Disabling headers

[felipecrs]

What would you like to be added:

Something like the kubectl --no-headers option, to disable showing the + pod › container line every time stern starts tailing one pod.

Why is this needed:

I use stern in CI/CD and I don't want it to output the list of all pods when it begins, when combined with --since=1s, to avoid flooding the output.

[superbrothers]

headers are output to stderr. Therefore, you can avoid outputting them by doing the following:

$ stern . 2>/dev/null
nginx-587df8d89d-m7xx8 nginx-unprivileged /docker-entrypoint.sh: /docker-entrypoint.d/ is not empty, will attempt to perform configuration
nginx-587df8d89d-m7xx8 nginx-unprivileged /docker-entrypoint.sh: Looking for shell scripts in /docker-entrypoint.d/
nginx-587df8d89d-m7xx8 nginx-unprivileged /docker-entrypoint.sh: Launching /docker-entrypoint.d/10-listen-on-ipv6-by-default.sh
nginx-587df8d89d-m7xx8 nginx-unprivileged 10-listen-on-ipv6-by-default.sh: info: Getting the checksum of /etc/nginx/conf.d/default.conf
nginx-587df8d89d-m7xx8 nginx-unprivileged 10-listen-on-ipv6-by-default.sh: info: /etc/nginx/conf.d/default.conf differs from the packaged version
nginx-587df8d89d-m7xx8 nginx-unprivileged /docker-entrypoint.sh: Launching /docker-entrypoint.d/20-envsubst-on-templates.sh
nginx-587df8d89d-m7xx8 nginx-unprivileged /docker-entrypoint.sh: Launching /docker-entrypoint.d/30-tune-worker-processes.sh
nginx-587df8d89d-m7xx8 nginx-unprivileged /docker-entrypoint.sh: Configuration complete; ready for start up
nginx-587df8d89d-m7xx8 nginx-unprivileged 2022/12/19 00:17:20 [notice] 1#1: using the "epoll" event method
nginx-587df8d89d-m7xx8 nginx-unprivileged 2022/12/19 00:17:20 [notice] 1#1: nginx/1.23.2
nginx-587df8d89d-m7xx8 nginx-unprivileged 2022/12/19 00:17:20 [notice] 1#1: built by gcc 10.2.1 20210110 (Debian 10.2.1-6)
nginx-587df8d89d-m7xx8 nginx-unprivileged 2022/12/19 00:17:20 [notice] 1#1: OS: Linux 5.4.0-131-generic
nginx-587df8d89d-m7xx8 nginx-unprivileged 2022/12/19 00:17:20 [notice] 1#1: getrlimit(RLIMIT_NOFILE): 1048576:1048576
nginx-587df8d89d-m7xx8 nginx-unprivileged 2022/12/19 00:17:20 [notice] 1#1: start worker processes
nginx-587df8d89d-m7xx8 nginx-unprivileged 2022/12/19 00:17:20 [notice] 1#1: start worker process 34
nginx-587df8d89d-m7xx8 nginx-unprivileged 2022/12/19 00:17:20 [notice] 1#1: start worker process 35
nginx-587df8d89d-m7xx8 nginx-unprivileged 2022/12/19 00:17:20 [notice] 1#1: start worker process 36
nginx-587df8d89d-m7xx8 nginx-unprivileged 2022/12/19 00:17:20 [notice] 1#1: start worker process 37
nginx-587df8d89d-m7xx8 nginx-unprivileged 2022/12/19 00:17:20 [notice] 1#1: start worker process 38
nginx-587df8d89d-m7xx8 nginx-unprivileged 2022/12/19 00:17:20 [notice] 1#1: start worker process 39
nginx-587df8d89d-m7xx8 nginx-unprivileged 2022/12/19 00:17:20 [notice] 1#1: start worker process 40
nginx-587df8d89d-m7xx8 nginx-unprivileged 2022/12/19 00:17:20 [notice] 1#1: start worker process 41
nginx-587df8d89d-m7xx8 nginx-unprivileged 2022/12/19 00:17:20 [notice] 1#1: start worker process 42
nginx-587df8d89d-m7xx8 nginx-unprivileged 2022/12/19 00:17:20 [notice] 1#1: start worker process 43
nginx-587df8d89d-m7xx8 nginx-unprivileged 2022/12/19 00:17:20 [notice] 1#1: start worker process 44
nginx-587df8d89d-m7xx8 nginx-unprivileged 2022/12/19 00:17:20 [notice] 1#1: start worker process 45

If you do not want to include pod info in the log line, you can use the --template flag.

$ stern --template '{{.Message}}{{"\n"}}' . 2>/dev/null
/docker-entrypoint.sh: /docker-entrypoint.d/ is not empty, will attempt to perform configuration
/docker-entrypoint.sh: Looking for shell scripts in /docker-entrypoint.d/
/docker-entrypoint.sh: Launching /docker-entrypoint.d/10-listen-on-ipv6-by-default.sh
10-listen-on-ipv6-by-default.sh: info: Getting the checksum of /etc/nginx/conf.d/default.conf
10-listen-on-ipv6-by-default.sh: info: /etc/nginx/conf.d/default.conf differs from the packaged version
/docker-entrypoint.sh: Launching /docker-entrypoint.d/20-envsubst-on-templates.sh
/docker-entrypoint.sh: Launching /docker-entrypoint.d/30-tune-worker-processes.sh
/docker-entrypoint.sh: Configuration complete; ready for start up
2022/12/19 00:17:20 [notice] 1#1: using the "epoll" event method
2022/12/19 00:17:20 [notice] 1#1: nginx/1.23.2
2022/12/19 00:17:20 [notice] 1#1: built by gcc 10.2.1 20210110 (Debian 10.2.1-6)
2022/12/19 00:17:20 [notice] 1#1: OS: Linux 5.4.0-131-generic
2022/12/19 00:17:20 [notice] 1#1: getrlimit(RLIMIT_NOFILE): 1048576:1048576
2022/12/19 00:17:20 [notice] 1#1: start worker processes
2022/12/19 00:17:20 [notice] 1#1: start worker process 34
2022/12/19 00:17:20 [notice] 1#1: start worker process 35
2022/12/19 00:17:20 [notice] 1#1: start worker process 36
2022/12/19 00:17:20 [notice] 1#1: start worker process 37
2022/12/19 00:17:20 [notice] 1#1: start worker process 38
2022/12/19 00:17:20 [notice] 1#1: start worker process 39
2022/12/19 00:17:20 [notice] 1#1: start worker process 40
2022/12/19 00:17:20 [notice] 1#1: start worker process 41
2022/12/19 00:17:20 [notice] 1#1: start worker process 42
2022/12/19 00:17:20 [notice] 1#1: start worker process 43
2022/12/19 00:17:20 [notice] 1#1: start worker process 44
2022/12/19 00:17:20 [notice] 1#1: start worker process 45

If you still have any issue, please feel free to reopen this issue.

[rkmathi]

@superbrothers
Admittedly, headers feel more like the beginning of a row than the beginning of a column.
e.g. CSV

Since it is the origin of the log, I thought that the source might be good.

Still, I don't think it would matter if it will be header.

[superbrothers]

Umm, the following are likely candidates

--no-headers
--no-source
--silent
--quiet

[floryut]

I like the --silent one, but I think the --no-source is the most close to what it is doing 👍

[felipecrs]

Also: --only-log-lines, --no-announcements.

[superbrothers]

--only-log-lines seems like a good idea!

[superbrothers]

We've released stern v1.23.0. It allows you to print only log lines with --only-log-line flag.

$ stern . --tail=1 --no-follow
+ nginx-cfbcb7b98-96xsv › nginx
+ nginx-cfbcb7b98-29wn7 › nginx
nginx-cfbcb7b98-96xsv nginx 2023/01/27 13:20:48 [notice] 1#1: start worker process 46
- nginx-cfbcb7b98-96xsv › nginx
nginx-cfbcb7b98-29wn7 nginx 2023/01/27 13:20:45 [notice] 1#1: start worker process 46
- nginx-cfbcb7b98-29wn7 › nginx

$ stern . --tail=1 --no-follow --only-log-lines
nginx-cfbcb7b98-96xsv nginx 2023/01/27 13:20:48 [notice] 1#1: start worker process 46
nginx-cfbcb7b98-29wn7 nginx 2023/01/27 13:20:45 [notice] 1#1: start worker process 46

You should try it.

[felipecrs]

This is awesome, thanks a lot!!!