Deploying Rails with Docker

Slides for a 5-minute lightning talk that actually lasted about 10 minutes, that I sped through way-too-fast at Austin on Rails in February 2014.

Transcript

1. Deploying Rails with
   James Adam @lazyatom http://exciting.io
   

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2. TL;DR
   It’s
   NOT EASY
   BUT it’s
   GETTING
   EASIER
   

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3. Virtualisation
   Hypervisor / Host Kernel
   Actual computer (or VPS)
   Guest O/S
   App App App
   Guest Kernel
   OS Processes
   App Binaries
   Guest O/S
   App App App
   Guest Kernel
   OS Processes
   App Binaries
   Guest O/S
   App App App
   Guest Kernel
   OS Processes
   App Binaries
   

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4. Containers
   Host O/S
   OS Processes
   Host Kernel with container technology
   Actual computer (or VPS)
   App
   App Binaries
   App
   App Binaries
   App
   App Binaries
   Service
   

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5. Deployment benefits
   • Reliable behaviour between environments
   • Easier to isolate dependencies
   • Easy to scale
   … and containers in particular:!
   • Boot faster than VMs (seconds, not minutes)
   • Use less memory on host machine
   

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7. # Dockerfile
   !
   FROM stackbrew/ubuntu
   !
   RUN apt-get update
   RUN apt-get install -y ruby
   

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8. $ docker build -t lazyatom/demo .
   

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9. Uploading context 2.56 kB
   Uploading context
   Step 0 : FROM stackbrew/ubuntu
   ---> 3aa646e4f1d2
   Step 1 : RUN apt-get update
   ---> Running in 5c965759ddef
   Ign http://archive.ubuntu.com precise InRelease
   # ... etc ..
   Fetched 13.9 MB in 19s (727 kB/s)
   ---> 31720a59342f
   Step 2 : RUN apt-get install -y ruby
   ---> Running in af8e63489460
   The following extra packages will be installed:
   libgdbm3 libreadline5 libruby1.8 ruby1.8
   The following NEW packages will be installed:
   libgdbm3 libreadline5 libruby1.8 ruby ruby1.8
   # ... etc ...
   Setting up ruby1.8 (1.8.7.352-2ubuntu1.4) ...
   Setting up ruby (4.8) ...
   Processing triggers for libc-bin ...
   ldconfig deferred processing now taking place
   ---> 2fc06d92167e
   Successfully built 2fc06d92167e
   $
   

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10. $ docker run lazyatom/demo which ruby
    => /usr/bin/ruby
    $ docker run lazyatom/demo \
    ruby -e 'p ["hello", "world"].join(" ")'
    => "hello world"
    

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11. $ docker run -i -t lazyatom/demo bash
    root@f531a20cc02b:/# echo 'HELLO' > hello.txt
    root@f531a20cc02b:/# ls *.txt
    hello.txt
    root@f531a20cc02b:/# exit
    !
    $ docker run -i -t lazyatom/demo bash
    root@75c5024c8acd:/# ls *.txt
    ls: cannot access *.txt: No such file or directory
    

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12. Uploading context 2.56 kB
    Uploading context
    Step 0 : FROM stackbrew/ubuntu
    ---> 3aa646e4f1d2
    Step 1 : RUN apt-get update
    ---> Running in 5c965759ddef
    Ign http://archive.ubuntu.com precise InRelease
    # ... etc ..
    Fetched 13.9 MB in 19s (727 kB/s)
    ---> 31720a59342f
    Step 2 : RUN apt-get install -y ruby
    ---> Running in af8e63489460
    The following extra packages will be installed:
    libgdbm3 libreadline5 libruby1.8 ruby1.8
    The following NEW packages will be installed:
    libgdbm3 libreadline5 libruby1.8 ruby ruby1.8
    # ... etc ...
    Setting up ruby1.8 (1.8.7.352-2ubuntu1.4) ...
    Setting up ruby (4.8) ...
    Processing triggers for libc-bin ...
    ldconfig deferred processing now taking place
    ---> 2fc06d92167e
    Successfully built 2fc06d92167e
    $
    

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13. $ docker build -t lazyatom/demo .
    Uploading context 2.56 kB
    Uploading context
    Step 0 : FROM stackbrew/ubuntu
    ---> 3aa646e4f1d2
    Step 1 : RUN apt-get update
    ---> Using cache
    ---> 31720a59342f
    Step 2 : RUN apt-get install -y ruby
    ---> Using cache
    ---> 2fc06d92167e
    Successfully built 2fc06d92167e
    

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16. FROM lazyatom/ruby-2.0
    !
    # Set up environment
    ENV RAILS_ENV production
    ENV PORT 5000
    !
    # Set up initial bundle; this should get cached
    RUN mkdir /docker-rails-app
    WORKDIR /docker-rails-app
    ADD Gemfile /docker-rails-app/Gemfile
    ADD Gemfile.lock /docker-rails-app/Gemfile.lock
    RUN bundle install
    !
    # Install app
    ADD . /docker-rails-app
    !
    EXPOSE 5000
    ENTRYPOINT ["bundle", "exec"]
    CMD ["rails", "server", "-p", "5000"]
    

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17. $ dockerapp build .
    Building as Dockerapp::Builder
    Moving ignored files out of the way
    running: docker build -rm -t lazyatom/build .
    Uploading context 528.4 kB
    Uploading context
    Step 0 : FROM lazyatom/ruby-2.0
    ---> a7a5f987e587
    Step 1 : MAINTAINER james@lazyatom.com
    ---> Running in c63d5ee22226
    ---> 229a9370eb6f
    Step 2 : ENV RAILS_ENV production
    ---> Running in 98a138e0a7f4
    ---> 629210201c8f
    Step 3 : ENV PORT 5000
    ---> Running in eaa09e56eef6
    ---> 9b55f80ffbc3
    Step 4 : RUN mkdir /docker-rails-app
    ---> Running in 319947c0b6d8
    ---> 8a001fb5a96f
    Step 5 : WORKDIR /docker-rails-app
    ---> Running in 6677861994d0
    ---> cc3a91632970
    Step 6 : ADD Gemfile /docker-rails-app/Gemfile
    ---> c9373bb90928
    Step 7 : ADD Gemfile.lock /docker-rails-app/Gemfile.lock
    ---> 0023f2d2d3e4
    Step 8 : RUN bundle install
    ---> Running in 0b498ceaef92
    Installing rake (10.1.1)
    

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18. Installing i18n (0.6.9)
    # … etc …
    Installing uglifier (2.4.0)
    Your bundle is complete!
    ---> e9cec88d8f8f
    Step 9 : ADD . /docker-rails-app
    ---> 3ecbf489366a
    Step 10 : EXPOSE 5000
    ---> Running in af09bc405e0a
    ---> b5ce944c3189
    Step 11 : ENTRYPOINT ["bundle", "exec"]
    ---> Running in dec03819c646
    ---> 404edaeeca65
    Step 12 : CMD ["rails", "server", "-p", "5000"]
    ---> Running in 576357f082ab
    ---> 3c52a1b8dd73
    Successfully built 3c52a1b8dd73
    Tagged as lazyatom/docker-rails-app
    Restoring ignored files
    $
    

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19. # Set a name for the database container
    $ export DB_CONTAINER_NAME=test_app_db
    # Start the database container
    $ docker run -d \
    -name $DB_CONTAINER_NAME \
    -p 5432:5432 \
    -e POSTGRESQL_USER=docker_rails_app \
    -e POSTGRESQL_PASS=pa$$w0rd \
    -e POSTGRESQL_DB=docker_rails_app_production \
    orchardup/postgresql
    $ docker ps
    CONTAINER ID IMAGE PORTS NAMES
    c83f16772e56 postgresql 5432->5432 test_app_db
    

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20. $ docker run -link $DB_CONTAINER_NAME:db \
    lazyatom/docker-rails-app rake db:schema:load
    -- enable_extension("plpgsql")
    -> 0.0317s
    -- create_table("tacos", {:force=>true})
    -> 0.0152s
    -- initialize_schema_migrations_table()
    -> 0.0075s
    $
    

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21. # config/database.yml
    !
    production: &default
    adapter: postgresql
    database: <%= ENV['DB_ENV_POSTGRESQL_DB'] %>
    username: <%= ENV['DB_ENV_POSTGRESQL_USER'] %>
    password: <%= ENV['DB_ENV_POSTGRESQL_PASS'] %>
    host: <%= ENV['DB_PORT_5432_TCP_ADDR'] %>
    port: <%= ENV['DB_PORT_5432_TCP_PORT'] %>
    $ docker run -link $DB_CONTAINER_NAME:db # etc
    

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22. $ docker run -d \
    -p 6789:5000 \
    -link $DB_CONTAINER_NAME:db \
    lazyatom/docker-rails-app
    

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24. docker push lazyatom/docker-rails-app
    http://cactus.lazyatom.com:6789/
    # then run all those commands on a VPS...
    

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25. But what about…
    • Reverse proxying?
    • Private docker indexes?
    • Managing containers?
    • Deploying to more than one ‘server’?
    

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26. LIKE I SAID
    It’s
    NOT EASY
    BUT… it’s
    GETTING
    EASIER
    

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27. Things to keep an eye on
    • docker-osx
    • boot2docker (faster but not quite there yet)
    • fig & orchardup.com
    • flynn.io
    • quay.io
    Thanks!
    James Adam @lazyatom http://exciting.io
    

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