ensure protoc is installed for CI

Change-Id: I5b22ab5aeb21ecb04437c13da271830b94c268e9

.circleci/config.yml

@@ -15,6 +15,9 @@ jobs:
         # test needs dep ensure to be run again, since the Mixer plugin install
         # will have removed the vendor link.
       - run: dep ensure
+      - run:
+          command: ./bin/install_protoc.sh
+          name: install protoc
       - run:
           command: go generate ./...
           name: generate protos
@@ -73,6 +76,9 @@ jobs:
     steps:
       - checkout
       - run: dep ensure
+      - run:
+          command: ./bin/install_protoc.sh
+          name: install protoc
       - run:
           command: go generate ./...
           name: generate protos

bin/install_protoc.sh

@@ -0,0 +1,10 @@
+#!/usr/bin/env bash
+
+if [[ `command -v protoc` == "" ]]; then
+  mkdir /tmp/protoc
+  wget -O /tmp/protoc/protoc.zip https://github.com/google/protobuf/releases/download/v3.5.1/protoc-3.5.1-linux-x86_64.zip
+  unzip /tmp/protoc/protoc.zip -d /tmp/protoc
+  sudo mv -f /tmp/protoc/bin/protoc /usr/bin/
+  sudo mv -f /tmp/protoc/include/google /usr/local/include/
+  rm -rf /tmp/protoc
+fi