fix(docker): address Greptile review (depends_on health + exact port tests)

Two issues raised in Greptile 4/5 review:

1. gateway depends_on used the list form which starts the gateway before
   Postgres is ready. Switch to condition: service_healthy so the
   gateway waits for pg_isready to pass on cold boots.

2. Port tests used substring matching ("3000" in str(p)) which could
   pass spurious mappings like "13000:3000". Change to exact string
   equality "3000:3000" / "4000:4000". Also assert service_healthy
   in test_gateway_depends_on_db.

Resolves LIT-2815

docker-compose.yml

@@ -38,7 +38,8 @@ services:
     env_file:
       - .env # Load local .env file
     depends_on:
-      - db  # Indicates that this service depends on the 'db' service, ensuring 'db' starts first
+      db:
+        condition: service_healthy  # Wait for Postgres to pass pg_isready before starting gateway
     healthcheck:  # Defines the health check configuration for the container
       test:
         - CMD-SHELL

tests/test_litellm/test_docker_compose.py

@@ -91,16 +91,16 @@ def test_gateway_builds_from_gateway_dockerfile(services):
 
 
 def test_ui_exposes_port_3000(services):
-    ports = services["ui"].get("ports", [])
-    assert any("3000" in str(p) for p in ports), (
-        f"ui service should expose port 3000, got ports={ports}"
+    ports = [str(p) for p in services["ui"].get("ports", [])]
+    assert "3000:3000" in ports, (
+        f"ui service should expose port mapping 3000:3000, got ports={ports}"
     )
 
 
 def test_gateway_exposes_port_4000(services):
-    ports = services["gateway"].get("ports", [])
-    assert any("4000" in str(p) for p in ports), (
-        f"gateway service should expose port 4000, got ports={ports}"
+    ports = [str(p) for p in services["gateway"].get("ports", [])]
+    assert "4000:4000" in ports, (
+        f"gateway service should expose port mapping 4000:4000, got ports={ports}"
     )
 
 
@@ -142,8 +142,15 @@ def test_ui_healthcheck_configured(services):
 
 
 def test_gateway_depends_on_db(services):
-    depends_on = services["gateway"].get("depends_on", [])
-    assert "db" in depends_on, "gateway service must depend on the 'db' service"
+    depends_on = services["gateway"].get("depends_on", {})
+    # depends_on can be a list or a dict (service_healthy condition form)
+    if isinstance(depends_on, dict):
+        assert "db" in depends_on, "gateway service must depend on the 'db' service"
+        assert depends_on["db"].get("condition") == "service_healthy", (
+            "gateway should wait for db to be healthy before starting"
+        )
+    else:
+        assert "db" in depends_on, "gateway service must depend on the 'db' service"
 
 
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