Support domain socket

[daixiang0]

Describe the proposal

Ref https://github.com/dapr/dapr/issues/2864

Release Note

RELEASE NOTE: ADD support domain socket.

[dapr-bot]

This issue has been automatically marked as stale because it has not had activity in the last 60 days. It will be closed in the next 7 days unless it is tagged (pinned, good first issue, help wanted or triaged/resolved) or other activity occurs. Thank you for your contributions.

[dapr-bot]

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[berndverst]

@daixiang0

I think this won't be as useful until the CLI can actually return the UDS path in an environment variable: https://github.com/dapr/cli/issues/969

Once that is complete I am happy to add support for UDS (and it will be easier for us to test too).

Implementing UDS support isn't hard for gRPC, but is trickier for HTTP.

[daixiang0]

I am curious why it is trickier for HTTP, listen one UDS likes addr+port both for gRPC and HTTP, do you mean the limit of python-sdk itself.

[berndverst]

@daixiang0 because the Python requests library - the most commonly used HTTP client - does not have support for UDS. I am against replacing this library.

I found the following https://pypi.org/project/requests-unixsocket/ but I do not trust this package so far.

Perhaps monkeypatching as described here https://github.com/msabramo/requests-unixsocket might be possible -- in this case I prefer using a context manager instead of global monkey patching to avoid any unintended side effects.

https://github.com/msabramo/requests-unixsocket#implicit-monkeypatching

[tmacam]

/assign

[berndverst]

This is already supported for gRPC, but will not be implemented for HTTP which only supports service invocation anyway.

Example: dapr run -u /Users/bverst/testfolder this will create a dapr-$appid-grpc.socket file in this folder.

Now in Python we can use this socket like so:

from dapr.clients import DaprClient
d = DaprClient(address='unix:///Users/bverst/testfolder/dapr-flying-giraffe-grpc.socket')
d.get_metadata()

[berndverst]

Ironically this was supported all along thanks to the underlying gRPC library!