Move over plugins manager to a shared library

[amoghrajesh]

Why

As of today, workers unfortunately need plugins for macros (template rendering), listeners, and operator extra links. Now, the plugins manager is present in core airflow and sdk code needs to have a cross package import for it.

What

I am trying to move the generic plugin management code to a shared library (shared/plugins_manager) to support client-server separation between airflow-core and task-sdk. This ensures both components use the same plugin discovery and integration logic without code duplication which can happen if we just copy paste the entire code in both packages.

Changes of note

What was moved into shared library

• Generic methods, classes, ABCs etc

For example:

• AirflowPlugin base class
• AirflowPluginSource, PluginsDirectorySource, EntryPointSource
• _load_plugins_from_plugin_directory(), _load_entrypoint_plugins()
• integrate_macros_plugins(), integrate_listener_plugins()
• is_valid_plugin(), make_module()

The principle I used here was that we have to keep the library standalone and hence move no provider discovery, logic to get plugins (read from providers too), anything similar like this.

In order to do this, we maintain wrappers in core airflow and sdk now and the code within each of those use their own versions.

Some function signature changed for dependency injection

Some methods needed a change in signature to be able to inject library specific values to these functions.

Shared code couldn't import airflow.settings or airflow.configuration.conf, so:

Function	Old Params	New Params
PluginsDirectorySource.__init__	(self, path)	(self, path, plugins_folder: str)
_load_plugins_from_plugin_directory	()	(plugins_folder: str, load_examples: bool = False, example_plugins_module: str | None = None)
integrate_macros_plugins	()	(macros_module: ModuleType, macros_module_name_prefix: str, plugins: list[AirflowPlugin])
integrate_listener_plugins	()	(listener_manager: ListenerManager, plugins: list[AirflowPlugin])

These values are injected via core airflow / task sdk wrappers

Providers

Added AirflowPlugin to common.compat.sdk. Added # use next version to affected providers.

TODO / Open Qns

1. Docs: Unsure what to do about it, should we continue endorsing imports of format: from airflow.plugins_manager or move to from airflow.sdk.plugins_manager? I am doubtful because plugins can also be used for CORE only modifications like react_apps or fastapi_apps.
2. Guess I can move most of the tests to shared

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[amoghrajesh]

Docs: Unsure what to do about it, should we continue endorsing imports of format: from airflow.plugins_manager or move to from airflow.sdk.plugins_manager? I am doubtful because plugins can also be used for CORE only modifications like react_apps or fastapi_apps.

I think what we should do now is to define sdk.AirflowProviderPlugin and airflow.AirflowCorePlugin and make the old "AirflowPlugin" (for now) - and possibly we can already start importing the right ones in the right places as base classes. There is a bit of difficulty with Listeners though - because some listeners are "core" listeners, and some are "worker" listeners - but I think making it clear which listener is "task-sdk" and which one is "core" is something that we should do long time ago anyway. Our users (and ousrselves) are utterly confused where each listener is executed and it would be nice to make it clear by separating the "core" and "task-sdk" plugin interfaces now - even if for now we will use the same discovery mechanism in both. Possibly also eventually those two different plugin types should be advertised using different entrypoints - but that's something we can do later likely.

A bit more context why and what is my "North Star" here.

I think eventually we should have two (or maybe even 3) types of plugins. I thought about it in the past when discussing the task isolation with @ashb and splitting the distributions, and I am quite sure we will have to do it sooner or later (and rather sooner) and have different distribution for "core" and "task.sdk" plugins - when things are different than regular "providers" (i.e. when we have provider-specific executors, listeners and macros).

This is related to something we discussed yesterday with @kacpermuda in #59921 (comment) -> and it's clearly visible there because as of Airflow 3.2. openlineage is a bit in a Shroedinger state - it both needs, and does not need sqlalchemy, depending if it is installed with airflow-core (needs), or with task-sdk (might use when installed but does not need it). We get-by for now by declaring sqlalchemy as an optional dependency, and handling the optionality in the "worker" side of things.

I don't think we are "ready" to discuss the exact way how to do the split - with naming and implementation details - (we need to complete core isolation from task.sdk first).

But I think I have a very clear idea how it can work on high level (and would be the ultimate distribution split I had in mind when we started discussing task-isolation).

My thinking is that we might have two types of distribution - current task-sdk providers (hooks, operators, macros and other task-sdk side plugins) - and core-plugins (apache-airflow-core-plugins-openlineage) where we will only have "core" types of plugins. Possibly even later we can split out UI plugin types apache-airflow-ui-plugins-openlineage ??) - but that would only be needed if we decide to split out "airflow-ui" from "airflow-core" - which we might not want to do at all - depending on how different "UI" and "core" dependencies turn out after we complete current isolation work.

That would be very, very visible with edge provider - which (if we do all the split till the end) should have all 3 (!) types of distributions (cc: @jscheffl):

• apache-airflow-providers-edge3 -> worker side (edge3 does not have task-sdk plugins I think but they coudl be defined here)
• apache-airflow-core-plugins-edge3 -> executor
• apache-airlfow-ui-plugins-edge3 -> UI plugin

Similarly:

• apache-airflow-providers-amazon (including amazon-specific macros if there are any).
• apache-airflow-core-plugins-amazon -> executor

A little bit of problem there is that those "separate" distributions will necessarlily need to share some code. But this problem is largely solved now with shared concept of ours. We would just have to extend the shared concept we have now to providers - because those different distributions (say for amazon) will have some common code. We should have for example shared.amazon_common and use it in both apache-airflow-providers-amazon and apache-airflow-providers-core-plugins for example.

That is my dream structure of Airflow 3 that is my "North Star".

We do not have to decide on all that now - naming, folders, etc. can (and should be) discussed later when we complete the current isolation work. But we can do some preliminary work - i.e. start separating "types" of plugins.

Guess I can move most of the tests to shared

Yes.

That's a lot of good detail and very valid! I had similar thoughts and would probably want to have a plugins sdk some time in the future (I was discussing this with @uranusjr just a while earlier) and the motivation to do that was #59093.

The thought was to have a plugin SDK that allows loading components into protected processes without serialization. But we can probably chat about that just a little later.

@potiuk would you be OK to throw these thoughts you have into a issue for broader reach and formulation of some plan? Let me know if you would want me to take a look too

[amoghrajesh]

@jscheffl @potiuk you might want to take one more look since I made some changes to account for failing tests

[potiuk]

@potiuk would you be OK to throw these thoughts you have into a issue for broader reach and formulation of some plan? Let me know if you would want me to take a look too

I think it's a bit too early for that - see a discussion in devlist - this goes far beyond the current set of changes, and also it might change as we implement those "necessary" isolation changes now. I prefer to keep it here as a comment that I can find out later when we turn it into a plan for 3.3 - but I think that will be way better time and we will have way more "datapoints" to define the actual plan - and this should be preceded by a discussion where we will iterate over high level proposal first. So ... happy to do such a high-level proposal and turn it into a plan - but probabl;y closer to the time when we will be finalizing 3.2 and have all the task-isolation steps done.

[amoghrajesh]

@potiuk sounds good, please keep me in the loop on the same :)

[jscheffl]

Second pass review looks good for me.

[amoghrajesh]

Thanks for review folks, merging this one.