Integrating Buildbot and Mattermost

In this journal, I would like to explain how to integrate Mattermost slash command to build, test, and deploy project on specific repository and branch on Buildbot worker; and report the project build status back to Mattermost.

The integration can be illustrated with the following graph,

+------+   /build repo branch    +------------+
| User | ----------------------> | Mattermost |
+------+                         +------------+
   ^                                   |
   |                                   | /change_hook/mattermost
   |                                   |
   |                                   v
   |                             +----------------------+
   |                             | Build master         |
   |                             | /hooks/mattermost.py |
   |                             +----------------------+
   |                                   |
   |                                   | change-dictionary
   |                                   |
   |                                   v
   |   build-status              +-----------------------+
   +---------------------------- | Build master          |
                                 | SingleBranchScheduler |
                                 +-----------------------+

Environment

The following application must have already installed, either in one machine or in separater machines,

Mattermost version 5.x.x
Buildbot version 1.x.x

Customize Mattermost Integrations

Create Slash Command on Mattermost

The first thing that we will do is creating the Mattermost slash command. In Mattermost menu, click Integrations and after that click Slash Command, and Add Slash Command. A form for creating new slash command will opened. Here is the field that you need to fill,

Command Trigger Word: build
- When typing / on channel, it will list build as one of the option
Request URL: "http://{{ http_auth }}:{{ http_password }}@{{ buildbot_master_ip }}:{{ buildbot_master_port }}/change_hook/mattermost"
- http_auth and http_password is for authenication
- buildbot_master_ip is the IP address where Buildbot master running
- buildbot_master_port is the port where Buildbot master running, default to 8010
- /change_hook/mattermost is the custom hook for Buildbot. We will talk about it later.
Request Method: POST
Autocomplete Hint: [repo] [branch] [revision]

Request URL is the URL where Mattermost will send POST request contains the parameter. In this scenario we want the first parameter to be the repository name, second parameter to be branch name, and third (optional) parameter to be revision number. For example, sending the following text on Mattermost,

/build project-example master

will checkout the latest project-example source code on branch master and run the test, build, and deploy the project.

Save, and Mattermost will generate a token for authentication that we will use the later.

Create Incoming Webhooks

Incoming webhooks is used to send status of build back to Mattermost. The only field that is required for incoming webhooks is the channel name. After creating incoming hooks, Mattermost will generate a URL for you, for example,

http://{{ mattermost_ip }}:{{ mattermost_port }}/hooks/randomstring

Customize Buildbot

Add Changehook Authentication

In the buildmaster directory create a file called changehook.passwd with content as in

{{ http_auth }}:{{ http_password }}

Remember, it must be the same http_auth and http_password values as in Request URL above.

Add Reporter and Change Hook Script

In order for Buildbot to process the /change_hook/mattermost and report the status to Mattermost, you must copy my change hook into Buildbot hooks (In CentOS 7, it was located in /usr/lib/python2.7/site-packages/buildbot/www/hooks/) and reporter script to build master directory.

Update Master Config

In the master.cfg, set the services options to the following values,

from buildbot.plugins import reporters
import mattermost_reporter

mmpush = reporters.HttpStatusPush(
		serverUrl="http://{{ mattermost_ip }}:{{ mattermost_port }}{{ chat_hook }}"
	,	format_fn=mattermost_reporter.formatter
	,	wantProperties=True
	)

c['services'].append(mmpush)

The serverUrl is the incoming webhooks for Mattermost.

In the master.cfg, set the www options to the following values,

c['www'] = {
		"port": {{ buildmaster_http_port }}
	,	"plugins": {
			"console_view": True
		}
	,	"change_hook_dialects":{
			"github": {
				"secret": "{{ buildmaster_github_secret }}"
			,	"strict": True
			}
		,	"mattermost": {
				"token": "{{ mattermost_slash_build_token }}"
			,	"channel": "ci"
			,	"repo_base_url": "git@github.com:{{ github_username }}/"
			}
		}
	}

The important part is the mattermost option inside change_hook_dialects option.

token value is the token that generated by Mattermost after creating slash command.
channel value is the name of channel in Mattermost. We would like to limit where the user can execute the slash command /build from here.
repo_base_url is base url where the buildbot will checkout the repository. Its value will be concatenated with parameter repo (the first parameter) from slash command.

Integrate Your Build

If you already have configured scheduler, factory, and builder for your repository; you need to add the new scheduler,

c["schedulers"].append(
	schedulers.SingleBranchScheduler(
		name="mattermost_%s" % repo_name
	,	change_filter=util.ChangeFilter(
			project_re="mattermost_build_project-example_master"
		,	category="mattermost"
		)
	,	treeStableTimer=None
	,	builderNames=[repo_name]
	)
)

The key was in project_re (aka project regular expression). The change-hook script will generate project name using "mattermost_build_[repo]_[branch]" and send it to build master to be processed.

That’s it

If you still confused, see the full master.cfg as an example that can be found on my repository.