Installing Linkerd with Helm

Linkerd can be installed via Helm rather than with the linkerd install command. This is recommended for production, since it allows for repeatability.

Prerequisite: generate identity certificates

To do automatic mutual TLS, Linkerd requires trust anchor certificate and an issuer certificate and key pair. When you’re using linkerd install, we can generate these for you. However, for Helm, you will need to generate these yourself.

Please follow the instructions in Generating your own mTLS root certificates to generate these.

Helm install procedure for stable releases

# add the repo for stable releases:
helm repo add linkerd https://helm.linkerd.io/stable

helm install linkerd2 \
  --set-file identityTrustAnchorsPEM=ca.crt \
  --set-file identity.issuer.tls.crtPEM=issuer.crt \
  --set-file identity.issuer.tls.keyPEM=issuer.key \
  linkerd/linkerd2

The chart values will be picked from the chart’s values.yaml file.

You can override the values in that file by providing your own values.yaml file passed with a -f option, or overriding specific values using the family of --set flags like we did above for certificates.

Helm install procedure for edge releases

You need to install two separate charts in succession: first linkerd-crds and then linkerd-control-plane. This new method will eventually make its way into the 2.12.0 stable release as well when it comes out.

linkerd-crds

The linkerd-crds chart sets up the CRDs linkerd requires:

# add the repo for edge releases:
helm repo add linkerd-edge https://helm.linkerd.io/edge

helm install linkerd-crds -n linkerd --create-namespace --devel linkerd-edge/linkerd-crds

linkerd-control-plane

The linkerd-control-plane chart sets up all the control plane components:

helm install linkerd-control-plane \
  -n linkerd \
  --devel \
  --set-file identityTrustAnchorsPEM=ca.crt \
  --set-file identity.issuer.tls.crtPEM=issuer.crt \
  --set-file identity.issuer.tls.keyPEM=issuer.key \
  linkerd-edge/linkerd-control-plane

Enabling high availability mode

The linkerd2 chart (or, for edge releases, the linkerd-control-plane chart) contains a file called values-ha.yaml that overrides some default values to enable high availability mode, analogous to the --ha option in linkerd install.

You can get the values-ha.yaml by fetching the chart files:

# for stable
helm fetch --untar linkerd/linkerd2

# for edge
helm fetch --untar --devel linkerd-edge/linkerd-control-plane

Then use the -f flag to provide this override file. For example:

# for stable
helm install linkerd2 \
  --set-file identityTrustAnchorsPEM=ca.crt \
  --set-file identity.issuer.tls.crtPEM=issuer.crt \
  --set-file identity.issuer.tls.keyPEM=issuer.key \
  -f linkerd2/values-ha.yaml \
  linkerd/linkerd2

# for edge
helm install linkerd-control-plane \
  -n linkerd \
  --devel \
  --set-file identityTrustAnchorsPEM=ca.crt \
  --set-file identity.issuer.tls.crtPEM=issuer.crt \
  --set-file identity.issuer.tls.keyPEM=issuer.key \
  -f linkerd-control-plane/values-ha.yaml \
  linkerd-edge/linkerd-control-plane

Customizing the namespace

To install Linkerd to a different namespace, you can override the Helm Namespace variable.

By default, the chart creates the control plane namespace with the config.linkerd.io/admission-webhooks: disabled label. This is required for the control plane to work correctly. This means that the chart won’t work with Helm’s --namespace option. If you’re relying on a separate tool to create the control plane namespace, make sure that:

1. The namespace is labeled with config.linkerd.io/admission-webhooks: disabled
2. The installNamespace is set to false
3. The namespace variable is overridden with the name of your namespace

Upgrading with Helm

First, make sure your local Helm repos are updated:

helm repo update

helm search repo linkerd2
NAME                    CHART VERSION          APP VERSION            DESCRIPTION
linkerd/linkerd2        <chart-semver-version> 
stable-2.14.10    Linkerd gives you observability, reliability, and securit...

During an upgrade, you must choose whether you want to reuse the values in the chart or move to the values specified in the newer chart. Our advice is to use a values.yaml file that stores all custom overrides that you have for your chart.

The helm upgrade command has a number of flags that allow you to customize its behavior. Special attention should be paid to --reuse-values and --reset-values and how they behave when charts change from version to version and/or overrides are applied through --set and --set-file. For example:

• --reuse-values with no overrides - all values are reused
• --reuse-values with overrides - all except the values that are overridden are reused
• --reset-values with no overrides - no values are reused and all changes from provided release are applied during the upgrade
• --reset-values with overrides - no values are reused and changed from provided release are applied together with the overrides
• no flag and no overrides - --reuse-values will be used by default
• no flag and overrides - --reset-values will be used by default

Finally, before upgrading, check whether there are breaking changes to the chart (i.e. renamed or moved keys, etc). You can consult the edge or the stable chart docs, depending on which one your are upgrading to. If there are, make the corresponding changes to your values.yaml file. Then you can use:

helm upgrade linkerd2 linkerd/linkerd2 --reset-values -f values.yaml --atomic

The --atomic flag will ensure that all changes are rolled back in case the upgrade operation fails.