update dind machine image to run dockerd in background

.dockerignore

@@ -4,6 +4,7 @@
 # Allow files and directories.
 !cmd/
 !internal/
+!scripts/docker-entrypoint.sh
 !go.*
 
 # Ignore unnecessary files inside allowed directories.

Dockerfile

@@ -3,6 +3,13 @@ FROM golang:1.23.2-alpine AS uncloudd
 ARG TARGETOS
 ARG TARGETARCH
 
+ENV CGO_ENABLED=0
+
+WORKDIR /build
+# Download and cache dependencies and only redownload them in subsequent builds if they change.
+COPY go.mod go.sum ./
+RUN go mod download && go mod verify
+
 COPY . .
 RUN GOOS=${TARGETOS} GOARCH=${TARGETARCH} go build -o uncloudd cmd/uncloudd/main.go
 
@@ -15,15 +22,19 @@ RUN wget -q -O /tmp/corrosion.tar.gz \
     && rm /tmp/corrosion.tar.gz /tmp/corrosion
 
 FROM chainguard/wolfi-base:latest AS corrosion
-# TODO: create uncloud user
 COPY --from=corrosion-download /usr/local/bin/corrosion /usr/local/bin/corrosion
+CMD ["corrosion", "agent"]
 
 
-FROM docker:27.3.1-dind
+FROM docker:27.3.1-dind AS machine
 RUN apk --no-cache add \
     wireguard-tools
 # Create system group and user 'uncloud'.
 RUN addgroup -S uncloud && adduser -SHD -h /nonexistent -G uncloud -g "" uncloud
-COPY --from=uncloudd /go/uncloudd /usr/local/bin/uncloudd
+
+COPY scripts/docker-entrypoint.sh /usr/local/bin/
+COPY --from=uncloudd /build/uncloudd /usr/local/bin/
 # TODO: socat to forward uncloud.sock unix socket?
+
+ENTRYPOINT ["docker-entrypoint.sh"]
 CMD ["uncloudd"]

scripts/docker-entrypoint.sh

@@ -0,0 +1,6 @@
+#!/bin/sh
+set -eu
+
+dind dockerd &
+
+exec "$@"