Merge lp:~vila/ubuntu-ci-services-itself/tricks into lp:ubuntu-ci-services-itself

[Vincent Ladeuil]

How to install a hotfix on a deployed worker.

This documents the tricks I used to install hot fixes in a worker already deployed.

This works for the code in our payload but NOT for the charms !

Yet, it saved me from re-deploying the whole engine during the crazy
debugging session around private ppas and their fallouts.

[PS Jenkins bot (ps-jenkins)]

PASSED: Continuous integration, rev:377
http://s-jenkins.ubuntu-ci:8080/job/uci-engine-ci/400/
Executed test runs:

Click here to trigger a rebuild:
http://s-jenkins.ubuntu-ci:8080/job/uci-engine-ci/400/rebuild

review: Approve (continuous-integration)

[Andy Doan (doanac)]

nice trick - better than what i'd been doing.

review: Approve

=== modified file 'TRICKS'
--- TRICKS	2014-03-10 22:30:06 +0000
+++ TRICKS	2014-03-13 08:57:27 +0000
@@ -281,3 +281,75 @@
 
 This works because relations are independent of individual instances. A
 relation can exist before any units do.
+
+Testing hot fixes on a specific instance
+========================================
+
+If you want to test a specific fix for our code base (NOT a charm fix), you
+can setup a branch on the instance and merge public branches into it.
+
+Using the test runner as an example, the process is to:
+- turn the payload into a branch,
+- acquire additional branches,
+- merge branches into the payload,
+- restart the service.
+
+
+Turning the payload into a branch
+---------------------------------
+
+Go to the instance and become root:
+
+$ juju ssh tr-rabbit-worker/0 
+$ sudo -H bash
+
+Setup a bzr shared repo so we don't need to download the whole history for
+each branch we'll use.
+
+# bzr whoami "bugfixer <[e-mail]>"
+# cd /srv
+# bzr init-repo .
+# bzr branch lp:ubuntu-ci-services-itself trunk
+
+Really turn the payload into a branch:
+
+# cp -r trunk/.bzr tr_rabbit_worker/
+# cd tr_rabbit_worker
+# bzr st
+# bzr commit -m 'Uploaded payload as of `date`'
+
+From there you have a real branch and can use the usual commands to check
+its state: 'bzr status', 'bzr diff'.
+
+The expected output of 'bzr st' at that point is:
+
+# bzr st
+unknown:
+  amqp_config.py
+  unit_config
+
+'amqp_config.py' has been generated by the rabbit charm, 'unit_config' comes
+from the worker charm.
+
+Acquire additional branches
+---------------------------
+
+$ cd /srv
+$ bzr branch lp:~vila/ubuntu-ci-services-itself/hotfix
+
+Merge branches into the payload
+-------------------------------
+
+$ cd /srv/tr_rabbit_worker
+$ bzr merge ../hotfix
+
+Restart the service
+-------------------
+
+$ initctl restart tr_rabbit_worker
+
+And voila, you're now running the worker in your deployment with the hot fix
+applied.
+
+
+