Suppress tailscaled logs after 200 lines

[lmagyar]

Proposed Changes

Tailscaled is quite chatty and emits a really large amount of log messages.

This PR disables these messages after 200 lines, but makes it possible to re-enable the full logging for troubleshooting.

Based on the idea from tailscale/tailscale-synology#110

Related Issues

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[frenck]

Tailscaled is quite chatty and emits a really large amount of log messages.

I'm missing: Why is that a concern?

[lmagyar]

Tailscaled is quite chatty and emits a really large amount of log messages.

I'm missing: Why is that a concern?

Tailscaled writes into the log something in nearly each second.

• This debug noise hides any useful log entry.
• The logs finally are written to SD card, so I prefer to minimize the wear.

[lmagyar]

I've spent a few hours googling, and found the same discussion in tailscaled-synology: tailscale/tailscale-synology#110

Solution: the logs suppressed after 200 lines, so the startup can be seen in details, but after a few minutes it will stop emitting noise.

I had to modify it a bit due to busybox/sed limitations.

UPDATE

sample log, redacted the most of it:

...
s6-rc: info: service tailscaled successfully started
s6-rc: info: service post-tailscaled: starting
[16:42:33] INFO: Starting Tailscale...
[16:42:33] INFO: Starting Tailscale web...
[16:42:34] NOTICE: Tailscale logs will be suppressed after 200 lines, set add-on's configuration option 'log_level' to 'debug' to see further logs
2023/03/30 16:42:34 web server running on: http://127.0.0.1:25898
2023/03/30 16:42:34 You have disabled logging. Tailscale will not be able to provide support.
2023/03/30 16:42:34 logtail started
2023/03/30 16:42:34 Program starting: v1.38.3-ta972b8565-g55f6b9a5f, Go 1.20.1-tsdb4dc90: []string{"/opt/tailscaled", "--state=/data/tailscaled.state", "--statedir=/data", "--no-logs-no-support", "--tun=userspace-networking"}
2023/03/30 16:42:34 LogID: 42a3b8494218545b4e7ff9c63bb9c6ab214214b37ade177b3f0832dc48b2104e
...
2023/03/30 16:52:49 magicsock: endpoints changed: 172.30.32.1:58177 (local), 172.30.232.1:58177 (local), 192.168.1.9:58177 (local)
2023/03/30 16:53:04 Accept: TCP{[fd7a:115c:a1e0:ab12:4843:cd96:6249:ba61]:51068 > [fd7a:115c:a1e0:ab12:4843:cd96:6269:b357]:37009} 72 tcp non-syn
[further tailscaled logs suppressed, set add-on's configuration option 'log_level' to 'debug' to see further tailscaled logs]

[frenck]

Thanks, @lmagyar 👍

../Frenck