aws-serverless

Name: aws-serverless
Author: tranhieutt

69stars41forks

How to install aws-serverless?

tranhieutt/software_development_department/aws-serverless

$npx -y skills add tranhieutt/software_development_department --skill aws-serverless

Installs into the current project.

Summary

Provides AWS serverless architecture patterns for Lambda, API Gateway, DynamoDB, SQS, and SAM/CDK. Use when working with AWS serverless files (serverless.yml, CDK stacks) or when the user mentions Lambda, API Gateway, serverless, or AWS SAM.

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SKILL.md

1	# AWS Serverless
2
3	## Critical rules (non-obvious)
4
5	- Initialize clients OUTSIDE handler — Lambda reuses execution environments across invocations; creating clients inside costs 100-500ms per cold start
6	- `context.callbackWaitsForEmptyEventLoop = false` — prevents Node.js from hanging on open async handles (DB connections, etc.)
7	- SQS `VisibilityTimeout` = 6× Lambda timeout — if Lambda takes 30s, set 180s; otherwise messages return to queue mid-processing
8	- `FunctionResponseTypes: [ReportBatchItemFailures]` — partial batch failure; without this, any single failure retries the entire batch
9	- *Never use `` in `Access-Control-Allow-Origin` with `credentials: true`** — browsers block it; use explicit origin
10
11	## Lambda handler pattern
12
13	```javascript
14	// Initialize once (reused across invocations = faster after cold start)
15	const { DynamoDBClient } = require("@aws-sdk/client-dynamodb");
16	const { DynamoDBDocumentClient, GetCommand } = require("@aws-sdk/lib-dynamodb");
17
18	const docClient = DynamoDBDocumentClient.from(new DynamoDBClient({}));
19
20	exports.handler = async (event, context) => {
21	context.callbackWaitsForEmptyEventLoop = false; // don't hang on open handles
22	try {
23	const body = typeof event.body === "string" ? JSON.parse(event.body) : event.body;
24	const result = await docClient.send(new GetCommand({
25	TableName: process.env.TABLE_NAME,
26	Key: { id: body.id },
27	}));
28	return { statusCode: 200, headers: { "Content-Type": "application/json" }, body: JSON.stringify(result.Item) };
29	} catch (err) {
30	console.error(JSON.stringify({ error: err.message, requestId: context.awsRequestId }));
31	return { statusCode: err.statusCode ?? 500, body: JSON.stringify({ error: err.message }) };
32	}
33	};
34	```
35
36	## SAM template: HTTP API + DynamoDB
37
38	```yaml
39	# template.yaml
40	AWSTemplateFormatVersion: "2010-09-09"
41	Transform: AWS::Serverless-2016-10-31
42
43	Globals:
44	Function:
45	Runtime: nodejs20.x
46	Timeout: 30
47	MemorySize: 256
48	Environment:
49	Variables:
50	TABLE_NAME: !Ref ItemsTable
51
52	Resources:
53	HttpApi:
54	Type: AWS::Serverless::HttpApi
55	Properties:
56	CorsConfiguration:
57	AllowOrigins: ["https://yourdomain.com"] # never * with credentials
58	AllowMethods: [GET, POST, DELETE]
59	AllowHeaders: ["*"]
60
61	GetItemFunction:
62	Type: AWS::Serverless::Function
63	Properties:
64	Handler: src/handlers/get.handler
65	Events:
66	GetItem:
67	Type: HttpApi
68	Properties:
69	ApiId: !Ref HttpApi
70	Path: /items/{id}
71	Method: GET
72	Policies:
73	- DynamoDBReadPolicy:
74	TableName: !Ref ItemsTable
75
76	ItemsTable:
77	Type: AWS::DynamoDB::Table
78	Properties:
79	AttributeDefinitions:
80	- AttributeName: id
81	AttributeType: S
82	KeySchema:
83	- AttributeName: id
84	KeyType: HASH
85	BillingMode: PAY_PER_REQUEST
86
87	Outputs:
88	ApiUrl:
89	Value: !Sub "https://${HttpApi}.execute-api.${AWS::Region}.amazonaws.com"
90	```
91
92	## SQS async processing with partial batch failure
93
94	```yaml
95	# In template.yaml
96	ProcessorFunction:
97	Type: AWS::Serverless::Function
98	Properties:
99	Events:
100	SQSEvent:
101	Type: SQS
102	Properties:
103	Queue: !GetAtt ProcessingQueue.Arn
104	BatchSize: 10
105	FunctionResponseTypes:
106	- ReportBatchItemFailures # critical: retry only failed items
107
108	ProcessingQueue:
109	Type: AWS::SQS::Queue
110	Properties:
111	VisibilityTimeout: 180 # 6x Lambda timeout (30s)
112	RedrivePolicy:
113	deadLetterTargetArn: !GetAtt DeadLetterQueue.Arn
114	maxReceiveCount: 3
115
116	DeadLetterQueue:
117	Type: AWS::SQS::Queue
118	Properties:
119	MessageRetentionPeriod: 1209600 # 14 days
120	```
121
122	```javascript
123	// Handler with partial batch failure reporting
124	exports.handler = async (event) => {
125	const batchItemFailures = [];
126	for (const record of event.Records) {
127	try {
128	await processMessage(JSON.parse(record.body));
129	} catch (err) {
130	console.error(`Failed ${record.messageId}:`, err.message);
131	batchItemFailures.push({ itemIdentifier: record.messageId });
132	}
133	}
134	return { batchItemFailures }; // only failed items are retried
135	};
136	```
137
138	## Sharp edges
139
140	\| Issue \| Severity \| Fix \|
141	\|---\|---\|---\|
142	\| Cold start > 1s \| High \| Move SDK init outside handler; use `--no-install-suggests` in Docker layers \|
143	\| Timeout without response \| High \| Always set explicit timeout < Lambda timeout in downstream ca

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Type

aws-serverless

69stars41forks

View on GitHub

How to install aws-serverless?

tranhieutt/software_development_department/aws-serverless

$npx -y skills add tranhieutt/software_development_department --skill aws-serverless

Installs into the current project.

Summary

Files · 1

View on GitHub

SKILL.md

1	# AWS Serverless
2
3	## Critical rules (non-obvious)
4
5	- Initialize clients OUTSIDE handler — Lambda reuses execution environments across invocations; creating clients inside costs 100-500ms per cold start
6	- `context.callbackWaitsForEmptyEventLoop = false` — prevents Node.js from hanging on open async handles (DB connections, etc.)
7	- SQS `VisibilityTimeout` = 6× Lambda timeout — if Lambda takes 30s, set 180s; otherwise messages return to queue mid-processing
8	- `FunctionResponseTypes: [ReportBatchItemFailures]` — partial batch failure; without this, any single failure retries the entire batch
9	- *Never use `` in `Access-Control-Allow-Origin` with `credentials: true`** — browsers block it; use explicit origin
10
11	## Lambda handler pattern
12
13	```javascript
14	// Initialize once (reused across invocations = faster after cold start)
15	const { DynamoDBClient } = require("@aws-sdk/client-dynamodb");
16	const { DynamoDBDocumentClient, GetCommand } = require("@aws-sdk/lib-dynamodb");
17
18	const docClient = DynamoDBDocumentClient.from(new DynamoDBClient({}));
19
20	exports.handler = async (event, context) => {
21	context.callbackWaitsForEmptyEventLoop = false; // don't hang on open handles
22	try {
23	const body = typeof event.body === "string" ? JSON.parse(event.body) : event.body;
24	const result = await docClient.send(new GetCommand({
25	TableName: process.env.TABLE_NAME,
26	Key: { id: body.id },
27	}));
28	return { statusCode: 200, headers: { "Content-Type": "application/json" }, body: JSON.stringify(result.Item) };
29	} catch (err) {
30	console.error(JSON.stringify({ error: err.message, requestId: context.awsRequestId }));
31	return { statusCode: err.statusCode ?? 500, body: JSON.stringify({ error: err.message }) };
32	}
33	};
34	```
35
36	## SAM template: HTTP API + DynamoDB
37
38	```yaml
39	# template.yaml
40	AWSTemplateFormatVersion: "2010-09-09"
41	Transform: AWS::Serverless-2016-10-31
42
43	Globals:
44	Function:
45	Runtime: nodejs20.x
46	Timeout: 30
47	MemorySize: 256
48	Environment:
49	Variables:
50	TABLE_NAME: !Ref ItemsTable
51
52	Resources:
53	HttpApi:
54	Type: AWS::Serverless::HttpApi
55	Properties:
56	CorsConfiguration:
57	AllowOrigins: ["https://yourdomain.com"] # never * with credentials
58	AllowMethods: [GET, POST, DELETE]
59	AllowHeaders: ["*"]
60
61	GetItemFunction:
62	Type: AWS::Serverless::Function
63	Properties:
64	Handler: src/handlers/get.handler
65	Events:
66	GetItem:
67	Type: HttpApi
68	Properties:
69	ApiId: !Ref HttpApi
70	Path: /items/{id}
71	Method: GET
72	Policies:
73	- DynamoDBReadPolicy:
74	TableName: !Ref ItemsTable
75
76	ItemsTable:
77	Type: AWS::DynamoDB::Table
78	Properties:
79	AttributeDefinitions:
80	- AttributeName: id
81	AttributeType: S
82	KeySchema:
83	- AttributeName: id
84	KeyType: HASH
85	BillingMode: PAY_PER_REQUEST
86
87	Outputs:
88	ApiUrl:
89	Value: !Sub "https://${HttpApi}.execute-api.${AWS::Region}.amazonaws.com"
90	```
91
92	## SQS async processing with partial batch failure
93
94	```yaml
95	# In template.yaml
96	ProcessorFunction:
97	Type: AWS::Serverless::Function
98	Properties:
99	Events:
100	SQSEvent:
101	Type: SQS
102	Properties:
103	Queue: !GetAtt ProcessingQueue.Arn
104	BatchSize: 10
105	FunctionResponseTypes:
106	- ReportBatchItemFailures # critical: retry only failed items
107
108	ProcessingQueue:
109	Type: AWS::SQS::Queue
110	Properties:
111	VisibilityTimeout: 180 # 6x Lambda timeout (30s)
112	RedrivePolicy:
113	deadLetterTargetArn: !GetAtt DeadLetterQueue.Arn
114	maxReceiveCount: 3
115
116	DeadLetterQueue:
117	Type: AWS::SQS::Queue
118	Properties:
119	MessageRetentionPeriod: 1209600 # 14 days
120	```
121
122	```javascript
123	// Handler with partial batch failure reporting
124	exports.handler = async (event) => {
125	const batchItemFailures = [];
126	for (const record of event.Records) {
127	try {
128	await processMessage(JSON.parse(record.body));
129	} catch (err) {
130	console.error(`Failed ${record.messageId}:`, err.message);
131	batchItemFailures.push({ itemIdentifier: record.messageId });
132	}
133	}
134	return { batchItemFailures }; // only failed items are retried
135	};
136	```
137
138	## Sharp edges
139
140	\| Issue \| Severity \| Fix \|
141	\|---\|---\|---\|
142	\| Cold start > 1s \| High \| Move SDK init outside handler; use `--no-install-suggests` in Docker layers \|
143	\| Timeout without response \| High \| Always set explicit timeout < Lambda timeout in downstream ca

People who liked this also viewed

6 picks

Type