SKILL.md
Amazon EC2 Compute
Best experience with the AWS MCP server; also works with the AWS CLI alone — no hard dependency on either.
Critical Warnings
Launch configurations are deprecated and do not support current EC2 instance types; new accounts cannot create them. Use launch templates for every new Auto Scaling group. See auto-scaling.md.
ASGs ignore ELB health checks by default: An Auto Scaling group only uses EC2 status checks unless you set --health-check-type ELB. Without it, instances failing the load balancer's health check stay in service forever. See auto-scaling.md.
IMDSv2 hop limit breaks containers: the default HttpPutResponseHopLimit of 1 makes the IMDSv2 token PUT response fail to reach a containerized process (the extra hop exceeds the response TTL), so the token request times out. Set HttpPutResponseHopLimit=2 for bridge/awsvpc container workloads. (If IMDSv2 is required, a subsequent tokenless GET returns 401; if optional, it silently falls back to IMDSv1.) See provisioning.md.
T3/T3a/T4g default to unlimited mode: Unlike T2 (standard), these burst without throttling but bill surplus CPU credits when 24h-average CPU exceeds baseline — a silent cost leak. See instance-selection.md.
Instance store is ephemeral: Data on instance store volumes is lost on stop, hibernate, terminate, instance-type change, and host failure — it survives only a reboot. Put anything durable on EBS/EFS/S3. See instance-selection.md.