Polyman

Polyman is a simple HTTP to gRPC proxy.

Polyman is designed to work with Postman and bring gRPC to their rich enironment via Polyglot.

Benifits of Polyman

• Brings gRPC to Postman:
• Amazing UI
• Allows saving of collections
• Replayable requests
• Call many gRPC services from one place
• Simplifies Polyglot usage:
• No need to run via command line

Installation

curl -LO https://github.com/domgreen/polyman/releases/download/v0.0.0-alpha/polyman-darwin-amd64
mv polyman-darwin-amd64 polyman
chmod +x polyman 

(will need Java8 to run polyglot under the hood)

From Source

Download source:

git clone git@github.com:domgreen/polyman.git

Build source (with vgo):

make

Adding Polyman Proxy to Postman

• Settings > Proxy
• Enable "Global Proxy Configuration"
• Add localhost:8000

Starting Polyman

polyman [--polyglot] [--port]

--polyglot - optional parameter to supply a different polyglot.jar file. If this is not supplied the latest version will be downloaded to ~/.polyglot and used.

--port     - optional parameter to supply a new port for polyman.

Making A Request

Making a request via Polyman is done via a HTTP POST and using a json representation of the proto message that will be sent to the server.

Request:

POST http://0.0.0.0:50051/helloworld.Greeter/SayHello

The URL of the request is made up of the host and port where the gRPC service is running, followed by the Service name and method you are calling.

Headers:

x-polyman-root: ~/go/src/google.golang.org/grpc/examples/helloworld

x-polyman-root is the most commonly set Header, this sets the --proto_discovery_root in Polyglot that is used to discover protos and generate messages to send via gRPC.

Body:

{
  "name":"world"
}

Response:

{
  "message": "Hello world"
}

Listing Services

Listing Services gives you detailed information about the Services, Methods and their message structure via a HTTP GET request.

Request:

GET http://0.0.0.0:50051/list_services

The request is made to /list_services and uses the headers to decide where to look for the proto information.

Headers:

x-polyman-root: ~/go/src/google.golang.org/grpc/examples/helloworld

Response:

helloworld.Greeter -> ~/go/src/google.golang.org/grpc/examples/helloworld/helloworld.proto
  helloworld.Greeter/SayHello
    name[<optional> <single>]: STRING

  helloworld.Greeter/SayHelloAgain
    name[<optional> <single>]: STRING

This response shows a single service helloworld.Greeter with two methods SayHello and SayHelloAgain. It also shows the message definition for making the call.

Optional Headers

Polyman Config:

x-polyman-config: ~/mydir/myconfig.pb.json

x-polyman-config header tells the proxy the location for the Polyglot configuration. If this is supplied you may not need to supply the x-polyman-root header, depending on the configuration file that you are using.

Polyman Endpoint:

x-polyman-endpoint: 0.0.0.0:50051

x-polyman-endpoint can be supplied if you are not using the Postman proxy settings; the URL would then be the location of the Polyman proxy, which would use this header to correctly forward the call.

Polyman Metadata:

x-polyman-metadata: key1:value1,key2:value2

x-polyman-metadata can be supplied to add custom grpc metadata headers to calls made using Polyglot.