Drop gRPC support

Knative does not (yet) support gRPC. Since only HTTP is supported,
including any other protocol is pure overhead. Once Knative Serving has
support for gRPC, we'll restore support here. Even then, Knative
Eventing will use a different proto, so the existing gRPC support
wouldn't work anyway.

The facilities for supporting multiple protocols remain in place, even
though only HTTP is supported at the moment.

Fixes projectriff#65

Dockerfile

@@ -2,7 +2,6 @@ FROM node:10.7.0-alpine
 WORKDIR /usr/app
 COPY . .
 ENV HOST 0.0.0.0
-ENV GRPC_PORT 10382
 ENV HTTP_PORT 8080
 RUN npm install --production
 EXPOSE 10382 8080

README.md

@@ -2,15 +2,15 @@
 
 ## Purpose
 The *node function invoker* provides a Docker base layer for a function consisting of a single NodeJS module.
-It accepts gRPC requests, invokes the command for each request in the input stream, and sends the command's output to the stream of gRPC responses.
+It accepts HTTP requests, invokes the function for each request in the input stream, and sends the function's output to the HTTP response.
 
 ## Development
 
 ### Prerequisites
 
 The following tools are required to build this project:
 
-- `node` 8 (only for tests)
+- `node` 10 (only for tests)
 - [jq](https://stedolan.github.io/jq/download/)
 - Docker
 

lib/interaction-models/node-streams.js

@@ -35,7 +35,7 @@ function nodeStreamsInteractionModel(fn, argumentTransformer, messageStream) {
             const errorMessage = buildErrorMessage(e, {
                 correlationId: headers.getValue('correlationId')
             });
-            // write errors directly to grpcStream
+            // write errors directly to messageStream
             messageStream.write(errorMessage.toRiffMessage());
         }
         callback();

node-invoker.yaml

@@ -10,7 +10,7 @@ spec:
   - "*.js"
   functionTemplate:
     spec:
-      protocol: grpc
+      protocol: http
   files:
   - path: Dockerfile
     template: |