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.
This commit changes the scraper interface to accept a timestamp
so the reported timestamp by the caller and the timestamp
attached to samples does not differ.
This commit moves Scraper handling into a separate scrapePool type.
TargetSets only manage TargetProvider lifecycles and sync the
retrieved updates to the scrapePool.
TargetProviders are now expected to send a full initial target set
within 5 seconds. The scrapePools preserve target state across reloads
and only drop targets after the initial set was synced.
Double acquisition of the RLock usually doesn't blow up, but if the
write lock is called for between the two RLock's, we are deadlocked.
This deadlock does not exist in release-0.17, BTW.
With recent changes to a Target's internal data representation
updating by fullLabels() assigns the additional default
instance label. This breaks target identity comparison and causes
identical targets from service discovery to be constantly swapped.
For historic reasons we were enforcing a timeout directly
via the TCP dialer. This is no longer necessary for quite a while now.
Switching to context.Context will allow us to properly terminate
requests on shutdown as well.
To evenly distribute scraping load we currently rely on random
jittering. This commit hashes over the target's identity and calculates
a consistent offset. This also ensures that scrape intervals
are constantly spaced between config/target changes.
This gives up on the idea to communicate throuh the Append() call (by
either not returning as it is now or returning an error as
suggested/explored elsewhere). Here I have added a Throttled() call,
which has the advantage that it can be called before a whole _batch_
of Append()'s. Scrapes will happen completely or not at all. Same for
rule group evaluations. That's a highly desired behavior (as discussed
elsewhere). The code is even simpler now as the whole ingestion buffer
could be removed.
Logging of throttled mode has been streamlined and will create at most
one message per minute.
Move defer resp.Body.Close() up to make sure it's called even when the
HTTP request returns something other than 200 or Decoder construction
fails. This avoids leaking and eventually running out of file descriptors.
This is with `golint -min_confidence=0.5`.
I left several lint warnings untouched because they were either
incorrect or I felt it was better not to change them at the moment.
Allow scrape_configs to have an optional proxy_url option which specifies
a proxy to be used for all connections to hosts in that config.
Internally this modifies the various client functions to take a *url.URL pointer
which currently must point to an HTTP proxy (but has been left open-ended to
allow the url format to be extended to support others, such as maybe SOCKS if
needed).
Changes to the UI:
- "Active Since" timestamps are now human-readable.
- Alerting rules are now pretty-printed better.
- Labels are no longer just strings, but alert bubbles (like we do on
the status page for base labels).
- Alert states and target health states are now capitalized in the
presentation layer rather than at the source.
This commit adds the honor_labels and params arguments to the scrape
config. This allows to specify query parameters used by the scrapers
and handling scraped labels with precedence.
The main purpose of this is to allow for blacklisting
of expensive metrics as a tactical option.
It could also find uses for renaming and removing labels
from federation.
