#Quick Start

This guide helps new users quickly set up Tekton Chains to secure their CI/CD pipelines by generating and verifying cryptographic signatures for Tekton TaskRuns.

#Introduction

#Use Cases

Tekton Chains helps you secure your software supply chain by automatically generating cryptographic signatures for your build artifacts. This quick start demonstrates how to set up Tekton Chains, generate a signing key, run a simple task, and verify its signature.

#Estimated Reading Time

10-15 minutes

#Important Notes

• Tekton Chains is installed by default in the tekton-pipelines namespace when using Alauda Devops Pipelines Operator
• The signing keys should be securely managed; in production environments, consider using a key management system (KMS)
• This guide uses the simplest configuration for demonstration purposes

#Prerequisites

• A Kubernetes cluster with Tekton Pipelines and Tekton Chains installed via Alauda Devops Pipelines Operator
• kubectl CLI installed and configured to access your cluster
• tkn (Tekton CLI) installed
• cosign CLI installed (for key generation and signature verification)

#Process Overview

Step	Operation	Description
1	Generate signing keys	Create a key pair for signing artifacts
2	Configure Tekton Chains	Set up Chains to use the Tekton storage backend
3	Run a sample task	Create and run a simple TaskRun
4	Verify the signature	Extract and verify the signature of the TaskRun

#Step-by-Step Instructions

#Step 1: Generate Signing Keys

Tekton Chains uses cryptographic keys to sign artifacts. By default, it looks for a secret named signing-secrets in the Chains namespace.

1. Install cosign if you haven't already

2. Generate a key pair and store it as a Kubernetes secret:

   cosign generate-key-pair k8s://tekton-pipelines/signing-secrets

   You'll be prompted to enter a password, which will be stored in the secret. This command also generates a public key cosign.pub in the current folder that will be used later during verification.

3. Verify the secret was created:

   kubectl get secret signing-secrets -n tekton-pipelines

#Step 2: Configure Tekton Chains

By default, Tekton Chains is configured to store signatures in an OCI registry. For this quick start, we'll configure it to store signatures as annotations on the TaskRun itself.

1. Configure Chains to use the Tekton storage backend:

   kubectl patch configmap chains-config -n tekton-pipelines -p='{"data":{"artifacts.taskrun.storage": "tekton"}}'

2. Set the format to in-toto (SLSA v0.2):

   kubectl patch configmap chains-config -n tekton-pipelines -p='{"data":{"artifacts.taskrun.format": "in-toto"}}'

3. Restart the Chains controller to apply the changes:

   kubectl delete pod -n tekton-pipelines -l app=tekton-chains-controller

#Step 3: Run a Sample Task

Now let's create a simple TaskRun that Chains will automatically sign.

1. Create a simple Task and TaskRun:

   cat <<EOF | kubectl apply -f -
   apiVersion: tekton.dev/v1
   kind: Task
   metadata:
     name: hello-world
   spec:
     steps:
       - name: hello
         image: alpine
         script: |
           #!/bin/sh
           
           echo 'Hello, Tekton Chains!'
   ---
   apiVersion: tekton.dev/v1
   kind: TaskRun
   metadata:
     name: hello-world-run
   spec:
     taskRef:
       name: hello-world
   EOF
   TIP

   If working in a air-gapped environment, please modify the image to a local containing sh.

2. Wait for the TaskRun to complete:

   kubectl get taskrun hello-world-run -w

   Wait until the status shows Succeeded.

#Step 4: Verify the Signature

Once the TaskRun completes, Tekton Chains will automatically sign it. Let's verify the signature.

1. Get the TaskRun UID:

   export TASKRUN_UID=$(kubectl get taskrun hello-world-run -o jsonpath='{.metadata.uid}')

2. Extract the signature:

   kubectl get taskrun hello-world-run -o jsonpath="{.metadata.annotations.chains\\.tekton\\.dev/signature-taskrun-$TASKRUN_UID}" | base64 -d > signature

3. Verify the signature using cosign:

   cosign verify-blob-attestation \
     --key cosign.pub \
     --signature signature \
     --type slsaprovenance \
     --check-claims=false \
     --insecure-ignore-tlog \
     /dev/null

   If successful, you'll see Verified OK.

4. Clean up:

   kubectl delete taskrun hello-world-run
   kubectl delete task hello-world

#Expected Results

After completing this quick start:

• You have a working Tekton Chains setup with a signing key
• Your TaskRuns are automatically signed when they complete
• You can verify the signatures to ensure the integrity of your builds

This demonstrates the basic functionality of Tekton Chains. In a real-world scenario, you would:

1. Configure Chains to sign container images and store signatures in your registry
2. Set up a verification step in your deployment process
3. Potentially use a cloud KMS for more secure key management

For more advanced configurations, refer to the Tekton Chains documentation.