Cluster Health Monitoring with Prometheus

Question

Pulumi · Accepted Answer

To monitor the health of a cluster with Prometheus, we'll need to do a couple of things. Prometheus is an open-source systems monitoring and alerting toolkit. It collects and stores its metrics as time series data, i.e., metrics information is stored with the timestamp at which it was recorded, alongside optional key-value pairs called labels.

In the context of Pulumi and cloud infrastructure, we'll typically want to deploy Prometheus within our Kubernetes cluster, configure it to scrape metrics from our applications, and potentially integrate it with Grafana for dashboarding purposes.

Here's a high-level overview of the steps we'll take in our Pulumi program:
1. Provision a Kubernetes cluster (if you don't already have one).
2. Deploy Prometheus into this cluster using a `Deployment` and `Service`.
3. Apply the necessary Prometheus configuration to scrape metrics from our applications.
4. (Optional) Deploy Grafana and configure it to use Prometheus as a data source for monitoring.

Below is a simple Pulumi program using AWS as the cloud provider (running a Kubernetes cluster with the Elastic Kubernetes Service, EKS), showing you how to set up Prometheus for monitoring cluster health. I'm assuming you have preconfigured your AWS provider and have Pulumi installed.

Here is how to install Pulumi:
```bash
# With Homebrew on macOS:
brew install pulumi

# With Chocolatey on Windows:
choco install pulumi

# With PowerShell on Windows, macOS, or Linux:
iwr https://get.pulumi.com | sh
```

After installing Pulumi, you'll need to log in to the Pulumi service:
```bash
pulumi login
```

Next, ensure you have your AWS credentials properly set up. You can do that by configuring the AWS CLI with:
```bash
aws configure
```

Now, let's proceed to the code:

```python
import pulumi
import pulumi_aws as aws
import pulumi_kubernetes as k8s

# Create an AWS EKS cluster for our Kubernetes cluster.
eks_cluster = aws.eks.Cluster("eks-cluster",
                               role_arn=aws_iam_role.eks_role.arn,
                               vpc_config=aws_eks.ClusterVpcConfigArgs(
                                   public_access_cidrs=["0.0.0.0/0"],
                                   security_group_ids=[aws_security_group.eks_sg.id]
                               ))

# Use the EKS cluster's kubeconfig as the kubeconfig for Pulumi Kubernetes Provider 
kubeconfig = eks_cluster.kubeconfig.apply(lambda kc: kc)
k8s_provider = k8s.Provider("k8s-provider", kubeconfig=kubeconfig)

# Deploy Prometheus to the Kubernetes cluster.
app_labels = {"app": "prometheus"}
prometheus_deployment = k8s.apps.v1.Deployment("prometheus-deployment",
                                               metadata=k8s.meta.v1.ObjectMetaArgs(labels=app_labels),
                                               spec=k8s.apps.v1.DeploymentSpecArgs(
                                                   selector=k8s.meta.v1.LabelSelectorArgs(match_labels=app_labels),
                                                   replicas=1,
                                                   template=k8s.core.v1.PodTemplateSpecArgs(
                                                       metadata=k8s.meta.v1.ObjectMetaArgs(labels=app_labels),
                                                       spec=k8s.core.v1.PodSpecArgs(
                                                           containers=[k8s.core.v1.ContainerArgs(
                                                               name="prometheus",
                                                               image="prom/prometheus:v2.26.0"
                                                           )]
                                                       )
                                                   )
                                               ), opts=pulumi.ResourceOptions(provider=k8s_provider))

# Expose Prometheus using a Kubernetes Service.
prometheus_service = k8s.core.v1.Service("prometheus-service",
                                         metadata=k8s.meta.v1.ObjectMetaArgs(labels=app_labels),
                                         spec=k8s.core.v1.ServiceSpecArgs(
                                             selector=app_labels,
                                             ports=[k8s.core.v1.ServicePortArgs(
                                                 port=9090,
                                                 target_port=9090
                                             )]
                                         ), opts=pulumi.ResourceOptions(provider=k8s_provider))

# Export the Prometheus service endpoint.
prometheus_endpoint = pulumi.Output.concat("http://", prometheus_service.status.apply(lambda s: s.load_balancer.ingress[0].hostname))

pulumi.export("prometheus_endpoint", prometheus_endpoint)

# Replace aws_iam_role, aws_security_group, and other AWS specific resources with the actual declarations.
```
This Pulumi program performs the following actions:
- Provisions an EKS cluster and sets up the required network configuration.
- Creates a deployment for Prometheus within the EKS cluster using Pulumi's Kubernetes provider.
- Sets up a service to expose Prometheus inside the cluster.
- Exports the endpoint where Prometheus can be accessed.

Please replace the placeholder AWS resources such as `aws_iam_role`, `aws_security_group`, etc., with actual declarations according to your environment and requirements.

Also, note that the above code only sets up Prometheus but does not configure scraping or alerting rules. You'll need to create a `ConfigMap` with the Prometheus scrape configuration according to what services you need to monitor in your cluster.

For detailed configuration, such as setting up scraping rules, alerting rules, and Grafana dashboarding, you'll need to refer to the Prometheus and Grafana documentation and apply the necessary resources via Pulumi's Kubernetes provider.