Chapter 1. About Prometheus
Prometheus is an open-source systems and service monitoring and alerting toolkit that you can use to monitor services deployed in your Red Hat OpenShift environment. Prometheus collects and stores metrics from configured services at given intervals, evaluates rule expressions, displays the results, and can trigger alerts if a specified condition becomes true.
Red Hat support for Prometheus is limited to the setup and configuration recommendations provided in Red Hat product documentation.
To monitor OpenShift services, you must configure each service to expose an endpoint to Prometheus format. This endpoint is an HTTP interface that provides a list of metrics and the current values of the metrics. Prometheus periodically scrapes each target-defined endpoint and writes the collected data to its database. Prometheus gathers data over an extended time, rather than just for the currently running session. Prometheus stores the data so that you can graphically visualize and run queries on the data.
1.1. Prometheus queries
In the Prometheus web interface, you can write queries in Prometheus Query Language (PromQL) to select and aggregate the collected data.
For example, you can use the following query to select all of the values that Prometheus has recorded within the last five minutes for all time-series data that has http_requests_total as the metric name:
http_requests_total[5m]
To further define or filter the results of the query, specify a label (a key:value pair) for the metric. For example, you can use the following query to select all the values that Prometheus has recorded within the last five minutes for all time-series data that has the metric name http_requests_total and a job label set to integration:
http_requests_total{job="integration"}[5m]1.2. Options for displaying Prometheus data
You can specify how Prometheus handles the result of a query:
- View Prometheus data as tabular data in Prometheus’s expression browser.
- Consume Prometheus data by external systems through the Prometheus HTTP API.
Display Prometheus data in a graph.
Prometheus provides a default graphical view of the data that it collects. If you prefer a more robust graphical dashboard to view Prometheus data, Grafana is a popular choice.
NoteGrafana is a community-supported feature. Deploying Grafana to monitor Red Hat products is not supported with Red Hat production service level agreements (SLAs).
You can also use the PromQL language to configure alerts in Prometheus’s Alertmanager tool.
1.3. Using Prometheus to monitor Fuse
You can use Prometheus to monitor Fuse services as follows:
- Fuse applications on OpenShift
- Fuse on OpenShift is the distribution of Fuse for running integration applications on OpenShift (supported on the Red Hat Enterprise Linux operating system). You can use Prometheus on an on-premise OpenShift cluster or on a single-node cluster, such as Minishift or the Red Hat Container Development Kit. For more information about Fuse on OpenShift, see Fuse on OpenShift Guide.
- Fuse Online infrastructure components and Fuse Online integration applications
- Fuse Online is the distribution of Fuse for non-expert integrators with a simplified workflow accessed through a browser based UI. For more information about Fuse Online, see Integrating Applications with Fuse Online.
- Using Prometheus to monitor Fuse applications on OpenShift Online is not supported.
- Grafana is a community-supported feature. Deploying Grafana to monitor Red Hat Integration products is not supported with Red Hat production service level agreements (SLAs).
Additional resources
For information on installing and developing with Fuse on OpenShift, see the Fuse on OpenShift Guide.
