This application consumes application and service metrics from Cloud Foundry. All the metrics are exposed on a
/metrics endpoint for a Prometheus server to scrape.
The application will get metrics for all apps and services that the user has access to.
To use paas-prometheus-exporter with GOV.UK PaaS, see Use the PaaS Prometheus exporter app in the documentation.
If you use StatsD rather than Prometheus see alphagov/paas-metric-exporter.
How metrics are collected
The applications and services are automatically discovered using the Cloud Foundry API every
update-frequency seconds. This means it might take a little time while a new application or service's metrics are exposed.
If an application is stopped or deleted, or a service it deleted, the relevant metrics will be removed. (Only when the next app/service list refresh happens)
When the metrics collection for an app/service encounters an error it will be restarted, but the metrics might be missing for one update cycle. In this case you should see an error logged.
For every application we create a persistent connection to a Doppler endpoint which automatically sends any new application event or metric. When a Prometheus scrape occurs the latest metric values are exposed.
For every service instance we poll all metrics for the last 15 minutes from Log Cache every
scrape-interval seconds. Only the newest values are used for any metrics. When a Prometheus scrape occurs we expose the state of the metrics from the last refresh, but we also add the original timestamps.
Available application metrics
The following metrics will be exported for every application instance.
||gauge||CPU utilisation in percent (0-100)|
||gauge||Disk usage in bytes|
||gauge||Disk utilisation in percent (0-100)|
||gauge||Memory usage in bytes|
||gauge||Memory utilisation in percent (0-100)|
||counter||Increased by one if the application crashed for any reason|
||counter||Number of requests processed broken down by
||histogram||Timing of processed requests broken down by
Available service metrics
The service metrics are different service-by-service, please check the
/metrics endpoint to see what metrics are exposed exactly.
Refer to the PaaS Technical Documentation for instructions on how to set up the metrics exporter app. Information on the configuration options are in the following table.
|Configuration Option||Application Flag||Environment Variable||Notes|
|Configuration Option||Application Flag||Environment Variable||Default value||Notes|
|Bind port||prometheus-bind-port||PORT||8080||The port that the application will bind to.|
|Update frequency||update-frequency||UPDATE_FREQUENCY||300||The time in seconds, that takes between each apps update call|
|Scrape interval||scrape-interval||SCRAPE_INTERVAL||60||Scrape interval in seconds. Set this to the same value as the Prometheus scrape interval. The service metrics will be refreshed using the same interval|
||Usually it's unnecessary to override this|
|Basic-auth username||auth-username||AUTH_USERNAME||Apply basic auth protection to the /metrics endpoint||Leave this field blank to disable basic auth|
With each update of the PaaS Prometheus Exporter you should update the version number located in
main.go file at the top of the
To run the test suite, then run
make test from the root of this repository.
We generate some test mocks using counterfeiter. The mocks need to be regenerated if the mocked interfaces are changed.
To install counterfeiter please run first:
go get github.com/maxbrunsfeld/counterfeiter
To generate the mocks:
The application is partly based on