explicit plugin inheritance not working in meltano

[bdewilde]

I have multiple tap-postgres-based extractors in my meltano project, so would like to name each descriptively and have them explicitly inherit from tap-postgres. According to the docs, I believe something like this ought to work:

plugins:
  extractors:
    - name: tap-postgres--some-descriptive-qualifier
      inherit_from: tap-postgres
      variant: meltanolabs
      pip_url: meltanolabs-tap-postgres~=0.2.0
      config: ...

However, this raises an error on install, and doesn't actually generate a lockfile:

$ meltano install
Extractor 'tap-postgres' is not known to Meltano. Try running `meltano lock --update --all` to ensure your plugins are up to date, or add a `namespace` to your plugin if it is a custom one.
$ meltano lock --update tap-postgres--some-descriptive-qualifier
Locking 1 plugin(s)...
Extractor tap-postgres--some-descriptive-qualifier is an inherited plugin
$ ls plugins/extractors

As a result, I can't run the plugin:

$ meltano invoke tap-postgres--some-descriptive-qualifier
2025-05-29T20:25:23.174730Z [info     ] Environment 'dev' is active
Extractor 'tap-postgres' is not known to Meltano. Try running `meltano lock --update --all` to ensure your plugins are up to date.

I've tried a half-dozen different variations in the meltano.yml file, but nothing works. Assuming this is user error, but I am stumped. I'm using meltano v3.7.6 btw.

[edgarrmondragon]

I'll take a look!

[bdewilde]

Hi @edgarrmondragon , just a friendly bump. Would this ticket be better served over on the meltano repo itself? (I wasn't sure where the problem was, so defaulted to posting here.)

[edgarrmondragon]

@bdewilde Did you try adding the parent plugin to the project? i.e.

plugins:
  extractors:
    - name: tap-postgres
      variant: meltanolabs
      pip_url: meltanolabs-tap-postgres~=0.2.0
    - name: tap-postgres--some-descriptive-qualifier
      inherit_from: tap-postgres
      variant: meltanolabs
      pip_url: meltanolabs-tap-postgres~=0.2.0
      config: ...

and then running meltano lock --update --all?

[ralichkov]

Had the exact same issue a couple days ago. Not sure exactly how I resolved it, but these are some things I tried:

• git clone the project to a new directory and retry meltano install
• Pruning .meltano/extractors or the loaders subdir, maybe even the entire .meltano dir
• meltano install tap-postgres--some-descriptive-qualifier
  • Personally I don't trust meltano install much anymore due to this

And your config should probably look similar to the one @edgarrmondragon showed, but:

• I think that for the inherited one, you can do without pip_url and variant. That's how I have it on my end.

Hopefully you manage to find exactly what fixes it. Probably others out there hitting the same error :)

[edgarrmondragon]

If anyone can provide a MRE, that would help a ton in identifying the problem.

Either

• A meltano.yml with inheritance that reproduces the error
• OR a sequence of commands that lead to the broken meltano.yml

[bdewilde]

Hi @edgarrmondragon , here are a couple minimal examples:

in meltano.yml:

plugins:
  - extractors
    - name: tap-postgres--meltanolabs
      inherit_from: tap-postgres
      variant: meltanolabs
      pip_url: meltanolabs-tap-postgres~=0.3.0
    - name: tap-postgres--transferwise
      inherit_from: tap-postgres
      variant: transferwise
      pip_url: pipelinewise-tap-postgres

=>

$ meltano lock --update --all
Locking 2 plugin(s)...
Extractor tap-postgres--meltanolabs is an inherited plugin
Extractor tap-postgres--transferwise is an inherited plugin
$ meltano install --clean
2025-07-16T15:35:10.051725Z [error    ] Extractor 'tap-postgres' is not known to Meltano. Try running `meltano lock --update --all` to ensure your plugins are up to date, or add a `namespace` to your plugin if it is a custom one.
...
FileNotFoundError: [Errno 2] No such file or directory: '/Users/burtondewilde/Desktop/workspace/wg-dwh/plugins/extractors/tap-postgres--meltanolabs.lock'

Okay, sure. If I add the parent plugin to the existing (above) configuration...

in meltano.yml:

plugins:
  - extractors
    - name: tap-postgres
    - name: tap-postgres--meltanolabs
      ...
    - name: tap-postgres--transferwise
      ...

=>

$ meltano lock --update --all
Locking 3 plugin(s)...
Locked definition for extractor tap-postgres
Extractor tap-postgres--meltanolabs is an inherited plugin
Extractor tap-postgres--transferwise is an inherited plugin
$ meltano install --clean
2025-07-16T15:38:43.978704Z [error    ] Extractor 'tap-postgres' is not known to Meltano. Try running `meltano lock --update --all` to ensure your plugins are up to date, or add a `namespace` to your plugin if it is a custom one.
...
FileNotFoundError: [Errno 2] No such file or directory: '/Users/burtondewilde/Desktop/workspace/wg-dwh/plugins/extractors/tap-postgres--original.lock'

Previously, it was looking for a *--meltanolabs lockfile, but now it's looking for *--original. In that directory I do indeed see tap-postgres--meltanolabs.lock, presumably because that's the default variant.

[edgarrmondragon]

If I add the parent plugin to the existing (above) configuration...

Did you use meltano add for that or typed it in manually in meltano.yml? I see it's missing a variant.

[bdewilde]

I manually added this in, trying to create a minimal example for you. The variant was left off, so it would use the default, which is "meltanolabs". :)

I can give you a third example:

plugins:
  - extractors:
    - name: tap-postgres
      variant: meltanolabs
      pip_url: meltanolabs-tap-postgres~=0.3.0
    - name: tap-postgres--meltanolabs
      inherit_from: tap-postgres
    - name: tap-postgres--transferwise
      inherit_from: tap-postgres
      variant: transferwise
      pip_url: pipelinewise-tap-postgres

=>

$ meltano lock --update --all
Locking 3 plugin(s)...
Locked definition for extractor tap-postgres
Extractor tap-postgres--meltanolabs is an inherited plugin
Extractor tap-postgres--transferwise is an inherited plugin
$ meltano install --clean
2025-07-16T15:46:00.819005Z [error    ] Extractor 'tap-postgres' is not known to Meltano. Try running `meltano lock --update --all` to ensure your plugins are up to date, or add a `namespace` to your plugin if it is a custom one.
...
FileNotFoundError: [Errno 2] No such file or directory: '/Users/burtondewilde/Desktop/workspace/wg-dwh/plugins/extractors/tap-postgres--transferwise.lock'

It's now looking for a different lockfile that also does not exist.

[edgarrmondragon]

Ok, I think I see the issue. Meltano doesn't currently have good support for using multiple variants of the same plugin in the same project. It's possible, but requires some manual intervention.

Could you try these steps:

1. Add a parent plugin for the first variant

meltano add tap-postgres --variant=meltanolabs

2. Rename the plugin and the lockfile

plugins:
  extractors:
  - name: tap-postgres-mlabs # notice the new name
    variant: meltanolabs
    pip_url: meltanolabs-tap-postgres

mv plugins/extractors/tap-postgres--meltanolabs.lock plugins/extractors/tap-postgres-mlabs--meltanolabs.lock

3. Add a parent plugin for the second variant

meltano add tap-postgres --variant=transferwise

4. Rename the plugin and the lockfile

plugins:
  extractors:
  - name: tap-postgres-mlabs # notice the new name
    variant: meltanolabs
    pip_url: meltanolabs-tap-postgres
  - name: tap-postgres-wise # notice the new name
    variant: transferwise
    pip_url: git+https://github.com/transferwise/pipelinewise.git#subdirectory=singer-connectors/tap-postgres

mv plugins/extractors/tap-postgres--transferwise.lock plugins/extractors/tap-postgres-wise--transferwise.lock

4. Add inherited plugins

meltano add tap-postgres-mlabs--child --inherit-from tap-postgres-mlabs
meltano add tap-postgres-wise--child --inherit-from tap-postgres-wise

5. Final meltano.yml

version: 1
default_environment: dev
project_id: 8d44ca16-1400-495d-852c-b4ca9c316e31
environments:
- name: dev
- name: staging
- name: prod
send_anonymous_usage_stats: false
plugins:
  extractors:
  - name: tap-postgres-mlabs
    variant: meltanolabs
    pip_url: meltanolabs-tap-postgres
  - name: tap-postgres-wise
    variant: transferwise
    pip_url: 
      git+https://github.com/transferwise/pipelinewise.git#subdirectory=singer-connectors/tap-postgres
  - name: tap-postgres-mlabs--child
    inherit_from: tap-postgres-mlabs
  - name: tap-postgres-wise--child
    inherit_from: tap-postgres-wise

---

Links

• Guidance for side-by-side installations of multiple variants of the same plugin meltano/meltano#6731
• https://docs.meltano.com/guide/plugin-management/#multiple-variants (this example might work for you as well)