func tests: "I! Starting Telegraf" isn't reliable to detect the last restart in logs

[Laurent Sesquès]

In the compute functional tests, we rely on "I! Starting Telegraf" to discard logs priori to the last restart.
But Telegraf doesn't always log it. I found that the only reliable log line was "I! Loaded inputs:".
We should determine if this is a bug in telegraf itself (in which case, we'll file a bug upstream), or if it's intended in which case we should:

--- a/src/tests/functional/tests/test_compute.py
+++ b/src/tests/functional/tests/test_compute.py
@@ -42,7 +42,7 @@ class TestTelegrafCompute(BaseTelegrafTest):
         )
         # Sometimes, the logs show errors on Telegraf first start because br-int isn't
         # yet started. To overcome this, just check the most recent start of Telegraf.
- up_to_word = "I! Starting Telegraf"
+ up_to_word = "I! Loaded inputs:"
         rx_to_last = r"^.*{}".format(re.escape(up_to_word))
         last_logs = re.sub(rx_to_last, "", content, flags=re.DOTALL).strip()
         error_pattern = "E!"

[Laurent Sesquès (sajoupa)]

The root cause is (imho) a but in telegraf upstream, so I filed:
https://github.com/influxdata/telegraf/issues/9120

Until a fix is released, we should handle this case in the test suite though.

[Eric Chen (eric-chen)]

Upstream solved.