feature: Warn when `namespace` is not specified for a plugin about meltano HOT 4 OPEN

Hey @haleemur, thanks for raising!

I think the problem is Meltano uses namespace to identify custom plugins:

But otherwise the property is not really required.

That makes me think we may need to:

1. Update the troubleshooting instruction in

   meltano/src/meltano/core/project_plugins_service.py

   Lines 81 to 84 in b54c1c2

   	instruction = (
   	"Try running `meltano lock --update --all` to ensure your plugins are "
   	"up to date"
   	)

   to include something like or add the 'namespace' property to your plugin definition.
2. Warn when namespace is missing, regardless of the type of plugin
3. Have a different, clearer, way of identifying custom plugins

Number 1 and 2 are probably the easiest.

from meltano.

Related:

• #3296, especially #3296 (comment)
• #3116

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Thanks @edgarrmondragon,

I have a slight preference towards option 1 as its the simplest code change, and will suffice. If the documentation is improved according to #3116, maybe we should also update the warning message to point to it.

Option 2 feels a bit incorrect in the sense that the meltano install command succeeds but the user sees a warning. I think it would just create unnecessary doubt for the end-user. So far, we're assuming that the error message is invoked at the right time, but its text does not direct the user towards all the potential root causes.

Option 3 sounds great, I just don't know yet what it would be.

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On further thought, maybe meltano should test whether namespace is present under the scenarios where it needs to be present (is a custom plugin), and emit specific instructions to the user to help resolve installation issues easily.

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