rsyncd: secrets file is set up by entrypoint script

rsyncd/Dockerfile

@@ -0,0 +1,9 @@
+FROM alpine:3.16
+
+COPY entrypoint.sh /entrypoint.sh 
+
+RUN chmod +x /entrypoint.sh && \
+    apk add --no-cache rsync
+
+ENTRYPOINT ["/entrypoint.sh"]
+CMD ["/usr/bin/rsync", "--daemon", "--no-detach", "--config", "/etc/rsyncd.conf", "--verbose"]

rsyncd/Makefile

@@ -0,0 +1,19 @@
+IMG_NAME=rsyncd
+REGISTRY=registry.monotremata.xyz
+IMG=$(REGISTRY)/$(IMG_NAME)
+PLATFORMS=linux/amd64,linux/arm64
+
+.PHONY: build push buildx
+
+build: Dockerfile entrypoint.sh
+	docker build -t $(IMG) .
+
+push: build
+	docker image push $(IMG)
+
+buildx: Dockerfile entrypoint.sh
+	docker buildx build \
+		--platform $(PLATFORMS) \
+		--tag $(IMG) \
+		--push \
+		.

rsyncd/entrypoint.sh

@@ -0,0 +1,8 @@
+#!/bin/sh
+
+if [ -n "$SECRETS" ]; then
+    echo "$SECRETS" > /etc/rsyncd.secrets
+    chmod 600 /etc/rsyncd.secrets
+fi
+
+exec "$@"