Deploy the deploy-flask helm chart on Kubernetes

Question

Pulumi · Accepted Answer

To deploy a Flask application using a Helm chart on a Kubernetes cluster, you would typically follow these steps:

1. Ensure you have a Kubernetes cluster running and `kubectl` is configured to interact with it.
2. Package your Flask application into a Docker image and push it to a container registry.
3. Create a Helm chart for your Flask application or use an existing one if available.
4. Update the Helm chart values to use your Docker image.
5. Deploy the Helm chart to your Kubernetes cluster using Helm commands or manage it through Pulumi.

Pulumi can be used to automate the deployment of the Helm chart to Kubernetes. Below is a Pulumi program written in TypeScript that demonstrates how to deploy a Flask application packaged as a Helm chart. This assumes you have a `deploy-flask` Helm chart that's accessible in a chart repository or your file system.

Before you run this program, ensure you have Pulumi installed and configured with the appropriate Kubernetes provider.

Firstly, you'll need to import the required Pulumi and Kubernetes packages for TypeScript:

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

Then, you can create a new Pulumi stack that deploys your `deploy-flask` Helm chart:

```typescript
const flaskAppChart = new k8s.helm.v3.Chart("flask-app", {
    chart: "deploy-flask", // The name of your Helm chart.
    version: "1.0.0", // Specify the version of the Helm chart.
    fetchOpts: {
        // If your chart is hosted in a remote repository, specify the repo URL here.
        // Example: repo: "http://myhelmrepo.org/charts"
    },
    values: {
        // Override default values from the Helm chart here.
        // For instance, you might want to specify the image repository and tag for your Flask app:
        // image: {
        //     repository: "my-repo/my-flask-app",
        //     tag: "v1.0.0"
        // }
        // Refer to your Helm chart's 'values.yaml' file for value keys and structure.
    },
});

// Export the deployment's service name and IP address to easily access the deployed Flask application.
export const appName = flaskAppChart.getResourceProperty("v1/Service", "my-flask-app-service", "metadata").apply(m => m.name);
export const appExternalIP = flaskAppChart.getResourceProperty("v1/Service", "my-flask-app-service", "status").apply(status => status.loadBalancer.ingress[0].ip);

```

Explanation:

1. `import * as k8s from "@pulumi/kubernetes";` - This line imports the Pulumi Kubernetes package which allows you to write Kubernetes resources in Pulumi programs.

2. `import * as pulumi from "@pulumi/pulumi";` - This imports the core Pulumi package.

3. `const flaskAppChart = new k8s.helm.v3.Chart("flask-app", {...});` - Here, we are creating a new Helm chart resource within our Pulumi program. The first argument (`"flask-app"`) is the name we're assigning to this instance of the Chart resource.

- `chart: "deploy-flask"` - Replace this with the name of your Helm chart.

- `version: "1.0.0"` - This is the version of the Helm chart that you wish to deploy. It's important to specify this to ensure that the right version is being used.

- `fetchOpts: {}` - This optional block can be used if your Helm chart is in a remote Helm repository. Use it to specify the repo URL and other fetching options.

- `values: {}` - This is a set of overrides for default values specified in the Helm chart's `values.yaml` file. It is essential to align these values with your application requirements.

4. `export` statements - These lines will output the service name and IP address of your Flask application, assuming it is exposed via a Kubernetes Service of type `LoadBalancer`. This way, once the deployment is complete, Pulumi will print these values to the console, and you'll be able to access your Flask application.

Once this program is set up, you can run it using the Pulumi CLI. First, create a new Pulumi stack with `pulumi stack init`, then run `pulumi up` to deploy your Helm chart. Pulumi will automatically handle the dependencies between resources, create a new release using the Helm chart, and provide you with the outputs that can be used to access your Flask application.