telegraf package maintainer scripts broken - telegraf service not restarting after upgrade

[Junien F]

Hi,

(not a charm bug, but this is the best way I found to report a package bug)

On xenial, the telegraf service is not started back up after a pakage upgrade. Simulation with --reinstall below. This is impacting at least version 1.6.4+git-d5dde16~201807170838~ubuntu16.04.1.

I believe this is because prerm disables the service. We probably should only be using dh to handle service start/stop/restart/deactivation/activation.

ubuntu@ubuntu:~$ sudo systemctl status telegraf.service
● telegraf.service - The plugin-driven server agent for reporting metrics into InfluxDB
   Loaded: loaded (/lib/systemd/system/telegraf.service; enabled; vendor preset: enabled)
   Active: active (running) since Mon 2018-08-06 08:02:00 UTC; 1min 45s ago
     Docs: https://github.com/influxdata/telegraf
 Main PID: 3275 (telegraf)
   CGroup: /system.slice/telegraf.service
           └─3275 /usr/bin/telegraf -config /etc/telegraf/telegraf.conf -config-directory /etc/telegraf/telegraf.d

Aug 06 08:02:00 ubuntu systemd[1]: Started The plugin-driven server agent for reporting metrics into InfluxDB.
Aug 06 08:02:00 ubuntu telegraf[3275]: 2018-08-06T08:02:00Z I! Starting Telegraf v1.6.0~unknown
Aug 06 08:02:00 ubuntu telegraf[3275]: 2018-08-06T08:02:00Z I! Loaded outputs: prometheus_client
Aug 06 08:02:00 ubuntu telegraf[3275]: 2018-08-06T08:02:00Z I! Loaded inputs: inputs.cpu inputs.disk inputs.diskio inputs.mem inputs.net inputs.netstat inputs.swap inputs.system
Aug 06 08:02:00 ubuntu telegraf[3275]: 2018-08-06T08:02:00Z I! Tags enabled: host=controller:ubuntu-0
Aug 06 08:02:00 ubuntu telegraf[3275]: 2018-08-06T08:02:00Z I! Agent Config: Interval:10s, Quiet:false, Hostname:"controller:ubuntu-0", Flush Interval:10s

ubuntu@ubuntu:~$ sudo apt-get install --reinstall telegraf
Reading package lists... Done
Building dependency tree
Reading state information... Done
0 upgraded, 0 newly installed, 1 reinstalled, 0 to remove and 4 not upgraded.
Need to get 0 B/6,737 kB of archives.
After this operation, 0 B of additional disk space will be used.
(Reading database ... 135172 files and directories currently installed.)
Preparing to unpack .../telegraf_1.6.4+git-d5dde16~201807170838~ubuntu16.04.1_amd64.deb ...
Removed symlink /etc/systemd/system/telegraf.service.
Removed symlink /etc/systemd/system/multi-user.target.wants/telegraf.service.
Unpacking telegraf (1.6.4+git-d5dde16~201807170838~ubuntu16.04.1) over (1.6.4+git-d5dde16~201807170838~ubuntu16.04.1) ...
Setting up telegraf (1.6.4+git-d5dde16~201807170838~ubuntu16.04.1) ...
telegraf.service is a disabled or a static unit not running, not starting it.
telegraf.service is a disabled or a static unit, not starting it.

ubuntu@ubuntu:~$ sudo systemctl status telegraf.service
● telegraf.service - The plugin-driven server agent for reporting metrics into InfluxDB
   Loaded: loaded (/lib/systemd/system/telegraf.service; disabled; vendor preset: enabled)
   Active: inactive (dead)
     Docs: https://github.com/influxdata/telegraf

Aug 06 07:55:46 ubuntu systemd[1]: Stopped The plugin-driven server agent for reporting metrics into InfluxDB.
Aug 06 08:02:00 ubuntu systemd[1]: Started The plugin-driven server agent for reporting metrics into InfluxDB.
Aug 06 08:02:00 ubuntu telegraf[3275]: 2018-08-06T08:02:00Z I! Starting Telegraf v1.6.0~unknown
Aug 06 08:02:00 ubuntu telegraf[3275]: 2018-08-06T08:02:00Z I! Loaded outputs: prometheus_client
Aug 06 08:02:00 ubuntu telegraf[3275]: 2018-08-06T08:02:00Z I! Loaded inputs: inputs.cpu inputs.disk inputs.diskio inputs.mem inputs.net inputs.netstat inputs.swap inputs.system
Aug 06 08:02:00 ubuntu telegraf[3275]: 2018-08-06T08:02:00Z I! Tags enabled: host=controller:ubuntu-0
Aug 06 08:02:00 ubuntu telegraf[3275]: 2018-08-06T08:02:00Z I! Agent Config: Interval:10s, Quiet:false, Hostname:"controller:ubuntu-0", Flush Interval:10s
Aug 06 08:03:53 ubuntu systemd[1]: Stopping The plugin-driven server agent for reporting metrics into InfluxDB...
Aug 06 08:03:53 ubuntu systemd[1]: Stopped The plugin-driven server agent for reporting metrics into InfluxDB.
Aug 06 08:03:53 ubuntu systemd[1]: Stopped The plugin-driven server agent for reporting metrics into InfluxDB.

[Laurent Sesquès (sajoupa)]

Fixed with:
https://git.launchpad.net/~telegraf-devs/telegraf/+git/packaging/commit/?id=2e1f49eeb8cd9027bb7fcba4f3912c75744d7f6e