Add liveness check for workers

[shubhwip]

closes #72

Dependent on PR getredash/redash#5886 and it is merged already.

Related Issues :

getredash/redash#5885
#124
#72
getredash/redash#5801

More context

liveness check is based on
rq info command returns monitoring status of redash workers and other status checks
Sample Output

redash@redash-adhocworker-778fc5dbb6-jpscq:/app$ rq info --url $REDASH_REDIS_URL -R
queries      | 0
default      | 2
periodic     |██████████████████ 748
emails       | 0
schemas      | 0
5 queues, 750 jobs total

queries:  1a6d953d53984424ab775d3647427e7b (idle), 29dbf1ec1f774bacbd91ca36ccef6e43 (idle)
default:  –
periodic: –
emails:   –
schemas:  –
2 workers, 5 queues

[shubhwip]

@grugnog can you please check this PR ? This issue has been reported by many.
We can remove default values(in case PR on redash repo doesn't get merged) and get it merged and people who are using this helm charts can supply their own values with liveness checks.

[grugnog]

@shubhwip we will need to add the new values to the README but otherwise this looks good to me. We don't want to break installs though, so I don't think we should merge until upstream is merged however, and we can't release until upstream is released.

[shubhwip]

@grugnog made the changes as requested and now upstream is merged.
getredash/redash#5886

[aneagoe]

Would love to see this merged; currently facing issues with workers silently dying and we can only manually bounce them.

[shubhwip]

@grugnog when do you plan to merge the changes as upstream changes are merged months ago :) ?

[ffzzhong]

@grugnog please kindly take a look

[grugnog]

@shubhwip @ffzzhong it's merged upstream, but still no stable release to point at - I can try and get a preview release up that folks can try, but I would be wary in terms of upgrade path.

[justinclift]

Now that Redash is a Community led project, we've been madly working through the outstanding PRs, Dependabot issues, (etc) getting things cleaned up and ready for a next release.

It's going to be a few weeks away though. We might be able to get something like an "Redash 11.0.0 alpha 1" (or beta) out the door in a fortnight or so, but we'll see. 😄

[justinclift]

@grugnog If you want to create some kind of preview release for people to do with in the meantime, then please feel encouraged to do so. It could be considered a good initial shake out to see if we've busted anything non-obvious in the mad rush of merging PRs and similar. 😄

[grugnog]

That sounds good - I am working on getting the other PRs tested and merged, then will look at this

[justinclift]

@AndrewChubatiuk Does this PR seem sensible to you?