An Intro to Docker for Djangonauts

If you’ve never used it before, Docker can be a little overwhelming. There is new vocabulary to learn, new commands to memorize, and new files to add to each project. Most resources fall into one of two camps: they teach you the bare bones of Docker but still leave you with too many questions to comfortably try it on your own, or they throw you into the deep end by assuming you’re more familiar with Docker than you are.

In this talk, you will find that middle ground: a talk that doesn’t assume you’re familiar with Docker and so keeps everything simple, but leaves you with enough information that you can get started as soon as you leave the room. Together, we will step through the parts of a Dockerfile and learn what they do. Then, I’ll introduce you to Docker Compose and explain why using it to run multiple containers is helpful. Finally, you will learn to run commands and execute scripts from the command line using Docker, how to enter a container and why you might need to, and what to do before you go home for the day.

Transcript

1. An Intro to
   Docker for Djangonauts
   Lacey Williams Henschel
   DjangoCon US 2018
   !
   @laceynwilliams | @revsys
   

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2. @laceynwilliams | @revsys
   

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3. What is
   Docker?
   !
   @laceynwilliams | Source: XKCD
   

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4. magic
   @laceynwilliams | @revsys
   

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5. Docker
   ✓ Separate dependencies
   ✓ Shares your OS
   ✓ All team members on the same page
   ✓ No Python installs needed!
   @laceynwilliams | @revsys
   

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6. But...
   ✓ Learning curve
   @laceynwilliams | @revsys
   

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7. What about
   virtualenvs?
   @laceynwilliams | Source: XKCD
   

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8. Polyjuice Potion
   Images and Containers
   @laceynwilliams | @revsys
   

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9. Docker is the potion
   @laceynwilliams | Source: Karen Roe
   

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10. The image is
    the person you want
    to turn into
    @laceynwilliams | Source: Harry Po5er Wiki
    

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11. The
    container
    is you
    @laceynwilliams | @revsys
    

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12. image
    executable that contains
    all the packages for your
    project
    container
    run6me instance of
    image
    @laceynwilliams | @revsys
    

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13. The Dockerfile is
    the hair of the
    person you want to turn into
    @laceynwilliams | Source: Beth Purchases
    

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14. Dockerfile is
    the DNA
    @laceynwilliams | @revsys
    

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15. image
    executable that contains
    all the packages for your
    project
    container
    run6me instance of image
    Dockerfile
    file that defines your
    image
    @laceynwilliams | @revsys
    

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16. Use hair to tell the po-on how to
    change into someone else.
    Drink it to transform your body.
    Use Dockerfile to tell Docker how to
    build your image.
    Run project in a container.
    @laceynwilliams | @revsys
    

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17. FROM python:3.6
    ENV PYTHONUNBUFFERED 1
    ENV PYTHONDONTWRITEBYTECODE 1
    COPY ./requirements.txt /code/requirements.txt
    RUN pip install -r /code/requirements.txt
    COPY . /code/
    WORKDIR /code/
    EXPOSE 8000
    CMD [ "python", "./manage.py", "runserver",
    "0.0.0.0:8000", "--settings=mysite.settings" ]
    @laceynwilliams | @revsys
    

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18. FROM python:3.6
    ENV PYTHONUNBUFFERED 1
    ENV PYTHONDONTWRITEBYTECODE 1
    COPY ./requirements.txt /code/requirements.txt
    RUN pip install -r /code/requirements.txt
    COPY . /code/
    WORKDIR /code/
    EXPOSE 8000
    CMD [ "python", "./manage.py", "runserver",
    "0.0.0.0:8000", "--settings=mysite.settings" ]
    @laceynwilliams | @revsys
    

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19. FROM python:3.6
    ENV PYTHONUNBUFFERED 1
    ENV PYTHONDONTWRITEBYTECODE 1
    COPY ./requirements.txt /code/requirements.txt
    RUN pip install -r /code/requirements.txt
    COPY . /code/
    WORKDIR /code/
    EXPOSE 8000
    CMD [ "python", "./manage.py", "runserver",
    "0.0.0.0:8000", "--settings=mysite.settings" ]
    @laceynwilliams | @revsys
    

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20. FROM python:3.6
    ENV PYTHONUNBUFFERED 1
    ENV PYTHONDONTWRITEBYTECODE 1
    COPY ./requirements.txt /code/requirements.txt
    RUN pip install -r /code/requirements.txt
    COPY . /code/
    WORKDIR /code/
    EXPOSE 8000
    CMD [ "python", "./manage.py", "runserver",
    "0.0.0.0:8000", "--settings=mysite.settings" ]
    @laceynwilliams | @revsys
    

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21. FROM python:3.6
    ENV PYTHONUNBUFFERED 1
    ENV PYTHONDONTWRITEBYTECODE 1
    COPY ./requirements.txt /code/requirements.txt
    RUN pip install -r /code/requirements.txt
    COPY . /code/
    WORKDIR /code/
    EXPOSE 8000
    CMD [ "python", "./manage.py", "runserver",
    "0.0.0.0:8000", "--settings=mysite.settings" ]
    @laceynwilliams | @revsys
    

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22. FROM python:3.6
    ENV PYTHONUNBUFFERED 1
    ENV PYTHONDONTWRITEBYTECODE 1
    COPY ./requirements.txt /code/requirements.txt
    RUN pip install -r /code/requirements.txt
    COPY . /code/
    WORKDIR /code/
    EXPOSE 8000
    CMD [ "python", "./manage.py", "runserver",
    "0.0.0.0:8000", "--settings=mysite.settings" ]
    @laceynwilliams | @revsys
    

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23. FROM python:3.6
    ENV PYTHONUNBUFFERED 1
    ENV PYTHONDONTWRITEBYTECODE 1
    COPY ./requirements.txt /code/requirements.txt
    RUN pip install -r /code/requirements.txt
    COPY . /code/
    WORKDIR /code/
    EXPOSE 8000
    CMD [ "python", "./manage.py", "runserver",
    "0.0.0.0:8000", "--settings=mysite.settings" ]
    @laceynwilliams | @revsys
    

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24. FROM python:3.6
    ENV PYTHONUNBUFFERED 1
    ENV PYTHONDONTWRITEBYTECODE 1
    COPY ./requirements.txt /code/requirements.txt
    RUN pip install -r /code/requirements.txt
    COPY . /code/
    WORKDIR /code/
    EXPOSE 8000
    CMD [ "python", "./manage.py", "runserver",
    "0.0.0.0:8000", "--settings=mysite.settings" ]
    @laceynwilliams | @revsys
    

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25. FROM python:3.6
    ENV PYTHONUNBUFFERED 1
    ENV PYTHONDONTWRITEBYTECODE 1
    COPY ./requirements.txt /code/requirements.txt
    RUN pip install -r /code/requirements.txt
    COPY . /code/
    WORKDIR /code/
    EXPOSE 8000
    CMD [ "python", "./manage.py", "runserver",
    "0.0.0.0:8000", "--settings=mysite.settings" ]
    @laceynwilliams | @revsys
    

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26. Brew your potion
    $ docker build .
    @laceynwilliams | @revsys
    

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27. $ docker build .
    Sending build context to Docker daemon 246.8kB
    Step 1/8 : FROM python:3.6
    ---> c1e459c00dc3
    Step 2/8 : ENV PYTHONUNBUFFERED 1
    ---> 4a0a06578949
    Step 3/8 : COPY ./requirements.txt /code/requirements.txt
    ---> 5295a62d7c36
    Step 4/8 : RUN pip install -r /code/requirements.txt
    ---> Running in 18b4fa19c07e
    Collecting Django (from -r /code/requirements.txt (line 1))
    Downloading https://.../Django-2.0.5-py3-none-any.whl (7.1MB)
    Installing collected packages: Django
    Successfully installed Django-2.0.5
    Removing intermediate container 18b4fa19c07e
    ---> 371f3b29d141
    Step 5/8 : COPY . /code/
    ---> 5443237e1306
    Step 6/8 : WORKDIR /code/
    Removing intermediate container cbafa8b61bd9
    ---> 5a50cee784e7
    Step 7/8 : EXPOSE 8000
    ---> Running in a0b9b3f4da6f
    Removing intermediate container a0b9b3f4da6f
    ---> 80fbc70dc709
    Step 8/8 : CMD [ "python", "./manage.py", "runserver",
    "0.0.0.0:8000", "--settings=mysite.settings" ]
    ---> Running in 351cfbc91fa2
    Removing intermediate container 351cfbc91fa2
    Successfully built 80fbc70dc709
    @laceynwilliams | @revsys
    

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28. Name of your image
    80fbc70dc709
    @laceynwilliams | @revsys
    

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29. $ docker build -t hogwarts .
    Successfully built 4521a153fa19
    Successfully tagged hogwarts:latest
    @laceynwilliams | @revsys
    

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30. # image:tag
    python:3.6
    hogwarts:latest
    @laceynwilliams | @revsys
    

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31. Layers
    @laceynwilliams | S/ll from Harry Po5er and
    the Chamber of Secrets
    

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32. Step 1/8 : FROM python:3.6
    ...
    Step 2/8 : ENV PYTHONUNBUFFERED 1
    ...
    @laceynwilliams | @revsys
    

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33. • First (me through: Docker builds each layer
    by hand
    • Second (me through: Docker uses a cache if
    nothing has changed
    • Docker rebuilds changed layers and all layers
    a;er them
    @laceynwilliams | @revsys
    

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34. Step 1/8 : FROM python:3.6
    ---> c1e459c00dc3
    Step 2/8 : ENV PYTHONUNBUFFERED 1
    ---> Using cache
    ---> 4a0a06578949
    Step 3/8 : COPY ./requirements.txt /code/requirements.txt
    ---> 630e64f66d85
    Step 4/8 : RUN pip install -r /code/requirements.txt
    ---> Running in b9ef1258f655
    Collecting Django (from -r /code/requirements.txt (line 1))
    Downloading https://.../Django-2.0.5-py3-none-any.whl (7.1MB)
    ...
    Step 8/8 : CMD [ "python", "./manage.py", "runserver",
    "0.0.0.0:8000", "--settings=mysite.settings" ]
    ---> Running in 351cfbc91fa2
    Removing intermediate container 351cfbc91fa2
    Successfully built a5392bb186c4
    Successfully tagged hogwarts:latest
    @laceynwilliams | @revsys
    

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35. The Standard Book of Spells
    Grade 1
    Docker Edition
    @laceynwilliams | @revsys
    

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36. Imago Revelio
    $ docker images
    REPOSITORY TAG IMAGE ID CREATED SIZE
    hogwarts latest 4521a153fa19 42 hours ago 734MB
    @laceynwilliams
    ✨
    spell to reveal images
    

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37. Continens Revelio
    $ docker container ls
    CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
    @laceynwilliams
    ✨
    spell to reveal containers
    

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38. Drink your potion
    $ docker run -p 8000:8000 hogwarts
    @laceynwilliams | @revsys
    

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39. Continens Revelio
    $ docker container ls
    CONTAINER ID IMAGE COMMAND CREATED
    2021341641d7 hogwarts "python ./manage.py …"About a minute ago
    STATUS PORTS NAMES
    Up About a minute 0.0.0.0:8000->8000/tcp fervent_allen
    @laceynwilliams
    ✨
    spell to reveal containers
    

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40. Apparate
    $ docker exec -it 2021341641d7 shell
    root@2021341641d7:/code#
    @laceynwilliams
    ✨
    magical teleporta2on into container
    

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41. root@2021341641d7:/code# ls
    Dockerfile blog mysite requirements.txt
    README.md manage.py
    @laceynwilliams | @revsys
    

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42. root@2021341641d7:/code# cd ..
    root@2021341641d7:/# ls
    bin code etc lib media opt root sbin sys usr
    boot dev home lib64 mnt proc run srv tmp var
    @laceynwilliams | @revsys
    

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43. Disapparate
    ctrl + d
    @laceynwilliams
    ✨
    magical teleporta2on out of container shell
    

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44. $ docker container ls
    CONTAINER ID IMAGE COMMAND
    2021341641d7 hogwarts "python ./manage.py …"
    @laceynwilliams | @revsys
    

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45. Stupefy
    $ docker stop 2021341641d7
    @laceynwilliams
    ✨
    stunning spell to stop container
    

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46. Rennervate
    $ docker start 2021341641d7
    @laceynwilliams
    ✨
    spell to revive a stupefied container
    

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47. Avada Kedavra
    $ docker kill 2021341641d7
    @laceynwilliams
    ☠
    spell to kill a container
    

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48. Advanced
    Potions
    Docker Compose
    @laceynwilliams | @revsys
    

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49. $ docker run -p 8000:8000 hogwarts
    @laceynwilliams | @revsys
    

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50. Docker Compose
    ✓ Free
    ✓ Included with Mac, extra download otherwise
    ✓ Run more than one container at once
    ✓ Relate containers to each other
    @laceynwilliams | @revsys
    

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51. Hermione's
    magic bag
    @laceynwilliams | @revsys
    

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52. # docker-compose.yml
    version: '3'
    services:
    db:
    image: postgres
    web:
    build: .
    command: bash -c "python /code/manage.py migrate --noinput
    && python /code/manage.py runserver 0.0.0.0:8000"
    volumes:
    - .:/code
    ports:
    - "8000:8000"
    depends_on:
    - db
    @laceynwilliams | @revsys
    

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53. # docker-compose.yml
    version: '3'
    services:
    db:
    image: postgres
    web:
    build: .
    command: bash -c "python /code/manage.py migrate --noinput
    && python /code/manage.py runserver 0.0.0.0:8000"
    volumes:
    - .:/code
    ports:
    - "8000:8000"
    depends_on:
    - db
    @laceynwilliams | @revsys
    

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54. # docker-compose.yml
    version: '3'
    services:
    db:
    image: postgres
    web:
    build: .
    command: bash -c "python /code/manage.py migrate --noinput
    && python /code/manage.py runserver 0.0.0.0:8000"
    volumes:
    - .:/code
    ports:
    - "8000:8000"
    depends_on:
    - db
    @laceynwilliams | @revsys
    

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55. # docker-compose.yml
    version: '3'
    services:
    db:
    image: postgres
    web:
    build: .
    command: bash -c "python /code/manage.py migrate --noinput
    && python /code/manage.py runserver 0.0.0.0:8000"
    volumes:
    - .:/code
    ports:
    - "8000:8000"
    depends_on:
    - db
    @laceynwilliams | @revsys
    

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56. then update
    settings.py
    @laceynwilliams | @revsys
    

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57. # docker-compose.yml
    version: '3'
    services:
    db:
    image: postgres
    web:
    build: .
    command: bash -c "python /code/manage.py migrate --noinput
    && python /code/manage.py runserver 0.0.0.0:8000"
    volumes:
    - .:/code
    ports:
    - "8000:8000"
    depends_on:
    - db
    @laceynwilliams | @revsys
    

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58. # docker-compose.yml
    version: '3'
    services:
    db:
    image: postgres
    web:
    build: .
    command: bash -c "python /code/manage.py migrate --noinput
    && python /code/manage.py runserver 0.0.0.0:8000"
    volumes:
    - .:/code
    ports:
    - "8000:8000"
    depends_on:
    - db
    @laceynwilliams | @revsys
    

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59. # docker-compose.yml
    version: '3'
    services:
    db:
    image: postgres
    web:
    build: .
    command: bash -c "python /code/manage.py migrate --noinput
    && python /code/manage.py runserver 0.0.0.0:8000"
    volumes:
    - .:/code
    ports:
    - "8000:8000"
    depends_on:
    - db
    @laceynwilliams | @revsys
    

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60. # docker-compose.yml
    version: '3'
    services:
    db:
    image: postgres
    web:
    build: .
    command: bash -c "python /code/manage.py migrate --noinput
    && python /code/manage.py runserver 0.0.0.0:8000"
    volumes:
    - .:/code
    ports:
    - "8000:8000"
    depends_on:
    - db
    @laceynwilliams | @revsys
    

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61. # docker-compose.yml
    version: '3'
    services:
    db:
    image: postgres
    web:
    build: .
    command: bash -c "python /code/manage.py migrate --noinput
    && python /code/manage.py runserver 0.0.0.0:8000"
    volumes:
    - .:/code
    ports:
    - "8000:8000"
    depends_on:
    - db
    @laceynwilliams | @revsys
    

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62. FROM python:3.6
    ENV PYTHONUNBUFFERED 1
    ENV PYTHONDONTWRITEBYTECODE 1
    COPY ./requirements.txt /code/requirements.txt
    RUN pip install -r /code/requirements.txt
    COPY . /code/
    WORKDIR /code/
    EXPOSE 8000
    CMD [ "python", "./manage.py", ... ]
    @laceynwilliams | @revsys
    

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63. FROM python:3.6
    ENV PYTHONUNBUFFERED 1
    ENV PYTHONDONTWRITEBYTECODE 1
    COPY ./requirements.txt /code/requirements.txt
    RUN pip install -r /code/requirements.txt
    COPY . /code/
    WORKDIR /code/
    EXPOSE 8000
    !
    @laceynwilliams | @revsys
    

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64. Lumos
    $ docker-compose up
    $ docker-compose up --build
    @laceynwilliams
    ✨
    spell to start compose containers
    

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65. $ docker-compose up
    Creating network "hogwarts_default" with the default driver
    Creating hogwarts_db_1 ... done
    Creating hogwarts_web_1 ... done
    Attaching to hogwarts_db_1, hogwarts_web_1
    db_1 | The files belonging to this database system will be owned by user "postgres".
    db_1 | This user must also own the server process.
    web_1 | Operations to perform:
    web_1 | Apply all migrations: admin, auth, blog, contenttypes, sessions
    web_1 | Running migrations:
    web_1 | No migrations to apply.
    db_1 | LOG: database system is ready to accept connections
    db_1 | LOG: autovacuum launcher started
    web_1 | Performing system checks...
    web_1 |
    web_1 | System check identified no issues (0 silenced).
    web_1 | May 03, 2018 - 12:12:57
    web_1 | Django version 2.0.5, using settings 'mysite.settings'
    web_1 | Starting development server at http://0.0.0.0:8000/
    web_1 | Quit the server with CONTROL-C.
    @laceynwilliams | @revsys
    

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66. Continens Revelio
    $ docker container ls
    CONTAINER ID IMAGE ... NAMES
    f78a4fac4772 hogwarts_web ... hogwarts_web_1
    1fdf3604ce5c postgres:9.6.8 ... hogwarts_db_1
    @laceynwilliams
    ✨
    spell to reveal containers
    

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67. $ docker-compose run --rm web ./manage.py makemigrations
    Starting hogwarts_db_1 ... done
    No changes detected
    @laceynwilliams | @revsys
    

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68. --rm
    Remove this container when I'm done with it
    @laceynwilliams | @revsys
    

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69. apparate into the shell
    $ docker-compose run --rm web ./manage.py shell
    Starting hogwarts_db_1 ... done
    ...
    In [1]: from spells.models import Spell
    In [2]: Spell.objects.all()
    Out[2]:
    @laceynwilliams | @revsys
    

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70. stop and start at will
    $ docker-compose stop web
    Stopping hogwarts_web_1 ... done
    $ docker-compose start web
    Starting web ... done
    @laceynwilliams | @revsys
    

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71. Nox
    $ docker-compose down
    Removing hogwarts_web_1 ... done
    Removing hogwarts_db_1 ... done
    Removing network hogwarts_default
    @laceynwilliams
    ✨
    spell to darken containers
    

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72. bit.ly/hogwarts-docker
    @laceynwilliams | @revsys
    

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73. It is the
    unknown we
    fear when we
    look upon Docker,
    nothing more.
    — Albus Dumbledore, probably
    @laceynwilliams | S/ll from Harry Po5er and the Order of the Phoenix
    

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74. Hogwarts Library
    · An Intro to Docker for Djangonauts
    · Docker: Useful Command Line Stuff
    · Docker tutorial
    · Docker Compose tutorial, Compose and Django tutorial
    · Best PracAces for WriAng Dockerfiles
    · 10 Things to Avoid in Docker Containers, Rafael Benevides
    · Video: 5 Things About Docker, Jessie Frazelle
    · Docker CheatSheet
    · Dockerizing Django, UWISGI, and Postgres the Serious Way, Oliver Eidel
    · How to use Django, PostgreSQL, and Docker, William S. Vincent
    · Managing SensiAve Data with Docker Secrets
    @laceynwilliams | @revsys
    

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