Introduction to Service Pipeline - Tekton basic

As modern software development shifts towards cloud-native architectures, service pipelines have become key to deploying, managing, and scaling microservices independently. In this post, we’ll explore the fundamentals of Tekton, a Kubernetes-native framework, is built to automate CI/CD processes for services and the power to build complex workflows.

We'll also discuss why you might want to use Tekton over traditional CI/CD tools like GitLab CI or GitHub Actions.

What is Tekton?

Tekton is a Kubernetes-based framework for defining, running, and managing CI/CD pipelines. Unlike traditional CI/CD systems that typically handle the deployment of entire applications, Tekton excels at managing service pipelines, which allow individual microservices to be built, tested, and deployed independently. This gives you the ability to release services faster and with more flexibility.

Why Use Tekton for Service Pipelines?

1. Kubernetes-Native and Cloud-Native Integration

Tekton is designed specifically for Kubernetes environments, making it a perfect fit for organizations running microservices or cloud-native applications. Unlike GitLab CI or GitHub Actions, which require some integration overhead, Tekton runs directly within Kubernetes clusters, taking full advantage of Kubernetes’ features.

2. Fine-Grained Control and Flexibility

Tekton provides more control over task execution, pipeline structure, and parameterization compared to traditional CI/CD tools. This flexibility allows you to build complex, customized workflows for each microservice from your code.

3. Vendor-Neutral, Open-Source Solution

Tekton is completely open-source and vendor-neutral, meaning you’re not locked into a specific CI/CD ecosystem like GitLab or GitHub. This gives you the freedom to use Tekton in any Kubernetes environment.

Key Concepts

• Tasks: Individual units of work, such as running a build or test.
• Pipelines: Collections of tasks that run in sequence or parallel.
• TaskRuns and PipelineRuns: Runtime instances of tasks and pipelines, allowing you to pass parameters dynamically.

Tekton Service Pipeline Example

Let’s walk through building a service pipeline that retrieves content from a URL, displays it, and then uses that content to generate a personalized message. I will add the in-line comments for clarification.

Tekton Task

A Task is the basic building block of a Tekton service pipeline. Below is a task that greets a user based on an input parameter.

cat <<EOF | kubectl apply --validate=false -f -
apiVersion: tekton.dev/v1
kind: Task
metadata:
  name: greet-task
spec:
  # params used to define input of the task
  params:
  - name: person
    type: string
    description: Who should we greet?
    default: world
  # we will define "what to do" in the steps [] here
  steps:
  - name: greet
    image: alpine # using whatever build image
    command:
    - echo
    args:
    - "Hello \$(params.person)!"
EOF

This task uses the Alpine image to echo a personalized greeting, which can be customized by passing a value for the person parameter.

tip

A Task is like docker image, meanwhile the TaskRun is a container

TaskRun Definition

The TaskRun below executes the task, allowing us to pass a specific value to the person parameter.

cat <<EOF | kubectl apply --validate=false -f -
apiVersion: tekton.dev/v1
kind: TaskRun
metadata:
  name: greet-task-run-1
spec:
  # this TaskRun is called from greet-task above
  taskRef:
    name: greet-task
  # we can pass argument(s) here
  params:
  - name: person
    value: "future engineers"
EOF

Applying this task, we can see the output in pod log:

$ kubectl get pod | grep greet-task-run-1
greet-task-run-1-pod        0/1     Completed   0              34s

$ kubectl logs greet-task-run-1-pod
Defaulted container "step-greet" out of: step-greet, prepare (init)
Hello future engineers!

info

There are a Tekton hub containing Tasks which has been written by community.

We will examine the community wget Task in next section

Tekton Pipeline and PipelineRun

Now, let’s define a service pipeline that uses multiple tasks. We’ll use the wget task to fetch content from the internet and then pass that content into our greeting task.

Install the Wget Task

First, install the wget community task from Tekton Hub:

kubectl apply -f https://api.hub.tekton.dev/v1/resource/tekton/task/wget/0.1/raw

Verify with kubectl get task we'll see the new wget Task.

Pipeline Definition

The following pipeline defines a sequence of tasks: fetching content from a URL wget, displaying that content cat, and greeting the user with the content as a message greet-task. Flow will be like this:

In this pipeline:

• fetch-content: Uses wget to download content from a URL and store it in a workspace.
• display-content: Reads the content and outputs it as a pipeline result.
• greet-with-content: Passes the fetched content as the greeting message in the final task.

cat <<EOF | kubectl apply --validate=false -f -
apiVersion: tekton.dev/v1
kind: Pipeline
metadata:
  name: greet-service-pipeline
  annotations:
    description: |
      Fetch content using wget, display it, and greet the user.
spec:
  # this Pipeline required a single URL param
  params:
  - name: sourceUrl
    description: The URL to fetch the content from
    type: string
    default: ""
  # workspace is used to share information between tasks
  # think of it like a persistent volume
  workspaces:
  - name: storage
  tasks:
  # start of "wget" task
  - name: fetch-content
    taskRef:
      name: wget
    params:
    - name: url
      value: "\$(params.sourceUrl)"
    - name: diroptions
      value:
        - "-P"
    workspaces:
    # you may wonder why name `wget-workspace`
    # please check https://hub.tekton.dev/tekton/task/wget
    - name: wget-workspace
      workspace: storage
  # start of "cat" task
  - name: display-content
    runAfter: [fetch-content]
    workspaces:
    - name: output
      workspace: storage
    # we can define the Task directly inside the Pipeline
    taskSpec:
      workspaces:
      - name: output
      steps:
      - name: cat-content
        image: busybox
        script: |
          #!/bin/sh
          cat \$(workspaces.output.path)/name | tee /tekton/results/fetchedContent
      # store the content and can be used in later tasks without workspace
      results:
      - name: fetchedContent
        description: The content fetched from the URL
  # start of "greet-task"
  - name: greet-with-content
    runAfter: [display-content]
    taskRef:
      name: greet-task
    params:
    - name: person
      value: "\$(tasks.display-content.results.fetchedContent)" # get value from another task
EOF

PipelineRun Definition

Here’s how you run the pipeline using a PipelineRun, specifying a URL to fetch content from:

cat <<EOF | kubectl apply --validate=false -f -
apiVersion: tekton.dev/v1
kind: PipelineRun
metadata:
  name: greet-service-pipeline-run-1
spec:
  workspaces:
  - name: storage
    volumeClaimTemplate:
      spec:
        accessModes:
        - ReadWriteOnce
        resources:
          requests:
            storage: 2Mi
  params:
  - name: sourceUrl
    value: "https://raw.githubusercontent.com/nhatsangvn/nhatsangvn/refs/heads/main/name"
  pipelineRef:
    name: greet-service-pipeline
EOF

Applying this pipeline will get the content from the specified URL, display it, and greet the information from the file.

$ kubectl get pod | grep greet-service-pipeline
greet-service-pipeline-run-1-display-content-pod               0/1     Completed   0              74s
greet-service-pipeline-run-1-fetch-content-pod                 0/1     Completed   0              95s
greet-service-pipeline-run-1-greet-with-content-pod            0/1     Completed   0              67s

$ kubectl logs greet-service-pipeline-run-1-greet-with-content-pod
Defaulted container "step-greet" out of: step-greet, prepare (init)
Hello SangNN
!

Here we go: "Hello SangNN"

Conclusion

In this blog post, we’ve covered the basics of Tekton and how it can be used to build service pipelines tailored for microservices and cloud-native architectures. By leveraging Tekton, you gain the flexibility, control, and scalability needed to manage independent service deployments, allowing for faster and more frequent updates. Whether you're building for Kubernetes, looking to decouple CI/CD processes, or need a vendor-agnostic solution, Tekton's service pipeline approach is a strong candidate for modern DevOps workflows.

Stay tuned for more advanced topics on Tekton in future posts!