headscale: refactor container to include headscale-ui

fly.io now charges for dedicated IP. gRPC requires a dedicated port (or
a lot of fiddling), so let's just use headscale-ui from now on.

headscale/Caddyfile

@@ -0,0 +1,11 @@
+:8080 {
+    root * /srv
+
+    handle /web* {
+        file_server
+    }
+
+    handle {
+        reverse_proxy * http://127.0.0.1:8081
+    }
+}

headscale/Dockerfile

@@ -1,10 +1,12 @@
 # Builder image
 FROM docker.io/golang:1.20-bullseye AS build
 ARG VERSION=v0.22.3
+ARG CADDY_VERSION=v2.7.6
 ENV GOPATH /go
 
 RUN apt-get install -y git && \
-    git clone https://github.com/juanfont/headscale -b $VERSION /go/src/headscale
+    git clone https://github.com/juanfont/headscale -b $VERSION /go/src/headscale && \
+    git clone https://github.com/caddyserver/caddy.git -b $CADDY_VERSION /go/src/caddy
 
 WORKDIR /go/src/headscale
 
@@ -14,12 +16,35 @@ RUN CGO_ENABLED=0 GOOS=linux go install -tags ts2019 -ldflags="-s -w -X github.c
 RUN strip /go/bin/headscale
 RUN test -e /go/bin/headscale
 
+# Caddy build
+WORKDIR /go/src/caddy
+
+RUN go mod download
+
+RUN GOOS=linux go install ./cmd/caddy
+RUN strip /go/bin/caddy
+RUN test -e /go/bin/caddy
+
+# Node build image
+FROM docker.io/node:19-bullseye AS build-node
+ARG UI_COMMIT=a9db179089e3ae2b417fb657a2d3da68a54b1f2d
+
+RUN apt-get install -y git && \
+    git clone https://github.com/gurucomputing/headscale-ui /headscale-ui
+
+WORKDIR /headscale-ui
+
+RUN git checkout $UI_COMMIT && npm install --development && npm run build
+
 # Production image
 # Note that we do not use "distroless" because we actually want to have a shell in the image
 # to run app.sh (in order to perform custom initialization)
 FROM docker.io/golang:1.20-bullseye
 
 COPY --from=build /go/bin/headscale /bin/headscale
+COPY --from=build /go/bin/caddy /bin/caddy
+COPY --from=build-node /headscale-ui/build /srv/web
+ADD Caddyfile /etc/
 ENV TZ UTC
 
 ADD app.sh /

headscale/app.sh

@@ -3,4 +3,6 @@
 touch /var/lib/headscale/db.sqlite
 mkdir /var/lib/headscale/.cache
 mkdir -p /var/run/headscale
+
+caddy run --config /etc/Caddyfile &
 exec headscale -c /etc/headscale/config.yaml serve