make+lnrpc: use docker to compile protos

This commit aims to make it easier for developers to compile our
protobuf definitions. They now only need to have docker installed
instead of a whole set of binaries and libraries all pinned to very
specific versions.

Makefile

@@ -262,7 +262,7 @@ list:
 
 rpc:
 	@$(call print, "Compiling protos.")
-	cd ./lnrpc; ./gen_protos.sh
+	cd ./lnrpc; ./gen_protos_docker.sh
 
 rpc-format:
 	@$(call print, "Formatting protos.")

lnrpc/Dockerfile

@@ -0,0 +1,22 @@
+FROM golang:1.15.6-buster
+
+RUN apt-get update && apt-get install -y \
+  git \
+  protobuf-compiler='3.6.1*' \
+  clang-format='1:7.0*'
+
+# We don't want any default values for these variables to make sure they're
+# explicitly provided by parsing the go.mod file. Otherwise we might forget to
+# update them here if we bump the versions.
+ARG PROTOC_GEN_VERSION
+ARG GRPC_GATEWAY_VERSION
+
+RUN cd /tmp \
+  && export GO111MODULE=on \
+  && go get github.com/golang/protobuf/protoc-gen-go@${PROTOC_GEN_VERSION} \
+  && go get github.com/grpc-ecosystem/grpc-gateway/protoc-gen-grpc-gateway@${GRPC_GATEWAY_VERSION} \
+  && go get github.com/grpc-ecosystem/grpc-gateway/protoc-gen-swagger@${GRPC_GATEWAY_VERSION}
+
+WORKDIR /build
+
+CMD ["/bin/bash", "/build/lnrpc/gen_protos.sh"]

lnrpc/gen_protos.sh

@@ -1,28 +1,44 @@
-#!/bin/sh
+#!/bin/bash
 
-echo "Generating root gRPC server protos"
+set -e
 
-PROTOS="rpc.proto walletunlocker.proto **/*.proto"
+# generate compiles the *.pb.go stubs from the *.proto files.
+function generate() {
+  echo "Generating root gRPC server protos"
+  
+  PROTOS="rpc.proto walletunlocker.proto **/*.proto"
+  
+  # For each of the sub-servers, we then generate their protos, but a restricted
+  # set as they don't yet require REST proxies, or swagger docs.
+  for file in $PROTOS; do
+    DIRECTORY=$(dirname "${file}")
+    echo "Generating protos from ${file}, into ${DIRECTORY}"
+  
+    # Generate the protos.
+    protoc -I/usr/local/include -I. \
+      --go_out=plugins=grpc,paths=source_relative:. \
+      "${file}"
+  
+    # Generate the REST reverse proxy.
+    protoc -I/usr/local/include -I. \
+      --grpc-gateway_out=logtostderr=true,paths=source_relative,grpc_api_configuration=rest-annotations.yaml:. \
+      "${file}"
+  
+  
+    # Finally, generate the swagger file which describes the REST API in detail.
+    protoc -I/usr/local/include -I. \
+      --swagger_out=logtostderr=true,grpc_api_configuration=rest-annotations.yaml:. \
+      "${file}"
+  done
+}
 
-# For each of the sub-servers, we then generate their protos, but a restricted
-# set as they don't yet require REST proxies, or swagger docs.
-for file in $PROTOS; do
-  DIRECTORY=$(dirname "${file}")
-  echo "Generating protos from ${file}, into ${DIRECTORY}"
+# format formats the *.proto files with the clang-format utility.
+function format() {
+  find . -name "*.proto" -print0 | xargs -0 clang-format --style=file -i
+}
 
-  # Generate the protos.
-  protoc -I/usr/local/include -I. \
-    --go_out=plugins=grpc,paths=source_relative:. \
-    "${file}"
-
-  # Generate the REST reverse proxy.
-  protoc -I/usr/local/include -I. \
-    --grpc-gateway_out=logtostderr=true,paths=source_relative,grpc_api_configuration=rest-annotations.yaml:. \
-    "${file}"
-
-
-  # Finally, generate the swagger file which describes the REST API in detail.
-  protoc -I/usr/local/include -I. \
-    --swagger_out=logtostderr=true,grpc_api_configuration=rest-annotations.yaml:. \
-    "${file}"
-done
+# Compile and format the lnrpc package.
+pushd lnrpc
+format
+generate
+popd

lnrpc/gen_protos_docker.sh

@@ -0,0 +1,23 @@
+#!/bin/bash
+
+set -e
+
+# Directory of the script file, independent of where it's called from.
+DIR="$(cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd)"
+
+PROTOC_GEN_VERSION=$(go list -f '{{.Version}}' -m github.com/golang/protobuf)
+GRPC_GATEWAY_VERSION=$(go list -f '{{.Version}}' -m github.com/grpc-ecosystem/grpc-gateway)
+
+echo "Building protobuf compiler docker image..."
+docker build -q -t lnd-protobuf-builder \
+  --build-arg PROTOC_GEN_VERSION="$PROTOC_GEN_VERSION" \
+  --build-arg GRPC_GATEWAY_VERSION="$GRPC_GATEWAY_VERSION" \
+  .
+
+echo "Compiling and formatting *.proto files..."
+docker run \
+  --rm \
+  --user "$UID:$(id -g)" \
+  -e UID=$UID \
+  -v "$DIR/../:/build" \
+  lnd-protobuf-builder