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Nathan Baulch
8342a109ae
Continuation of #37541 but focused on Python. Top typos are: * resolveable (5) * dedecated (4) * everyting (4) * programatically (3) * supercede (3) * wil (3) * acknowledgment (2) * corutine (2) * coversion (2) * operaton (2) * wich (2) Closes #38029 PiperOrigin-RevId: 695759207
44 lines
1.7 KiB
Markdown
44 lines
1.7 KiB
Markdown
# gRPC Python Async Interceptor Example
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This example demonstrate the usage of Async interceptors and context propagation using [contextvars](https://docs.python.org/3/library/contextvars.html#module-contextvars).
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## When to use contextvars
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`Contextvars` can be used to propagate context in a same thread or coroutine, some example usage include:
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1. Propagate from interceptor to another interceptor.
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2. Propagate from interceptor to the server handler.
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3. Propagate from client to server.
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## How does this example works
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This example have the following steps:
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1. Generate RPC ID on client side and propagate to server using `metadata`.
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* `contextvars` can be used here if client and server is running in a same coroutine (or same thead for Sync).
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2. Server interceptor1 intercept the request, it checks `rpc_id_var` and decorate it with its tag `Interceptor1`.
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3. Server interceptor2 intercept the request, it checks `rpc_id_var` and decorate it with its tag `Interceptor2`.
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4. Server handler receives the request with `rpc_id_var` decorated by both interceptor1 and interceptor2.
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## How to run this example
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1. Start server: `python3 -m async_greeter_server_with_interceptor`
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2. Start client: `python3 -m async_greeter_client`
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### Expected outcome
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* On client side, you should see logs similar to:
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```
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Sending request with rpc id: 59ac966558b3d7d11a06bd45f1a0f89d
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Greeter client received: Hello, you!
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```
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* On server side, you should see logs similar to:
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```
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INFO:root:Starting server on [::]:50051
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INFO:root:Interceptor1 called with rpc_id: default
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INFO:root:Interceptor2 called with rpc_id: Interceptor1-59ac966558b3d7d11a06bd45f1a0f89d
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INFO:root:Handle rpc with id Interceptor2-Interceptor1-59ac966558b3d7d11a06bd45f1a0f89d in server handler.
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```
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