I understand that metadata_call_credentials() takes a AuthMetadataPlugin object and returns a proper CallCredentials object. What I don't understand is how to create an AuthMetadataPlugin that performs the same action as PasswordCallCredentials's applyRequestMetadata() method in the Java implementation above: adding a key-value pair to the request header.
Furthermore, it appears that the Java client implementation above creates a plain text channel, and then passes in the PasswordCallCredentials object when creating the stub. However, I don't believe this is possible using the Python gRPC API. Instead, credentials must be passed upon channel creation, and the credentials must be ChannelCredentials, not CallCredentials or any other type. So even if I knew how to create a AuthMetadataPlugin that could put the proper values in the request header, I still couldn't use metadata_call_credentials() to do what I want, since that method returns a CallCredentials object, whereas I need a ChannelCredentials object. Am I missing something? On Sunday, February 28, 2021 at 1:14:33 PM UTC-5 [email protected] wrote: > This one > https://grpc.github.io/grpc/python/_modules/grpc.html#metadata_call_credentials > > talks about metadata call credentials which seems to be similar to what the > Java client is doing. Examples of authMetadataPlugin are available at > https://www.programcreek.com/python/example/113599/grpc.AuthMetadataPlugin > > Although I doubt the error "Method not found: GetVersion/GetVersion" is > because of missing CallCredentials. > > > > On Sun, Feb 28, 2021 at 9:35 AM James Telzrow <[email protected]> wrote: > >> Hello, >> >> I am continuously getting the following error when making a gRPC call: >> >> grpc._channel._InactiveRpcError: <_InactiveRpcError of RPC that >> terminated with: >> status = StatusCode.UNIMPLEMENTED >> details = "Method not found: GetVersion/GetVersion" >> debug_error_string = >> "{"created":"@1614530914.104036000","description":"Error received from peer >> ipv4:192.168.0.69:9998","file":"src/core/lib/surface/call.cc","file_line":1068,"grpc_message":"Method >> >> not found: GetVersion/GetVersion","grpc_status":12}" >> >> I am making the call using this bit of Python code: >> >> def runFunc(): >> channel = grpc.insecure_channel('192.168.0.69:9998') >> stub = grpcBisq_pb2_grpc.GetVersionStub(channel) >> response = stub.GetVersion(grpcBisq_pb2.GetVersionRequest()) >> print(response.version) >> >> However, I know that the server has a GetVersion gRPC service with a >> GetVersion endpoint that takes a GetVersionRequest, since both the client >> and server have the following in their .proto file: >> >> service GetVersion { >> rpc GetVersion (GetVersionRequest) returns (GetVersionReply) { >> } >> } >> message GetVersionRequest { >> } >> message GetVersionReply { >> string version = 1; >> } >> >> The server is written in Java (and wasn't written by me) and I wrote my >> client in Python. However, the server has an example client (also written >> in Java) that uses some sort of authentication scheme, and as of now my >> Python client isn't using any type of authentication. I'm guessing this is >> what is causing the server to return the above error. In that Java client, >> the stub is created as follows: >> >> public final class GrpcStubs { >> public final GetVersionGrpc.GetVersionBlockingStub versionService; >> public GrpcStubs(String apiHost, int apiPort, String apiPassword) { >> CallCredentials credentials = new >> PasswordCallCredentials(apiPassword); >> var channel = ManagedChannelBuilder.forAddress(apiHost, >> apiPort).usePlaintext().build(); >> Runtime.getRuntime().addShutdownHook(new Thread(() -> { >> try { >> channel.shutdown().awaitTermination(1, SECONDS); >> } catch (InterruptedException ex) { >> throw new IllegalStateException(ex); >> } >> })); >> this.versionService >> = GetVersionGrpc.newBlockingStub(channel).withCallCredentials(credentials); >> } >> } >> >> PasswordCallCredentials is defined in PasswordCallCredentials.java as >> follows: >> >> /** >> * Sets the {@value PASSWORD_KEY} rpc call header to a given value. >> */ >> class PasswordCallCredentials extends CallCredentials { >> public static final String PASSWORD_KEY = "password"; >> private final String passwordValue; >> public PasswordCallCredentials(String passwordValue) { >> if (passwordValue == null) >> throw new IllegalArgumentException(format("'%s' value must >> not be null", PASSWORD_KEY)); >> this.passwordValue = passwordValue; >> } >> @Override >> public void applyRequestMetadata(RequestInfo requestInfo, Executor >> appExecutor, MetadataApplier metadataApplier) { >> appExecutor.execute(() -> { >> try { >> var headers = new Metadata(); >> var passwordKey = Key.of(PASSWORD_KEY, >> ASCII_STRING_MARSHALLER); >> headers.put(passwordKey, passwordValue); >> metadataApplier.apply(headers); >> } catch (Throwable ex) { >> metadataApplier.fail(UNAUTHENTICATED.withCause(ex)); >> } >> }); >> } >> @Override >> public void thisUsesUnstableApi() { >> } >> } >> >> If I understand correctly, PasswordCallCredentials is subclassing >> CallCredentials, and when called, it causes the key-value pair "password: >> {apiPasswordHere}" to be placed in the header of every gRPC request. If my >> understanding is wrong, please correct me. >> >> I have tested the Java client, and it works perfectly. >> >> Unfortunately, even after thoroughly searching through the documentation, >> I do not understand how to implement this in Python. I know I need to >> create a grpc.secure_channel and pass a ChannelCredentials object, but I'm >> not sure how to proceed from there. Can someone help me? >> >> -- >> You received this message because you are subscribed to the Google Groups >> "grpc.io" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to [email protected]. >> To view this discussion on the web visit >> https://groups.google.com/d/msgid/grpc-io/eec9603c-2dc5-45a4-bfd1-f0d5ef796059n%40googlegroups.com >> >> <https://groups.google.com/d/msgid/grpc-io/eec9603c-2dc5-45a4-bfd1-f0d5ef796059n%40googlegroups.com?utm_medium=email&utm_source=footer> >> . >> > -- You received this message because you are subscribed to the Google Groups "grpc.io" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/grpc-io/3d7f11ff-72cb-4f35-aa03-897fe7da92bcn%40googlegroups.com.
