feat: Add dockerfile

Dockerfile

@@ -0,0 +1,25 @@
+# Using Alpine to keep the images smaller
+# Change to using the official NodeJS Alpine container
+FROM node:16-alpine
+
+# Pushing all files into image
+WORKDIR /app
+RUN wget -q https://github.com/NickColley/semaphore/archive/refs/tags/1.0.0.tar.gz \
+	     -O /tmp/semaphore.tar.gz \
+ && tar xavf /tmp/1.0.0.tar.gz --strip-components 1 \
+ && rm -f /tmp/semaphore.tar.gz
+
+# Install Semaphore
+RUN yarn --production --pure-lockfile \
+ && yarn build \
+ && yarn cache clean \
+ && rm -rf ./src ./docs ./tests ./bin
+
+# Expose port 4002
+EXPOSE 4002
+
+# Setting run-command, using explicit `node` command
+# rather than `yarn` or `npm` to use less memory
+# https://github.com/nolanlawson/pinafore/issues/971
+CMD ["PORT=4002", "node", "server.js"]
+