Enabling Add-Ons

Linkerd can also be installed with a number of Add-On's, allowing users to get a great out of the box experience around popular service mesh use-cases. These Add-On's are coupled with the control plane installation and integrate well with Linkerd.

Add-On's in Linkerd are optional and configurable. A configuration file is passed to the install operation (available both through Helm and CLI). This config is also stored as a configmap called linkerd-values, allowing upgrades to work seamlessly without having user to pass the config file again. Configuration can be updated during upgrades.

You can find the list of add-ons present in the Linkerd2 Add-On's charts directory.

Now, Let us see the installation of the Tracing Add-On. In this demo, We also enable the control-plane-tracing flag which would, make the control-plane components send traces to the collector.

Other Add-On's would also have a similar installation approach.

Add-On's Configuration

The following is the Add-On configuration file, that will be passed to installation. Here we configure the Tracing Add-On to be enabled, and also overwrite the trace collector's resources. If values are not overwritten, The default values will be used.

cat > config.yaml << EOF
  enabled: true
        limit: 100m
        request: 10m
        limit: 100Mi
        request: 50Mi

The same configuration file can be used both through the CLI and Helm.

Installation through CLI

linkerd CLI now supports a addon-config flag, which is used to pass the confiugration of add-ons. Now, the above configuration file can be passed as

# Install with control plane tracing enabled, and a add-on configuration file
linkerd install --control-plane-tracing --addon-config ./config.yaml

Installation through Helm

First, You have to follow the usual process of installing Linkerd2 through Helm, . Only the final installation command is changed to include the add-on configuration.

Now, we pass the add-on configuration file to the helm install command.

# Install with control plane tracing enabled, and a add-on configuration file
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 \
  --set global.controlPlaneTracing=true \
  -f config.yaml \

Tracing Demo

First, you should also see two new components be installed i.e linkerd-collector and linkerd-jaeger.

$ kubectl -n linkerd  get deployments
NAME                     READY   UP-TO-DATE   AVAILABLE   AGE
linkerd-collector        1/1     1            1           4m11s
linkerd-controller       1/1     1            1           4m11s
linkerd-destination      1/1     1            1           4m11s
linkerd-grafana          1/1     1            1           4m11s
linkerd-identity         1/1     1            1           4m11s
linkerd-jaeger           1/1     1            1           4m11s
linkerd-prometheus       1/1     1            1           4m11s
linkerd-proxy-injector   1/1     1            1           4m11s
linkerd-smi-metrics      1/1     1            1           4m11s
linkerd-sp-validator     1/1     1            1           4m11s
linkerd-tap              1/1     1            1           4m11s
linkerd-web              1/1     1            1           4m11s

Now, The control-plane components traces, along with the linkerd-proxy traces are sent to the linkerd-collector, which are then sent to the linkerd-jaeger. These Traces can be viewed in the jaeger UI by port-forwarding the service as

kubectl -n linkerd port-forward svc/linkerd-jaeger 16686:16686

Traces from the control-plane components can be viewed at localhost:16886