Docker Cookbook

2.12 Setting Up an Automated Build on Docker Hub for Continuous Integration/Deployment | 65

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delivery pipeline. In the Build Details page of your automated build, you will be able
to access the Web Hooks page. In it you can add URLs that will receive an HTTP
POST when a successful build happens. The body of this POST request will contain a
callback URL. In response, you will need to send another HTTP POST with a JSON
payload containing the 
state
key and the value of either 
success
, 
failure
, or 
error
.
On receiving a successfull state, the automated build can call another webhook,
henceforth allowing you to chain several actions together.
See Also
• The automated build 
reference
 documentation
2.13 Setting Up a Local Automated Build by Using a Git
Hook and a Private Registry
Problem
Automated builds using Docker Hub and GitHub or Bitbucket are great (see 
Recipe
2.12
), but you might be using a private registry (i.e., local hub) and may want to trig‐
ger Docker builds when you commit to your local Git projects.
Solution
Create a 
post-commit
Git hook that triggers a build and pushes the new image to
your private registry.
In the root tree of your Git project, create a bash script, 
./git/hooks/post-commit
, that
contains something as simple as this:
#!/bin/bash
tag=`git log -1 HEAD --format="%h"`
docker build -t flask:$tag /home/sebgoa/docbook/examples/flask
Make it executable with 
chmod +x .git/hooks/post-commit
.
Now every time you make a commit to this Git project, this 
post-commit
bash script
will run. It will create a 
tag
using the short version of the SHA of the latest commit
and then trigger the build based on the Dockerfile referenced. It will then create a
new image with the name 
flask
and the computer tag:
$ git commit -m "fixing hook"
9c38962
Sending build context to Docker daemon 3.584 kB
Sending build context to Docker daemon
Step 0 : FROM ubuntu:14.04