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Running Gnocchi
To run Gnocchi, simply run the HTTP server and metric daemon:
gnocchi-api
gnocchi-metricdRunning As A WSGI Application
It's possible – and strongly advised – to run Gnocchi through a WSGI service such as mod_wsgi or any other WSGI application. The file gnocchi/rest/app.wsgi provided with Gnocchi allows you to enable Gnocchi as a WSGI application. For other WSGI setup you can refer to the pecan deployment documentation.
How to scale out the Gnocchi HTTP REST API tier
The Gnocchi API tier runs using WSGI. This means it can be run using Apache httpd and mod_wsgi, or other HTTP daemon such as uwsgi. You should configure the number of process and threads according to the number of CPU you have, usually around 1.5 × number of CPU. If one server is not enough, you can spawn any number of new API server to scale Gnocchi out, even on different machines.
How many metricd workers do we need to run
By default, gnocchi-metricd daemon spans all your CPU power in order to maximize CPU utilisation when computing metric aggregation. You can use the gnocchi status command to query the HTTP API and get the cluster status for metric processing. It’ll show you the number of metric to process, known as the processing backlog for gnocchi-metricd. As long as this backlog is not continuously increasing, that means that gnocchi-metricd is able to cope with the amount of metric that are being sent. In case this number of measure to process is continuously increasing, you will need to (maybe temporarily) increase the number of gnocchi-metricd daemons. You can run any number of metricd daemon on any number of servers.
How to monitor Gnocchi
The /v1/status endpoint of the HTTP API returns various information, such as the number of measures to process (measures backlog), which you can easily monitor (see How many metricd workers do we need to run). Making sure that the HTTP server and gnocchi-metricd daemon are running and are not writing anything alarming in their logs is a sign of good health of the overall system.
Total measures for backlog status may not accurately reflect the number of points to be processed when measures are submitted via batch.
How to backup and restore Gnocchi
In order to be able to recover from an unfortunate event, you need to backup both the index and the storage. That means creating a database dump (PostgreSQL or MySQL) and doing snapshots or copy of your data storage (Ceph, S3, Swift or your file system). The procedure to restore is no more complicated than initial deployment: restore your index and storage backups, reinstall Gnocchi if necessary, and restart it.