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

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

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

The following instructions use the linkerd repo. For installing an edge release, just replace with linkerd-edge, and add the --devel flag to all commands.

Helm install procedure

You need to install two separate charts in succession: first linkerd-crds and then linkerd-control-plane.

linkerd-crds

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

helm install linkerd-crds linkerd/linkerd-crds \
  -n linkerd --create-namespace 

linkerd-control-plane

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

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

Enabling high availability mode

The linkerd-control-plane chart contains a file values-ha.yaml that overrides some default values to set things up under a high-availability scenario, analogous to the --ha option in linkerd install. Values such as higher number of replicas, higher memory/cpu limits, and affinities are specified in those files.

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

helm fetch --untar linkerd/linkerd-control-plane

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

helm install linkerd-control-plane \
  --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/linkerd-control-plane

Upgrading with Helm

First, make sure your local Helm repos are updated:

helm repo update

helm search repo linkerd
NAME                          CHART VERSION          APP VERSION              DESCRIPTION
linkerd/linkerd-crds          <chart-semver-version>                          Linkerd gives you observability, reliability, and securit...
linkerd/linkerd-control-plane <chart-semver-version> stable-2.12.1    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 stable or the edge 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:

# the linkerd-crds chart currently doesn't have a values.yaml file
helm upgrade linkerd-crds linkerd/linkerd-crds

# whereas linkerd-control-plane does
helm upgrade linkerd-control-plane linkerd/linkerd-control-plane --reset-values -f values.yaml --atomic

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