xs = helper 0 xs
+
+
+inv :: [a] -> [a] -> [a]
+inv acc (x:xs) = inv (x : acc) xs
+inv acc [] = acc
+
+rev :: [a] -> [a]
+rev xs = inv [] xs
+
+-- 1 : 2 : 3 : []
+-- 3 : 2 : 1 : []
+
+
+getF :: Name -> Maybe Name
+getF n = lookup n fathers

07_python/README.md

@@ -0,0 +1,21 @@
+### Задаание 1
+
+Используя библиотеку `time`, написать декоратор `@bench(n)`,
+который меняет функцию так, чтобы при каждом её вызове она
+вычислялась не один раз, а `n` раз, при этом необходимо выводить:
+
+- имя функции;
+- аргументы;
+- средняя время работы за `n` запусков;
+
+```python
+
+@bench(50)
+def foo(a: int, b: int):
+    ...
+
+
+>>> foo(5, 5)
+<... foo> (5, 5) {}
+Mean execution time on <N> calls: ???ns
+```

07_python/bench.py

@@ -0,0 +1 @@
+

07_python/closure.py

@@ -0,0 +1,9 @@
+def adder():
+    n = 0
+
+    def add():
+        nonlocal n
+        n += 1
+        return n
+
+    return add

07_python/debugger.py

@@ -0,0 +1,14 @@
+def debug_call(f):
+    def inner(*args, **kwargs):
+        print(f, args, kwargs)
+        return f(*args, **kwargs)
+
+    return inner
+
+
+# @debug_call
+def foo(a, b):
+    return a + b
+
+
+foo = debug_call(foo)

07_python/deco_troubles.py

@@ -0,0 +1,17 @@
+def deco(f):
+    def inner(*args, **kwargs):
+        print(f)
+        return f(*args, **kwargs)
+
+    return inner
+
+
+# @deco
+def foo():
+    """
+    Foo is just a function.
+    """
+    return None
+
+
+foo = deco(foo)

07_python/ex.py

@@ -0,0 +1,8 @@
+def deco_ch(f):
+    f.jjjjj = 10
+    return f
+
+
+@deco_ch
+def foo():
+    print(foo.jjjjj)

07_python/name_test.py

@@ -0,0 +1,77 @@
+# first attempt
+def deco_first(f):
+    def inner(*args, **kwargs):
+        return f(*args, **kwargs)
+
+    inner.__name__ = f.__name__
+    inner.__doc__ = f.__doc__
+    inner.__qualname__ = f.__qualname__
+
+    return inner
+
+
+# second attempt
+from functools import update_wrapper
+
+
+def deco_second(f):
+    def inner(*args, **kwargs):
+        return f(*args, **kwargs)
+
+    update_wrapper(inner, f)
+    return inner
+
+
+# third attempt
+
+
+def my_wraps(original):
+    def deco(wrapper):
+        update_wrapper(wrapper, original)
+        return wrapper
+
+    return deco
+
+
+from functools import partial
+
+
+def partial_wraps(original):
+    return partial(update_wrapper, wrapped=original)
+
+
+# def deco_third(f):
+#     def inner(*args, **kwargs):
+#         return f(*args, **kwargs)
+#
+#     deco = my_wraps(f)
+#     inner = deco(inner)
+#     return inner
+
+
+def deco_third(f):
+    @partial_wraps(f)
+    def inner(*args, **kwargs):
+        return f(*args, **kwargs)
+
+    return inner
+
+
+# third attempt
+from functools import wraps
+
+
+def deco_fourth(f):
+    @wraps(f)
+    def inner(*args, **kwargs):
+        return f(*args, **kwargs)
+
+    return inner
+
+
+@deco_third
+def foo(a, b, c):
+    """
+    Foo function docstring
+    """
+    return a + b + c

07_python/partial.py

@@ -0,0 +1,8 @@
+from functools import partial
+
+
+def foo(a, b, new_name):
+    return new_name * (b + a)
+
+
+bar = partial(foo, c=500)

07_python/retry.py

@@ -0,0 +1,33 @@
+def adder():
+    n = 0
+
+    def add():
+        nonlocal n
+        n += 1
+        return n
+
+    return add
+
+
+def retry(n: int = 5):
+    def deco(f):
+        def inner(*args, **kwargs):
+            for _ in range(n):
+                f(*args, **kwargs)
+
+        return inner
+
+    return deco
+
+
+# @retry(5)
+def foo():
+    print("Hello world!")
+
+
+foo = (retry(5))(foo)
+
+
+@retry(15)
+def bar():
+    print("Bar")

08_python/README.md

@@ -0,0 +1,11 @@
+### Практика про классы в питоне
+
+Что здесь есть полезного?
+- [definition](./definition) -- определения классов;
+- [descriptor](./descriptor) -- про модификаторы и как использовать `@property`;
+- [magic](./magic) -- куча примеров магических методов;
+- [mro](./mro) -- method resolution order или примеры про плату за сомнительные решения;
+- [class-deco](./class-deco) -- как использовать класс в качестве декоратора;
+- [dataclasses](./dataclasses) -- датаклассы (классы без методов, но только с
+данными);
+- [mixins](./mixins) -- пример паттерна mixin;

08_python/class-deco/getter.py

@@ -0,0 +1,15 @@
+class ClassDeco:
+    def __init__(self, f):
+        self.f = f
+
+    def __call__(self, *args, **kwargs):
+        print(self.f, args, kwargs)
+        return self.f(*args, **kwargs)
+
+
+@ClassDeco
+def foo():
+    return 45
+
+
+# foo = ClassDeco(foo)

08_python/dataclasses/dcls.py

@@ -0,0 +1,28 @@
+from dataclasses import dataclass
+from typing import Union
+
+
+#  def dataclass(cls=None, /, *, init=True, repr=True, eq=True, order=False,
+#                unsafe_hash=False, frozen=False):
+#      """Returns the same class as was passed in, with dunder methods
+#      added based on the fields defined in the class.
+#
+#      Examines PEP 526 __annotations__ to determine fields.
+#
+#      If init is true, an __init__() method is added to the class. If
+#      repr is true, a __repr__() method is added. If order is true, rich
+#      comparison dunder methods are added. If unsafe_hash is true, a
+#      __hash__() method function is added. If frozen is true, fields may
+#      not be assigned to after instance creation.
+#      """
+
+
+@dataclass(frozen=True)
+class A:
+    a: int
+    b: bool
+    c: str = "asd"
+    f: Union[int, bool, str] = 0
+
+    def foo(self):
+        print(self)

08_python/definition/cl_defo.py

@@ -0,0 +1,17 @@
+class A:
+    pass
+
+
+class C:
+    a, b = 1, 1
+    for i in range(15):
+        a, b = b, a + b
+
+    print(a)
+    f = lambda self, a: a
+    g = lambda self, a: self.f(a)
+
+    def __init__(self, x, y):
+        print(self)
+        self.x = x
+        self.y = y

08_python/definition/dct.py

@@ -0,0 +1,7 @@
+class A:
+    n = 5
+    e = 50
+    f = lambda self: 42
+
+    def __init__(self):
+        self.a = 1000

08_python/definition/def_cls.py

@@ -0,0 +1,12 @@
+class C:
+    f = 50
+
+    a, b = 1, 1
+    for _ in range(10):
+        a, b = b, a + b
+    print(a, b)
+
+    def __init__(self, a, b):
+        print(self)
+        self.a = a
+        self.b = b

08_python/definition/inheritance.py

@@ -0,0 +1,14 @@
+# class Base(object)
+class Base:
+    def foo(self):
+        return 42
+
+
+class NotBase:
+    def foo(self):
+        return 43
+
+
+class A(NotBase, Base):
+    def bar(self):
+        return 41

08_python/descriptor/modifiers.py

@@ -0,0 +1,17 @@
+class A:
+    def __init__(self, a, b):
+        self._a = a
+        self.__b = b
+
+    @property
+    def super_duper_var(self):
+        print(self)
+        return self.__b
+
+    @super_duper_var.setter
+    def super_duper_var(self, value):
+        self.__b = value
+
+    # @super_duper_var.deleter
+    # def super_duper_var(self):
+    #     pass

08_python/magic/MyHashable.py

@@ -0,0 +1,8 @@
+from abc import ABC
+
+
+class MyHashable(ABC):
+    @classmethod
+    def __subclasshook__(cls, sbcls):
+        hash_func = getattr(sbcls, "__hash__", None)
+        return hash_func is not None

08_python/magic/always_field.py

@@ -0,0 +1,3 @@
+class AlwaysHaveField:
+    def __getattr__(self, value):
+        return value

08_python/magic/ex_for.py

@@ -0,0 +1,23 @@
+class Iterator:
+    def __init__(self, origin_list):
+        self._ref = origin_list
+        self.n = -1
+
+    def __next__(self):
+        if self.n < len(self._ref) - 1:
+            self.n += 1
+            return self._ref[self.n]
+        raise StopIteration()
+
+
+class A:
+    def __init__(self):
+        self.a = [1, 2, 3, 4]
+
+    def __iter__(self):
+        return Iterator(self.a)
+
+
+a = A()
+for el in a:
+    print(el)

08_python/magic/ex_for2.py

@@ -0,0 +1,11 @@
+class A:
+    def __init__(self):
+        self.a = [1, 2, 3, 4]
+
+    def __getitem__(self, ind):
+        return self.a[ind]
+
+
+a = A()
+for el in a:
+    print(el)

08_python/magic/hasheq.py

@@ -0,0 +1,20 @@
+class MADATA:
+    def __init__(
+        self,
+        a: int,
+        b: int,
+        c: int,
+    ):
+        self.a = a
+        self.b = b
+        self.c = c
+
+    @property
+    def _tup_view(self):
+        return self.a, self.b, self.c
+
+    def __hash__(self):
+        return hash(self._tup_view)
+
+    def __eq__(self, o):
+        return isinstance(o, type(self)) and o._tup_view == self._tup_view

08_python/magic/new_getattr.py

@@ -0,0 +1,11 @@
+class A:
+    def __init__(self):
+        self.a = 1
+        self.b = 2
+
+    def foo(self):
+        print("Hello")
+
+    def __getattr__(self, name):
+        print(f"Called __getattr__ with arg: {name}")
+        return name

08_python/magic/nmp.py

@@ -0,0 +1,6 @@
+class DF:
+    def __getitem__(self, key):
+        return key
+
+    def __setitem__(self, key, value):
+        print(key, value)

08_python/mixins/cat_girl.py

@@ -0,0 +1,14 @@
+class GirlsMixin:
+    def hooray(self):
+        print("Hoooray")
+
+
+class CatMixin:
+    def feed(self, hp):
+        print("Meow")
+
+
+class CatGirls(GirlsMixin, CatMixin):
+    def main(self):
+        super().feed(50)
+        super().hooray()

08_python/mro/broken_mro.py

@@ -0,0 +1,34 @@
+class Base:
+    def foo(self):
+        print("Base")
+
+
+class A(Base):
+    def foo(self):
+        print("A")
+        super().foo()
+
+
+class B(Base):
+    def foo(self):
+        print("B")
+        super().foo()
+
+
+class C(A, B):
+    def foo(self):
+        print("C")
+        super().foo()
+
+
+class D(B, A):
+    def foo(self):
+        print("D")
+        super().foo()
+
+
+class E(C, D):
+    pass
+
+
+print("HEELLO")

08_python/mro/completely_f_cked.py

@@ -0,0 +1,21 @@
+class Base:
+    def __init__(self, a):
+        self.x = a
+
+
+class A(Base):
+    def __init__(self):
+        super().__init__(5)
+
+
+class B(Base):
+    def __init__(self, x):
+        super().__init__(x)
+
+
+class C(A, B):
+    ...
+
+
+class D(B, A):
+    ...

08_python/mro/mro.py

@@ -0,0 +1,24 @@
+class Base:
+    def foo(self):
+        print("Base")
+
+
+class A(Base):
+    def foo(self):
+        print("A")
+        super().foo()
+
+
+class B(Base):
+    def foo(self):
+        print("B")
+        super().foo()
+
+
+class C(A, B):
+    def foo(self):
+        print("C")
+        super().foo()
+
+
+print("HEELLO")

09_python/dict_gen.py

@@ -0,0 +1,2 @@
+a = {k: k * 379 for k in range(10)}
+print(a)

09_python/enum.py

@@ -0,0 +1,9 @@
+els = ["a", "b", "c"]
+
+
+def _enum(els):
+    return zip(range(len(els)), els)
+
+
+for idx, el in _enum(els):
+    print(idx, el)

09_python/for_loop.py

@@ -0,0 +1,36 @@
+class IterableStack:
+    def __init__(self):
+        self._lst = [1, 2, 3, 4, 5]
+
+    def __iter__(self):
+        return ReverseIterator(self._lst)
+
+
+class ReverseIterator:
+    def __init__(self, _lst):
+        self._lst = _lst
+        self.position = len(_lst)
+
+    def __next__(self):
+        self.position -= 1
+        if self.position < 0:
+            raise StopIteration()
+
+        return self._lst[self.position]
+
+
+# container = IterableStack()
+# for v in container:
+#     print(v)
+
+container = IterableStack()
+it_container = iter(container)  # container.__iter__()
+while True:
+    try:
+        v = next(it_container)  # it_container.__next__()
+
+        # тело фора
+        print(v)
+        # конец тела фора
+    except StopIteration:
+        break

09_python/func_stream.py

@@ -0,0 +1,9 @@
+def local_gen():
+    n = 0
+
+    def next():
+        nonlocal n
+        n += 1
+        return n
+
+    return next

09_python/gen.py

@@ -0,0 +1,17 @@
+def _range(start, stop):
+    assert start < stop
+
+    def inside_gen():
+        nonlocal start
+        while start < stop:
+            print("Going to return: ", start)
+            yield start
+            start += 1
+
+        print("here")
+
+    return inside_gen()
+
+
+# for el in _range(0, 10):
+#     print(el)

09_python/lzy_load.py

@@ -0,0 +1,20 @@
+from typing import List
+
+
+def load_files(paths: List[str]):
+    for path in paths:
+        with open(path) as f:
+            yield f.readlines()
+
+
+paths = [
+    "dict_gen.py",
+    "enum.py",
+    "for_loop.py",
+    "gen.py",
+    "lzy_load.py",
+]
+
+for cont in load_files(paths):
+    # code working with content
+    print(cont)

10_docker/README.md

@@ -0,0 +1,13 @@
+# Docker Tutorial
+
+
+* [Prerequisites](prerequisites)
+* [Useful external links](links)
+* [Summary of commands](summary)
+* [Lesson 1: Docker basics and running a container](lesson01)
+* [Lesson 2: Introduction to Docker image builds](lesson02)
+* [Lesson 3: Image layers](lesson03)
+* [Lesson 4: Persisting data](lesson04)
+* [Lesson 5: Network access](lesson05)
+* [Lesson 6: Environment variables and configuration](lesson06)
+* [Good Docker practices](practices)

10_docker/lesson01/README.md

@@ -0,0 +1,100 @@
+# Lesson 1: Docker basics and running a container
+
+1. Download the `busybox` Docker image from Docker Hub:
+
+        $ docker images
+        $ docker pull busybox
+        $ docker images
+
+1. What do the columns mean? The first two are `REPOSITORY` and
+`TAG`. Think of these as a way to name-space docker images. The
+`REPOSITORY` is the name for a group of related repositories. For the case
+of `busybox` the repository name is `busybox`. The second part of the
+namespace is `TAG` and is separated from `REPOSITORY` with a `:`
+(colon). If not explictly given, the tag defaults to `latest`.
+
+1. We will discuss tagging and the other columns later.
+
+1. Let's run busybox.
+
+        $ docker run busybox /bin/sh -c "echo 'Hello' | md5sum"
+        09f7e02f1290be211da707a266f153b3  -
+
+1. What _is_ a docker container?
+
+    > A container is a standard unit of software that packages up code and all
+    > its dependencies so the application runs quickly and reliably from one
+    > computing environment to another. (From https://www.docker.com)
+
+1. At heart a Docker container is a set of processes running in a
+["namespace"](https://en.wikipedia.org/wiki/Linux_namespaces). These
+namespaces isolate the processes from the other processes running on the
+server. You can think of all this as a light-weight virtual machine.
+
+1. List the namespace of a running docker container (`lsns` is a Linux
+command):
+
+        $ docker run busybox /bin/sh -c "sleep 1000" &
+        root> lsns  (must run as root to see the namespaces)
+
+1. Because Docker containers are just processes running on an existing
+server inside of a namespace, Docker images use the server's kernel. Thus,
+only functionality supported by the underlying kernel will work in a
+Docker container.
+
+1. Docker containers also use ["control
+groups"](https://en.wikipedia.org/wiki/Cgroups) which allow the host
+operating system to put limits on the resources used by the running Docker
+container. Limits can be placed on CPU, memory use, and I/O.
+
+        # Limit docker to 10MB an use up all the memory
+        # (idea from https://unix.stackexchange.com/questions/99334/how-to-fill-90-of-the-free-memory)
+        $ docker run -m=10m busybox /bin/sh -c "cat /dev/zero | head -c 1m | tail"
+        $ docker run -m=10m busybox /bin/sh -c "cat /dev/zero | head -c 20m | tail"
+
+1. Unless you use an extra option the containers that you run will stick
+around. To see this, use the `docker ps` command:
+
+        $ docker ps --all
+        $ docker ps -a    # (-a is the same as --all)
+
+1. Note that the names of the containers are random words. To give your
+container a name, use the `--name` command:
+
+        $ docker run --name=fuzzle busybox /bin/sh -c "echo 'Hello' | md5sum"
+        $ docker ps -a | grep fuzzle
+
+1. To remove one of these left over containers use `docker rm`:
+
+        $ docker ps -a | grep fuzzle
+        $ docker rm fuzzle
+        $ docker ps -a | grep fuzzle
+
+1. To remove all stopped containers use `docker container prune`:
+
+        $ docker ps -a
+        $ docker container prune
+        $ docker ps -a
+
+1. To avoid the whole stopped container messiness, tell Docker to remove
+the container once it exits with teh `--rm` option:
+
+        $ docker run --rm --name=fuzzle busybox /bin/sh -c "echo 'Hello' | md5sum"
+        $ docker ps -a | grep fuzzle
+
+1. You can "login" to a running docker container:
+
+        $ docker run --rm --name=fuzzle busybox /bin/sh -c "sleep 10000" &
+        $ docker ps -a | grep fuzzle
+        $ docker exec -ti fuzzle /bin/sh
+        / # # You are "inside" the running container; run some commands
+        / # ps -eaf
+        / # df -h
+
+1. The `-ti` options tell Docker that you want to allocate a pseudo-TTY
+and use "interactive mode". *Warning:* logging into a running container is
+not exactly like ssh'ing into a server: some commands that depend on the
+terminal type may not work like you expect (e.g., editors, pagers, etc.)
+
+1. Being able to login to a running container is **very** useful when debugging
+your Docker builds.

10_docker/lesson02/Dockerfile

@@ -0,0 +1,7 @@
+# Dockerfile
+FROM debian:buster-slim
+LABEL maintainer="adamhl@stanford.edu"
+
+ADD run.sh /root/run.sh
+RUN chmod a+x /root/run.sh
+CMD /root/run.sh

10_docker/lesson02/README.md

@@ -0,0 +1,97 @@
+# Lesson 2: Introduction to Docker image builds
+
+1. Clone this git repository.
+
+1. Change directory into `lesson02`:
+
+        $ cd lesson02
+
+1. Why are containers useful? What are their advantages over a
+traditional server?
+
+   - containers are light
+   - containers are portable
+   - containers are isolated
+   - containers can be run "immutably"
+   - containers are built hierarchically
+   - developers can create applications without a full server-stack
+
+1. What are some limitations of containers?
+
+   - interaction is more difficult for multiple containers than for
+     multiple server process (although Kubernetes helps)
+   - some overhead so not quite as fast as "bare-metal" processes
+   - there are several decades worth of server administration best practices
+     and tools but only a few years for containers
+   - not good for large tightly-integrated applications (e.g., Oracle database)
+
+1. Question: what is the difference between an "image" and a "container"?
+(See also [this Stackoverflow
+question](https://stackoverflow.com/questions/23735149/what-is-the-difference-between-a-docker-image-and-a-container)).
+
+1. Most Docker images are build on top of existing "base" images. These
+base containers are usually hosted in Docker Hub. For example, all Debian
+releases come as Docker images; see https://hub.docker.com/_/debian for a
+list of the base Debian Docker images.
+
+1. Let's build a "Hello, world." Docker image. We will build it on a
+Debian buster base. First, pull the Docker image:
+
+        $ docker pull debian:buster-slim
+        # We pull the "slim" image to save disk space
+
+1. Here is an application that echos "Hello, world." and then exits (this
+file is also in the current directory).
+
+        #!/bin/sh
+        echo "Hello, world."
+        exit 0
+
+1. Now we create a "Dockerfile" that tells the build process how to create
+the image. We use `debian:buster-slim` as the base and "add" the command
+`run.sh`. The first argument of `ADD` is the *local* copy of the file and
+the second argument is where we want the file to be in the image.
+
+        # Dockerfile
+        FROM debian:buster-slim
+        LABEL maintainer="adamhl@stanford.edu"
+
+        ADD run.sh /root/run.sh
+
+
+1. We want to make sure that the script will run, so make it executable.
+
+        # Dockerfile
+        FROM debian:buster-slim
+        LABEL maintainer="adamhl@stanford.edu"
+
+        ADD run.sh /root/run.sh
+        RUN chmod a+x /root/run.sh
+
+1. Docker containers must be told which command to run. We do this with
+the `CMD` directive
+
+        # Dockerfile
+        FROM debian:buster-slim
+        LABEL maintainer="adamhl@stanford.edu"
+
+        ADD run.sh /root/run.sh
+        RUN chmod a+x /root/run.sh
+        CMD /root/run.sh
+
+1. We are now ready to build the image:
+
+        $ docker build . -t hello-world
+        $ docker images | grep hello-world
+
+1. Question: what is the purpose of `.` (dot) in the above `docker build`
+command?
+
+1. Note that the tag is `latest` (the default).
+
+1. Let's run this image in a container:
+
+        $ docker run --rm hello-world
+
+1. Did you see what you expected?
+

10_docker/lesson02/run.sh

@@ -0,0 +1,3 @@
+#!/bin/sh
+echo "Hello, world."
+exit 0

10_docker/lesson03/Dockerfile

@@ -0,0 +1,7 @@
+# Dockerfile
+FROM debian:buster-slim
+LABEL maintainer="adamhl@stanford.edu"
+
+ADD run.sh /root/run.sh
+RUN chmod a+x /root/run.sh
+CMD /root/run.sh

10_docker/lesson03/Dockerfile-v2

@@ -0,0 +1,7 @@
+# Dockerfile
+FROM debian:buster-slim
+LABEL maintainer="adamhl@stanford.edu"
+
+ADD run.sh /root/run.sh
+RUN chmod a+rx /root/run.sh
+CMD /root/run.sh

10_docker/lesson03/README.md

@@ -0,0 +1,211 @@
+# Lesson 3: Image layers
+
+1. Change directory into `lesson03`.
+
+1. Build the `hello-world` image with the tag `v1`:
+
+        $ docker build . -t hello-world:v1
+
+1. Each Docker image consists of a sequence of file system _layers_ with the
+later layers overwriting earlier ones. Each layer corresponds to an
+instruction in the `Dockerfile`. Let's look at the layers. (Note: in this and
+subsequent displays I leave off the CREATED column to save space).
+
+        $ docker history hello-world:v1
+        IMAGE          CREATED BY
+        f38d648975d5   /bin/sh -c #(nop)  CMD ["/bin/sh" "-c" "/roo...
+        09b895731b10   /bin/sh -c chmod a+x /root/run.sh
+        07d951eff6a0   /bin/sh -c #(nop) ADD file:ae2a94e6e79a95786â¦...
+        34fd6d6fbb15   /bin/sh -c #(nop)  LABEL maintainer=adamhl@s...
+        589ac6f94be4   /bin/sh -c #(nop)  CMD ["bash"]
+        <missing>      /bin/sh -c #(nop) ADD file:422aca8901ae3d869...
+
+        $ docker history debian:buster-slim
+        IMAGE          CREATED BY
+        589ac6f94be4   /bin/sh -c #(nop)  CMD ["bash"]
+        <missing>      /bin/sh -c #(nop) ADD file:422aca8901ae3d869...
+
+1. Notice that the `hello-world:v1` image's first two layers are the same
+as `debian:buster-slim`'s layers. This reflects the fact that
+`hello-world:v1` starts FROM the `debian:buster-slim` image.
+
+1. The subsequent layers of the `hello-world:v1` image each correspond to
+the commands in the `Dockerfile`. Here is the Dockerfile again as a
+reminder:
+
+        # Dockerfile
+        FROM debian:buster-slim
+        LABEL maintainer="adamhl@stanford.edu"
+
+        ADD run.sh /root/run.sh
+        RUN chmod a+x /root/run.sh
+        CMD /root/run.sh
+
+1. When you create a running Docker container using `docker run` the
+Docker system loads your image with each layer being _read-only_ with a
+final, new layer being added. This last layer is writable. Let's try it.
+
+        $ docker run --rm --name=fuzzle busybox /bin/sh -c "sleep 10000" &
+        $ docker exec -ti fuzzle /bin/sh (we "login" to the running container)
+        / # cd /root; ls
+        ~ # date > date.txt; ls -l
+        -rw-r--r--    1 root     root             0 Jan 16 03:56 date.txt
+        ~ # cat /root/date.txt
+        Sat Jan 16 03:57:15 UTC 2021
+        ~ # exit
+
+1. The container is still running. Let's make sure the file we created is
+still there.
+
+        $ docker exec -ti fuzzle /bin/sh
+        ~ # cat /root/date.txt
+        Sat Jan 16 03:57:15 UTC 2021
+        ~ # exit
+
+1. However, once the container exits, that final writable layer is thrown away.
+**It does not persist**. Let's see.
+
+        $ docker rm fuzzle
+        # You should get an error here. Why?
+
+1. To stop a running container from the outside use the `docker kill` command.
+
+        $ docker kill fuzzle
+        $ docker rm fuzzle
+        # This last command returns an error. Why?
+
+1. To see that the file `/root/date.txt` is really gone, let's start the
+container again and look.
+
+        $ docker run --rm --name=fuzzle busybox /bin/sh -c "sleep 10000" &
+        $ docker exec fuzzle ls -l /root
+
+1. Notice that we did not login to the container to do an `ls`, rather, we used
+the `exec` command.
+
+1. To reiterate, changes made to the containers top writable layer do not
+persist. If you want the container to make persistent changes to files
+another mechanism is needed such as mounting an external volume or writing
+to some other persistent data store; more on that in a later lesson.
+
+1. Back to layers.
+
+1. When we looked at the history of the `hello-world:v1` image we saw this:
+
+        $ docker history hello-world:v1
+        IMAGE          CREATED BY
+        f38d648975d5   /bin/sh -c #(nop)  CMD ["/bin/sh" "-c" "/roo...
+        09b895731b10   /bin/sh -c chmod a+x /root/run.sh
+        07d951eff6a0   /bin/sh -c #(nop) ADD file:ae2a94e6e79a95786â¦...
+        34fd6d6fbb15   /bin/sh -c #(nop)  LABEL maintainer=adamhl@s...
+        589ac6f94be4   /bin/sh -c #(nop)  CMD ["bash"]
+        <missing>      /bin/sh -c #(nop) ADD file:422aca8901ae3d869...
+
+1. Under the `IMAGE` column are hex strings. Those correspond to the
+SHA256 hash of the new layer's content. (More precisely, the SHA256 hash
+of the layers configuration object.)
+
+1. Think of these hashes (roughly) corresponding to git commit hashes. The
+layers and their hashes are useful for they tell Docker when a layer has
+changed. We use a copy of `Dockerfile` with one small change:
+
+        # Dockerfile-v2
+        FROM debian:buster-slim
+        LABEL maintainer="adamhl@stanford.edu"
+
+        ADD run.sh /root/run.sh
+        RUN chmod a+rx /root/run.sh  # This is the changed line.
+        CMD /root/run.sh
+
+1. Build the image and look at its history:
+
+        $ docker build . -f Dockerfile-v2 -t hello-world:v2
+        $ docker history hello-world:v2
+        IMAGE          CREATED BY
+        0dd6cfe9bb51   /bin/sh -c #(nop)  CMD ["/bin/sh" "-c" "/roo...
+        39085b76a64f   /bin/sh -c chmod a+rx /root/run.sh
+        07d951eff6a0   /bin/sh -c #(nop) ADD file:ae2a94e6e79a95786...
+        34fd6d6fbb15   /bin/sh -c #(nop)  LABEL maintainer=adamhl@s...
+        589ac6f94be4   /bin/sh -c #(nop)  CMD ["bash"]
+        <missing>      /bin/sh -c #(nop) ADD file:422aca8901ae3d869...
+
+        $ docker history hello-world:v1
+        IMAGE          CREATED BY
+        f38d648975d5   /bin/sh -c #(nop)  CMD ["/bin/sh" "-c" "/roo...
+        09b895731b10   /bin/sh -c chmod a+x /root/run.sh
+        07d951eff6a0   /bin/sh -c #(nop) ADD file:ae2a94e6e79a95786â¦...
+        34fd6d6fbb15   /bin/sh -c #(nop)  LABEL maintainer=adamhl@s...
+        589ac6f94be4   /bin/sh -c #(nop)  CMD ["bash"]
+        <missing>      /bin/sh -c #(nop) ADD file:422aca8901ae3d869...
+
+1. Note that the layers have the same image ID except for the layers
+starting with the one we changed. The top layers have different id's
+since even though they are the same Dockerfile command they derive from
+the layer that changed (again, think of a git commit).
+
+1. This has the pleasant result that if the first N Dockerfile commands do
+not change but the N+1'st command _does_ change, then `docker build` will
+use the cached layers for the first N layers and only rebuild from layer
+N+1 onwards. This means rebuilds can be quite fast.
+
+1. **Important.** The image changes whenever one or more of the Dockerfile
+`ADD`, `COPY`, or `RUN` command lines change. Even adding whitespace to a
+line that has no real effect can trigger a new layer.
+
+1. What does it mean for a Dockerfile line to change? Either the line in
+the Dockerfile itself changes (as we saw above) **or**, for commands that
+add files from the local environment, the file being added changes. For
+example, if we added a comment line to `run.sh` this counts as a change to
+the `ADD run.sh /root/run.sh` line and would trigger a layer rebuild from
+that layer forward.
+
+1. Edit the file `run.sh` by adding a comment and then rebuild:
+
+        #!/bin/sh
+        # An extra comment
+        echo "Hello, world."
+        exit 0
+
+        $ docker build . -t hello-world:v3
+        $ docker history hello-world:v1
+        IMAGE          CREATED BY
+        2131b85a91d5   /bin/sh -c #(nop)  CMD ["/bin/sh" "-c" "/roo...
+        30a489d1e5b0   /bin/sh -c chmod a+x /root/run.sh
+        94667dcd1388   /bin/sh -c #(nop) ADD file:ae2a94e6e79a95786...
+        ebca792f7949   /bin/sh -c #(nop)  LABEL maintainer=adamhl@s...
+        589ac6f94be4   /bin/sh -c #(nop)  CMD ["bash"]
+        <missing>      /bin/sh -c #(nop) ADD file:422aca8901ae3d869...
+        $ docker history hello-world:v3
+        IMAGE          CREATED BY
+        acc54a5d1b49   /bin/sh -c #(nop)  CMD ["/bin/sh" "-c" "/roo...
+        82b9cde2c517   /bin/sh -c chmod a+x /root/run.sh
+        2a19083a38b0   /bin/sh -c #(nop) ADD file:997845d6d2fdc9492...
+        ebca792f7949   /bin/sh -c #(nop)  LABEL maintainer=adamhl@s...
+        589ac6f94be4   /bin/sh -c #(nop)  CMD ["bash"]
+        <missing>      /bin/sh -c #(nop) ADD file:422aca8901ae3d869...
+
+1. Notice that the `ADD` line has changed its image id.
+
+1. A gotcha: your Dockerfile installs a package downloaded from an
+external repository (like Debian). You build the image. A little while
+later the package is updated in the Debian repository. You rebuild the
+container thinking the rebuild will catch this change. But is does
+NOT. The docker build only notices changes to the Dockerfile itself, not
+to sources external to the build environment.
+
+1. A way around this gotcha. If you want to be sure that every time you
+build your container it rebuilds each layer regardless of any changes to
+the Dockerfile use the `--no-cache` option. This has the advantage of
+reliability but the disadvantage that it can take significantly more time.
+
+        $ docker build . -t hello-world:v3            (this will be fast)
+        $ docker build . --no-cache -t hello-world:v3 (this will slower)
+
+1. Another advantage of Docker caching layers is that different images
+built off the same layer help save space. Recall that images layers are
+loaded read-only, so if two different running containers are built off the
+same layer, both containers can point to the same physical file. This is
+why spawning a second container running on the same image as the first can
+be so quick: the base layer is already loaded into memory so all that has
+to be done is add the final writable layer that is distinct for each
+container.

10_docker/lesson03/run.sh

@@ -0,0 +1,4 @@
+#!/bin/sh
+# Hello
+echo "Hello, world."
+exit 0

10_docker/lesson04/Dockerfile

@@ -0,0 +1,7 @@
+# Dockerfile (version 1)
+FROM debian:buster-slim
+LABEL maintainer="adamhl@stanford.edu"
+
+ADD date.sh /root/date.sh
+RUN chmod a+x /root/date.sh
+CMD /root/date.sh

10_docker/lesson04/README.md

@@ -0,0 +1,100 @@
+# Lesson 4: Persisting data
+
+1. Change directory into `lesson04`.
+
+1. We saw in Lesson 3 that data written to the final container layer does
+not persist. How do we deal with this? One option is to have the container
+write to an external system like a database system or cloud storage. There
+is, however, another method: mounting a local file system or directory.
+
+1. Let's create a Docker container that saves the current date to a file. Here is
+our first attempt:
+
+        # Dockerfile
+        FROM debian:buster-slim
+        LABEL maintainer="adamhl@stanford.edu"
+
+        ADD date.sh /root/date.sh
+        RUN chmod a+x /root/date.sh
+        CMD /root/date.sh
+
+        # date.sh
+        #!/bin/sh
+        echo "echoing date to /tmp/date.output"
+        date > /tmp/date.output
+
+        $ docker build . -t date
+        $ docker run --rm --name=fuzzle date
+        echoing date to /tmp/date.output
+
+1. The above will create the file `/tmp/date.output` containing the date
+but we know that the file will not persist after the container stops
+running. To get around this we "mount" a local directory into the
+container's `/tmp` directory. By "local directory" we mean a directory on
+the computer where we run the our `docker` commands. We mount the colume
+when we run the container.
+
+        $ mkdir -p /tmp/docker
+        $ docker run --rm --name=fuzzle --volume=/tmp/docker:/tmp date
+        echoing date to /tmp/date.output
+        $ cat /tmp/docker/date.output
+
+1. You can run a container and override the `CMD` command.
+
+        $ docker run --rm --name=fuzzle date ls -ld /etc
+        drwxr-xr-x 1 root root 4096 Jan 17 17:23 /etc/
+        (The date.sh script did NOT run)
+
+1. This is especially useful when you want to login to the container and
+debug the filesystem or CMD command.
+
+1. You can overwrite a file in the image using the same `--volume`
+option. For example, let's overwrite `/etc/debian_version` with a
+different file.
+
+        $ docker run --rm --name=fuzzle date cat /etc/debian_version
+        10.7
+        $ echo "fake-version" > /tmp/deb_ver
+        $ docker run --rm --name=fuzzle --volume=/tmp/deb_ver:/etc/debian_version date cat /etc/debian_version
+        fake-version
+
+1. If you mount an external directory onto a container directory
+**everything** in the directory in the container is **replaced** with the
+external directory.
+
+        $ docker run --rm --name=fuzzle date ls -l /usr
+        total 32
+        drwxr-xr-x  2 root root 4096 Jan 11 00:00 bin
+        drwxr-xr-x  2 root root 4096 Nov 22 12:37 games
+        ... more ...
+
+        # Create a directory in /tmp with a single file.
+        $ mkdir -p /tmp/usr; cp test.txt /tmp/usr
+
+        # Mount /tmp/usr over /usr in the container
+        $ docker run --rm --name=fuzzle --volume=/tmp/usr:/usr date ls -l /usr
+        total 4
+        -rw-r--r-- 1 52777 root 7 Jan 17 18:04 test.txt
+
+1. You can mount an external directory in read-only mode. This is
+particularly useful when injecting secrets or configuration information
+into a container. Look for the `ro` in the `--volume` option below.
+
+        $ mkdir -p /tmp/secrets
+        $ echo "my-password" > /tmp/secrets/password
+
+        $ docker run --rm --name=fuzzle --volume=/tmp/secrets:/secrets:ro date sleep 100000 &
+
+        $ docker exec -ti fuzzle /bin/sh
+        # cat /secrets/password
+        my-password
+        # echo "another secret" >> /secrets/password
+        /bin/sh: 5: cannot create /secrets/password: Read-only file system
+
+        $ docker kill fuzzle
+
+1. You can run the entire container in read-only mode. The `docker run`
+option `--read-only` mounts the root filesystem (i.e., everything) in
+read-only excepting any externally mounted volumes. This lets you
+lock-down the filesystem except for those parts of the filesystem you
+know need to be written to (e.g., `/tmp`, `/var/log`, etc.).

10_docker/lesson04/date.sh

@@ -0,0 +1,3 @@
+#!/bin/sh
+echo "echoing date to /tmp/date.output"
+date > /tmp/date.output

10_docker/lesson04/test.txt

@@ -0,0 +1 @@
+Hello.

10_docker/lesson05/README.md

@@ -0,0 +1,36 @@
+# Lesson 5: Network access
+
+1. Change directory into `lesson05`.
+
+1. A very popular use for containers is for serving web applications. How
+do users get network access to a running container? Put simply, the host
+acts as the network proxy for its containers: a network conection is made
+to the host which directs the traffic into the container, and vice versa
+for outbound traffic.
+
+1. Let's try it:
+
+        $ docker pull httpd
+        $ docker run -dit --name apache --rm -p 8080:80 httpd
+        $ docker ps
+        CONTAINER ID   IMAGE     COMMAND              CREATED          STATUS          PORTS                  NAMES
+        23c146b78377   httpd     "httpd-foreground"   20 seconds ago   Up 19 seconds   0.0.0.0:8080->80/tcp   apache
+
+1. Note that traffic sent to port 8080 on the *host* gets sent to port 80
+in the *container*. The `-d` option tells Docker to run the container in
+"detached" mode, i.e., in the background.
+
+1. Look at the network (look for the `Containers` element):
+
+        $ docker network inspect bridge
+
+1. Test the application. If running docker on your local machine put this
+URL into your browser's address bar: `http://localhost:8080`.
+
+1. If running on a remote host run this command:
+
+        $ wget http://localhost:8080 --quiet -O -
+
+1. Don't forget to kill the container:
+
+        $ docker kill apache

10_docker/lesson06/Dockerfile

@@ -0,0 +1,7 @@
+# Dockerfile
+FROM debian:buster-slim
+LABEL maintainer="adamhl@stanford.edu"
+
+ADD demo.sh /root/demo.sh
+RUN chmod a+x /root/demo.sh
+CMD /root/demo.sh

10_docker/lesson06/README.md

@@ -0,0 +1,35 @@
+# Lesson 6: Environment variables and configuration
+
+1. Change directory into `lesson06`.
+
+1. A popular way to provide configuration information to a docker container is
+via environment variables.
+
+1. Let's try it:
+
+        $ docker build . -t demo
+        $ docker run -it --rm --name fuzzle demo
+
+1. Does the output make sense?
+
+1. Let's pass in a value for the environment variable `HELLO_WORLD`:
+
+        $ docker run -it --rm --name fuzzle -e HELLO_WORLD='Hello, world.' demo
+
+1. You can also pass in environment variables via a file:
+
+        $ cat file.env
+        # We define two environment variables (you CAN comment!)
+        HELLO_WORLD="Hello, world."
+        ENV_VAR2="another environment variable"
+
+        $ docker run -it --rm --name fuzzle --env-file=file.env demo
+
+1. If your Docker application does not have many configuration options
+configuring via environment variables is a good method. However, if the
+application has complicated or extnesive configuration this may not be
+feasible.
+
+1. Don't forget to clean up:
+
+        $ docker rmi demo:latest (removes the image demo:latest)

10_docker/lesson06/demo.sh

@@ -0,0 +1,9 @@
+#!/bin/bash
+# demo.sh
+
+if [ -z "${HELLO_WORLD}" ]; then
+    echo "The environment variable HELLO_WORLD is not defined."
+else
+    echo "The environment variable HELLO_WORLD is '${HELLO_WORLD}'."
+fi
+

10_docker/lesson06/file.env

@@ -0,0 +1,3 @@
+# We define two environment variables (you CAN comment!)
+HELLO_WORLD="Hello, world."
+ENV_VAR2="another environment variable"

10_docker/links/README.md

@@ -0,0 +1,6 @@
+# Useful External Links
+
+* [Container and
+layers](https://docs.docker.com/storage/storagedriver/#container-and-layers):
+a good explanation from Docker on image and container layers
+

10_docker/practices/README.md

@@ -0,0 +1,49 @@
+[[_TOC_]]
+
+# Good Docker Practices
+
+## Keep the Docker image simple (micro-services)
+
+Although you can run as many processes in a single container as you want,
+it is usually a good idea to design a container to do a single task. If
+your application does several different things you can always add
+"sidecar" containers that do the extra work.
+
+There will be situations where splitting an application into different
+containers is too complicated.  Be flexible and use your own judgement.
+
+## Use small base images
+
+A smaller image means faster start-up times and less memory used on the
+container host. One way to acheive is to use a small base image. A popular
+small image is `alpine` based on Alpine Linux. This is a complete Linux
+with image size of 5.5MB with its own packages. By comparison,
+`debian:buster-slim` is about 70MB.
+
+On the other hand, don't let the drive toward small size get in the way
+of needed functionality; remember the IBM Pollyanna Principle: "machines
+should work; people should think".
+
+## When possible use container orchestration
+
+Getting containers to interact and cooperate can be tricky, so use one of
+the orcestration tools like Kubernetes or Docker Compose to do this.
+
+## Use CI/CD (i.e., automation) to keep Docker images up-to-date
+
+Set up automation to rebuild your Docker images periodically making sure
+that you disable caching when building. This way your image will have the
+most up-to-date and secure base images.
+
+## Send diagnostic output to standard output
+
+In the traditional server world we are used to sending logs to files. With
+Docker containers it is usually better to send diagnostic output to
+standard output. Kubernetes and other orchestration tools are designed
+with the expectation that logging is sent to standard output.
+
+## Run containers in "read-only" mode
+
+Running a Docker container in read-only mode helps to reduce the attack
+surface area of your application. Mount external volumes for those parts
+of the file system that need to be writable (`/var/log`, `/tmp`, etc.).

10_docker/prerequisites/README.md

@@ -0,0 +1,15 @@
+# Prequisites
+
+1. Installation of Docker.
+
+1. Test your Docker install (the hex ID shown below will differ):
+
+        $ docker images
+        # REPOSITORY    TAG   IMAGE ID    CREATED         SIZE
+        ... more ...
+
+        $ docker pull busybox
+        Using default tag: latest
+        latest: Pulling from library/busybox
+        e5d9363303dd: Pull complete
+

10_docker/summary/README.md

@@ -0,0 +1,23 @@
+# Summary of Docker commands used in this tutorial
+
+    # List images
+    docker images
+
+    # Pull an image from Docker Hub
+    docker pull busybox
+
+    # Build a Docker image
+    docker build -t my-tag .
+
+    # Build image ignoring cached layers
+    docker build --no-cache -t my-tag .
+
+    # Run container in "interactive" mode
+    docker run -it <image-name>
+
+    # List containers
+    docker ps
+    docker ps -a  (include stopped containers)
+
+    # Connect to a running container (i.e., "login")
+    docker exec -it <container-name> -- /bin/bash

README.md

@@ -4,7 +4,7 @@
 для курса *Основы программирования*.
 
 Код желательно запускать из терминала.
-Например, в linux можно :
+Например, в linux можно:
 
 ```sh
 $ cd programming-basics
@@ -16,15 +16,46 @@ $ cd 01
 $ cat README.md
 ```
 
-
+## Как решать задания
-**(!)** Не забывайте читать литературу: [список литературы на CSCWiki].
+
-
+- внимательно прочитайте задание;
-**(!)** И пользоваться ресурсами:
+- если в задании упоминается команда, например, `find`,
+попробуйте поискать/попинать `man`, `info`, `help`; но не торопитесь усердствовать
+с их чтением: за раз всё в голове, скорее всего, не осядет, поэтому интересные
+вещи лучше отложить и читать постепенно и последовательно (а ещё хорошо спать
+и регулярно питаться, ага);
+- вместо усердного чтения лучше попробуйте прочитать краткое описание и
+предположить _что_ эта программа могла бы делать
+(обычно секции **NAME**, **SYNOPSIS** в man-страницах или листать оглавление info-страниц
+и искать что-нибудь со словами `introduction`, `example`, `real use` и пр.);
+unix (и, как следствие, linux) так устроен, что _обычно_ одна программа выполняет
+одну функцию, но делает это по возможности хорошо; 
+- после этого попытайтесь накидать _хоть какое-нибудь рабочее решение_;
+- как только у Вас получилось написать первое рабочее решение, вспомните, что Вы
+прекрасны;
+- попробуйте (возможно, кстати, не сразу, а на следующий день или через
+несколько дней) упростить или улучшить Ваше решение; обычно это идёт на пользу
+и Вам и Вашим скриптам;
+- с каждым таким улучшением, опять же, постарайтесь себя похвалить и
+порадоваться, что у Вас получился, _возможно_, более читаемый и красивый
+скрипт;
+
+## Материалы
+
+**(!)** [wiki-страница курса]
+
+**(!)** [список литературы на CSCWiki]
+
+**(!)** web-ресурсы:
 
 * посмотреть как исполняется код в ваших любимых языках программирования:
 [pythontutor];
 * почитать объяснение shell-команды: [explain shell];
 
+
+
+
+[wiki-страница курса]: https://cs-sh.xyz/d/ompwiki
 [pythontutor]: https://pythontutor.com
 [explain shell]: https://explainshell.com/explain?cmd=find+.+-name+%27*.py%27+-printf+%22x%22+%7C+grep+-oc+x
 [список литературы на CSCWiki]: https://wiki.compscicenter.ru/index.php/%D0%9E%D0%9C%D0%9F_1MIT_%D0%BE%D1%81%D0%B5%D0%BD%D1%8C_1_2022#.D0.9B.D0.B8.D1.82.D0.B5.D1.80.D0.B0.D1.82.D1.83.D1.80.D0.B0