Configuring PodMonitor label selectors for specific pods

Question

Pulumi · Accepted Answer

To configure a `PodMonitor` for specific pods in Kubernetes using Pulumi, you would define a set of label selectors that match the labels on the pods you wish to monitor. A `PodMonitor` is a custom resource used in conjunction with the Prometheus Operator to define the desired scraping targets for Prometheus.

Here is a step-by-step explanation of how to achieve this:

1. **Defining Pod Labels**: Make sure the pods you want to monitor have specific labels assigned to them. These labels will be used by the `PodMonitor` to discover the pods.

Example pod label:
   ```yaml
   labels:
     app: my-app
     monitor: "true"
   ```

2. **Creating a `PodMonitor` Custom Resource**: A `PodMonitor` is a Custom Resource Definition (CRD) provided by the Prometheus Operator. You would define a `PodMonitor` resource with label selectors that match the labels of the pods you want to monitor.

3. **Label Selectors in `PodMonitor`**: Inside the `PodMonitor` definition, under the `spec` section, you would specify `selector.matchLabels` or `selector.matchExpressions` to define which pod labels should be targeted for monitoring.

Here's how this could look in a Pulumi program written in TypeScript:

```typescript
import * as k8s from '@pulumi/kubernetes';

// This is a Pulumi program that creates a PodMonitor resource with specific label selectors.
// The PodMonitor will match pods that have the labels 'app: my-app' and 'monitor: "true"'.

// Define the PodMonitor resource using the Kubernetes provider
const podMonitor = new k8s.apiextensions.CustomResource("my-pod-monitor", {
    apiVersion: "monitoring.coreos.com/v1",
    kind: "PodMonitor",
    metadata: {
        // Replace with the namespace where your pods and Prometheus Operator are located
        namespace: "monitoring",
        name: "my-app-pod-monitor",
    },
    spec: {
        // Define which pods to select based on their labels
        // This should match the labels on your pods you want to monitor
        selector: {
            matchLabels: {
                app: "my-app",
                monitor: "true",
            },
        },
        // Define the endpoints for scraping metrics from the matched pods
        podMetricsEndpoints: [
            {
                port: "http-metrics", // The name of the port in your pod spec that exposes metrics
                path: "/metrics", // The path that exposes metrics, default for Prometheus is /metrics
            },
        ],
    },
}, {
    dependsOn: [], // Here you would optionally specify any other resources that need to be created first
    provider: undefined, // Set the Kubernetes provider if using a specific one
});

// Optionally, you can export the PodMonitor's name to use it elsewhere
export const podMonitorName = podMonitor.metadata.name;
```

In the program above, we are defining a `PodMonitor` resource named `my-app-pod-monitor` in the `monitoring` namespace. The `selector` field contains `matchLabels`, which points to the set of labels on the pods that Prometheus should monitor.

This assumes the presence of the Prometheus Operator in your cluster, which defines the `PodMonitor` CRD.

**Note:** Make sure your Pulumi CLI and Kubernetes provider support the `PodMonitor` CRD and the API version you are targeting. The Prometheus Operator must be installed in your cluster, and its CRD definitions must be loaded. If you need to install the Prometheus Operator, you can find resources and Helm charts to do this as part of the Prometheus community or operator documentation.