feature: add supports for zipkin-dependencies job as a k8s cronjob

[meveno]

Feel free to suggest some changes

Regards

[codefromthecrypt]

sorry I accidentally wasn't watching this repo. looking now

[codefromthecrypt]

In general, the config approach is the same for mysql or cassandra, (prefixed variables associated to the storage type should be re-used for the dependency job)

one thing needed is how to test this here, as the job is something easy to get wrong by accident. I assume this is "out sourcing" the cron part to k8s itself, in this case, it should be changing the entrypoint also to prevent the container from using its cron. You can look at this

https://github.com/openzipkin/zipkin/tree/master/docker/examples#elasticsearch

Probably the best thing before starting this would be to add a better test, that generates a trace.. like this in a separate PR https://github.com/openzipkin/brave-example/blob/14a408d0bf2197bfc24e2d8935256e2508ad2d30/build-bin/docker-compose.base.yml

Then, this a test for dependencies could layer on that, and once the trace is readable, run the dependnecies job and see if the dependency endpoint has the "frontend" -> "backend" link

[codefromthecrypt]

#13 will backfill a basic test.

[codefromthecrypt]

I think to help I'll try to get a test for elasticsearch config in the first place, then doing something like this will be easier to verify. I'll plug at this slowly unless you beat me to it!

[codefromthecrypt]

ok #17 sets up the baseline to test this #17

Here's the jist of things needed to land this reliably:

1. make sure the dependencies job is overriding "command" to "start-zipkin-dependencies", so it doesn't also start its own cron
2. update schema for the new values
3. make ci/elasticsearch-values.yaml extend dependencies-values.yaml
4. change test/test-connection to invoke the dependencies container when the storage type isn't mem, between calling the frontend and reading back the dependencies links

I'll wait on you to tell me how comfortable you feel with these steps, and forgive me not eyeballing some change I didn't think about.