Fix dovecot regression in #9415

[srebhan]

• Updated associated README.md.
• Wrote appropriate unit tests.

resolves #9415

This PR tries to resolve the regression above.

[popey]

Thanks for the PR! This appears to fix the issue for me.

Before this patch:

2021-06-24T16:07:16Z E! [inputs.dovecot] Error in plugin: copying message failed for dovecot server '10.55.242.189:24242': read tcp 10.55.242.1:60994->10.55.242.189:24242: i/o timeout

After this patch:

> dovecot,host=ac,server=10.55.242.189,type=global auth_cache_hits=0i,auth_cache_misses=0i,auth_db_tempfails=0i,auth_failures=0i,auth_master_successes=0i,auth_successes=0i,clock_time=0,disk_input=0i,disk_output=0i,invol_cs=0i,mail_cache_hits=0i,mail_lookup_attr=0i,mail_lookup_path=0i,mail_read_bytes=0i,mail_read_count=0i,maj_faults=0i,min_faults=0i,num_cmds=0i,num_connected_sessions=0i,num_logins=0i,read_bytes=0i,read_count=0i,sys_cpu=0,user_cpu=0,vol_cs=0i,write_bytes=0i,write_count=0i 1624546810000000000

[popey]

Here's the full output..

telegraf 1.18.3

$ ../telegraf-1.18.3/usr/bin/telegraf --debug --config etc/telegraf/telegraf.conf --test
2021-06-24T18:45:52Z I! Starting Telegraf 1.18.3
2021-06-24T18:45:52Z D! [agent] Initializing plugins
2021-06-24T18:45:52Z D! [agent] Starting service inputs
2021-06-24T18:45:57Z D! [agent] Stopping service inputs
2021-06-24T18:45:57Z D! [agent] Input channel closed
2021-06-24T18:45:57Z D! [agent] Stopped Successfully
> dovecot,host=ac,server=10.55.242.189,type=global auth_cache_hits=0i,auth_cache_misses=0i,auth_db_tempfails=0i,auth_failures=0i,auth_master_successes=0i,auth_successes=0i,clock_time=0,disk_input=0i,disk_output=0i,invol_cs=0i,mail_cache_hits=0i,mail_lookup_attr=0i,mail_lookup_path=0i,mail_read_bytes=0i,mail_read_count=0i,maj_faults=0i,min_faults=0i,num_cmds=0i,num_connected_sessions=0i,num_logins=0i,read_bytes=0i,read_count=0i,sys_cpu=0,user_cpu=0,vol_cs=0i,write_bytes=0i,write_count=0i 1624560357000000000

telegraf 1.19.0

$ usr/bin/telegraf --debug --config etc/telegraf/telegraf.conf --test
2021-06-24T18:40:00Z I! Starting Telegraf 1.19.0
2021-06-24T18:40:00Z D! [agent] Initializing plugins
2021-06-24T18:40:00Z D! [agent] Starting service inputs
2021-06-24T18:40:05Z E! [inputs.dovecot] Error in plugin: copying message failed for dovecot server '10.55.242.189:24242': read tcp 10.55.242.1:35066->10.55.242.189:24242: i/o timeout
2021-06-24T18:40:05Z D! [agent] Stopping service inputs
2021-06-24T18:40:05Z D! [agent] Input channel closed
2021-06-24T18:40:05Z D! [agent] Stopped Successfully
2021-06-24T18:40:05Z E! [telegraf] Error running agent: input plugins recorded 1 errors

This PR.

$ ../pr9429/telegraf-1.20.0/usr/bin/telegraf --debug --config etc/telegraf/telegraf.conf --test
2021-06-24T18:40:16Z I! Starting Telegraf 
2021-06-24T18:40:16Z D! [agent] Initializing plugins
2021-06-24T18:40:16Z D! [agent] Starting service inputs
copying message failed after 5.000958463s for dovecot server '10.55.242.189:24242': read tcp 10.55.242.1:35172->10.55.242.189:24242: i/o timeout  --> is net.Error (timeout=true)2021-06-24T18:40:21Z D! [agent] Stopping service inputs
2021-06-24T18:40:21Z D! [agent] Input channel closed
2021-06-24T18:40:21Z D! [agent] Stopped Successfully
> dovecot,host=ac,server=10.55.242.189,type=global auth_cache_hits=0i,auth_cache_misses=0i,auth_db_tempfails=0i,auth_failures=0i,auth_master_successes=0i,auth_successes=0i,clock_time=0,disk_input=0i,disk_output=0i,invol_cs=0i,mail_cache_hits=0i,mail_lookup_attr=0i,mail_lookup_path=0i,mail_read_bytes=0i,mail_read_count=0i,maj_faults=0i,min_faults=0i,num_cmds=0i,num_connected_sessions=0i,num_logins=0i,read_bytes=0i,read_count=0i,sys_cpu=0,user_cpu=0,vol_cs=0i,write_bytes=0i,write_count=0i 1624560022000000000

[telegraf-tiger]

Looks like new artifacts were built from this PR. Get them here!

Artifact URLs

• darwin_amd64.tar.gz

• windows_amd64.zip

• windows_i386.zip

• i386.rpm

• freebsd_i386.tar.gz

• linux_i386.tar.gz

• i386.deb

• aarch64.rpm

• linux_arm64.tar.gz

• arm64.deb

• ppc64le.rpm

• linux_ppc64le.tar.gz

• ppc64el.deb

• s390x.rpm

• linux_s390x.tar.gz

• s390x.deb

• static_linux_amd64.tar.gz

• armel.rpm

• linux_armel.tar.gz

• armel.deb

• x86_64.rpm

• freebsd_amd64.tar.gz

• linux_amd64.tar.gz

• amd64.deb

• linux_mipsel.tar.gz

• mipsel.deb

• armv6hl.rpm

• freebsd_armv7.tar.gz

• linux_armhf.tar.gz

• armhf.deb

• linux_mips.tar.gz

• mips.deb

[popey]

Latest update looks good.

$ ../pr9429v2/telegraf-1.20.0/usr/bin/telegraf --debug --config etc/telegraf/telegraf.conf --test
2021-06-24T19:50:16Z I! Starting Telegraf 
2021-06-24T19:50:16Z D! [agent] Initializing plugins
2021-06-24T19:50:16Z D! [agent] Starting service inputs
> dovecot,host=ac,server=10.55.242.189,type=global auth_cache_hits=0i,auth_cache_misses=0i,auth_db_tempfails=0i,auth_failures=0i,auth_master_successes=0i,auth_successes=0i,clock_time=0,disk_input=0i,disk_output=0i,invol_cs=0i,mail_cache_hits=0i,mail_lookup_attr=0i,mail_lookup_path=0i,mail_read_bytes=0i,mail_read_count=0i,maj_faults=0i,min_faults=0i,num_cmds=0i,num_connected_sessions=0i,num_logins=0i,read_bytes=0i,read_count=0i,sys_cpu=0,user_cpu=0,vol_cs=0i,write_bytes=0i,write_count=0i 1624564221000000000
2021-06-24T19:50:21Z D! [agent] Stopping service inputs
2021-06-24T19:50:21Z D! [agent] Input channel closed
2021-06-24T19:50:21Z D! [agent] Stopped Successfully

[reimda]

Looks like this PR works the same as before the linter change so we should take it to fix the regression.

We should investigate whether dovecot provides a newer metric api (this is called the "old" api in dovecot docs) that is easier to use and doesn't require ignoring the timeout