fix: use container hostname for volume server to enable automatic volume creation

Root cause identified:
- Volume server was using -ip=127.0.0.1
- Master couldn't reach volume server at 127.0.0.1 from its container
- When Spark requested assignment, master tried to create volume via gRPC
- Master's gRPC call to 127.0.0.1:18080 failed (reached itself, not volume server)
- Result: 'No writable volumes' error

Solution:
- Change volume server to use -ip=seaweedfs-volume (container hostname)
- Master can now reach volume server at seaweedfs-volume:18080
- Automatic volume creation works as designed
- Kept -publicUrl=127.0.0.1:8080 for external clients (host network)

Workflow changes:
- Remove forced volume creation (curl POST to /vol/grow)
- Volumes will be created automatically on first write request
- Keep diagnostic output for troubleshooting
- Simplified startup verification

This matches how other SeaweedFS tests work with Docker networking.

.github/workflows/spark-integration-tests.yml

@@ -180,31 +180,10 @@ jobs:
         curl -f http://localhost:9333/cluster/status || exit 1
         curl -f http://localhost:8888/ || exit 1
         
-        # Check volume server registration and force volume creation
+        # Check volume server registration
         echo "Checking volume server status..."
         curl -s http://localhost:9333/dir/status | jq '.' || echo "jq not available"
-        
-        echo "Triggering initial volume growth..."
-        curl -X POST "http://localhost:9333/vol/grow?replication=000&count=3" || echo "Volume growth request sent"
-        sleep 2
-        
-        echo "Verifying volumes were created..."
-        for i in {1..10}; do
-          VOLUME_COUNT=$(curl -s http://localhost:9333/dir/status | jq -r '.Topology.DataCenters[0].Racks[0].DataNodes[0].Volumes // 0' 2>/dev/null || echo "0")
-          echo "Attempt $i/10: Volume count = $VOLUME_COUNT"
-          if [ "$VOLUME_COUNT" -gt 0 ] 2>/dev/null; then
-            echo "✓ Volume server has $VOLUME_COUNT volumes registered"
-            curl -s http://localhost:9333/dir/status | jq -r '.Topology.Layouts[]' || true
-            break
-          fi
-          if [ $i -eq 10 ]; then
-            echo "⚠️ Warning: No volumes created, tests may fail with 'No writable volumes'"
-            exit 1
-          fi
-          sleep 1
-        done
-        
-        echo "✓ All SeaweedFS services are healthy and volumes are ready"
+        echo "✓ Volume server registered, volumes will be created on-demand during tests"
 
     - name: Build Spark integration tests
       working-directory: test/java/spark
@@ -378,31 +357,10 @@ jobs:
         curl -f http://localhost:9333/cluster/status || exit 1
         curl -f http://localhost:8888/ || exit 1
         
-        # Check volume server registration and force volume creation
+        # Check volume server registration
         echo "Checking volume server status..."
         curl -s http://localhost:9333/dir/status | jq '.' || echo "jq not available"
-        
-        echo "Triggering initial volume growth..."
-        curl -X POST "http://localhost:9333/vol/grow?replication=000&count=3" || echo "Volume growth request sent"
-        sleep 2
-        
-        echo "Verifying volumes were created..."
-        for i in {1..10}; do
-          VOLUME_COUNT=$(curl -s http://localhost:9333/dir/status | jq -r '.Topology.DataCenters[0].Racks[0].DataNodes[0].Volumes // 0' 2>/dev/null || echo "0")
-          echo "Attempt $i/10: Volume count = $VOLUME_COUNT"
-          if [ "$VOLUME_COUNT" -gt 0 ] 2>/dev/null; then
-            echo "✓ Volume server has $VOLUME_COUNT volumes registered"
-            curl -s http://localhost:9333/dir/status | jq -r '.Topology.Layouts[]' || true
-            break
-          fi
-          if [ $i -eq 10 ]; then
-            echo "⚠️ Warning: No volumes created, tests may fail with 'No writable volumes'"
-            exit 1
-          fi
-          sleep 1
-        done
-        
-        echo "✓ All SeaweedFS services are healthy and volumes are ready"
+        echo "✓ Volume server registered, volumes will be created on-demand during tests"
 
     - name: Build project
       working-directory: test/java/spark

test/java/spark/docker-compose.yml

@@ -27,7 +27,7 @@ services:
     ports:
       - "8080:8080"
       - "18080:18080"
-    command: "volume -mserver=seaweedfs-master:9333 -ip=127.0.0.1 -ip.bind=0.0.0.0 -port=8080 -port.grpc=18080 -publicUrl=127.0.0.1:8080 -max=0 -dir=/data -preStopSeconds=1"
+    command: "volume -mserver=seaweedfs-master:9333 -ip=seaweedfs-volume -ip.bind=0.0.0.0 -port=8080 -port.grpc=18080 -publicUrl=127.0.0.1:8080 -max=0 -dir=/data -preStopSeconds=1"
     volumes:
       - seaweedfs-volume-data:/data
     depends_on: