build: add docker run script for container deployment

Author: dgraf-gh

docker-run.sh

@@ -0,0 +1,15 @@
+#!/bin/bash
+
+# Build the Docker image if needed
+# mvn clean package
+# docker build -t reitti/reitti:test .
+
+# Run the container with custom UID/GID
+docker run -p 8080:8080 \
+  -e APP_UID=1001 \
+  -e APP_GID=1001 \
+  -e SPRING_DATASOURCE_URL=jdbc:postgresql://postgres:5432/reitti \
+  reitti/reitti:test
+
+# To verify the user ID inside the container, run:
+# docker exec -it $(docker ps -q --filter ancestor=reitti/reitti:test) sh -c "id"