remove some select state that is most likely obsoleete and hoepfully doesn't braje anything :)
merge targets will sort by Discoverer name so we can have consistent tests for the maps.
* Adds a test covering the case where a target providers sends updated versions of the same target groups and the system should reconcile to the latest version of each of the target groups
* Refactors how input data is represented in the tests. It used to be literal declarations of necessary structs, now it is parsing yaml. Yaml declarations are half as long as the former. And these can be put in a fixture file
* Adds a tiny bit of refactoring on test timeouts
* flaky test caused by invalid fsnotify updates before the test files are written to disk causing the fd service to send empty `group[]` struct
* `close(filesReady)` needs to be before the file closing so that fsnotify triggers a new loop of the discovery service.
* nits
* use filepath.Join for the path url to be cross platform
* stupid mistake revert
* Allow getting credentials via EC2 role
This is subtly different than the existing `role_arn` solution, which
allows Prometheus to assume an IAM role given some set of credentials
already in-scope. With EC2 roles, one specifies the role at instance
launch time (via an instance profile.) The instance then exposes
temporary credentials via its metadata. The AWS Go SDK exposes a
credential provider that polls the [instance metadata endpoint][1]
already, so we can simply use that and it will take care of renewing the
credentials when they expire.
Without this, if this is being used inside EC2, it is difficult to
cleanly allow the use of STS credentials. One has to set up a proxy role
that can assume the role you really want, and launch the EC2 instance
with the proxy role. This isn't very clean, and also doesn't seem to be
[supported very well][2].
[1]:
http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/ec2-instance-metadata.html
[2]: https://github.com/aws/aws-cli/issues/1390
* Automatically try to detect EC2 role credentials
The `Available()` function exposed on ec2metadata returns a simple
true/false if the ec2 metadata is available. This is the best way to
know if we're actually running in EC2 (which is the only valid use-case
for this credential provider.)
This allows this to "just work" if you are using EC2 instance roles.
This change enables the OpenStack service discovery to read the
authentication parameters from the OS_* environment variables when the
identity endpoint URL is not defined in the Prometheus configuration
file.
The problem reported in #2799 was that in the event that all records for a
name were removed, the target group was never updated to be the "empty" set.
Essentially, whatever Prometheus last saw as a non-empty list of targets
would stay that way forever (or at least until Prometheus restarted...). This
came about because of a fairly naive interpretation of what a valid-looking
DNS response actually looked like -- essentially, the only valid DNS responses
were ones that had a non-empty record list. That's fine as long as your
config always lists only target names which have non-empty record sets; if
your environment happens to legitimately have empty record sets sometimes,
all hell breaks loose (otherwise-cleanly shutdown systems trigger up==0 alerts,
for instance).
This patch is a refactoring of the DNS lookup behaviour that maintains
existing behaviour with regard to search paths, but correctly handles empty
and non-existent record sets.
RFC1034 s4.3.1 says there's three ways a recursive DNS server can respond:
1. Here is your answer (possibly an empty answer, because of the way DNS
considers all records for a name, regardless of type, when deciding
whether the name exists).
2. There is no spoon (the name you asked for definitely does not exist).
3. I am a teapot (something has gone terribly wrong).
Situations 1 and 2 are fine and dandy; whatever the answer is (empty or
otherwise) is the list of targets. If something has gone wrong, then we
shouldn't go updating the target list because we don't really *know* what
the target list should be.
Multiple DNS servers to query is a straightforward augmentation; if you get
an error, then try the next server in the list, until you get an answer or
run out servers to ask. Only if *all* the servers return errors should you
return an error to the calling code.
Where things get complicated is the search path. In order to be able to
confidently say, "this name does not exist anywhere, you can remove all the
targets for this name because it's definitely GORN", at least one server for
*all* the possible names need to return either successful-but-empty
responses, or NXDOMAIN. If any name errors out, then -- since that one
might have been the one where the records came from -- you need to say
"maintain the status quo until we get a known-good response".
It is possible, though unlikely, that a poorly-configured DNS setup (say,
one which had a domain in its search path for which all configured recursive
resolvers respond with REFUSED) could result in the same "stuck" records
problem we're solving here, but the DNS configuration should be fixed in
that case, and there's nothing we can do in Prometheus itself to fix the
problem.
I've tested this patch on a local scratch instance in all the various ways I
can think of:
1. Adding records (targets get scraped)
2. Adding records of a different type
3. Remove records of the requested type, leaving other type records intact
(targets don't get scraped)
4. Remove all records for the name (targets don't get scraped)
5. Shutdown the resolver (targets still get scraped)
There's no automated test suite additions, because there isn't a test suite
for DNS discovery, and I was stretching my Go skills to the limit to make
this happen; mock objects are beyond me.
The changes [1][] to Marathon service discovery to support multiple
ports mean that Prometheus now attempts to scrape all ports belonging to
a Marathon service.
You can use port definition or port mapping labels to filter out which
ports to scrape but that requires service owners to update their
Marathon configuration.
To allow for a smoother migration path, add a
`__meta_marathon_port_index` label, whose value is set to the port's
sequential index integer. For example, PORT0 has the value `0`, PORT1
has the value `1`, and so on.
This allows you to support scraping both the first available port (the
previous behaviour) in addition to ports with a `metrics` label.
For example, here's the relabel configuration we might use with
this patch:
- action: keep
source_labels: ['__meta_marathon_port_definition_label_metrics', '__meta_marathon_port_mapping_label_metrics', '__meta_marathon_port_index']
# Keep if port mapping or definition has a 'metrics' label with any
# non-empty value, or if no 'metrics' port label exists but this is the
# service's first available port
regex: ([^;]+;;[^;]+|;[^;]+;[^;]+|;;0)
This assumes that the Marathon API returns the ports in sorted order
(matching PORT0, PORT1, etc), which it appears that it does.
[1]: https://github.com/prometheus/prometheus/pull/2506
* k8s: Support discovery of ingresses
* Move additional labels below allocation
This makes it more obvious why the additional elements are allocated.
Also fix allocation for node where we only set a single label.
* k8s: Remove port from ingress discovery
* k8s: Add comment to ingress discovery example
