Add post "Making docker-compose easier with wdocker"

1 files changed, 160 insertions, 0 deletions

diff --git a/wdocker_compose.org b/wdocker_compose.org
new file mode 100644
index 0000000..e1190eb
--- /dev/null
+++ b/wdocker_compose.org
@@ -0,0 +1,160 @@
+#+TITLE: Making docker-compose easier with wdocker
+#+OPTION: num:nil
+
+* Introduction
+
+  [[https://github.com/babab/wdocker][wdocker]] is a little utility written by a [[https://benjamin.althu.es][friend]] and former colleague
+  of mine. It allows you to define commands for it in a
+  ~Dockerfile~. He wrote it because he used a lot of composite
+  commands when writing docker images like:
+
+  #+BEGIN_SRC sh
+    docker stop CONTAINER && docker rm CONTAINER && docker rmi IMAGE \
+        docker build -t IMAGE && docker start -n CONTAINER IMAGE
+  #+END_SRC
+
+  By using wdocker to define a command he can greatly simplify his own
+  workflow. Let's call it rebuild:
+
+  #+BEGIN_SRC dockerfile
+    #wd# container = CONTAINER
+    #wd# image = IMAGE
+    #wd# stop = docker stop {container}
+    #wd# rm = docker rm {container}
+    #wd# rmi = docker rmi {container}
+    #wd# build = docker build -t {image}
+    #wd# start = docker start -n {container} {image}
+
+    #wd# rebuild: {stop} && {rm} && {rmi} && {build} && {start}
+
+    FROM ubuntu
+
+    # ...
+  #+END_SRC
+
+  Now he can use the following command instead of the list presented
+  before:
+
+  : wdocker rebuild
+
+* Syntax
+
+  wdocker has very simple syntax. You can define variables and
+  commands:
+
+  : #wd# variable = value
+  : #wd# command: program
+
+  Variables can be used by putting them in braces, including in other
+  variables, as you've seen in the first example.
+
+  : #wd# variable = -l
+  : #wd# list: ls {variable}
+
+  This would run =ls -l= when the command =wdocker list= is called.
+
+  As you can see you're not limited to using docker in your wdocker
+  commands. This property is what allows me to use wdocker in my
+  workflow.
+
+* Combining with docker-compose
+
+  I started using docker not too long ago at work to develop our
+  projects in. This is nice because it allows me to completely isolate
+  my development environments. Since we have a few processes running
+  together a single docker image isn't a great option, so I use
+  docker-compose to define and combine the containers I need.
+
+  As a side-effect this requires me to write long commands to do
+  something like run rspec tests:
+
+  : docker-compose run --rm -e RACK_ENV=test -e RAILS_ENV=test \
+  :     container bundle exec rspec
+
+  The alternative is defining a specialized test container with a
+  bogus entry command (such as ~true~) and use that, which would still
+  make the command:
+
+  : docker-compose run --rm test-container bundle exec rspec
+
+  Instead I can define a wdocker command in the ~Dockerfile~ used to
+  build the containers used:
+
+  #+BEGIN_SRC dockerfile
+    #wd# rspec: docker-compose run --rm -e RACK_ENV=test -e RAILS_ENV=test container bundle exec rspec
+
+    FROM ruby
+
+    #...
+  #+END_SRC
+
+  Now I can run the following, much shorter, command to run the rspec
+  tests:
+
+  : wdocker rspec
+
+  We also use cucumber for some other tests, which is even longer to
+  type in, adding the ~cucumber~ command is easy:
+
+  #+BEGIN_SRC dockerfile
+    #wd# rspec: docker-compose run --rm -e RACK_ENV=test -e RAILS_ENV=test container bundle exec rspec
+    #wd# cucumber: docker-compose run --rm -e RACK_ENV=test -e RAILS_ENV=test container bundle exec cucumber
+
+    FROM ruby
+
+    # ...
+  #+END_SRC
+
+  Now I can run =wdocker cucumber= as well.
+
+  The latest git version of wdocker passes any arguments after the
+  command name directly to the command to be executed. So if I need to
+  run tests in a single spec file I can just do:
+
+  : wdocker rspec spec/models/mymodel_spec.rb
+
+  We have two commands defined now that are 90% the same. I always use
+  the ~--rm~ switch to remove the started container after it's done, I
+  don't want a lot of containers piling up. I also always have to use
+  ~bundle exec~ to run commands, since the containers don't use rvm or
+  add the script directories to ~$PATH~. We can extract them to some
+  variables:
+
+  #+BEGIN_SRC dockerfile
+    #wd# run = docker-compose run --rm
+    #wd# exec = bundle exec
+    #wd# test = -e RACK_ENV=test -e RAILS_ENV=test
+
+    #wd# rspec: {run} {test} container {exec} rspec
+    #wd# cucumber: {run} {test} container {exec} cucumber
+
+    FROM ruby
+
+    # ...
+  #+END_SRC
+
+  Right now these commands always use the ~container~ service defined
+  in ~docker-compose.yml~. I could add it to the ~run~ command, but I
+  might need to run some commands on another container, but I can
+  define another variable:
+
+  #+BEGIN_SRC dockerfile
+    #wd# run = docker-compose run --rm
+    #wd# test = -e RACK_ENV=test -e RAILS_ENV=test
+    #wd# run-test-container = {run} {test} container
+    #wd# exec = bundle exec
+
+    #wd# rspec: {run-test-container} {exec} rspec
+    #wd# cucumber: {run-test-container} {exec} cucumber
+
+    FROM ruby
+
+    # ...
+  #+END_SRC
+
+  Now you also see that variables can be nested in other variables.
+
+  If you ever forget what you defined or if the mix of commands and
+  variables becomes too much for you, you can call the wdocker command
+  without arguments to see the commands you defined and the shell
+  commands they'll run.