chore: import upstream snapshot with attribution

doc/source/serve/doc_code/external_scaler_predictive_client.py

@@ -0,0 +1,82 @@
+# __client_script_begin__
+import logging
+import time
+from datetime import datetime
+import requests
+
+APPLICATION_NAME = "my-app"
+DEPLOYMENT_NAME = "TextProcessor"
+SERVE_ENDPOINT = "http://localhost:8265"
+SCALING_INTERVAL = 300  # Check every 5 minutes
+
+logger = logging.getLogger(__name__)
+
+
+def get_current_replicas(app_name: str, deployment_name: str) -> int:
+    """Get current replica count. Returns -1 on error."""
+    try:
+        resp = requests.get(
+            f"{SERVE_ENDPOINT}/api/serve/applications/",
+            timeout=10
+        )
+        if resp.status_code != 200:
+            logger.error(f"Failed to get applications: {resp.status_code}")
+            return -1
+            
+        apps = resp.json().get("applications", {})
+        if app_name not in apps:
+            logger.error(f"Application {app_name} not found")
+            return -1
+
+        deployments = apps[app_name].get("deployments", {})
+        if deployment_name in deployments:
+            return deployments[deployment_name]["target_num_replicas"]
+                
+        logger.error(f"Deployment {deployment_name} not found")
+        return -1
+    except requests.exceptions.RequestException as e:
+        logger.error(f"Request failed: {e}")
+        return -1
+
+
+def scale_deployment(app_name: str, deployment_name: str):
+    """Scale deployment based on time of day."""
+    hour = datetime.now().hour
+    current = get_current_replicas(app_name, deployment_name)
+    
+    # Check if we successfully retrieved the current replica count
+    if current == -1:
+        logger.error("Failed to get current replicas, skipping scaling decision")
+        return
+    
+    target = 10 if 9 <= hour < 17 else 3  # Peak hours: 9am-5pm
+    
+    delta = target - current
+    if delta == 0:
+        logger.info(f"Already at target ({current} replicas)")
+        return
+    
+    action = "Adding" if delta > 0 else "Removing"
+    logger.info(f"{action} {abs(delta)} replicas ({current} -> {target})")
+    
+    try:
+        resp = requests.post(
+            f"{SERVE_ENDPOINT}/api/v1/applications/{app_name}/deployments/{deployment_name}/scale",
+            headers={"Content-Type": "application/json"},
+            json={"target_num_replicas": target},
+            timeout=10
+        )
+        if resp.status_code == 200:
+            logger.info("Successfully scaled deployment")
+        else:
+            logger.error(f"Scale failed: {resp.status_code} - {resp.text}")
+    except requests.exceptions.RequestException as e:
+        logger.error(f"Request failed: {e}")
+
+
+def main():
+    logger.info(f"Starting predictive scaling for {APPLICATION_NAME}/{DEPLOYMENT_NAME}")
+    while True:
+        scale_deployment(APPLICATION_NAME, DEPLOYMENT_NAME)
+        time.sleep(SCALING_INTERVAL)
+# __client_script_end__