Require COMMAND env var, remove default, add docker-compose example

Dockerfile

@@ -14,8 +14,6 @@ RUN apk add --no-cache ca-certificates
 
 COPY --from=builder /app/sshserver /usr/local/bin/sshserver
 
-ENV COMMAND /app/tui
-
 EXPOSE 22
 
 CMD ["/usr/local/bin/sshserver"]

docker-compose.yml

@@ -0,0 +1,12 @@
+services:
+  ssh-server:
+    image: dcorral/ssh-remote:latest
+    ports:
+      - "22:22"
+    volumes:
+      - ../tui:/app/tui:ro
+    cap_add:
+      - SYS_CHROOT
+    environment:
+      - COMMAND=/app/tui
+    restart: unless-stopped

main.go

@@ -14,6 +14,9 @@ import (
 )
 
 func main() {
+	if os.Getenv("COMMAND") == "" {
+		log.Fatal("COMMAND environment variable must be set")
+	}
 	config := &ssh.ServerConfig{
 		NoClientAuth: true,
 	}