[stable/nginx-ingress] Custom NGINX template support

[DavidHuie]

Many NGINX configuration parameters cannot be overridden with the
nginx-ingress Helm chart. With this change, a custom nginx.tmpl
template can be provided, which allows for any configuration value to
be changed.

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[DavidHuie]

CLA's ready.

[s4nch3z]

It looks like we have a duplicate implementation. You were 8 hours ahead of me =). However, mine includes DHParam stuff
#2342

[viglesiasce]

I like this implementation of the custom config better because it allows for an arbitrary configmap name and key.

@s4nch3z can you submit just the DHparam change in your PR?

[viglesiasce]

/ok-to-test

[killfill]

+1 !

[killfill]

BTW, the daemonset file seems to be missing the change to do something with the customTemplate variables.

Copying the change from the deployment file works fine.

Thanks!

[DavidHuie]

@killfill just added! Sorry about that.

[DavidHuie]

@mgoodness any updates on this guy? Thanks.

[DavidHuie]

@mgoodness @viglesiasce Can I do anything to move this forward? Thanks.

[jeff-french]

+1 for merging this. Looks like it's been ready for over a month. Any way to get this merged?

[jeff-french]

Well, it looks like the chart version will need to be bumped again since PR #2573 took 0.8.12

[DavidHuie]

@jeff-french fixed!

[jeff-french]

@mgoodness @viglesiasce Is there anything else that needs to be done to get this merged?