[metricbeat] Support secrets

[erihanse]

• Chart version not bumped (the versions are all bumped and released at the same time)
• README.md updated with any new values or changes
• Updated template tests in ${CHART}/tests/*.py
• Updated integration tests in ${CHART}/examples/*/test/goss.yaml
  closes Support creating k8s helm secrets for metricbeat helm chart #777

Here's an initial attempt to adding secrets to the metricbeat chart, I hope the PR is welcome. I looked at what was done in #712, and copied and adjusted the template for metricbeat accordingly. Was unsure whether or not to add tests, since similar tests are covered in the logstash chart.

[elasticmachine]

Since this is a community submitted pull request, a Jenkins build has not been kicked off automatically. Can an Elastic organization member please verify the contents of this patch and then kick off a build manually?

[erihanse]

@fatmcgav sorry to bother you directly. Will this PR be reviewed any time soon?

[fatmcgav]

Jenkins test this please

[erihanse]

Is there anything missing here?

[blurpy]

I would really like to see this PR merged so we can start using this chart. How do we get hold of someone who can verify?

[fatmcgav]

Sorry for the radio silence here.

@erihanse This is looking good. Would you be able to add a new test to exercise creating a secret?
Something like https://github.com/erihanse/helm-charts/blob/b6f54a621a0797e58ab047f4f6014d3d7c4162fa/metricbeat/tests/metricbeat_test.py#L1152-L1173 should do the job...

[erihanse]

@fatmcgav would it make sense to copy the secret-related tests from the logstash chart (#712) and make necessary adjustments? The template is the same.

[fatmcgav]

@erihanse sounds like an awesome idea!

[erihanse]

@fatmcgav it's ready for review again. I rebased on master, therefore the force-push. I copied the tests, the only change I made was to remove the assert of secretschecksum in the test method test_adding_a_secret.

[fatmcgav]

Cool, thanks for that @erihanse

Jenkins test this please

[fatmcgav]

LGTM

[fatmcgav]

This has been back-ported to the relevant branches, and will be included in the next 7.9 minor release.

Thanks again for the contribution @erihanse