DevOps Bootcamp · Lesson

Parameterizing the Container Image

Wiring image repository and tag to values.

Lesson 2 of 413 steps

Parameterizing the Container Image is a free DevOps Bootcamp lesson on CoddyKit. This is lesson 2 of 4. Any 3 lessons of this learning path are free to read in full — after that, CoddyKit PRO unlocks every lesson, plus hands-on practice with a built-in code editor and a 24/7 AI tutor. It is part of the DevOps Bootcamp learning path, and your progress syncs across the web and the CoddyKit app. The DevOps Bootcamp course includes 4 lessons in total.

Why Parameterize the Image

A hard-coded image locks every user to one version. Wiring the image to values lets people pick the repository and tag they need.

Split Repository and Tag

By convention charts store the image as two fields: a repository and a tag. Keeping them separate makes version bumps clean.

# values.yaml
image:
  repository: nginx
  tag: "1.27"

Read Nested Values

Reach nested keys by chaining dots. Here .Values.image.repository walks into the image map you just defined.

image: {{ .Values.image.repository }}

Join Repository and Tag

An image reference is repository, then a colon, then tag. Build it inside the template so the rendered line is a single valid string.

image: "{{ .Values.image.repository }}:{{ .Values.image.tag }}"

Always Quote the Tag

A tag like 1.27 can be read as a number by YAML. Quote tags in values so they stay strings and never lose a trailing zero.

tag: "1.27.0"

Provide a Sensible Default Tag

The default function supplies a fallback when a value is empty. A common pattern uses the chart's appVersion as the default tag.

{{ .Values.image.tag | default .Chart.AppVersion }}

Expose the Pull Policy

Let users control when Kubernetes re-pulls an image by parameterizing imagePullPolicy too. IfNotPresent is a safe default.

imagePullPolicy: {{ .Values.image.pullPolicy }}

Default the Pull Policy

Set the pull policy default in values.yaml so an install works with zero overrides. Users still change it whenever they need to.

image:
  pullPolicy: IfNotPresent

The Full Container Block

Now your container is fully data-driven: image and pull policy both flow from .Values.image, with no literals left in the template.

containers:
  - name: app
    image: "{{ .Values.image.repository }}:{{ .Values.image.tag }}"
    imagePullPolicy: {{ .Values.image.pullPolicy }}

Override at Install Time

Users tweak a single nested value with --set. Dots in the key map straight onto your values tree, no file edits required.

helm install web . --set image.tag=1.28

Confirm the Rendered Image

Render with an override to prove the wiring works end to end. The output should show your chosen tag in the image line.

helm template web . --set image.tag=1.28

Quick Check

You want to install with a different image tag without editing files. What works?

Answer it in the interactive lesson

Recap: A Configurable Image

You split the image into repository and tag, added a pull policy, and let users override each with --set. Quote tags to stay safe.

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Frequently Asked Questions

Is the “Parameterizing the Container Image” lesson free?

Yes — any 3 lessons of the DevOps Bootcamp learning path, including “Parameterizing the Container Image”, are free to read in full here on the web. After that, CoddyKit PRO unlocks every lesson, plus interactive practice with a built-in code editor and a 24/7 AI tutor. The DevOps Bootcamp course includes 4 lessons in total.

What will I learn in “Parameterizing the Container Image”?

Wiring image repository and tag to values. You practise DevOps Bootcamp with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.

Do I need any experience to start DevOps Bootcamp?

No prior experience is required. DevOps Bootcamp on CoddyKit is structured for beginners through advanced learners, so you can start here or from the beginning and move at your own pace. This is lesson 2 of 4.

How long does the “Parameterizing the Container Image” lesson take?

Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.

Can I write and run code in this DevOps Bootcamp lesson?

Yes. Every DevOps Bootcamp lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.

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