feat: add AWS Lambda Managed Instances (LMI) skill to aws-serverless plugin by sbbhimji · Pull Request #140 · awslabs/agent-plugins

sbbhimji · 2026-04-20T21:25:36Z

Summary

Adds a new skill to help users evaluate, configure, and migrate workloads to AWS Lambda Managed Instances (LMI) — the
recently launched feature that runs Lambda functions on dedicated EC2 instances with AWS managing the lifecycle.

What's included

SKILL.md (205 lines) — core workflow with 6 steps:

Workload fitness assessment (decision table: LMI vs standard Lambda)
4-column cost comparison (Lambda OD, Lambda+SP, LMI OD, LMI+3yr SP)
Configuration recommendations (instance types, memory ratios, concurrency)
Code migration for multi-concurrency thread safety
Infrastructure setup (IAM, VPC, capacity providers)
Validation and gradual production cutover

6 reference files (42-96 lines each):

cost-comparison.md — pricing formulas, discount comparison, worked example, break-even guidance
configuration-guide.md — instance type decision tree, memory sizing from existing Lambda/EC2, concurrency tuning,
scaling controls
thread-safety.md — code review checklist, runtime-specific guidance (Node.js, Python, Java, .NET), common
anti-patterns
migration-patterns.md — before/after code examples per runtime (global state, file I/O, database connections)
infrastructure-setup.md — IAM roles, VPC requirements, CLI workflow, SAM template
troubleshooting.md — common issues, debugging steps for startup/performance/cost

Plugin registration:

Added managed-instances and lmi keywords to plugin.json
Added LMI skill triggers to README aws-serverless section
Added cross-references in aws-lambda/SKILL.md (Key Capabilities + When to Load Reference Files)

Design decisions

4-column cost comparison includes Lambda with Savings Plans (not just on-demand) since customers often already have
Compute Savings Plans covering Lambda duration
Thread safety is the critical migration gate — elevated to its own reference file with a per-runtime checklist since
this is the feat: initial branch #1 source of production issues when adopting LMI
Follows all plugin standards: SKILL.md under 300 lines, reference files under 100 lines, proper frontmatter,
progressive disclosure, explicit defaults, error handling

Test plan

Load plugin locally: claude --plugin-dir ./plugins/aws-serverless
Verify skill auto-triggers on "is LMI right for my workload?"
Verify skill auto-triggers on "migrate my Lambda to managed instances"
Verify cost comparison produces 4-column table (Lambda OD / Lambda+SP / LMI OD / LMI+SP)
Verify thread-safety checklist surfaces when reviewing function code
Verify cross-reference from aws-lambda skill routes to LMI skill
Confirm SKILL.md < 300 lines, all reference files < 100 lines
Run claude --plugin-dir ./plugins/aws-serverless --verbose to verify < 5000 token initial load

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of the project license.

…plugin Add a new skill for evaluating, configuring, and migrating workloads to AWS Lambda Managed Instances. Includes workload fitness assessment, 4-column cost comparison (Lambda OD/SP vs LMI OD/SP), configuration recommendations, thread-safety review, and end-to-end migration framework. Reference files cover cost analysis, configuration tuning, thread safety, runtime-specific migration patterns, infrastructure setup (CLI/SAM/CDK), and troubleshooting.

…nces - Add managed-instances and lmi keywords to plugin.json - Add LMI skill triggers to README aws-serverless section - Add cross-reference to LMI skill in aws-lambda SKILL.md (key capabilities and "When to Load Reference Files" sections) - Update plugin description to mention Lambda Managed Instances

Copilot

Pull request overview

Adds a new aws-lambda-managed-instances skill to the aws-serverless plugin, providing an agent workflow and reference material to evaluate, configure, and migrate workloads to Lambda Managed Instances (LMI), and wires it into existing plugin docs/metadata.

Changes:

Introduces a new aws-lambda-managed-instances skill (SKILL.md) plus several reference guides (cost, configuration, thread safety, migration patterns, infra setup, troubleshooting).
Updates the existing aws-lambda skill to cross-reference the new managed-instances skill.
Updates plugin metadata and root README to mention LMI and add trigger phrases/keywords.

Reviewed changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
plugins/aws-serverless/skills/aws-lambda/SKILL.md	Adds cross-references so the Lambda skill routes LMI questions to the new skill.
plugins/aws-serverless/skills/aws-lambda-managed-instances/SKILL.md	New core workflow and routing to reference files for LMI evaluation/config/migration.
plugins/aws-serverless/skills/aws-lambda-managed-instances/references/cost-comparison.md	Adds pricing formulas, comparison template, and worked example for Lambda vs LMI.
plugins/aws-serverless/skills/aws-lambda-managed-instances/references/configuration-guide.md	Adds instance/memory/concurrency tuning guidance and scaling controls.
plugins/aws-serverless/skills/aws-lambda-managed-instances/references/thread-safety.md	Adds a thread-safety checklist and runtime-specific guidance.
plugins/aws-serverless/skills/aws-lambda-managed-instances/references/migration-patterns.md	Adds before/after migration examples for multi-concurrency readiness.
plugins/aws-serverless/skills/aws-lambda-managed-instances/references/infrastructure-setup.md	Adds IAM/VPC/CLI + SAM template guidance for capacity provider setup.
plugins/aws-serverless/skills/aws-lambda-managed-instances/references/troubleshooting.md	Adds common issues table and debugging steps.
plugins/aws-serverless/.claude-plugin/plugin.json	Adds `managed-instances` and `lmi` keywords for discoverability.
README.md	Updates plugin description and adds the new skill to the aws-serverless trigger table.

+- **Cost comparison**, **pricing analysis**, **Lambda vs LMI cost**, **Savings Plans**, or **Reserved Instances** -> see [references/cost-comparison.md](references/cost-comparison.md)
+- **Instance types**, **memory sizing**, **vCPU ratios**, **scaling tuning**, or **capacity provider config** -> see [references/configuration-guide.md](references/configuration-guide.md)
+- **Thread safety**, **code review checklist**, or **multi-concurrency readiness** -> see [references/thread-safety.md](references/thread-safety.md)
+- **Before/after code examples**, **runtime-specific migration** (Node.js, Python, Java, .NET), or **connection pooling** -> see [references/migration-patterns.md](references/migration-patterns.md)


+- **Instance types**, **memory sizing**, **vCPU ratios**, **scaling tuning**, or **capacity provider config** -> see [references/configuration-guide.md](references/configuration-guide.md)
+- **Thread safety**, **code review checklist**, or **multi-concurrency readiness** -> see [references/thread-safety.md](references/thread-safety.md)
+- **Before/after code examples**, **runtime-specific migration** (Node.js, Python, Java, .NET), or **connection pooling** -> see [references/migration-patterns.md](references/migration-patterns.md)
+- **IAM roles**, **VPC setup**, **CLI commands**, **SAM template**, or **CDK example** -> see [references/infrastructure-setup.md](references/infrastructure-setup.md)


bfreiberg · 2026-05-03T20:34:17Z

+|--------|---------------------|---------------------------|
+| Traffic | Steady, predictable, 50M+ req/mo | Bursty, unpredictable, long idle |
+| Cost | Duration-heavy spend at scale | Low or sporadic invocations |
+| Cold starts | Unacceptable (LMI has zero) | Tolerable or mitigated by SnapStart |


I think that might be a bit misleading as this is only true if the currently provisioned instances can handle the load. What is the user experience on scale-out?

Clarified, now reads "LMI eliminates for provisioned capacity; scale-out may have brief delays"

bfreiberg · 2026-05-03T20:35:48Z

+| Cost | Duration-heavy spend at scale | Low or sporadic invocations |
+| Cold starts | Unacceptable (LMI has zero) | Tolerable or mitigated by SnapStart |
+| Compute | Latest CPUs, specific families, high network BW | Standard Lambda memory/CPU sufficient |
+| Compliance | Single-tenant required, VPC control | Multi-tenant Firecracker acceptable |


I'm not sure what you are trying to describe here

Reframed as "Isolation", "Dedicated EC2 instances in your account, full VPC control" vs "Shared Firecracker micro-VMs acceptable"

bfreiberg · 2026-05-03T20:38:47Z

+| Lambda on-demand | Low volume, bursty traffic |
+| Lambda + Savings Plan | Moderate steady volume (~17% duration discount) |
+| LMI on-demand | High volume, steady traffic |
+| LMI + 3yr Savings Plan | High volume + commitment (up to 72% EC2 discount) |


This requires forecasting with a high degree of certainty. Do we need to talk about financial constructs here?

Simplified, removed SP/RI from the main comparison table, now defers to AWS Pricing Calculator for discount analysis

bfreiberg · 2026-05-03T20:39:32Z

+
+### Step 5: Set Up Infrastructure
+
+Two IAM roles required (execution + operator). VPC with 3+ AZ subnets. Create capacity provider, attach function, publish version.


This should be structured as a list/procedure

Converted to 5-step numbered procedure

bfreiberg · 2026-05-03T20:40:19Z

+
+### Step 6: Validate and Cut Over
+
+1. Test locally with LocalStack (supports LMI emulation)


What about their recent licensing changes? Does this affect our guidance here?

Removed LocalStack reference entirely, now says "Deploy to a non-production environment first"

bfreiberg · 2026-05-03T20:41:50Z

+
+### Regional Availability
+
+us-east-1, us-east-2, us-west-2, ap-northeast-1, eu-west-1


Can we instead refer to the docs or builder central to avoid keeping it in sync

Replaced with link to Lambda Managed Instances docs

bfreiberg · 2026-05-03T20:44:48Z

+aws iam create-role --role-name LMIExecutionRole \
+  --assume-role-policy-document '{"Version":"2012-10-17","Statement":[{"Effect":"Allow","Principal":{"Service":"lambda.amazonaws.com"},"Action":"sts:AssumeRole"}]}'
+aws iam attach-role-policy --role-name LMIExecutionRole \
+  --policy-arn arn:aws:iam::aws:policy/service-role/AWSLambdaBasicExecutionRole


The managed roles are pretty broad (using wildcards), can we instead list the minimal permissions necessary? Or somehow surface that least-privilege needs to be applied after testing?

Replaced with least-privilege permissions using ec2:ManagedResourceOperator condition (sourced from aws-samples repo)

bfreiberg · 2026-05-03T20:45:30Z

+- Function invocations bypass VPC (routed through Lambda service)
+- Recommended VPC endpoints: CloudWatch Logs, X-Ray, S3, DynamoDB, SQS
+
+## CLI Workflow


Extract this into a bash script

Created scripts/setup-lmi.sh with parameterized setup

…model - Fix Python concurrency model: process-based isolation, no thread safety needed - Clarify cold starts claim (provisioned capacity only) - Replace hardcoded regional availability with docs link - Replace LocalStack reference with generic non-prod testing - Convert Step 5 to numbered procedure - Simplify cost comparison (defer SP/RI to pricing calculator) - Use least-privilege IAM with ec2:ManagedResourceOperator condition - Add setup-lmi.sh script for automated provisioning - Add VPC endpoint requirements table with costs - Add Powertools compatibility and SDK minimum versions - Add CloudWatch metrics dimensions guidance - Add pricing calculator, samples repo, and migration blog to resources

leandrodamascena

Hey @sbbhimji, nice work on this, the skill is well structured and the content is technically accurate. Left 2 small comments to address before merging.

leandrodamascena · 2026-05-09T17:22:42Z

+| Python | Powertools for AWS Lambda (Python) | 3.23.0 |
+| TypeScript | Powertools for AWS Lambda (TypeScript) | 2.29.0 |
+| Java | Powertools for AWS Lambda (Java) | 2.8.0 |
+| .NET | Powertools for AWS Lambda (.NET) | Not yet supported |


Powertools dotnet already support LMI.

#1078 (feat(logging): implement thread-safe logging with per-thread scope storage aws-powertools/powertools-lambda-dotnet#1078) — thread-safe logging with per-thread scope storage

#1076 (Feature request: Logger LMI support aws-powertools/powertools-lambda-dotnet#1076) — Logger LMI support (closed)

#1081 (Feature request: Tracing LMI support aws-powertools/powertools-lambda-dotnet#1081) — Tracing LMI support (closed)

#1083 (Feature request: Idempotency LMI support aws-powertools/powertools-lambda-dotnet#1083) — Idempotency LMI support (closed)

#1095 (Feature request: Batch LMI support aws-powertools/powertools-lambda-dotnet#1095) — Batch LMI support (closed)

#1097 (Feature request: Parameters LMI support aws-powertools/powertools-lambda-dotnet#1097) — Parameters LMI support (closed)

I'll fix the Lambda doc on our side to reflect this.

Thanks Leandro! Updated — removed the "not yet supported" note from .NET guidance and updated the Powertools compatibility table to reflect full support (logging, tracing, idempotency, batch, parameters).

leandrodamascena · 2026-05-09T17:23:49Z

+
+| Scenario | Monthly | Annual | Savings |
+|----------|---------|--------|---------|
+| Lambda on-demand | $484 | $5,808 | baseline |


I'd either remove the specific dollar amounts and point to the pricing calculator, or at minimum add a note with the assumptions (region, instance type, request volume) and a "last verified" date so people know when to re-check.

Good call. Removed the hardcoded dollar amounts and replaced with guidance to use the LMI Pricing Calculator for accurate, workload-specific comparisons.

…d cost example - Update Powertools .NET to supported (logging, tracing, idempotency, batch, parameters) - Remove hardcoded cost example, defer to LMI Pricing Calculator

sbbhimji added 2 commits April 20, 2026 16:16

sbbhimji requested review from a team, krokoko, scottschreckengaust and theagenticguy April 20, 2026 21:25

sbbhimji requested review from a team as code owners April 20, 2026 21:25

krokoko added 2 commits April 23, 2026 11:30

Merge branch 'main' into feature/aws-lambda-managed-instances

422c422

Merge branch 'main' into feature/aws-lambda-managed-instances

9d13eae

MichaelWalker-git requested a review from Copilot April 30, 2026 04:27

Copilot started reviewing on behalf of MichaelWalker-git April 30, 2026 04:28 View session

Copilot AI reviewed Apr 30, 2026

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bfreiberg requested changes May 3, 2026

View reviewed changes

leandrodamascena suggested changes May 9, 2026

View reviewed changes

fix(aws-serverless): address Leandro's feedback on Powertools .NET an…

e465e5b

…d cost example - Update Powertools .NET to supported (logging, tracing, idempotency, batch, parameters) - Remove hardcoded cost example, defer to LMI Pricing Calculator


		### Step 5: Set Up Infrastructure

		Two IAM roles required (execution + operator). VPC with 3+ AZ subnets. Create capacity provider, attach function, publish version.


		### Step 6: Validate and Cut Over

		1. Test locally with LocalStack (supports LMI emulation)


		### Regional Availability

		us-east-1, us-east-2, us-west-2, ap-northeast-1, eu-west-1

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sbbhimji commented Apr 20, 2026 •

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