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name: aws-compute description: "Provisions, scales, and operates Amazon EC2 virtual-machine workloads: instance-type selection (Graviton/Arm64, burstable T credits, GPU, instance store vs EBS), launch templates, Auto Scaling groups (scaling policies, instance refresh, mixed instances, Spot, warm pools, lifecycle hooks), IMDSv2, placement groups, Elastic IPs, AMI lifecycle, and Systems Manager fleet operations (Session Manager, Run Command, Patch Manager). Applies to EC2 instance and fleet questions, InsufficientInstanceCapacity, CPU-credit/surplus charges, IMDSv2 401s, instances stuck in Pending:Wait, ASG not replacing unhealthy instances, status-check failures, SSH refused/timed out, or instances missing as SSM managed nodes. For a single secure instance launch, the launching-ec2-instance-with-best-practices skill is more appropriate; for instance profiles, see setting-up-ec2-instance-profiles; for Image Builder, see amazon-ec2-image-builder. Does NOT cover Lambda, ECS/Fargate, EKS, VPC/ALB/NLB design, or IAM policy authoring." metadata: version: "2"

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.

Which do you need?

If you're deciding...	Guidance
Instance family / size / Graviton / GPU / burstable	instance-selection.md — start with the workload→family table
How to define instances once and reuse (launch template)	provisioning.md
How to run many instances that scale automatically	auto-scaling.md
How to access/patch/manage instances without SSH keys	systems-manager.md

Quick Navigation

You want to...	Go to
Pick an instance type, Graviton vs x86, burstable credits, GPU, instance store vs EBS	instance-selection.md
Create a launch template, user data, key pairs, IMDSv2, placement groups, Elastic IPs	provisioning.md
Set up or fix an Auto Scaling group, scaling policies, instance refresh, Spot, lifecycle hooks	auto-scaling.md
Get SSH-less access, patch a fleet, or fix an instance not showing as a managed node	systems-manager.md
Create, share, or retire (deprecate/disable/deregister) an AMI	ami-management.md
Fix something broken (can't connect, status-check fail, capacity error, stuck instances)	troubleshooting.md

Common Workflows

"Stand up an autoscaling web fleet" → Create a launch template (AMI, type, IMDSv2), then an ASG referencing it with --health-check-type ELB and a target-tracking policy, see auto-scaling.md. For the public entry point, secure the load balancer (TLS/ACM, WAF, security response headers) per the Security Considerations below and the load-balancer notes in auto-scaling.md — the load-balancer build itself belongs to aws-networking.

"Roll out a new AMI to my fleet" → New launch template version → instance refresh; pin a numeric launch-template version so rollback works, see auto-scaling.md.

"Connect to a private instance without a bastion" → Give the instance SSM permissions (an instance profile with AmazonSSMManagedInstanceCore, or account-level DHMC) plus a network path, then use Session Manager, see systems-manager.md.

"Cut EC2 cost" → Right-size (burstable vs fixed-performance), Graviton where the app supports Arm64, Spot with price-capacity-optimized for fault-tolerant fleets, release idle Elastic IPs, see instance-selection.md.

Troubleshooting

Symptom	Likely cause	Quick fix
SSH "Connection timed out"	Network path (SG/NACL/route/no public IP)	Open TCP 22 from your IP; check route to IGW; verify public IP — see troubleshooting.md
SSH "Connection refused"	Host: sshd down or still booting	Wait for boot; check sshd/port via Session Manager or serial console
InsufficientInstanceCapacity	AWS lacks capacity of that type in the AZ (NOT a quota)	Try another AZ / instance type / retry; don't request a quota increase
InstanceLimitExceeded	vCPU quota reached (this IS a quota)	Request a Service Quotas increase for the instance family
ASG never replaces LB-unhealthy instances	Health check type still EC2	Set --health-check-type ELB
Instances stuck in Pending:Wait, terminated after ~1h	Lifecycle hook never completed (heartbeat 3600s, default ABANDON)	Call complete-lifecycle-action CONTINUE, or set DefaultResult CONTINUE
System status check failed	AWS host/hardware	Stop/start to migrate to new hardware (reboot won't)
Instance status check failed	Instance OS/network config	Reboot or fix the OS/network config

Full tables and more errors in troubleshooting.md.

Security Considerations

• Enforce IMDSv2 (HttpTokens=required) on launch templates to block SSRF-based credential theft; set the account-level default per Region (applies to new launches only).
• Prefer Session Manager over inbound SSH — no open port 22, no key management, and a CloudTrail record of session API calls; enable Session Manager session logging to CloudWatch Logs/S3 (off by default) to capture the in-session commands themselves — see systems-manager.md.
• Use instance profiles, never embedded credentials; scope the role to least privilege.
• Encrypt EBS/AMIs; to share an encrypted AMI cross-account, re-encrypt under a customer-managed KMS key (the default aws/ebs key can't be shared).
• Enable CloudTrail in all Regions to audit EC2/ASG/SSM API activity, and alarm on sensitive actions (security-group changes, RunInstances/TerminateInstances from unexpected principals) so unauthorized changes surface.
• For public-facing web fleets, encrypt traffic in transit with an ACM certificate on the load balancer's HTTPS listener and add AWS WAF for defense in depth against common web exploits — the load-balancer/WAF setup itself lives in aws-networking.
• For hardening beyond this guidance, see AWS EC2 security best practices and CIS Benchmarks for the guest OS.

Not Covered By This Skill

• Launching a single hardened instance with best-practice defaults → use the launching-ec2-instance-with-best-practices skill
• Creating IAM roles / instance profiles for EC2 → use the setting-up-ec2-instance-profiles skill
• Building AMIs with an Image Builder pipeline → use the amazon-ec2-image-builder skill
• Lambda / serverless → aws-serverless; ECS/Fargate → aws-containers; EKS/Kubernetes → kubernetes
• VPC, subnets, ALB/NLB, endpoints → aws-networking or built-in knowledge
• IAM policy logic and CloudWatch dashboards/agent setup → aws-iam, aws-observability