support caddy-docker-proxy labels

src/lib/server/compose-docker-args.ts

@@ -0,0 +1,37 @@
+/**
+ * Pure helpers for how `docker compose` is told which daemon to talk to.
+ *
+ * The daemon MUST be passed via the `docker -H` CLI flag, NOT via DOCKER_HOST in the
+ * spawn env: shell env leaks into services that pass through (`- DOCKER_HOST`) or
+ * interpolate (`${DOCKER_HOST}`) that variable - e.g. a socket-proxy sidecar -
+ * overriding the value the stack set for itself (#1393). `-H` connects compose to the
+ * right daemon without polluting the compose interpolation env. Kept dependency-free
+ * so it unit-tests without spinning up the stack machinery.
+ */
+
+/**
+ * Resolves the daemon endpoint for a compose invocation: the per-environment
+ * dockerHost if given, else Dockhand's own DOCKER_HOST (socket-proxy setups), else
+ * undefined (plain local socket - compose uses the default). `ownDockerHost` is
+ * `process.env.DOCKER_HOST` (passed in so the resolver stays pure/testable).
+ */
+export function resolveComposeDockerHost(
+	dockerHost: string | undefined | null,
+	ownDockerHost: string | undefined | null
+): string | undefined {
+	return dockerHost || ownDockerHost || undefined;
+}
+
+/**
+ * Builds the argv for `docker compose`, putting the daemon on the GLOBAL `-H` flag
+ * (before `compose`) so it never enters the shell env. Returns the base args; callers
+ * append the compose subcommand + flags.
+ */
+export function buildComposeBaseArgs(
+	stackName: string,
+	composeDockerHost: string | undefined
+): string[] {
+	return composeDockerHost
+		? ['docker', '-H', composeDockerHost, 'compose', '-p', stackName]
+		: ['docker', 'compose', '-p', stackName];
+}