Improve signal handlers

Dockerfile

@@ -1,12 +1,12 @@
 FROM node:18-alpine as server-dependencies
 
 RUN apk -U upgrade \
-  && apk add build-base python3 \
+  && apk add build-base python3 tini \
   --no-cache
 
 WORKDIR /app
 
-COPY server/package.json server/package-lock.json .
+COPY server/package.json server/package-lock.json ./
 
 RUN npm install npm@latest --global \
   && npm install pnpm --global \
@@ -17,7 +17,7 @@ FROM node:lts AS client
 
 WORKDIR /app
 
-COPY client/package.json client/package-lock.json .
+COPY client/package.json client/package-lock.json ./
 
 RUN npm install npm@latest --global \
   && npm install pnpm --global \
@@ -27,7 +27,7 @@ RUN npm install npm@latest --global \
 COPY client .
 RUN DISABLE_ESLINT_PLUGIN=true npm run build
 
-FROM node:18-alpine
+FROM node:18-alpine AS final
 
 RUN apk -U upgrade \
   && apk add bash \
@@ -42,6 +42,7 @@ COPY --chown=node:node server .
 RUN mv .env.sample .env
 
 COPY --from=server-dependencies --chown=node:node /app/node_modules node_modules
+COPY --from=server-dependencies --chown=node:node /sbin/tini /sbin/tini
 
 COPY --from=client --chown=node:node /app/build public
 COPY --from=client --chown=node:node /app/build/index.html views/index.ejs
@@ -52,4 +53,8 @@ VOLUME /app/private/attachments
 
 EXPOSE 1337
 
+# Use Tini to start Planka and Shutdown gracefully:
+# https://github.com/nodejs/docker-node/blob/main/docs/BestPractices.md#handling-kernel-signals
+ENTRYPOINT ["/sbin/tini", "--"]
+
 CMD ["./start.sh"]