Installing Linkerd with Helm

Linkerd can optionally be installed via Helm rather than with the linkerd install command.

Prerequisite: identity certificates

The identity component of Linkerd requires setting up a trust anchor certificate, and an issuer certificate with its key. These must use the ECDSA P-256 algorithm and need to be provided to Helm by the user (unlike when using the linkerd install CLI which can generate these automatically). You can provide your own, or follow these instructions to generate new ones.

Adding Linkerd's Helm repository

# To add the repo for Linkerd2 stable releases:
helm repo add linkerd https://helm.linkerd.io/stable

# To add the repo for Linkerd2 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.

Helm install procedure

# set expiry date one year from now, in Mac:
exp=$(date -v+8760H +"%Y-%m-%dT%H:%M:%SZ")
# in Linux:
exp=$(date -d '+8760 hour' +"%Y-%m-%dT%H:%M:%SZ")

helm install \
  --name=linkerd2 \
  --set-file global.identityTrustAnchorsPEM=ca.crt \
  --set-file identity.issuer.tls.crtPEM=issuer.crt \
  --set-file identity.issuer.tls.keyPEM=issuer.key \
  --set identity.issuer.crtExpiry=$exp \
  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.

Disabling The Proxy Init Container

If installing with CNI, make sure that you add the --set global.cniEnabled=true flag to your helm install command.

Setting High-Availability

The chart contains a file values-ha.yaml that overrides some default values as 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 that file.

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

helm fetch --untar linkerd/linkerd2

Then use the -f flag to provide the override file, for example:

## see above on how to set $exp
helm install \
  --name=linkerd2 \
  --set-file global.identityTrustAnchorsPEM=ca.crt \
  --set-file identity.issuer.tls.crtPEM=issuer.crt \
  --set-file identity.issuer.tls.keyPEM=issuer.key \
  --set identity.issuer.crtExpiry=$exp \
  -f linkerd2/values-ha.yaml \
  linkerd/linkerd2

Customizing the Namespace

To install Linkerd to a different namespace than the default linkerd, override the Namespace variable.

By default, the chart creates the control plane namespace with the config.linkerd.io/admission-webhooks: disabled label. It is required for the control plane to work correctly. This means that the chart won't work with Helm v2'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 linkerd.io/admission-webhooks: disabled
  2. The installNamespace is set to false
  3. The namespace variable is overridden with the name of your namespace

Helm upgrade procedure

Make sure your local Helm repos are updated:

helm repo update

helm search linkerd2 -v stable-2.7.0
NAME                    CHART VERSION          APP VERSION            DESCRIPTION
linkerd/linkerd2        <chart-semver-version> stable-2.7.0    Linkerd gives you observability, reliability, and securit...

The helm upgrade command has a number of flags that allow you to customize its behaviour. The ones that special attention should be paid to are --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. To summarize there are the following prominent cases that can be observed:

  • --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

Bearing all that in mind, you have to decide whether you want to reuse the values in the chart or move to the values specified in the newer chart. The advised practice is to use a values.yaml file that stores all custom overrides that you have for your chart. Before upgrade, 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