Chapter 9. Managing metrics
You can collect metrics to monitor how cluster components and your own workloads are performing.
9.1. Understanding metrics
In Red Hat OpenShift Service on AWS, cluster components are monitored by scraping metrics exposed through service endpoints. You can also configure metrics collection for user-defined projects. Metrics enable you to monitor how cluster components and your own workloads are performing.
You can define the metrics that you want to provide for your own workloads by using Prometheus client libraries at the application level.
In Red Hat OpenShift Service on AWS, metrics are exposed through an HTTP service endpoint under the /metrics
canonical name. You can list all available metrics for a service by running a curl
query against http://<endpoint>/metrics
. For instance, you can expose a route to the prometheus-example-app
example application and then run the following to view all of its available metrics:
$ curl http://<example_app_endpoint>/metrics
Example output
# HELP http_requests_total Count of all HTTP requests # TYPE http_requests_total counter http_requests_total{code="200",method="get"} 4 http_requests_total{code="404",method="get"} 2 # HELP version Version information about this binary # TYPE version gauge version{version="v0.1.0"} 1
Additional resources
9.2. Setting up metrics collection for user-defined projects
You can create a ServiceMonitor
resource to scrape metrics from a service endpoint in a user-defined project. This assumes that your application uses a Prometheus client library to expose metrics to the /metrics
canonical name.
This section describes how to deploy a sample service in a user-defined project and then create a ServiceMonitor
resource that defines how that service should be monitored.
9.2.1. Deploying a sample service
To test monitoring of a service in a user-defined project, you can deploy a sample service.
Procedure
-
Create a YAML file for the service configuration. In this example, it is called
prometheus-example-app.yaml
. Add the following deployment and service configuration details to the file:
apiVersion: v1 kind: Namespace metadata: name: ns1 --- apiVersion: apps/v1 kind: Deployment metadata: labels: app: prometheus-example-app name: prometheus-example-app namespace: ns1 spec: replicas: 1 selector: matchLabels: app: prometheus-example-app template: metadata: labels: app: prometheus-example-app spec: containers: - image: ghcr.io/rhobs/prometheus-example-app:0.4.2 imagePullPolicy: IfNotPresent name: prometheus-example-app --- apiVersion: v1 kind: Service metadata: labels: app: prometheus-example-app name: prometheus-example-app namespace: ns1 spec: ports: - port: 8080 protocol: TCP targetPort: 8080 name: web selector: app: prometheus-example-app type: ClusterIP
This configuration deploys a service named
prometheus-example-app
in the user-definedns1
project. This service exposes the customversion
metric.Apply the configuration to the cluster:
$ oc apply -f prometheus-example-app.yaml
It takes some time to deploy the service.
You can check that the pod is running:
$ oc -n ns1 get pod
Example output
NAME READY STATUS RESTARTS AGE prometheus-example-app-7857545cb7-sbgwq 1/1 Running 0 81m
9.2.2. Specifying how a service is monitored
To use the metrics exposed by your service, you must configure Red Hat OpenShift Service on AWS monitoring to scrape metrics from the /metrics
endpoint. You can do this using a ServiceMonitor
custom resource definition (CRD) that specifies how a service should be monitored, or a PodMonitor
CRD that specifies how a pod should be monitored. The former requires a Service
object, while the latter does not, allowing Prometheus to directly scrape metrics from the metrics endpoint exposed by a pod.
This procedure shows you how to create a ServiceMonitor
resource for a service in a user-defined project.
Prerequisites
-
You have access to the cluster as a user with the
dedicated-admin
role or themonitoring-edit
role. For this example, you have deployed the
prometheus-example-app
sample service in thens1
project.NoteThe
prometheus-example-app
sample service does not support TLS authentication.
Procedure
-
Create a new YAML configuration file named
example-app-service-monitor.yaml
. Add a
ServiceMonitor
resource to the YAML file. The following example creates a service monitor namedprometheus-example-monitor
to scrape metrics exposed by theprometheus-example-app
service in thens1
namespace:apiVersion: monitoring.coreos.com/v1 kind: ServiceMonitor metadata: name: prometheus-example-monitor namespace: ns1 1 spec: endpoints: - interval: 30s port: web 2 scheme: http selector: 3 matchLabels: app: prometheus-example-app
NoteA
ServiceMonitor
resource in a user-defined namespace can only discover services in the same namespace. That is, thenamespaceSelector
field of theServiceMonitor
resource is always ignored.Apply the configuration to the cluster:
$ oc apply -f example-app-service-monitor.yaml
It takes some time to deploy the
ServiceMonitor
resource.Verify that the
ServiceMonitor
resource is running:$ oc -n <namespace> get servicemonitor
Example output
NAME AGE prometheus-example-monitor 81m
9.2.3. Example service endpoint authentication settings
You can configure authentication for service endpoints for user-defined project monitoring by using ServiceMonitor
and PodMonitor
custom resource definitions (CRDs).
The following samples show different authentication settings for a ServiceMonitor
resource. Each sample shows how to configure a corresponding Secret
object that contains authentication credentials and other relevant settings.
9.2.3.1. Sample YAML authentication with a bearer token
The following sample shows bearer token settings for a Secret
object named example-bearer-auth
in the ns1
namespace:
Example bearer token secret
apiVersion: v1
kind: Secret
metadata:
name: example-bearer-auth
namespace: ns1
stringData:
token: <authentication_token> 1
- 1
- Specify an authentication token.
The following sample shows bearer token authentication settings for a ServiceMonitor
CRD. The example uses a Secret
object named example-bearer-auth
:
Example bearer token authentication settings
apiVersion: monitoring.coreos.com/v1 kind: ServiceMonitor metadata: name: prometheus-example-monitor namespace: ns1 spec: endpoints: - authorization: credentials: key: token 1 name: example-bearer-auth 2 port: web selector: matchLabels: app: prometheus-example-app
Do not use bearerTokenFile
to configure bearer token. If you use the bearerTokenFile
configuration, the ServiceMonitor
resource is rejected.
9.2.3.2. Sample YAML for Basic authentication
The following sample shows Basic authentication settings for a Secret
object named example-basic-auth
in the ns1
namespace:
Example Basic authentication secret
apiVersion: v1 kind: Secret metadata: name: example-basic-auth namespace: ns1 stringData: user: <basic_username> 1 password: <basic_password> 2
The following sample shows Basic authentication settings for a ServiceMonitor
CRD. The example uses a Secret
object named example-basic-auth
:
Example Basic authentication settings
apiVersion: monitoring.coreos.com/v1 kind: ServiceMonitor metadata: name: prometheus-example-monitor namespace: ns1 spec: endpoints: - basicAuth: username: key: user 1 name: example-basic-auth 2 password: key: password 3 name: example-basic-auth 4 port: web selector: matchLabels: app: prometheus-example-app
9.2.3.3. Sample YAML authentication with OAuth 2.0
The following sample shows OAuth 2.0 settings for a Secret
object named example-oauth2
in the ns1
namespace:
Example OAuth 2.0 secret
apiVersion: v1 kind: Secret metadata: name: example-oauth2 namespace: ns1 stringData: id: <oauth2_id> 1 secret: <oauth2_secret> 2
The following sample shows OAuth 2.0 authentication settings for a ServiceMonitor
CRD. The example uses a Secret
object named example-oauth2
:
Example OAuth 2.0 authentication settings
apiVersion: monitoring.coreos.com/v1 kind: ServiceMonitor metadata: name: prometheus-example-monitor namespace: ns1 spec: endpoints: - oauth2: clientId: secret: key: id 1 name: example-oauth2 2 clientSecret: key: secret 3 name: example-oauth2 4 tokenUrl: https://example.com/oauth2/token 5 port: web selector: matchLabels: app: prometheus-example-app
- 1
- The key that contains the OAuth 2.0 ID in the specified
Secret
object. - 2 4
- The name of the
Secret
object that contains the OAuth 2.0 credentials. - 3
- The key that contains the OAuth 2.0 secret in the specified
Secret
object. - 5
- The URL used to fetch a token with the specified
clientId
andclientSecret
.
9.3. Querying metrics
The Red Hat OpenShift Service on AWS monitoring dashboard enables you to run Prometheus Query Language (PromQL) queries to examine metrics visualized on a plot. This functionality provides information about the state of a cluster and any user-defined workloads that you are monitoring.
As a dedicated-admin
, you can query one or more namespaces at a time for metrics about user-defined projects.
As a developer, you must specify a project name when querying metrics. You must have the required privileges to view metrics for the selected project.
9.3.1. Querying metrics for all projects as a cluster administrator
As a dedicated-admin
or as a user with view permissions for all projects, you can access metrics for all default Red Hat OpenShift Service on AWS and user-defined projects in the Metrics UI.
Only dedicated administrators have access to the third-party UIs provided with Red Hat OpenShift Service on AWS monitoring.
Prerequisites
-
You have access to the cluster as a user with the
dedicated-admin
role or with view permissions for all projects. -
You have installed the OpenShift CLI (
oc
).
Procedure
-
From the Administrator perspective in the Red Hat OpenShift Service on AWS web console, select Observe
Metrics. To add one or more queries, do any of the following:
Option Description Create a custom query.
Add your Prometheus Query Language (PromQL) query to the Expression field.
As you type a PromQL expression, autocomplete suggestions appear in a drop-down list. These suggestions include functions, metrics, labels, and time tokens. You can use the keyboard arrows to select one of these suggested items and then press Enter to add the item to your expression. You can also move your mouse pointer over a suggested item to view a brief description of that item.
Add multiple queries.
Select Add query.
Duplicate an existing query.
Select the Options menu next to the query, then choose Duplicate query.
Disable a query from being run.
Select the Options menu next to the query and choose Disable query.
To run queries that you created, select Run queries. The metrics from the queries are visualized on the plot. If a query is invalid, the UI shows an error message.
NoteQueries that operate on large amounts of data might time out or overload the browser when drawing time series graphs. To avoid this, select Hide graph and calibrate your query using only the metrics table. Then, after finding a feasible query, enable the plot to draw the graphs.
NoteBy default, the query table shows an expanded view that lists every metric and its current value. You can select ˅ to minimize the expanded view for a query.
- Optional: The page URL now contains the queries you ran. To use this set of queries again in the future, save this URL.
Explore the visualized metrics. Initially, all metrics from all enabled queries are shown on the plot. You can select which metrics are shown by doing any of the following:
Option Description Hide all metrics from a query.
Click the Options menu for the query and click Hide all series.
Hide a specific metric.
Go to the query table and click the colored square near the metric name.
Zoom into the plot and change the time range.
Either:
- Visually select the time range by clicking and dragging on the plot horizontally.
- Use the menu in the left upper corner to select the time range.
Reset the time range.
Select Reset zoom.
Display outputs for all queries at a specific point in time.
Hold the mouse cursor on the plot at that point. The query outputs will appear in a pop-up box.
Hide the plot.
Select Hide graph.
Additional resources
- For more information about creating PromQL queries, see the Prometheus query documentation.
9.3.2. Querying metrics for user-defined projects as a developer
You can access metrics for a user-defined project as a developer or as a user with view permissions for the project.
In the Developer perspective, the Metrics UI includes some predefined CPU, memory, bandwidth, and network packet queries for the selected project. You can also run custom Prometheus Query Language (PromQL) queries for CPU, memory, bandwidth, network packet and application metrics for the project.
Developers can only use the Developer perspective and not the Administrator perspective. As a developer, you can only query metrics for one project at a time. Developers cannot access the third-party UIs provided with Red Hat OpenShift Service on AWS monitoring.
Prerequisites
- You have access to the cluster as a developer or as a user with view permissions for the project that you are viewing metrics for.
- You have enabled monitoring for user-defined projects.
- You have deployed a service in a user-defined project.
-
You have created a
ServiceMonitor
custom resource definition (CRD) for the service to define how the service is monitored.
Procedure
-
From the Developer perspective in the Red Hat OpenShift Service on AWS web console, select Observe
Metrics. - Select the project that you want to view metrics for in the Project: list.
Select a query from the Select query list, or create a custom PromQL query based on the selected query by selecting Show PromQL. The metrics from the queries are visualized on the plot.
NoteIn the Developer perspective, you can only run one query at a time.
Explore the visualized metrics by doing any of the following:
Option Description Zoom into the plot and change the time range.
Either:
- Visually select the time range by clicking and dragging on the plot horizontally.
- Use the menu in the left upper corner to select the time range.
Reset the time range.
Select Reset zoom.
Display outputs for all queries at a specific point in time.
Hold the mouse cursor on the plot at that point. The query outputs appear in a pop-up box.
Additional resources
- For more information about creating PromQL queries, see the Prometheus query documentation.
9.4. Getting detailed information about a metrics target
In the Administrator perspective in the Red Hat OpenShift Service on AWS web console, you can use the Metrics targets page to view, search, and filter the endpoints that are currently targeted for scraping, which helps you to identify and troubleshoot problems. For example, you can view the current status of targeted endpoints to see when Red Hat OpenShift Service on AWS Monitoring is not able to scrape metrics from a targeted component.
The Metrics targets page shows targets for user-defined projects.
Prerequisites
-
You have access to the cluster as a user with the
dedicated-admin
role.
Procedure
In the Administrator perspective, select Observe
Targets. The Metrics targets page opens with a list of all service endpoint targets that are being scraped for metrics. This page shows details about targets for default Red Hat OpenShift Service on AWS and user-defined projects. This page lists the following information for each target:
- Service endpoint URL being scraped
- ServiceMonitor component being monitored
- The up or down status of the target
- Namespace
- Last scrape time
- Duration of the last scrape
Optional: The list of metrics targets can be long. To find a specific target, do any of the following:
Option Description Filter the targets by status and source.
Select filters in the Filter list.
The following filtering options are available:
Status filters:
- Up. The target is currently up and being actively scraped for metrics.
- Down. The target is currently down and not being scraped for metrics.
Source filters:
- Platform. Platform-level targets relate only to default Red Hat OpenShift Service on AWS projects. These projects provide core Red Hat OpenShift Service on AWS functionality.
- User. User targets relate to user-defined projects. These projects are user-created and can be customized.
Search for a target by name or label.
Enter a search term in the Text or Label field next to the search box.
Sort the targets.
Click one or more of the Endpoint Status, Namespace, Last Scrape, and Scrape Duration column headers.
Click the URL in the Endpoint column for a target to navigate to its Target details page. This page provides information about the target, including the following:
- The endpoint URL being scraped for metrics
- The current Up or Down status of the target
- A link to the namespace
- A link to the ServiceMonitor details
- Labels attached to the target
- The most recent time that the target was scraped for metrics