Reference

grpc_interceptor

Simplified Python gRPC interceptors.

class grpc_interceptor.AsyncExceptionToStatusInterceptor(status_on_unknown_exception: Optional[grpc.StatusCode] = None)

An interceptor that catches exceptions and sets the RPC status and details.

This is the async analogy to ExceptionToStatusInterceptor. Please see that class’ documentation for more information.

async handle_exception(ex: Exception, request_or_iterator: Any, context: grpc.aio._base_server.ServicerContext, method_name: str) → NoReturn

Override this if extending ExceptionToStatusInterceptor.

This will get called when an exception is raised while handling the RPC.

Parameters

• ex – The exception that was raised.

• request_or_iterator – The RPC request, as a protobuf message if it is a unary request, or an iterator of protobuf messages if it is a streaming request.

• context – The servicer context. You probably want to call context.abort(…)

• method_name – The name of the RPC being called.

Raises

• This method must raise and cannot return, as in general there's no –

• meaningful RPC response to return if an exception has occurred. You can –

• raise the original exception, ex, or something else. –

async intercept(method: Callable, request_or_iterator: Any, context: grpc.aio._base_server.ServicerContext, method_name: str) → Any

Do not call this directly; use the interceptor kwarg on grpc.server().

class grpc_interceptor.AsyncServerInterceptor

Base class for asyncio server-side interceptors.

To implement an interceptor, subclass this class and override the intercept method.

abstract async intercept(method: Callable, request_or_iterator: Any, context: grpc.aio._base_server.ServicerContext, method_name: str) → Any

Override this method to implement a custom interceptor.

You should await method(request_or_iterator, context) to invoke the next handler (either the RPC method implementation, or the next interceptor in the list).

Parameters

• method – Either the RPC method implementation, or the next interceptor in the chain.

• request_or_iterator – The RPC request, as a protobuf message if it is a unary request, or an iterator of protobuf messages if it is a streaming request.

• context – The ServicerContext pass by gRPC to the service.

• method_name – A string of the form “/protobuf.package.Service/Method”

Returns

This should return the result of method(request_or_iterator, context), which is typically the RPC method response, as a protobuf message. The interceptor is free to modify this in some way, however.

async intercept_service(continuation, handler_call_details)

Implementation of grpc.aio.ServerInterceptor.

This is not part of the grpc_interceptor.AsyncServerInterceptor API, but must have a public name. Do not override it, unless you know what you’re doing.

class grpc_interceptor.ClientCallDetails(method: str, timeout: Optional[float], metadata: Optional[Sequence[Tuple[str, Union[str, bytes]]]], credentials: Optional[grpc.CallCredentials], wait_for_ready: Optional[bool], compression: Any)

Describes an RPC to be invoked.

See https://grpc.github.io/grpc/python/grpc.html#grpc.ClientCallDetails

class grpc_interceptor.ClientInterceptor

Base class for client-side interceptors.

To implement an interceptor, subclass this class and override the intercept method.

abstract intercept(method: Callable, request_or_iterator: Any, call_details: grpc.ClientCallDetails) → grpc_interceptor.client.ClientInterceptorReturnType

Override this method to implement a custom interceptor.

This method is called for all unary and streaming RPCs. The interceptor implementation should call method using a grpc.ClientCallDetails and the request_or_iterator object as parameters. The request_or_iterator parameter may be type checked to determine if this is a singluar request for unary RPCs or an iterator for client-streaming or client-server streaming RPCs.

Parameters

• method – A function that proceeds with the invocation by executing the next interceptor in the chain or invoking the actual RPC on the underlying channel.

• request_or_iterator – RPC request message or iterator of request messages for streaming requests.

• call_details – Describes an RPC to be invoked.

Returns

The type of the return should match the type of the return value received by calling method. This is an object that is both a Call for the RPC and a Future.

The actual result from the RPC can be got by calling .result() on the value returned from method.

intercept_stream_stream(continuation: Callable, call_details: grpc.ClientCallDetails, request_iterator: Iterator[Any])

Implementation of grpc.StreamStreamClientInterceptor.

This is not part of the grpc_interceptor.ClientInterceptor API, but must have a public name. Do not override it, unless you know what you’re doing.

intercept_stream_unary(continuation: Callable, call_details: grpc.ClientCallDetails, request_iterator: Iterator[Any])

Implementation of grpc.StreamUnaryClientInterceptor.

This is not part of the grpc_interceptor.ClientInterceptor API, but must have a public name. Do not override it, unless you know what you’re doing.

intercept_unary_stream(continuation: Callable, call_details: grpc.ClientCallDetails, request: Any)

Implementation of grpc.UnaryStreamClientInterceptor.

This is not part of the grpc_interceptor.ClientInterceptor API, but must have a public name. Do not override it, unless you know what you’re doing.

intercept_unary_unary(continuation: Callable, call_details: grpc.ClientCallDetails, request: Any)

Implementation of grpc.UnaryUnaryClientInterceptor.

This is not part of the grpc_interceptor.ClientInterceptor API, but must have a public name. Do not override it, unless you know what you’re doing.

class grpc_interceptor.ExceptionToStatusInterceptor(status_on_unknown_exception: Optional[grpc.StatusCode] = None)

An interceptor that catches exceptions and sets the RPC status and details.

ExceptionToStatusInterceptor will catch any subclass of GrpcException and set the status code and details on the gRPC context. You can also extend this and override the handle_exception method to catch other types of exceptions, and handle them in different ways. E.g., you can catch and handle exceptions that don’t derive from GrpcException. Or you can set rich error statuses with context.abort_with_status().

Parameters

status_on_unknown_exception – Specify what to do if an exception which is not a subclass of GrpcException is raised. If None, do nothing (by default, grpc will set the status to UNKNOWN). If not None, then the status code will be set to this value if context.abort hasn’t been called earlier. It must not be OK. The details will be set to the value of repr(e), where e is the exception. In any case, the exception will be propagated.

Raises

ValueError – If status_code is OK.

handle_exception(ex: Exception, request_or_iterator: Any, context: grpc.ServicerContext, method_name: str) → NoReturn

Override this if extending ExceptionToStatusInterceptor.

This will get called when an exception is raised while handling the RPC.

Parameters

• ex – The exception that was raised.

• request_or_iterator – The RPC request, as a protobuf message if it is a unary request, or an iterator of protobuf messages if it is a streaming request.

• context – The servicer context. You probably want to call context.abort(…)

• method_name – The name of the RPC being called.

Raises

• This method must raise and cannot return, as in general there's no –

• meaningful RPC response to return if an exception has occurred. You can –

• raise the original exception, ex, or something else. –

intercept(method: Callable, request_or_iterator: Any, context: grpc.ServicerContext, method_name: str) → Any

Do not call this directly; use the interceptor kwarg on grpc.server().

class grpc_interceptor.MethodName(package: str, service: str, method: str)

Represents a gRPC method name.

gRPC methods are defined by three parts, represented by the three attributes.

package

This is defined by the package foo.bar; designation in the protocol buffer definition, or it could be defined by the protocol buffer directory structure, depending on the language (see https://developers.google.com/protocol-buffers/docs/proto3#packages).

service

This is the service name in the protocol buffer definition (e.g., service SearchService { … }.

method

This is the method name. (e.g., rpc Search(…) returns (…);).

property fully_qualified_service

Return the service name prefixed with the package.

Example

>>> MethodName("foo.bar", "SearchService", "Search").fully_qualified_service
'foo.bar.SearchService'

class grpc_interceptor.ServerInterceptor

Base class for server-side interceptors.

To implement an interceptor, subclass this class and override the intercept method.

abstract intercept(method: Callable, request_or_iterator: Any, context: grpc.ServicerContext, method_name: str) → Any

Override this method to implement a custom interceptor.

You should call method(request_or_iterator, context) to invoke the next handler (either the RPC method implementation, or the next interceptor in the list).

Parameters

• method – Either the RPC method implementation, or the next interceptor in the chain.

• request_or_iterator – The RPC request, as a protobuf message if it is a unary request, or an iterator of protobuf messages if it is a streaming request.

• context – The ServicerContext pass by gRPC to the service.

• method_name – A string of the form “/protobuf.package.Service/Method”

Returns

This should return the result of method(request, context), which is typically the RPC method response, as a protobuf message, or an iterator of protobuf messages for streaming responses. The interceptor is free to modify this in some way, however.

intercept_service(continuation, handler_call_details)

Implementation of grpc.ServerInterceptor.

This is not part of the grpc_interceptor.ServerInterceptor API, but must have a public name. Do not override it, unless you know what you’re doing.

grpc_interceptor.parse_method_name(method_name: str) → grpc_interceptor.server.MethodName

Parse a method name into package, service and endpoint components.

Parameters

method_name – A string of the form “/foo.bar.SearchService/Search”, as passed to ServerInterceptor.intercept().

Returns

A MethodName object.

Example

>>> parse_method_name("/foo.bar.SearchService/Search")
MethodName(package='foo.bar', service='SearchService', method='Search')

grpc_interceptor.exceptions

Exceptions for ExceptionToStatusInterceptor.

See https://grpc.github.io/grpc/core/md_doc_statuscodes.html for the source of truth on status code meanings.

exception grpc_interceptor.exceptions.Aborted(details: Optional[str] = None, status_code: Optional[grpc.StatusCode] = None)

The operation was aborted.

Typically this is due to a concurrency issue such as a sequencer check failure or transaction abort. See the guidelines on other exceptions for deciding between FAILED_PRECONDITION, ABORTED, and UNAVAILABLE.

exception grpc_interceptor.exceptions.AlreadyExists(details: Optional[str] = None, status_code: Optional[grpc.StatusCode] = None)

The entity that a client attempted to create already exists.

E.g., a file or directory that a client is trying to create already exists.

exception grpc_interceptor.exceptions.Cancelled(details: Optional[str] = None, status_code: Optional[grpc.StatusCode] = None)

The operation was cancelled, typically by the caller.

exception grpc_interceptor.exceptions.DataLoss(details: Optional[str] = None, status_code: Optional[grpc.StatusCode] = None)

Unrecoverable data loss or corruption.

exception grpc_interceptor.exceptions.DeadlineExceeded(details: Optional[str] = None, status_code: Optional[grpc.StatusCode] = None)

The deadline expired before the operation could complete.

For operations that change the state of the system, this error may be returned even if the operation has completed successfully. For example, a successful response from a server could have been delayed long.

exception grpc_interceptor.exceptions.FailedPrecondition(details: Optional[str] = None, status_code: Optional[grpc.StatusCode] = None)

The operation failed because the system is in an invalid state for execution.

For example, the directory to be deleted is non-empty, an rmdir operation is applied to a non-directory, etc. Service implementors can use the following guidelines to decide between FAILED_PRECONDITION, ABORTED, and UNAVAILABLE: (a) Use UNAVAILABLE if the client can retry just the failing call. (b) Use ABORTED if the client should retry at a higher level (e.g., when a client-specified test-and-set fails, indicating the client should restart a read-modify-write sequence). (c) Use FAILED_PRECONDITION if the client should not retry until the system state has been explicitly fixed. E.g., if an “rmdir” fails because the directory is non-empty, FAILED_PRECONDITION should be returned since the client should not retry unless the files are deleted from the directory.

exception grpc_interceptor.exceptions.GrpcException(details: Optional[str] = None, status_code: Optional[grpc.StatusCode] = None)

Base class for gRPC exceptions.

Generally you would not use this class directly, but rather use a subclass representing one of the standard gRPC status codes (see: https://grpc.github.io/grpc/core/md_doc_statuscodes.html for the official list).

status_code

A grpc.StatusCode other than OK. The only use case for this is if gRPC adds a new status code that isn’t represented by one of the subclasses of GrpcException. Must not be OK, because gRPC will not raise an RpcError to the client if the status code is OK.

details

A string with additional informantion about the error.

Parameters

• details – If not None, specifies a custom error message.

• status_code – If not None, sets the status code.

Raises

ValueError – If status_code is OK.

property status_string

Return status_code as a string.

Returns

The status code as a string.

Example

>>> GrpcException(status_code=StatusCode.NOT_FOUND).status_string
'NOT_FOUND'

exception grpc_interceptor.exceptions.Internal(details: Optional[str] = None, status_code: Optional[grpc.StatusCode] = None)

Internal errors.

This means that some invariants expected by the underlying system have been broken. This error code is reserved for serious errors.

exception grpc_interceptor.exceptions.InvalidArgument(details: Optional[str] = None, status_code: Optional[grpc.StatusCode] = None)

The client specified an invalid argument.

Note that this differs from FAILED_PRECONDITION. INVALID_ARGUMENT indicates arguments that are problematic regardless of the state of the system (e.g., a malformed file name).

exception grpc_interceptor.exceptions.NotFound(details: Optional[str] = None, status_code: Optional[grpc.StatusCode] = None)

Some requested entity (e.g., file or directory) was not found.

Note to server developers: if a request is denied for an entire class of users, such as gradual feature rollout or undocumented whitelist, NOT_FOUND may be used. If a request is denied for some users within a class of users, such as user-based access control, PERMISSION_DENIED must be used.

exception grpc_interceptor.exceptions.OutOfRange(details: Optional[str] = None, status_code: Optional[grpc.StatusCode] = None)

The operation was attempted past the valid range.

E.g., seeking or reading past end-of-file. Unlike INVALID_ARGUMENT, this error indicates a problem that may be fixed if the system state changes. For example, a 32-bit file system will generate INVALID_ARGUMENT if asked to read at an offset that is not in the range [0,2^32-1], but it will generate OUT_OF_RANGE if asked to read from an offset past the current file size. There is a fair bit of overlap between FAILED_PRECONDITION and OUT_OF_RANGE. We recommend using OUT_OF_RANGE (the more specific error) when it applies so that callers who are iterating through a space can easily look for an OUT_OF_RANGE error to detect when they are done.

exception grpc_interceptor.exceptions.PermissionDenied(details: Optional[str] = None, status_code: Optional[grpc.StatusCode] = None)

The caller does not have permission to execute the specified operation.

PERMISSION_DENIED must not be used for rejections caused by exhausting some resource (use RESOURCE_EXHAUSTED instead for those errors). PERMISSION_DENIED must not be used if the caller can not be identified (use UNAUTHENTICATED instead for those errors). This error code does not imply the request is valid or the requested entity exists or satisfies other pre-conditions.

exception grpc_interceptor.exceptions.ResourceExhausted(details: Optional[str] = None, status_code: Optional[grpc.StatusCode] = None)

Some resource has been exhausted.

Perhaps a per-user quota, or perhaps the entire file system is out of space.

exception grpc_interceptor.exceptions.Unauthenticated(details: Optional[str] = None, status_code: Optional[grpc.StatusCode] = None)

The request does not have valid authentication credentials for the operation.

exception grpc_interceptor.exceptions.Unavailable(details: Optional[str] = None, status_code: Optional[grpc.StatusCode] = None)

The service is currently unavailable.

This is most likely a transient condition, which can be corrected by retrying with a backoff. Note that it is not always safe to retry non-idempotent operations.

exception grpc_interceptor.exceptions.Unimplemented(details: Optional[str] = None, status_code: Optional[grpc.StatusCode] = None)

The operation is not implemented or is not supported/enabled in this service.

exception grpc_interceptor.exceptions.Unknown(details: Optional[str] = None, status_code: Optional[grpc.StatusCode] = None)

Unknown error.

For example, this error may be returned when a Status value received from another address space belongs to an error space that is not known in this address space. Also errors raised by APIs that do not return enough error information may be converted to this error.

grpc_interceptor.testing

A framework for testing interceptors.

class grpc_interceptor.testing.DummyRequest

class grpc_interceptor.testing.DummyResponse

class grpc_interceptor.testing.DummyService(special_cases: Dict[str, Callable[[str, Union[grpc.ServicerContext, grpc.aio._base_server.ServicerContext]], str]])

A gRPC service used for testing.

Parameters

special_cases – A dictionary where the keys are strings, and the values are functions that take and return strings. The functions can also raise exceptions. When the Execute method is given a string in the dict, it will call the function with that string instead, and return the result. This allows testing special cases, like raising exceptions.

Execute(request: dummy_pb2.DummyRequest, context: grpc.ServicerContext) → dummy_pb2.DummyResponse

Echo the input, or take on of the special cases actions.

ExecuteClientServerStream(request_iter: Iterable[dummy_pb2.DummyRequest], context: grpc.ServicerContext) → Iterable[dummy_pb2.DummyResponse]

Stream input to output.

ExecuteClientStream(request_iter: Iterable[dummy_pb2.DummyRequest], context: grpc.ServicerContext) → dummy_pb2.DummyResponse

Iterate over the input and concatenates the strings into the output.

ExecuteServerStream(request: dummy_pb2.DummyRequest, context: grpc.ServicerContext) → Iterable[dummy_pb2.DummyResponse]

Stream one character at a time from the input.

grpc_interceptor.testing.dummy_client(special_cases: Dict[str, Callable[[str, Union[grpc.ServicerContext, grpc.aio._base_server.ServicerContext]], str]], interceptors: Optional[List[grpc_interceptor.server.ServerInterceptor]] = None, client_interceptors: Optional[List[grpc_interceptor.client.ClientInterceptor]] = None, aio_server: bool = False, aio_client: bool = False, aio_read_write: bool = False)

A context manager that returns a gRPC client connected to a DummyService.

grpc_interceptor.testing.raises(e: Exception) → Callable

Return a function that raises the given exception when called.

Parameters

e – The exception to be raised.

Returns

A function that can take any arguments, and raises the given exception.