Working with other side-cars

It would be great to provide workaround-hooks in this container.

Problem:

• Given that Grafana only reads datasources on start
• Given that GKE doesn’t support anything but ReadWriteOnce persistency (else I’d spawn a Job with a shared PVC)
• Given that I use Istio in the Grafana namespace
• Given that Istio’s istio-proxy sidecar container is needed to access to the k8s API
• Given that I was using k8s-sidecar to list datasources from the k8s API as an init container
• And given that k8s KEP #753 is not yet done
• I have a crashing init sidecar
• Or else if I move it to “containers” and make it “WATCH” instead of “LIST”, I could have it run continously,
• However, see point 1, so we have a race condition

A workaround:

• Suppose this container exposed a HTTP interface that only returned 200 OK once “one watch iteration” was done
• I could then do

command: ["/bin/bash", "-c"]
args: ["until curl --head localhost:15000 ; do echo Waiting for Sidecar; sleep 3 ; done ; echo Sidecar available; ./init-stuff.sh && ./startup.sh"]

[haf]

This is really crap automation.

[jekkel]

It seems you could use the SCRIPT configuration to touch a file as soon as the listing succeeds. Your bash waiting wouldn’t then refer to an http request but the existence of that file.