Set Docker image tag when building

to prevent rebuild when nothing has changed

Co-authored-by: Copilot <copilot@github.com>

docker/docker-compose.yml

@@ -3,6 +3,7 @@ services:
     build: 
       context: ../backend
       dockerfile: ../docker/Dockerfile.backend
+    image: bamort-backend:${GIT_TAG:-latest}
     container_name: bamort-backend
     ports:
       - "8182:8180"
@@ -25,6 +26,7 @@ services:
     build:
       context: ../frontend
       dockerfile: ../docker/Dockerfile.frontend
+    image: bamort-frontend:${GIT_TAG:-latest}
     container_name: bamort-frontend
     ports:
       - "8181:80"

docker/start-prd.sh

@@ -24,11 +24,22 @@ else
     fi
 fi
 
+# Determine image tag from git commit hash (first 5 chars)
+GIT_TAG=$(git -C "$(dirname "$0")/.." rev-parse --short=5 HEAD 2>/dev/null || echo "latest")
+export GIT_TAG
+echo "🏷️  Image tag: ${GIT_TAG}"
+
 echo "📦 Building and starting production containers..."
 echo "🔧 Frontend will use API: ${API_URL:-https://bamort-api.trokan.de}"
 
-# Build before stopping existing containers
-docker-compose -f docker-compose.yml --env-file .env.prd -p bamort build
+# Build only if images for this commit don't exist yet
+if ! docker image inspect "bamort-backend:${GIT_TAG}" > /dev/null 2>&1 || \
+   ! docker image inspect "bamort-frontend:${GIT_TAG}" > /dev/null 2>&1; then
+    echo "🔨 Images not found for tag '${GIT_TAG}', building..."
+    docker-compose -f docker-compose.yml --env-file .env.prd -p bamort build
+else
+    echo "✅ Images already exist for tag '${GIT_TAG}', skipping build."
+fi
 
 # Stoppe vorhandene Container
 docker-compose -f docker-compose.yml -p bamort down