Helm: install, upgrade, roll back

Install an app from a Helm chart at a fixed version, then upgrade it, roll it back and remove it.

40 min 2 hands-on tasksArchitecture · 25% of the exam

Key ideas in this lesson · tap one for a simple explanation

What you will be able to do

Add a chart repository, list a chart's versions and read its default values.
Install a fixed chart version into a namespace with your own values, then upgrade it and roll it back.
Find a release in any namespace, read its history and its values, and uninstall it.

installs apps on Kubernetes the way apt or brew installs programs on a computer. One command creates every object an app needs: its , , and more. Many cluster add-ons ship this way, such as ingress controllers and monitoring tools.

On the exam, a Helm task names everything you need: the repository, , chart version, release name, and values. The grader checks every one. The helm.sh docs are allowed in the exam, but helm <command> --help is faster: it lists every flag with an example.

Four words: chart, repository, release, revision

Word	What it is	Example
Chart	A package: templates for an app's objects, plus default settings called values	`podinfo/podinfo`
Repository	A website that hosts charts. You add it once, under a short name.	`https://stefanprodan.github.io/podinfo`, added as `podinfo`
Release	One installed copy of a chart. It has a name and lives in one namespace.	`web` in `arx-demo`
Revision	A numbered version of a release. Every install, upgrade and rollback adds one.	1 (install), 2 (upgrade), 3 (rollback)

From a chart to a release

Chart + your values

Chart

the package

podinfo/podinfo

Values

your settings

replicaCount=2

helm install

fills the templates and applies them

Release web

the installed copy

Revision 1

install

Revision 2

upgrade

Revision 3

rollback

Helm fills the chart's templates with your values and applies the result. Each change to the release is saved as a new numbered revision.

A chart has two version numbers. The chart version is the package's own version, and --version picks it. The app version is the version of the software inside. On the exam, "version" means the chart version.
Helm is a program on your computer. Nothing of Helm runs in the cluster: it uses your , just like . Build your lab installs it.
Helm keeps each release's history in the release's namespace. That is why most Helm commands need the same -n you installed with.

Read a chart before you install it

Before you install, add the repository and check which chart versions exist. Then look up the exact names of the values you need to set.

Repositories, versions and values· Terminal

helm repo add podinfo https://stefanprodan.github.io/podinfo
helm repo update                                   # refresh every index (or: helm repo update podinfo)
helm repo list
helm search repo podinfo                           # newest chart version only
helm search repo podinfo/podinfo --versions | head # every chart version with its app version
helm show chart podinfo/podinfo --version 6.14.0
helm show values podinfo/podinfo --version 6.14.0 > /tmp/cka/podinfo-values.yaml   # every key and its default

# Render locally: no release is created and nothing reaches the cluster
helm template web podinfo/podinfo --version 6.14.0 -n arx-demo --set replicaCount=3 > /tmp/cka/web.yaml
grep -nE 'replicas:|image:' /tmp/cka/web.yaml

Install and inspect a release

Install, then look at what Helm did· Terminal

helm install web podinfo/podinfo --version 6.14.0 \
  -n arx-demo --create-namespace \
  --set replicaCount=2 --set ui.message="hello" \
  --wait --timeout 5m

helm list -n arx-demo                     # NAME, REVISION, STATUS, CHART (<name>-<chart version>), APP VERSION
helm list -A                              # every namespace; plain "helm list" shows the current namespace only
helm status web -n arx-demo
helm get values web -n arx-demo           # only the values you supplied
helm get values web -n arx-demo --all     # merged with the chart defaults
helm get manifest web -n arx-demo | grep -n 'kind:'

Upgrade, roll back, uninstall

An upgrade changes a release in place and adds a revision. Two habits save points. Repeat --version, or Helm moves to the newest chart. Add --reuse-values to keep the values you set before; without it, an upgrade with new --set values forgets the old ones.

Upgrade, go back, remove· Terminal

# Upgrade. Repeat --version, or Helm moves you to the newest chart in the repo.
helm upgrade web podinfo/podinfo --version 6.14.0 -n arx-demo \
  --reuse-values --set replicaCount=3 --wait --timeout 5m
# Install if it is missing, upgrade it if it exists, with values from a file
helm upgrade --install web podinfo/podinfo --version 6.14.0 -n arx-demo -f /tmp/cka/web-values.yaml

helm history web -n arx-demo
helm rollback web 1 -n arx-demo --wait --timeout 5m   # writes a NEW revision with revision 1's content
helm uninstall web -n arx-demo                        # deletes the objects and the release history

A rollback never deletes revisions. helm rollback web 1 copies revision 1 into a new revision. So after an install, an upgrade and a rollback, helm history shows three revisions.

Flag	What it does	Trap
`--version 6.14.0`	Picks the chart version, not the app version	Leave it off an upgrade and Helm takes the newest chart in the repository
`--set k=v`, `-f values.yaml`	Change values. A dot reaches a nested key, as in `ui.message`. If both are given, `--set` wins.	`--set` turns `4` and `true` into a number and a true/false value. Use `--set-string` when the chart expects text.
`--reuse-values`	Starts from the last revision's values, then applies your new ones	Upgrade with `--set` or `-f` but without it, and every earlier value you do not repeat is reset
`-n NS --create-namespace`	Sets the release's namespace, and creates it if it is missing	`helm list` does not show the release without the same `-n` (or `-A`)
`--wait --timeout 5m`	Waits until the release's are ready, for at most 5 minutes	Without it, Helm reports success as soon as the objects are accepted, even if no Pod ever starts

In the official docs· open on exam day too

Installing Helmsearch: installing helm
Using Helmsearch: using helm
helm upgradesearch: helm upgrade
helm rollbacksearch: helm rollback

Hands-on task 1 of 2ar-helm-1

~8 min7% weightArchitecture

Install a pinned chart, upgrade it, roll it back

Using Helm and the chart repository https://stefanprodan.github.io/podinfo (add it as podinfo): first, install a release named web of chart podinfo/podinfo, chart version 6.14.0, into namespace arx-helm (create the namespace) with replicaCount set to 2. Next, upgrade web so it runs 4 replicas and shows the UI message release two (value ui.message), keeping chart version 6.14.0. Finally, the message was not approved: roll web back to its first revision. The release must end with exactly three revisions and the Deployment must run 2 replicas.

Cluster:kubectl config use-context kind-cka

1
Set up the scenario
curl -fsSL https://codewithmuh.com/labs/cka/t/ar-helm-1/setup | bash
2
Solve it in your terminal
Use kubectl and the Kubernetes docs, like on exam day. Save any answer files under /tmp/cka/.
3
Check your work
curl -fsSL https://codewithmuh.com/labs/cka/t/ar-helm-1/verify | bash
Got FAIL? Read which check failed, fix it, run it again.
4
Clean up (optional)
curl -fsSL https://codewithmuh.com/labs/cka/t/ar-helm-1/cleanup | bash

Hands-on task 2 of 2ar-helm-2

~6 min5% weightArchitecture

Audit releases: remove the failed one, save the values of another

One Helm release in the cluster is in the failed state. Write its namespace and name as <namespace>/<name> to /tmp/cka/helm/failed-release.txt, then uninstall it. Next, save the values that were supplied when release catalog in namespace arx-helm-audit was installed (only the user-supplied values, not the chart defaults) to /tmp/cka/helm/catalog-values.yaml. Do not change catalog.

Cluster:kubectl config use-context kind-cka

1
Set up the scenario
curl -fsSL https://codewithmuh.com/labs/cka/t/ar-helm-2/setup | bash
2
Solve it in your terminal
Use kubectl and the Kubernetes docs, like on exam day. Save any answer files under /tmp/cka/.
3
Check your work
curl -fsSL https://codewithmuh.com/labs/cka/t/ar-helm-2/verify | bash
Got FAIL? Read which check failed, fix it, run it again.
4
Clean up (optional)
curl -fsSL https://codewithmuh.com/labs/cka/t/ar-helm-2/cleanup | bash

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