Add an option to develop in a reproducible and containerized environment

Dockerfile.develop

@@ -0,0 +1,46 @@
+FROM node:10-alpine
+
+# 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"
+
+# CRLF -> LF conversion
+RUN apk add --no-cache git dos2unix
+
+WORKDIR /riot
+
+# Install deps-only into separate Docker layer and run Riot when the container
+# starts, mount source as a volume and keep dev environment consistent
+COPY scripts /riot/scripts
+RUN dos2unix /riot/scripts/docker-link-repos.sh \
+    && sh /riot/scripts/docker-link-repos.sh
+
+# Cache package.json
+COPY package.json yarn.lock /riot/
+
+# Remove 'prepare' script because there is NO config in yarn and npm for
+# disabling it and is not necessary for development build
+RUN sed -i -e '/"prepare":/d' /riot/package.json
+RUN yarn --network-timeout=100000 install
+
+# Overlay src files with the original ones in case something was left out
+# from explicit copying above and doesn't work with mounting properly such as:
+#
+# "ERROR in Entry module not found: Error: Can't resolve './src' in '/riot'"
+# "ERROR in multi (webpack)-dev-server/client?http://0.0.0.0 ./src"
+COPY . /riot
+
+# Assemble entrypoint that copies the config at container start
+# and runs webpack server. Mount volume to /src/src for developing.
+RUN echo 'mkdir /riot/webapp' >> /entry.sh \
+    && echo 'cp /riot/config.sample.json /riot/webapp/config.json' >> /entry.sh \
+    && echo 'sh /riot/scripts/docker-link-repos.sh' >> /entry.sh \
+    && echo 'yarn start' >> /entry.sh \
+    && chmod +x /entry.sh
+
+# run webpack server to change the code on-the-go
+ENTRYPOINT /entry.sh

README.md

@@ -304,6 +304,72 @@ If any of these steps error with, `file table overflow`, you are probably on a m
 which has a very low limit on max open files. Run `ulimit -Sn 1024` and try again.
 You'll need to do this in each new terminal you open before building Riot.
 
+Using Docker image for development
+----------------------------------
+
+Avoids installation of Node, NPM and the rest of the environment by providing
+the same environment that's used in serving Riot via Dockerfile officially
+and at the same time allows to plug in the folder with source files so that
+you can edit outside of Docker container and let it compile inside where
+it is safely separated from your machine or any custom configuration.
+
+Note that hot-reloading via an open websocket might not work out of the box
+on Windows, check [WebPack ``watchOptions.poll``](https://webpack.js.org/configuration/watch/)
+as a workaround.
+
+Using this approach provides a reproducible environment between you and
+the maintainers if you share your changes in a pull request.
+
+Run it with:
+
+```bash
+# build image
+docker build --tag vectorim/riot-web:develop --file Dockerfile.develop .
+
+# remove old container or do nothing
+docker rm -f riot || true
+
+# run a new container with src folder mounted from git repository
+# located on the host machine. You can mount additional folders
+# such as res with additional --volume $PWD/res:/src/res
+docker run --interactive --tty \
+    --publish <port-on-host>:8080 \
+    --volume $PWD/src:/riot/src \
+    --name riot \
+    vectorim/riot-web:develop
+```
+
+And access ``yarn`` and other commands from inside of the container:
+
+```bash
+# run shell process from container
+docker exec -it riot sh
+
+# run yarn process from container
+docker exec -it riot yarn
+```
+
+In case you want to use own clones of
+[matrix-react-sdk](https://github.com/matrix-org/matrix-react-sdk)
+or
+[matrix-js-sdk](https://github.com/matrix-org/matrix-js-sdk)
+set additional environment variable ``USE_CUSTOM_SDKS`` in ``docker build``
+if it's a one-time operation. In case you want to use own clone and edit
+it at the same time as you edit ``riot-web``, set the environement
+variable in ``docker run`` command.
+
+```bash
+docker run --interactive --tty \
+    --publish <port-on-host>:8080 \
+    --volume $PWD/src:/riot/src \
+    --volume <path-to-matrix-js-sdk>:/riot/js-sdk \
+    --volume <path-to-matrix-react-sdk>:/riot/react-sdk \
+    --env USE_CUSTOM_SDKS=true \
+    --env NO_CLONE=true \
+    --name riot \
+    vectorim/riot-web:develop
+```
+
 Running the tests
 -----------------
 

scripts/docker-link-repos.sh

@@ -9,17 +9,27 @@ then
 fi
 
 echo "Linking js-sdk"
-git clone $JS_SDK_REPO js-sdk
+if [ -z ${NO_CLONE+x} ]
+then
+    git clone $JS_SDK_REPO js-sdk
+    cd js-sdk
+    git checkout $JS_SDK_BRANCH
+    cd ..
+fi
 cd js-sdk
-git checkout $JS_SDK_BRANCH
 yarn link
 yarn --network-timeout=100000 install
 cd ../
 
 echo "Linking react-sdk"
-git clone $REACT_SDK_REPO react-sdk
+if [ -z ${NO_CLONE+x} ]
+then
+    git clone $REACT_SDK_REPO react-sdk
+    cd react-sdk
+    git checkout $REACT_SDK_BRANCH
+    cd ..
+fi
 cd react-sdk
-git checkout $REACT_SDK_BRANCH
 yarn link
 yarn link matrix-js-sdk
 yarn --network-timeout=100000 install