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devel/ tree 80col updates; and other minor edits

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Signed-off-by: Mike Brown <brownwm@us.ibm.com>
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Mike Brown
2016-05-03 14:31:42 -05:00
parent 3a0d2d55c3
commit 136833f78e
6 changed files with 263 additions and 138 deletions
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docs/devel/instrumentation.md
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@@ -31,19 +31,30 @@ Documentation for other releases can be found at
<!-- END STRIP_FOR_RELEASE -->
<!-- END MUNGE: UNVERSIONED_WARNING -->
Instrumenting Kubernetes with a new metric
===================
The following is a step-by-step guide for adding a new metric to the Kubernetes code base.
## Instrumenting Kubernetes with a new metric
We use the Prometheus monitoring system's golang client library for instrumenting our code. Once you've picked out a file that you want to add a metric to, you should:
The following is a step-by-step guide for adding a new metric to the Kubernetes
code base.
We use the Prometheus monitoring system's golang client library for
instrumenting our code. Once you've picked out a file that you want to add a
metric to, you should:
1. Import "github.com/prometheus/client_golang/prometheus".
2. Create a top-level var to define the metric. For this, you have to:
1. Pick the type of metric. Use a Gauge for things you want to set to a particular value, a Counter for things you want to increment, or a Histogram or Summary for histograms/distributions of values (typically for latency). Histograms are better if you're going to aggregate the values across jobs, while summaries are better if you just want the job to give you a useful summary of the values.
1. Pick the type of metric. Use a Gauge for things you want to set to a
particular value, a Counter for things you want to increment, or a Histogram or
Summary for histograms/distributions of values (typically for latency).
Histograms are better if you're going to aggregate the values across jobs, while
summaries are better if you just want the job to give you a useful summary of
the values.
2. Give the metric a name and description.
3. Pick whether you want to distinguish different categories of things using labels on the metric. If so, add "Vec" to the name of the type of metric you want and add a slice of the label names to the definition.
3. Pick whether you want to distinguish different categories of things using
labels on the metric. If so, add "Vec" to the name of the type of metric you
want and add a slice of the label names to the definition.
https://github.com/kubernetes/kubernetes/blob/cd3299307d44665564e1a5c77d0daa0286603ff5/pkg/apiserver/apiserver.go#L53
https://github.com/kubernetes/kubernetes/blob/cd3299307d44665564e1a5c77d0daa0286603ff5/pkg/kubelet/metrics/metrics.go#L31
@@ -53,13 +64,17 @@ We use the Prometheus monitoring system's golang client library for instrumentin
https://github.com/kubernetes/kubernetes/blob/cd3299307d44665564e1a5c77d0daa0286603ff5/pkg/kubelet/metrics/metrics.go#L74
https://github.com/kubernetes/kubernetes/blob/cd3299307d44665564e1a5c77d0daa0286603ff5/pkg/apiserver/apiserver.go#L78
4. Use the metric by calling the appropriate method for your metric type (Set, Inc/Add, or Observe, respectively for Gauge, Counter, or Histogram/Summary), first calling WithLabelValues if your metric has any labels
4. Use the metric by calling the appropriate method for your metric type (Set,
Inc/Add, or Observe, respectively for Gauge, Counter, or Histogram/Summary),
first calling WithLabelValues if your metric has any labels
https://github.com/kubernetes/kubernetes/blob/3ce7fe8310ff081dbbd3d95490193e1d5250d2c9/pkg/kubelet/kubelet.go#L1384
https://github.com/kubernetes/kubernetes/blob/cd3299307d44665564e1a5c77d0daa0286603ff5/pkg/apiserver/apiserver.go#L87
These are the metric type definitions if you're curious to learn about them or need more information:
These are the metric type definitions if you're curious to learn about them or
need more information:
https://github.com/prometheus/client_golang/blob/master/prometheus/gauge.go
https://github.com/prometheus/client_golang/blob/master/prometheus/counter.go
https://github.com/prometheus/client_golang/blob/master/prometheus/histogram.go