chore: optimise Dockerfile

So far, the Dockerfile built hydrogen on the server running the image,
instead of building it during the building of the image. This blew up
the image size immensely and caused node+yarn to run in the resulting
image. This new Dockerfile builds hydrogen in a separate build stage and
then moves the target directory into an nginx based container image,
which takes care of serving the target webroot.

The existing Dockerfile has been moved to Dockerfile-dev for usage as a
development environment. The docs have been adjusted accordingly.

Additionally, this switched from a fixed alpine version of the node
image to the latest alpine version, and changed the container image
references in the `FROM` statements to use the fully qualified
references including the registry domain.

.dockerignore

@@ -0,0 +1,2 @@
+node_modules
+target

Dockerfile

@@ -1,7 +1,9 @@
-FROM node:alpine3.12
+FROM docker.io/node:alpine as builder
 RUN apk add --no-cache git
-COPY . /code
+COPY . /app
-WORKDIR /code
+WORKDIR /app
-RUN yarn install
+RUN yarn install \
-EXPOSE 3000
+ && yarn build
-ENTRYPOINT ["yarn", "start"]
+
+FROM docker.io/nginx:alpine
+COPY --from=builder /app/target /usr/share/nginx/html

Dockerfile-dev

@@ -0,0 +1,7 @@
+FROM docker.io/node:alpine
+RUN apk add --no-cache git
+COPY . /code
+WORKDIR /code
+RUN yarn install
+EXPOSE 3000
+ENTRYPOINT ["yarn", "start"]

doc/docker.md

@@ -1,13 +1,20 @@
+## Warning
+
 Usage of docker is a third-party contribution and not actively tested, used or supported by the main developer(s).
 
-Having said that, you can also use Docker to create a local dev environment.
+Having said that, you can also use Docker to create a local dev environment or a production deployment.
+
+## Dev environment
 
 In this repository, create a Docker image:
 
-    docker build -t hydrogen .
+```
+docker build -t hydrogen-dev -f Dockerfile-dev .
+```
 
 Then start up a container from that image:
 
+```
 docker run \
     --name hydrogen-dev \
     --publish 3000:3000 \
@@ -15,8 +22,37 @@ Then start up a container from that image:
     --interactive \
     --tty \
     --rm \
-        hydrogen
+    hydrogen-dev
+```
 
 Then point your browser to `http://localhost:3000`. You can see the server logs in the terminal where you started the container.
 
 To stop the container, simply hit `ctrl+c`.
+
+## Production deployment
+
+### Build or pull image
+
+In this repository, create a Docker image:
+
+```
+docker build -t hydrogen .
+```
+
+Or, pull the docker image from GitLab:
+
+```
+docker pull registry.gitlab.com/jcgruenhage/hydrogen-web
+docker tag registry.gitlab.com/jcgruenhage/hydrogen-web hydrogen
+```
+
+### Start container image
+
+Then, start up a container from that image:
+
+```
+docker run \
+    --name hydrogen \
+    --publish 80:80 \
+    hydrogen
+```