feat: init commit with main func

Dockerfile

@@ -0,0 +1,34 @@
+# syntax=docker/dockerfile:1
+
+# ─── Build stage ───────────────────────────────────────────────────────────────
+FROM golang:1.23-alpine AS builder
+
+WORKDIR /build
+
+# Download dependencies first for better layer caching.
+COPY go.mod go.sum ./
+RUN go mod download
+
+COPY *.go ./
+RUN CGO_ENABLED=0 GOOS=linux go build -ldflags="-s -w" -o traefik-dns-watcher .
+
+# ─── Final stage ───────────────────────────────────────────────────────────────
+FROM alpine:3.20
+
+# git      — required for all DNS repo operations
+# openssh-client — required for SSH-based git push/pull
+# ca-certificates — required for HTTPS git remotes and Traefik API calls
+RUN apk add --no-cache git openssh-client ca-certificates \
+    && adduser -D -u 1001 appuser
+
+WORKDIR /app
+COPY --from=builder /build/traefik-dns-watcher .
+
+# The container runs as a non-root user.
+# Required bind-mounts / volumes:
+#   /var/run/docker.sock  — Docker events API (read-only is sufficient)
+#   /dns-repo             — pre-cloned DNS git repository (DNS_REPO_PATH)
+#   /root/.ssh or /home/appuser/.ssh — SSH key for git authentication (if using SSH)
+USER appuser
+
+ENTRYPOINT ["/app/traefik-dns-watcher"]