What did you do?

Upgraded from beta.3 to beta.5

What did you expect to see?

The --log.format flag continuing to exist.

What did you see instead? Under which circumstances?

prometheus: error: unknown long flag '--log.format'

Environment

• Prometheus version:

$ ./bin/prometheus --version
prometheus, version 2.0.0-beta.5 (branch: HEAD, revision: 64c7932e851f3276391fc3e216cd30f447d4924e)
  build user:       root@df40cc0bd79b
  build date:       20170921-16:23:04
  go version:       go1.8.3

Additional Context

#promtheus
11:10 T<timsim> Were the changes from beta.4 to beta.5 supposed to remove the `--log.format` flag? https://github.com/prometheus/prometheus/pull/3152 It appears they have
11:11 G<gouthamve[m]> Yes. We were initially going to see if people really need another format and slowly add it back I guess
11:11 G<gouthamve[m]> Can you create an issue?

I was using --log.format="logger:syslog?appname=prometheus&local=7&json=true". If there's another way to do that in 2.0 that'll be preferred I'm happy to change. I suppose it could also be done with process supervisors or something. However, I would expect people upgrading from 1.x will be used to this flag/format and will have something that works for them.