b7bf11230a
A common problem in Prometheus alerting is to detect when no timeseries
exist for a given metric name and label combination. Unfortunately,
Prometheus alert expressions need to be of vector type, and
"count(nonexistent_metric)" results in an empty vector, yielding no
output vector elements to base an alert on. The newly introduced
absent() function solves this issue:
ALERT FooAbsent IF absent(foo{job="myjob"}) [...]
absent() has the following behavior:
- if the vector passed to it has any elements, it returns an empty
vector.
- if the vector passed to it has no elements, it returns a 1-element
vector with the value 1.
In the second case, absent() tries to be smart about deriving labels of
the 1-element output vector from the input vector:
absent(nonexistent{job="myjob"}) => {job="myjob"}
absent(nonexistent{job="myjob",instance=~".*"}) => {job="myjob"}
absent(sum(nonexistent{job="myjob"})) => {}
That is, if the passed vector is a literal vector selector, it takes all
"=" label matchers as the basis for the output labels, but ignores all
non-equals or regex matchers. Also, if the passed vector results from a
non-selector expression, no labels can be derived.
Change-Id: I948505a1488d50265ab5692a3286bd7c8c70cd78
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| .build | ||
| config | ||
| documentation | ||
| notification | ||
| retrieval | ||
| rules | ||
| stats | ||
| storage | ||
| templates | ||
| tools | ||
| utility | ||
| web | ||
| .gitignore | ||
| .pkgignore | ||
| .travis.yml | ||
| build_info.go | ||
| CHANGELOG.md | ||
| CONTRIBUTING.md | ||
| CONTRIBUTORS.md | ||
| Dockerfile | ||
| LICENSE | ||
| main.go | ||
| Makefile | ||
| Makefile.INCLUDE | ||
| MANIFEST | ||
| README.md | ||
| tests-for-die-in-a-fire-travis.sh | ||
Prometheus
Bedecke deinen Himmel, Zeus! A new kid is in town.
Prometheus is a generic time series collection and computation server that is useful in the following fields:
- Industrial Experimentation / Real-Time Behavioral Validation / Software Release Qualification
- Econometric and Natural Sciences
- Operational Concerns and Monitoring
The system is designed to collect telemetry from named targets on given intervals, evaluate rule expressions, display the results, and trigger an action if some condition is observed to be true.
TODO: The above description is somewhat esoteric. Rephrase it into somethith that tells normal people how they will usually benefit from using Prometheus.
Install
There are various ways of installing Prometheus.
Precompiled packages
We plan to provide precompiled binaries for various platforms and even packages for common Linux distribution soon. Once those are offered, it will be the recommended way of installing Prometheus.
Use make
In most cirumstances, the following should work:
$ make
$ ARGUMENTS="-config.file=documentation/examples/prometheus.conf" make run
${ARGUMENTS} is passed verbatim to the commandline starting the Prometheus binary.
This is useful for quick one-off invocations and smoke testing.
The above requires a number of common tools to be installed, namely
curl, git, gzip, hg (Mercurial CLI), sed, xxd. Should you
need to change any of the protocol buffer definition files
(*.proto), you also need the protocol buffer compiler
[protoc](http://code.google.com/p/protobuf/](http://code.google.com/p/protobuf/),
v2.5.0 or higher, in your $PATH.
Everything else will be downloaded and installed into a staging
environment in the .build sub-directory. That includes a Go
development environment of the appropriate version.
The Makefile offers a number of useful targets. Some examples:
make testruns tests.make tarballcreates a tar ball with the binary for distribution.make race_condition_runcompiles and runs a binary with the race detector enabled.
Use your own Go development environment
Using your own Go development environment with the usual tooling is
possible, too, but you have to take care of various generated files
(usually by running make in the respective sub-directory):
- Compiling the protocol buffer definitions in
config(only if you have changed them). - Generating the parser and lexer code in
rules(only if you have changedparser.yorlexer.l). - The
files.goblob inweb/blob, which embeds the static web content into the binary.
Furthermore, the build info (see build_info.go) will not be
populated if you simply run go build. You have to pass in command
line flags as defined in Makefile.INCLUDE (see ${BUILDFLAGS}) to
do that.
More information
- The source code is periodically indexed: Prometheus Core.
- You will find a Travis CI configuration in
.travis.yml. - All of the core developers are accessible via the Prometheus Developers Mailinglist.
Contributing
Refer to CONTRIBUTING.md
License
Apache License 2.0, see LICENSE.