Add TTL configuration for AWS instance management

- Introduced a new config module to manage TTL settings for EC2 instances, allowing for auto-termination based on environment variables.
- Updated the AWSProvider and manager to utilize the new TTL settings, including scheduling instance termination via EventBridge Scheduler.
- Added utility functions for resolving the scheduler role ARN and creating termination schedules, ensuring robust error handling and logging.
- Maintained existing code logic while integrating new features for improved instance lifecycle management.

desktop_env/providers/aws/config.py

@@ -0,0 +1,21 @@
+import os
+
+
+# Default TTL minutes for instance auto-termination (cloud-side scheduler)
+# Can be overridden via environment variable DEFAULT_TTL_MINUTES
+DEFAULT_TTL_MINUTES: int = int(os.getenv("DEFAULT_TTL_MINUTES", "60"))
+
+# Master switch for TTL feature
+ENABLE_TTL: bool = os.getenv("ENABLE_TTL", "true").lower() == "true"
+
+# EventBridge Scheduler role ARN for scheduling EC2 termination
+AWS_SCHEDULER_ROLE_ARN: str = os.getenv("AWS_SCHEDULER_ROLE_ARN", "").strip()
+
+
+def compute_ttl_seconds(ttl_minutes: int) -> int:
+    try:
+        return max(0, int(ttl_minutes) * 60)
+    except Exception:
+        return 0
+
+