From dd9b008c11bb18f61db4398ba95f673eca474a09 Mon Sep 17 00:00:00 2001
From: Michele Baldessari <michele@acksyn.org>
Date: Fri, 23 Feb 2018 12:17:21 +0100
Subject: [PATCH] Make the minor update for docker idempotent

Via Ic08468854ce92e81cd84bd6c86a6b672b5a9d49b we fixed the problem of
docker being restarted when puppet triggers a change while pacemaker is
up and running. That approach, while more correct than what existed
previously, is still suboptimal because we are stopping all docker
containers even though we don't have to.

Let's detect if applying the profile::base::docker manifest would
introduce any changes and also detect if the docker rpm is going to be
updated. If one of the two conditions is true we need to stop
containers.

This way rerunning the update workflow on a node should be much less
disruptive. Tested this and correctly observed that the first run did
correctly stopped the docker containers whereas subsequent runs did not
stop containers.

Change-Id: I9176da730b0156d06e2a1ef5f2fcc061e2a6abf6
Related-Bug: #1747851
---
 puppet/services/docker.yaml | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/puppet/services/docker.yaml b/puppet/services/docker.yaml
index 6194c27d3e..361e518c9e 100644
--- a/puppet/services/docker.yaml
+++ b/puppet/services/docker.yaml
@@ -103,16 +103,38 @@ outputs:
           yum: name=docker state=latest
       update_tasks:
         block:
+          - name: Detect if puppet on the docker profile would restart the service
+            # Note that due to https://tickets.puppetlabs.com/browse/PUP-686 --noop
+            # always exits 0, so we cannot rely on that to detect if puppet is going to change stuff
+            shell: |
+              puppet apply --noop --summarize --detailed-exitcodes --verbose \
+                --modulepath /etc/puppet/modules:/opt/stack/puppet-modules:/usr/share/openstack-puppet/modules \
+                --color=false -e "class { 'tripleo::profile::base::docker': step => 1, }" 2>&1 | \
+              awk -F ":" '/Out of sync:/ { print $2}'
+            register: puppet_docker_noop_output
+            failed_when: false
+          - name: Is docker going to be updated
+            shell: yum check-update docker
+            register: docker_check_update
+            failed_when: docker_check_update.rc not in [0, 100]
+            changed_when: docker_check_update.rc == 100
+          - name: Set docker_rpm_needs_update fact
+            set_fact: docker_rpm_needs_update={{ docker_check_update.rc == 100 }}
+          - name: Set puppet_docker_is_outofsync fact
+            set_fact: puppet_docker_is_outofsync={{ puppet_docker_noop_output.stdout|trim|int >= 1 }}
           - name: Stop all containers
             # xargs is preferable to docker stop $(docker ps -q) as that might generate a
             # a too long command line
             shell: docker ps -q | xargs --no-run-if-empty -n1 docker stop
+            when: puppet_docker_is_outofsync or docker_rpm_needs_update
           - name: Stop docker
             service:
               name: docker
               state: stopped
+            when: puppet_docker_is_outofsync or docker_rpm_needs_update
           - name: Update the docker package
             yum: name=docker state=latest update_cache=yes # cache for tripleo/+bug/1703830
+            when: docker_rpm_needs_update
           - name: Apply puppet which will start the service again
             shell: |
               puppet apply --detailed-exitcodes --verbose \