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Author SHA1 Message Date
beorn7 cf7e1caf17 Create a public registry interface and separate out HTTP exposition
General context and approch
===========================

This is the first part of the long awaited wider refurbishment of
`client_golang/prometheus/...`. After a lot of struggling, I decided
to not go for one breaking big-bang, but cut things into smaller steps
after all, mostly to keep the changes manageable and easy to
review. I'm aiming for having the invasive breaking changes
concentrated in as few steps as possible (ideally one). Some steps
will not be breaking at all, but typically there will be breaking
changes that only affect quite special cases so that 95+% of users
will not be affected. This first step is an example for that, see
details below.

What's happening in this commit?
================================

This step is about finally creating an exported registry
interface. This could not be done by simply export the existing
internal implementation because the interface would be _way_ too
fat. This commit introduces a qutie lean `Registry` interface
(compared to the previous interval implementation). The functions that
act on the default registry are retained (with very few exceptions) so
that most use cases won't see a change. However, several of those are
deprecated now to clean up the namespace in the future.

The default registry is kept in the public variable
`DefaultRegistry`. This follows the example of the http package in the
standard library (cf. `http.DefaultServeMux`, `http.DefaultClient`)
with the same implications. (This pattern is somewhat disputed within
the Go community but I chose to go with the devil you know instead of
creating something more complex or even disallowing any changes to the
default registry. The current approach gives everybody the freedom to
not touch DefaultRegistry or to do everything with a custom registry
to play save.)

Another important part in making the registry lean is the extraction
of the HTTP exposition, which also allows for customization of the
HTTP exposition. Note that the separation of metric collection and
exposition has the side effect that managing the MetricFamily and
Metric protobuf objects in a free-list or pool isn't really feasible
anymore. By now (with better GC in more recent Go versions), the
returns were anyway dimisishing. To be effective at all, scrapes had
to happen more often than GC cycles, and even then most elements of
the protobufs (everything excetp the MetricFamily and Metric structs
themselves) would still cause allocation churn. In a future breaking
change, the signature of the Write method in the Metric interface will
be adjusted accordingly. In this commit, avoiding breakage is more
important.

The following issues are fixed by this commit (some solved "on the
fly" now that I was touching the code anyway and it would have been
stupid to port the bugs):

https://github.com/prometheus/client_golang/issues/46
https://github.com/prometheus/client_golang/issues/100
https://github.com/prometheus/client_golang/issues/170
https://github.com/prometheus/client_golang/issues/205

Documentation including examples have been amended as required.

What future changes does this commit enable?
============================================

The following items are not yet implemented, but this commit opens the
possibility of implementing these independently.

- The separation of the HTTP exposition allows the implementation of
  other exposition methods based on the Registry interface, as known
  from other Prometheus client libraries, e.g. sending the metrics to
  Graphite.
  Cf. https://github.com/prometheus/client_golang/issues/197

- The public `Registry` interface allows the implementation of
  convenience tools for testing metrics collection. Those tools can
  inspect the collected MetricFamily protobufs and compare them to
  expectation. Also, tests can use their own testing instance of a
  registry.
  Cf. https://github.com/prometheus/client_golang/issues/58

Notable non-goals of this commit
================================

Non-goals that will be tackled later
------------------------------------

The following two issues are quite closely connected to the changes in
this commit but the line has been drawn deliberately to address them
in later steps of the refurbishment:

- `InstrumentHandler` has many known problems. The plan is to create a
  saner way to conveniently intrument HTTP handlers and remove the old
  `InstrumentHandler` altogether. To keep breakage low for now, even
  the default handler to expose metrics is still using the old
  `InstrumentHandler`. This leads to weird naming inconsistencies but
  I have deemed it better to not break the world right now but do it
  in the change that provides better ways of instrumenting HTTP
  handlers.
  Cf. https://github.com/prometheus/client_golang/issues/200

- There is work underway to make the whole handling of metric
  descriptors (`Desc`) more intuitive and transparent for the user
  (including an ability for less strict checking,
  cf. https://github.com/prometheus/client_golang/issues/47). That's
  quite invasive from the perspective of the internal code, namely the
  registry. I deliberately kept those changes out of this commit.

- While this commit adds new external dependency, the effort to vendor
  anything within the library that is not visible in any exported
  types will have to be done later.

Non-goals that _might_ be tackled later
---------------------------------------

There is a strong and understandable urge to divide the `prometheus`
package into a number of sub-packages (like `registry`, `collectors`,
`http`, `metrics`, …). However, to not run into a multitude of
circular import chains, this would need to break every single existing
usage of the library. (As just one example, if the ubiquitious
`prometheus.MustRegister` (with more than 2,000 uses on GitHub alone)
is kept in the `prometheus` package, but the other registry concerns
go into a new `registry` package, then the `prometheus` package would
import the `registry` package (to call the actual register method),
while at the same time the `registry` package needs to import the
`prometheus` package to access `Collector`, `Metric`, `Desc` and
more. If we moved `MustRegister` into the `registry` package,
thousands of code lines would have to be fixed (which would be easy if
the world was a mono repo, but it is not). If we moved everything else
the proposed registry package needs into packages of their own, we
would break thousands of other code lines.)

The main problem is really the top-level functions like
`MustRegister`, `Handler`, …, which effectively pull everything into
one package. Those functions are however very convenient for the easy
and very frequent use-cases.

This problem has to be revisited later.

For now, I'm trying to keep the amount of exported names in the
package as low as possible (e.g. I unexported expvarCollector in this
commit because the NewExpvarCollector constructor is enough to export,
and it is now consistent with other collectors, like the goCollector).

Non-goals that won't be tackled anytime soon
--------------------------------------------

Something that I have played with a lot is "streaming collection",
i.e. allow an implementation of the `Registry` interface that collects
metrics incrementally and serves them while doing so. As it has turned
out, this has many many issues and makes the `Registry` interface very
clunky. Eventually, I made the call that it is unlikely we will really
implement streaming collection; and making the interface more clunky
for something that might not even happen is really a big no-no. Note
that the `Registry` interface only creates the in-memory
representation of the metric family protobufs in one go. The
serializaton onto the wire can still be handled in a streaming fashion
(which hasn't been done so far, without causing any trouble, but might
be done in the future without breaking any interfaces).

What are the breaking changes?
==============================

- Signatures of functions pushing to Pushgateway have changed to allow
  arbitrary grouping (which was planned for a long time anyway, and
  now that I had to work on the Push code anyway for the registry
  refurbishment, I finally did it,
  cf. https://github.com/prometheus/client_golang/issues/100).
  With the gained insight that pushing to the default registry is almost
  never the right thing, and now that we are breaking the Push call
  anyway, all the Push functions were moved to their own package,
  which cleans up the namespace and is more idiomatic (pushing
  Collectors is now literally done by `push.Collectors(...)`).

- The registry is doing more consistency checks by default now. Past
  creators of inconsistent metrics could have masked the problem by
  not setting `EnableCollectChecks`. Those inconsistencies will now be
  detected. (But note that a "best effort" metrics collection is now
  possible with `HandlerOpts.ErrorHandling = ContinueOnError`.)

- `EnableCollectChecks` is gone. The registry is now performing some
  of those checks anyway (see previous item), and a registry with all
  of those checks can now be created with `NewPedanticRegistry` (only
  used for testing).

- `PanicOnCollectError` is gone. This behavior can now be configured
  when creating a custom HTTP handler.
2016-08-02 18:46:22 +02:00
Uwe Dauernheim c1e8a41238 Fix typo in doc string 2016-08-01 23:14:45 +02:00
Andrew Stuart e63e6e3db7
Extend MustRegister function to accept variadic args 2016-07-11 15:04:23 -07:00
beorn7 f6b16ed256 Document the issues of InstrumentHandler
Obvious next step: Fix those issues.
2016-05-15 17:59:51 +02:00
Michael Stapelberg c1370d07ca Strip trailing / from push URL.
This circumvents the following problem:
• The prometheus client library appends “/metrics/…” to the pushURL.
• When pushURL ends in a trailing slash, the URL becomes e.g.
  http://pushgateway.example.com:9091//metrics/…
• The pushgateway will reply with an HTTP 307 status code
  (temporary redirect).
• While Go’s net/http client follows redirects by default, it will only
  follow HTTP 302 (Found) and HTTP 303 (See Other) redirects for PUT and
  POST requests, which the prometheus client library uses.

Hence, when calling e.g.:

    prometheus.Push("foo", "bar", "http://pushgateway.example.com:9091/")

…your metrics would not actually get pushed successfully, but rather
you’d see the error message:

    2015/11/26 10:59:49 main.go:209: unexpected status code 307 while pushing to http://push...
2015-11-26 19:16:53 +01:00
Harmen 5d4fdca1a5 use local fnv hash everywhere 2015-11-12 14:07:23 +01:00
David Nesting b0bd184e74 Simplify metricSorter timestamp comparison and improve comment 2015-11-10 09:37:58 -05:00
David Nesting 544f65f7fc metricSorter stops relying on time.Now and respects nil timestamps 2015-11-09 17:14:07 -05:00
David Nesting 5fb1b89678 Make metric sort stable and sort by timestamp 2015-11-09 16:55:26 -05:00
beorn7 90ddfa1c1e Move from client_golang/text to common/expfmt 2015-09-17 13:06:43 +02:00
Fabian Reinartz f2de0f589a Remove client_golang/model als direct dependency 2015-08-23 13:51:32 +02:00
beorn7 59f2c7d8b0 Fix a number of minor things.
- Clarify documentation about sorting requirements.
- Add missing histogram support in consistency check.
- Add label sorting to consistency check.
- Improve error messages when reporting a metric.
  (Previously, the metric name was not printed.)
2015-06-09 12:03:07 +02:00
beorn7 63acb006f7 Purge another trace of ext -> pbutil. 2015-04-07 15:19:47 +02:00
beorn7 4ab527fc50 Fix merge conflicts. 2015-03-16 15:15:02 +01:00
beorn7 f3cda15667 Add functions to push individual collectors to a Pushgateway.
Move all Pushgateway related top-level functions to push.go.
2015-03-15 19:29:57 +01:00
beorn7 a762e0612e Allow the metric family injection hook to merge with existing metric families.
If a metric family returned by the injection hook already exists (with
the same name), then its metrics are simply merged into that metric
family. With enabled collect-time checks, even uniqueness is checked,
but in general, things stay the same that the caller is responsible to
ensure metric consistency.

This fixes https://github.com/prometheus/pushgateway/issues/27 .
2015-03-15 16:34:31 +01:00
Julius Volz 738b69e61a Use non-rewritten Godep imports. 2015-02-27 16:49:40 +01:00
Julius Volz 169c8a68e1 Use godep with import rewriting for vendoring.
The new vendoring was produced by running:

    godep save -r ./examples/... ./prometheus/... ./text/... ./model/... ./extraction/...

Two things to note:

- "extraction/processor0_0_{1,2}_test.go" imported a package from
  "github.com/prometheus/prometheus", all for just one tiny testing
  function. To not have to deal with a circular vendoring dependency, I
  simply replaced the usage of the function by some in-line logic.

- godep grouped the rewritten imports slightly differently for some
  reason, but at least the standard library imports are still in a
  separate section. Not sure if it's worth manually keeping our old
  import grouping scheme or if we should simply use that godep-generated
  one.
2015-02-26 00:47:03 +01:00
Peter Bourgon 69c8dc87e9 Fix for Histogram in registry.writePB 2015-02-20 19:08:36 +01:00
beorn7 000ef45157 Replaced http by HTTP if used as the name of the protocol in English. 2015-02-19 15:54:26 +01:00
Julius Volz 765fdaf37e Update protobuf library package name.
The Golang protocol buffer library has now moved to GitHub:

https://github.com/golang/protobuf

Although "go get"-ing the old package name still works, moving
everything to the new one will make vendoring cleaner.

See also https://github.com/matttproud/golang_protobuf_extensions/pull/7
2015-02-14 00:00:34 +01:00
Bjoern Rabenstein d7f8eb1083 Change "Prometheus Team" to "The Prometheus Authors". 2015-02-02 15:14:36 +01:00
Julius Volz f3e101bd1c Fix race condition in writePB().
The RLock already needs to be acquired when reading r.dimHashesByName.

This fixes https://github.com/prometheus/client_golang/issues/61
2015-01-31 22:10:27 +01:00
Bjoern Rabenstein 159e96f6c7 Allow error reporting during metrics collection and simplify Register().
Both are interface changes I want to get in before public
announcement. They only break rare usage cases, and are always easy to
fix, but still we want to avoid breaking changes after a wider
announcement of the project.

The change of Register() simply removes the return of the Collector,
which nobody was using in practice. It was just bloating the call
syntax. Note that this is different from RegisterOrGet(), which is
used at various occasions where you want to register something that
might or might not be registered already, but if it is, you want the
previously registered Collector back (because that's the relevant
one).

WRT error reporting: I first tried the obvious way of letting the
Collector methods Describe() and Collect() return error. However, I
had to conclude that that bloated _many_ calls and their handling in
very obnoxious ways. On the other hand, the case where you actually
want to report errors during registration or collection is very
rare. Hence, this approach has the wrong trade-off. The approach taken
here might at first appear clunky but is in practice quite handy,
mostly because there is almost no change for the "normal" case of "no
special error handling", but also because it plays well with the way
descriptors and metrics are handled (via channels).

Explaining the approach in more detail:

- During registration / describe: Error handling was actually already
  in place (for invalid descriptors, which carry an error anyway). I
  only added a convenience function to create an invalid descriptor
  with a given error on purpose.

- Metrics are now treated in a similar way. The Write method returns
  an error now (the only change in interface). An "invalid metric" is
  provided that can be sent via the channel to signal that that metric
  could not be collected. It alse transports an error.

NON-GOALS OF THIS COMMIT:

This is NOT yet the major improvement of the whole registry part,
where we want a public Registry interface and plenty of modular
configurations (for error handling, various auto-metrics, http
instrumentation, testing, ...). However, we can do that whole thing
without breaking existing interfaces. For now (which is a significant
issue) any error during collection will either cause a 500 HTTP
response or a panic (depending on registry config). Later, we
definitely want to have a possibility to skip (and only report
somehow) non-collectible metrics instead of aborting the whole scrape.
2015-01-12 19:16:09 +01:00
Jeff Younker 014d4bd173 Remove a Go 1.4ism to allow compilation under Go 1.3. 2015-01-09 14:52:23 +01:00
Tobias Schmidt d66557ae59 Register process and go collectors by default 2014-12-22 13:55:44 -05:00
Julius Volz 7fcb2c594a Drain collector channel when returning prematurely. 2014-12-19 14:18:55 +01:00
Bjoern Rabenstein b09d588309 Add missing error check.
Change-Id: I6fcf6d5d50333ff0c205fd87cdb9430f1bc02c43
2014-07-30 19:02:39 +02:00
Bjoern Rabenstein 96297bcbae Add a configurable version of InstrumentHandler and InstrumentHandlerFunc.
Also, remove quotes from the Content-type header. It's not illegal to
have quotes there, but they are not needed, and at other places, we
are not using them. So fewer characters and more consistency.

Change-Id: If7a78bde85154163e4426daec493d973213e83e9
2014-07-22 17:40:20 +02:00
Bjoern Rabenstein 23e5e5fefd Add gzip support.
Change-Id: I6ea6e0dcbe7234ad143403d262da6cb40e7d3b50
2014-07-04 17:08:57 +02:00
Bjoern Rabenstein 5ac9f00fa9 Add Content-Length header.
Since we prepare the whole content in a buf before sending, we can as
well set the Content-Length explicitly.

Change-Id: Ifd91764c90af53be49f93f0b33032138130b6f96
2014-07-03 13:12:39 +02:00
Bjoern Rabenstein 0afe1a813e Add pushgateway support.
Change-Id: I4730b150ac84ae38939b16effaf4b2ad4afa5bc0
2014-07-03 13:12:39 +02:00
Bjoern Rabenstein 998774096c Make the collectorID independent of the desc order.
This is actually the intended behavior, and (as a nice side effect)
makes things cheaper to calculate.

Also, introduce a separator character to avoid hash collisions
(like label values {"ab","c"} vs {"a", "bc"}).

Apply the same principles to signature.go.

Change-Id: I607db544f278ed89684fe5fa11abdbc3e03d3061
2014-06-26 15:50:11 +02:00
Bjoern Rabenstein 5122dc6cc0 Fix doc comment typo.
Change-Id: I19b4b553b01823da0c1015d779f1f05b2c2cfb5b
2014-06-23 11:45:49 +02:00
Bjoern Rabenstein 8234d12ed0 Add InstrumentHandlerFunc.
Also, fix seconds to microseconds fot the http instrumentation to
match the metric name.

Fix Desc.String().

Simplify http error display.

Change-Id: Ib7397f4eac1eeed92b291e1c9cc88c080aee99ca
2014-06-20 20:57:27 +02:00
Bjoern Rabenstein 5d40912fd2 Complete rewrite of the exposition library.
This rewrite had may backs and forths. In my git repository, it
consists of 35 commits which I cannot group or merge into reasonable
review buckets. Gerrit breaks fundamental git semantics, so I have to
squash the 35 commits into one for the review.

I'll push this not with refs/for/master, but with refs/for/next so
that we can transition after submission in a controlled fashion.

For the review, I recommend to start with looking at godoc and in
particular the many examples. After that, continue with a line-by-line
detailed review. (The big picture is hopefully as expected after
wrapping up the discussion earlier.)

Change-Id: Ib38cc46493a5139ca29d84020650929d94cac850
2014-06-17 14:08:22 +02:00
Bjoern Rabenstein 3dfae09d30 Fix things commented on in past code review.
Change-Id: I4dafd098eefa99bc37fdbfebeb4c61a7251ad0be
2014-04-29 13:37:49 +02:00
Bjoern Rabenstein 84dc53148d Enable the Golang client library to create the new text formats.
Most important here is the simple & flat text format, but while I'm on
it, I have also added the text representations for protobufs (which is
purely meant for debugging purposes). I hope my basic idea about
handling those various protocols (and the text package) becomes
clearer now.

Change-Id: I7299853eadc82a426101e907f2b3d4e37f9e4c71
2014-04-25 21:45:04 +02:00
Bjoern Rabenstein 9da2fbcce3 Eliminate a number of style-guide violations.
Change-Id: Iedcd611e5c7ad24c84c004d8d6c551d1734e443c
2014-04-25 21:18:04 +02:00
Bjoern Rabenstein e5dc0421cd Move signature.go and related tests to the model package.
The LabelsToSignature function is now used outside of the prometheus
package, too. Leaving it in the prometheuos package is misleading
design and will lead to circulat import chains soon.

Change-Id: If1ca442d4023b33b138cf79fee68e82ff2a355be
2014-04-25 20:48:16 +02:00
Bjoern Rabenstein ecac33bed0 Conversion back and forth between MetricFamily protobuf and text format.
The idea here is to always go via the protobufs if dealing with the
text format. That won't always be the most efficient way, but it
avoids the multiplicity of conversion routines required for direct
conversion (e.g. text format -> internal representation in the
Prometheus server). The loss of efficiency is acceptable because the
text format should not be used in high performance (high throughput,
low latency) situations anyway.

In that way, the text format stays perfectly isolated from other parts
of the code. To receive text format, just plug the conversion in
before the code path that normally reads protobufs. Correspondingly,
for sending text format, simply replace the WriteDelimited call by a
text.Create call.

Nevertheless, the conversion code itself is optimized for efficiency
and minimized memory churn (which was one of the reason for handcoding
the parser and not using a lexer/parser code generation tool).

Change-Id: Iee45ffe8aa421a844225d13a1f859becd8a3b066
2014-04-17 16:28:13 +02:00
Bjoern Rabenstein b83e1b7cad Remove redundant __name__ label from protobuf output.
Change-Id: I72d5dbccb0325d6edf7abe5bca88dc5a6001029c
2014-04-03 15:18:12 +02:00
Bjoern Rabenstein ee34486fa1 Add a low-level MetricFamily injection hook.
This hook is needed for the upcoming push gateway.

Also remove go vet warnings and add test for Handler().

Change-Id: If6c56676c7a0f10c16b4effae7285903f8267616
2014-04-02 19:41:44 +02:00
Julius Volz bb957bc145 Change internal metric name label to __name__.
This also adds a check that forbids any user-supplied metrics to start
with the reserved label name prefix "__".

Change-Id: I2fe94c740b685ad05c4c670613cf2af7b9e1c1c0
2014-03-14 12:28:25 +01:00
Bernerd Schaefer a9b3602cea Register copies the provided baseLabels
This ensures that you can pass the same base label set into multiple
Register() calls, e.g.:

    labels := map[string]string{"key": "value"}
    prometheus.Register("metric_1", "", labels, ...)
    prometheus.Register("metric_2", "", labels, ...)

Change-Id: I951e5c2ed7844c74eb3716d1bf07126ce558f266
2013-09-11 17:38:00 +02:00
Matt T. Proud 4956aea5ac Protocol Buffer negotiation support in handler. 2013-07-01 17:14:58 +02:00
Bernerd Schaefer f60c783b29 Adhere to telemetry schema 0.0.2
* The schema and version of telemetry data is exposed through the
  Content-Type header instead of through a custom HTTP Header.

See [Prometheus Client Data Exposition Format][1] for more details.

[1]: https://docs.google.com/a/soundcloud.com/document/d/1ZjyKiKxZV83VI9ZKAXRGKaUKK2BIWCT7oiGBKDBpjEY/edit#heading=h.wnviarbnyxcj
2013-04-25 17:43:03 +02:00
Bernerd Schaefer 71dd60e431 Registry and Metrics implement json.Marshaler
* Drop `AsMarshallable()` from the Metric interface. Use
  `json.Marshaler` and `MarshalJSON()`, and leverage JSON struct tags
  where possible.

* Add `MarshalJSON()` to Registry and remove `dumpToWriter`, which
  makes the registry handler much simpler.

In addition to simplifying some of the marshalling behavior, this also
has the nice side effect of cutting down the number of
`map[string]interface{}` instances.
2013-04-19 15:07:24 +02:00
Bernerd Schaefer 9fccb96989 Remove timer.go and timer_test.go 2013-04-19 14:44:15 +02:00
Matt T. Proud f320d28a6c Rearrange file and package per convention.
WIP - Please review but do not merge.
2013-04-04 15:27:09 +02:00