[chore][docs/rfc] Add RFC on configuring confmap Providers

[evan-bradley]

Description

Documents how we want to configure confmap Providers, with the default decision being to use URI fragments.

Per the SIG discussion on 2024-05-08, I have included as many alternatives as I could think of. I think a few of them have merit, but I don't think any of the options are without downsides.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 92.53%. Comparing base (c6b70a7) to head (d3485a9). Report is 266 commits behind head on main.

Additional details and impacted files

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+ Coverage   91.67%   92.53%   +0.85%     
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+ Hits        15359    16949    +1590     
+ Misses       1056     1022      -34     
- Partials      339      346       +7     

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[evan-bradley]

Can the RFC include any prior art on this type of configuration?

I spent some time thinking about this, but I'm not aware of anything that matches what we're doing closely enough to make sense. The best I can think of would be infrastructure as code tools like Terraform, Pulumi, or CloudFormation, but I think what they are doing is sufficiently different that it's hard to use them as a basis. If there are other tools or approaches you think would be worth investigating, let me know and I can take a look.

I can also do a writeup on how our configuration fits into the larger landscape of infrastructure configuration approaches if you think it would be beneficial to take a broader look at our whole approach, but didn't want to detract from the more practical discussion at hand of how to do things like authenticate requests in our HTTP providers.

[github-actions[bot]]

This PR was marked stale due to lack of activity. It will be closed in 14 days.

[github-actions[bot]]

This PR was marked stale due to lack of activity. It will be closed in 14 days.

[TylerHelmuth]

Is there an option to support a ${<provider>:URI}[params] style if we introduce a new specialized flag? Like instead of --config its --fancy-config? That way we get the best syntax without breaking users?

[evan-bradley]

I think at that point we should just have an alpha-stability feature gate that we use to determine whether params are supported. I see the benefit there, but I think it would also be confusing to have to opt-in per-file. In cases where I forget to use --fancy-config, I would get weird syntax errors (or worse, no error at all) without a clear indicator of why.

I'm also a bit nervous about committing long-term to maintaining two ways to parse the config.

[evan-bradley]

This is replaced by https://github.com/open-telemetry/opentelemetry-collector/pull/10776.