e22f26bc58
Starting a goroutine takes 1-2µs on my laptop. From the "numbers every Go programmer should know", I had 300ns for a channel send in my mind. Turns out, on my laptop, it takes only 60ns. That's fast enough to warrant the machinery of yet another channel with a fixed set of worker goroutines feeding from it. The number chosen (8 for now) is low enough to not really afflict a measurable overhead (a big Prometheus server has >1000 goroutines running), but high enough to not make sample ingestion a bottleneck.
Prometheus 
Prometheus is a systems and service monitoring system. It collects metrics from configured targets at given intervals, evaluates rule expressions, displays the results, and can trigger alerts if some condition is observed to be true.
Prometheus' main distinguishing features as compared to other monitoring systems are:
- a multi-dimensional data model (timeseries defined by metric name and set of key/value dimensions)
- a flexible query language to leverage this dimensionality
- no dependency on distributed storage; single server nodes are autonomous
- timeseries collection happens via a pull model over HTTP
- pushing timeseries is supported via an intermediary gateway
- targets are discovered via service discovery or static configuration
- multiple modes of graphing and dashboarding support
- federation support coming soon
Architecture overview
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 distributions soon. Once those are offered, it will be the recommended way of installing Prometheus.
Use make
In most cirumstances, the following should work:
$ make build
$ ./prometheus -config.file=documentation/examples/prometheus.conf
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, 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 tarball with the binary for distribution.make race_condition_runcompiles and runs a binary with the race detector enabled. To pass arguments when running Prometheus this way, set theARGUMENTSenvironment variable (e.g.ARGUMENTS="-config.file=./prometheus.conf" make race_condition_run).
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 and the
#prometheuschannel onirc.freenode.net.
Contributing
Refer to CONTRIBUTING.md
License
Apache License 2.0, see LICENSE.