This change does just signal a scrape target update to the scraping loop
once an initial target set is fetched.
Before, the scrape pool was directly synced, causing a race against an
uninitialized scrape pool.
Fixes#1703
The concurrency applied before is in most cases not even needed. With
a cap=1 channel, most tests are much cleaner.
TestMarathonSDRunAndStop was trickier. It could even have blocked
before.
This also includes a general refactoring of the whole file.
So far, out-of-order samples during rule evaluation were not logged,
and neither scrape health samples. The latter are unlikely to cause
any errors. That's why I'm logging them always now. (It's alway highly
irregular should it happen.) For rules, I have used the same plumbing
as for samples, just with a different wording in the message to mark
them as a result of rule evaluation.
But only on DEBUG level.
Also, count and report the two cases of out-of-order timestamps on the
one hand and same timestamp but different value on the other hand
separately.
Prometheus is Apache 2 licensed, and most source files have the
appropriate copyright license header, but some were missing it without
apparent reason. Correct that by adding it.
This fixes the case where a target provider closes the update
channel and exits before the context is canceled.
This should only be true for the static provider but it's safer
to generally handle this case.
This commit simplifies the TargetHealth type and moves the target
status into the target itself. This also removes a race where error
and last scrape time could have been out of sync.
This commit removes the scrapeConfig entirely from Target.
All identity defining parameters are thus immutable now and the mutex
can be removed..
Target identity is now correctly defined by the labels and the full URL.
This in particular includes URL parameters that are not specified in the
label set.
Fingerprint is also removed from hash to remove an unnecessary tight coupling
to the common/model package.
