No logs with PM2 2.6.1

[meyerbro]

What's going wrong?

We aren't getting any logs while running pm2 logs.
The only change we made was to upgrade PM2 from 2.5.0 to 2.6.1.

How could we reproduce this issue?

Going into the docker container and running pm2 logs.
Rolling back to PM2 2.5.0 fixes the issue.

Supporting information

===============================================================================
--- PM2 REPORT (Tue Jul 25 2017 11:28:30 GMT+0000 (UTC)) ----------------------
===============================================================================
--- Daemon -------------------------------------------------
pm2d version         : 2.6.1
node version         : 8.1.4
node path            : undefined
argv                 : /usr/local/bin/node,/home/app/src/node_modules/.bin/pm2,start,--no-daemon,pm2.json
argv0                : node
user                 : undefined
uid                  : 999
gid                  : 999
uptime               : 4min
===============================================================================
--- CLI ----------------------------------------------------
local pm2            : 2.6.1
node version         : 8.1.4
node path            : /usr/local/bin/pm2
argv                 : /usr/local/bin/node,/usr/local/bin/pm2,report
argv0                : node
user                 : undefined
uid                  : 0
gid                  : 0
===============================================================================
--- System info --------------------------------------------
arch                 : x64
platform             : linux
type                 : Linux
cpus                 : Intel(R) Xeon(R) CPU E5-2666 v3 @ 2.90GHz
cpus nb              : 4
freemem              : 6355111936
totalmem             : 7844544512
home                 : /home/app
===============================================================================
--- PM2 list -----------------------------------------------
┌─────────────────┬────┬─────────┬─────┬────────┬─────────┬────────┬─────┬────────────┬──────┬──────────┐
│ App name        │ id │ mode    │ pid │ status │ restart │ uptime │ cpu │ mem        │ user │ watching │
├─────────────────┼────┼─────────┼─────┼────────┼─────────┼────────┼─────┼────────────┼──────┼──────────┤
│ interface       │ 0  │ cluster │ 25  │ online │ 0       │ 4m     │ 0%  │ 164.6 MB   │ root │ disabled │
│ interface       │ 1  │ cluster │ 35  │ online │ 0       │ 4m     │ 0%  │ 162.1 MB   │ root │ disabled │
│ interface       │ 2  │ cluster │ 45  │ online │ 0       │ 4m     │ 0%  │ 166.0 MB   │ root │ disabled │
│ interface       │ 3  │ cluster │ 55  │ online │ 0       │ 4m     │ 0%  │ 167.3 MB   │ root │ disabled │
└─────────────────┴────┴─────────┴─────┴────────┴─────────┴────────┴─────┴────────────┴──────┴──────────┘
===============================================================================
--- Daemon logs --------------------------------------------

[vmarchaud]

Could you share the configuration of your application ?

[Unitech]

I guess out_log is set to /dev/null or NULL

#3037

[meyerbro]

Yes, it is, because we want the logs to go via logdriver (splunk).
How can we do that with PM2 2.6.1?

[meyerbro]

Ok, I just saw you're going to put that in the next version.

[Unitech]

Fixed on recently published pm2 (2.7.0):

$ npm install pm2@latest -g
$ pm2 update

Let me know if there is any issue

[cdm6a]

@Unitech, in the event you set out_file or error_file to /dev/null, it ignores log_file. I'm not sure if this is intentional but in my case where I had:

{
  ...
  error_file : 'error.log',
  out_file   : '/dev/null',
  log_file   : 'merged.log',
  merge_logs : true
}

The behavior changed between 2.5 and 2.6.

I've created #3156 to fix this issue.