Support custom SDKs and use yarn

Dockerfile

@@ -1,22 +1,31 @@
 # Builder
-FROM node:alpine as builder
+FROM node:10-alpine as builder
 
-RUN apk add --no-cache git
+# Support custom branches of the react-sdk and js-sdk. This also helps us build
+# images of riot-web develop.
+ARG USE_CUSTOM_SDKS=false
+ARG REACT_SDK_REPO="https://github.com/matrix-org/matrix-react-sdk.git"
+ARG REACT_SDK_BRANCH="master"
+ARG JS_SDK_REPO="https://github.com/matrix-org/matrix-js-sdk.git"
+ARG JS_SDK_BRANCH="master"
+
+RUN apk add --no-cache git dos2unix
 
 WORKDIR /src
 
-COPY package.json /src/package.json
-RUN npm install
-
 COPY . /src
-RUN npm run build
+RUN dos2unix /src/scripts/docker-link-repos.sh && sh /src/scripts/docker-link-repos.sh
+RUN yarn install
+RUN yarn build
+
+# Copy the config now so that we don't create another layer in the app image
+RUN cp /src/config.sample.json /src/webapp/config.json
 
 
 # App
 FROM nginx:latest
 
 COPY --from=builder /src/webapp /app
-COPY config.sample.json /app/config.json
 
 RUN rm -rf /usr/share/nginx/html \
  && ln -s /app /usr/share/nginx/html

scripts/docker-link-repos.sh

@@ -0,0 +1,30 @@
+#!/bin/sh
+
+set -ex
+
+if [ $USE_CUSTOM_SDKS == false ]
+then
+    echo "skipping react-sdk and js-sdk installs: USE_CUSTOM_SDKS is false"
+    exit 0
+fi
+
+echo "Linking js-sdk"
+git clone $JS_SDK_REPO js-sdk
+cd js-sdk
+git checkout $JS_SDK_BRANCH
+yarn link
+yarn install
+cd ../
+
+echo "Linking react-sdk"
+git clone $REACT_SDK_REPO react-sdk
+cd react-sdk
+git checkout $REACT_SDK_BRANCH
+yarn link
+yarn link matrix-js-sdk
+yarn install
+cd ../
+
+echo "Setting up riot-web with react-sdk and js-sdk packages"
+yarn link matrix-js-sdk
+yarn link matrix-react-sdk