How to write gRPC Plugins

The gRPC server

A gRPC server must be implemented in the language of your choice, we have prepared different tutorials for some of them:

Ruby
C#/.NET

Serving

You can serve gRPC plugins by simply adding hooks to the custom_middleware in the API Definition, or by bundling. Read more about bundles below.

API Definition example:

"custom_middleware": {
    "pre": [
      {
        "name": "MyPreMiddleware"
      }
    ],
    "post": [
      {
        "name": "MyPostMiddleware"
      }
    ],
    "auth_check": {
      "name": "MyAuthCheck"
    },
    "driver": "grpc"
  },

and in the root of your tyk.conf:

"coprocess_options" : {
  "enable_coprocess":   true,
  "coprocess_grpc_server": "tcp://localhost:5555"
},

Now Tyk will fire 3 different hooks to your gRPC server hosted on localhost:5555 in the same API request.

Bundle

Bundle reading

A gRPC plugin can use the standard bundling mechanism that we use for the rest of our rich plugins. The essential difference with a standard rich plugin bundle is that the the bundle contains the actual code, which will be executed by Tyk, whereas a gRPC plugin bundle contains just a custom middleware definition, and you handle the execution of your code independently, e.g. a gRPC server, listening on port 8080.

This is what a manifest could look like:

{
  "file_list": [
  ],
  "custom_middleware": {
    "pre": [
      {
        "name": "MyPreMiddleware"
      }
    ],
    "post": [
      {
        "name": "MyPostMiddleware"
      }
    ],
    "auth_check": {
      "name": "MyAuthCheck"
    },
    "driver": "grpc"
  },
  "checksum": "",
  "signature": ""
}

After saving this file as manifest.json, build it using tyk-cli:

tyk-cli bundle build -output mybundle.zip -key mykey.pem

For Tyk 2.8 and upwards use the bundle functionaliy integrated as part of the Tyk Gateway binary, located in “/opt/tyk-gateway/bin/tyk` by default:

tyk bundle build -output mybundle.zip -key mykey.pem

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