Docker File - Firebase Cloud Functions

FROM node:6.14

ENV FIREBASE_TOKEN ""

VOLUME ["/usr/src/data"]
EXPOSE 5000

WORKDIR /usr/src/data/functions
ADD package.json /usr/src/data/functions/package.json

RUN npm install -g firebase-tools
RUN npm install -save firebase-functions firebase-admin
RUN npm install --no-optional

CMD [ "/bin/bash", "-c", "firebase serve --host 0.0.0.0 --only functions" ]