Using kubernetes policy.linkerd.io with fluentbit.fluent.io

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Pulumi · Accepted Answer

When you want to work with Kubernetes, and particularly when dealing with specific services like Linkerd and Fluent Bit, you'll generally perform a couple of different actions:

1. **Deploy the services onto your cluster:** You'll need the appropriate container images and configurations to get Linkerd and Fluent Bit running on your Kubernetes cluster.
2. **Configure networking policies:** These can include defining how pods communicate within the cluster and how their communications are logged and tracked, which is where Linkerd and Fluent Bit can work together.

For Linkerd, you often use `NetworkPolicy` resources to define fine-grained control over the network traffic in and out of your services. On the other hand, Fluent Bit is a logging and monitoring solution which you can use to collect logs from within your cluster and ship them to various destinations. It's not directly related to Kubernetes Networking Policies, but you may want your `NetworkPolicy` to allow network traffic required for Fluent Bit to function correctly.

Below is a simplified Pulumi program written in TypeScript that demonstrates how you might set up a NetworkPolicy for a Linkerd-enabled Kubernetes cluster and configure it to allow Fluent Bit pods to communicate as needed.

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

// Define a Kubernetes NetworkPolicy that allows traffic to Linkerd-enabled pods
// and permits Fluent Bit to collect logs from those pods.
const linkerdPolicy = new k8s.networking.v1.NetworkPolicy("linkerd-policy", {
    metadata: {
        namespace: "linkerd", // Ensure this is the namespace where Linkerd is running.
    },
    spec: {
        // Select all pods with the label "linkerd.io/control-plane-ns: linkerd".
        // This label selects the Linkerd control plane components.
        podSelector: {
            matchLabels: {
                "linkerd.io/control-plane-ns": "linkerd",
            },
        },
        // We use an Ingress rule to allow all incoming traffic to the Linkerd pods,
        // You should restrict this based on your actual requirements.
        ingress: [{
            from: [{
                // This configuration allows pods with the 'app: fluentbit' label to communicate 
                // with Linkerd components. Make sure Fluent Bit pods have this label.
                podSelector: {
                    matchLabels: { "app": "fluentbit" },
                },
            }],
        }],
        // Outgoing traffic from Linkerd components to Fluent Bit is allowed.
        // Fluent Bit typically does not need to be contacted by Linkerd components,
        // but in case it does, you should tailor these rules according to your needs.
        egress: [{
            to: [{
                podSelector: {
                    matchLabels: { "app": "fluentbit" },
                },
            }],
        }],
        // The policy types "Ingress" and "Egress" indicate that the rules for incoming and outgoing traffic are set.
        policyTypes: ["Ingress", "Egress"],
    },
});

// Export the NetworkPolicy name
export const networkPolicyName = linkerdPolicy.metadata.name;
```

In the program:

- We're creating a `NetworkPolicy` resource that's designed to specifically target the pods that Linkerd uses based on a label selector.
- Ingress and Egress rules within a `NetworkPolicy` are used to control the flow of traffic. In this example, we've assumed that our Fluent Bit pods have the label "app: fluentbit".
- The `namespace` is set to "linkerd", which is a common namespace used for Linkerd deployments. Make sure you adjust this according to your actual Linkerd setup.

This basic setup assumes that you have already deployed Linkerd and Fluent Bit onto your Kubernetes cluster. If not, you would need additional Pulumi code to handle the deployment of these services, which typically involves applying their respective Helm Charts or Kubernetes manifests.

Remember that networking policies are like a firewall for Kubernetes pods, and they help secure your cluster by controlling ingress (incoming) and egress (outgoing) traffic.

You typically apply more granular and specific policies that align with the security and operational requirements of your environment. Always test policies in a development or staging environment before applying them to production.

Lastly, Pulumi programs must be run in an environment where Pulumi CLI is installed, and you've set up your desired cloud provider (in this case, a configured kubeconfig file that points to the cluster where you want to deploy these resources). To run the Pulumi program, you'd use commands like `pulumi up` to provision or update resources according to the specified program.