make probes on streaming and web deployments user configurable

[jstewart612]

Implements https://github.com/mastodon/chart/issues/9

[jstewart612]

@SISheogorath all requested changes made, please verify/review.

[jstewart612]

@SISheogorath @renchap rebased, please review

[timetinytim]

(Sorry for the huge delay in getting around to this)

Generally I think this is a great idea. The values look good to me, I just want to ping @renchap to take a look as well before I approve.

[timetinytim]

So we had a discussion internally about this.

Generally it's a good idea to allow the customization of healthcheck endpoints. But there are two concerns with this particular implementation:

• Increasing the complexity of the values.yaml file
• Possibility of future breaking changes

To clarify the second point, consider the possibility that we change the healthcheck endpoint in a future version. The onus to update the values file is then on everyone who uses the chart, and will lead to things breaking if people don't know they have to update it.

I would instead suggest that the probes be constructed out of whatever values the user chooses to define, and fills in the rest of the probes' parameters with default values.

Hopefully that makes sense!