move cmd/otel/components to internal/components

[jjackson-s]

Description:
Moving functionality - There is currently functionality to get all of the components in both core and contrib inside of cmd/otel/components, and it is also inaccessible because it is saved under a main package.

• Thought it would be useful to move it to internal/components to make it accessible and easier to find.

Link to tracking Issue:

• No tracking issue, but the file is inaccessible outside of cmd/otel, and is something that can be useful to the entire repo.

Testing:

• No new testing, but there is currently a linker error being thrown due to using both defaultcomponents and the components that we are local to contrib. I am currently working on resolving that issue, but am not sure exactly from where it is coming from. Also present when directory lives inside of cmd/otel/components.

Documentation:
n/a

[tigrannajaryan]

• Thought it would be useful to move it to internal/components to make it accessible and easier to find.

Why does it need to be accessible? What's the intended use case?

[jjackson-s]

• Thought it would be useful to move it to internal/components to make it accessible and easier to find.

Why does it need to be accessible? What's the intended use case?

• First, I am working on getting a project merged into contrib that relies on this change add Configwiz #4592
• But other use cases would be if there is anybody in the future that wants access to both the components inside of contrib and core for any future works. Very similar to default components in core repo ./service/defaultcomponents.

[tigrannajaryan]

Build failed:

2021-08-13T13:54:55.2084916Z make[2]: Entering directory '/home/runner/work/opentelemetry-collector-contrib/opentelemetry-collector-contrib'
2021-08-13T13:55:03.4447757Z make[2]: Leaving directory '/home/runner/work/opentelemetry-collector-contrib/opentelemetry-collector-contrib/testbed'
2021-08-13T13:55:04.0255796Z golangci-lint run --allow-parallel-runners
2021-08-13T13:55:09.1733581Z make[2]: Leaving directory '/home/runner/work/opentelemetry-collector-contrib/opentelemetry-collector-contrib/tracegen'
2021-08-13T13:55:17.3647703Z make[2]: Leaving directory '/home/runner/work/opentelemetry-collector-contrib/opentelemetry-collector-contrib/receiver/simpleprometheusreceiver'
2021-08-13T13:56:39.2522456Z cmd/otelcontribcol/unstable_components_disabled.go:23:6: `extraReceivers` is unused (deadcode)
2021-08-13T13:56:39.2523482Z func extraReceivers() []component.ReceiverFactory {
2021-08-13T13:56:39.2524162Z      ^
2021-08-13T13:56:39.2869715Z make[2]: *** [Makefile.Common:93: lint] Error 1
2021-08-13T13:56:39.2872264Z make[1]: *** [Makefile:153: for-all-target-/home/runner/work/opentelemetry-collector-contrib/opentelemetry-collector-contrib] Error 2
2021-08-13T13:56:39.2874243Z make[2]: Leaving directory '/home/runner/work/opentelemetry-collector-contrib/opentelemetry-collector-contrib'
2021-08-13T13:56:39.2876098Z make[1]: Leaving directory '/home/runner/work/opentelemetry-collector-contrib/opentelemetry-collector-contrib'
2021-08-13T13:56:39.2877485Z make: *** [Makefile:81: golint] Error 2
2021-08-13T13:56:39.2887705Z ##[error]Process completed with exit code 2.

[jjackson-s]

Where extraReceivers() was once called

[rmfitzpatrick]

This isn't the same, and refers to the enabled unstable components if the build tag is set: https://github.com/open-telemetry/opentelemetry-collector-contrib/blob/ac315e8e921efeba1565a6dddec1f7c09fa00667/cmd/otelcontribcol/unstable_components_enabled.go

edit: It's not being used now, but as new unstable components are added there's the ability to enable them conditionally without being locked into this file's contents.

second edit: missed your related comment. Is there a reason moving them to this new internal package is problematic?

[jjackson-s]

Ahh, its made this way for components that have yet to merged into contrib correct?

But because the unstable components files are apart of the main package, I won't have access to them when moving components.go to internal.

If I am understanding correctly though, you are saying to move over the unstable_components files over to internal as well correct?

[rmfitzpatrick]

They're for components that have been added to the contrib project (and are in the standard receiver, exporter, etc. directories) but haven't been added to the (previously) main component factories for vetting and reliability reasons. By building a collector distribution with the unstable tag are they available. Once hardened to a reasonable extent they get moved from the unstable_enabled location to the applicable slice.

[jjackson-s]

Oh wow ok that makes sense I was wondering about that unstable tag. I was thinking that makefiles were only used for testing purposes but it seems that it can also be used to help compilation maybe? Definitely going to look deeper into it but thanks for that explanation!

[jjackson-s]

cmd/otelcontribcol/unstable_components_disabled.go:23:6: extraReceivers is unused (deadcode)
2021-08-13T13:56:39.2523482Z func extraReceivers() []component.ReceiverFactory {

Ok so I looked into the failing test, and as stated in the error we are not using this extraReceivers function, but I am not sure what we should do with it.

• extraReceivers() was called before to add extra receivers, and there are 2 versions of its function (one returns nil and the other returns an empty component.ReceiverFactory{})
• both untouched in the entire repo, living in cmd/otelcontribcol/unstable_components_disabled.go and cmd/otelcontribcol/unstable_components_enabled.go.
• Due to the extraReceiver() functions residing in cmd/otelcontribcol, we do not have access to these functions any longer because they live in a main package instead of a named, exportable one.
• The two ideas of what we can do with it would that I can think of would either be to remove it altogether or to export the function, but let me know what you think.

[bogdandrutu]

Please fix the lint errors