假如每次修改了 lambda 程序, 都要打成 zip 包, 上传到 aws 后台看, 才能看到运行情况. 那这样效率太低了.
让人兴奋的是, 有这个工具, sam cli, 可以用它在本地调试 lambda 程序
Installation
前提
在本地用 sam cli 运行 serverless 程序必须安装和运行 docker. sam cli 用环境变量 DOCKER_HSOT 和 docker 进程连接
- macOS: Docker for Mac
- Windows: Docker for Windows
- Linux: yum install docker
使用 pip 安装 sam cli
在 aws 文档估计没人更新, 还是只有 npm 安装 sam cli 的说明. npm 安装下来的是旧 sam cli.
所以这里, 我推荐使用 sam cli 最新的版本, 也就是用 pip 安装出来的版本
要求 python 2.7
pip install --user aws-sam-cli
检查是否安装成功
sam --version
SAM CLI, version 0.3.0
Usage
继续沿用以上一篇文章 S3 事件触发的例子, 如果没有看过的, 建议先看 使用 aws lambda 开发无服务器程序
1. 代码例子
from __future__ import print_function
import json
import urllib
import boto3
print('Loading function')
s3 = boto3.client('s3')
def lambda_handler(event, context):
# Get the object from the event and show its content type
bucket = event['Records'][0]['s3']['bucket']['name']
key = urllib.unquote_plus(event['Records'][0]['s3']['object']['key'].encode('utf8'))
try:
response = s3.get_object(Bucket=bucket, Key=key)
print("CONTENT TYPE: " + response['ContentType'])
return response['ContentType']
except Exception as e:
print(e)
print('Error getting object {} from bucket {}. Make sure they exist and your bucket is in the same region as this function.'.format(key, bucket))
raise e
2. 初始目录
3. 建立测试用例
sam local generate-event s3 --region us-east-1 --bucket test4lambda --key lambda-test.txt > event.json
S3 的 bucket(test4lambda) 和 key(lambda-test.txt) 需要提前建好
生成如下用例
{
"Records": [
{
"eventVersion": "2.0",
"eventName": "ObjectCreated:Put",
"eventTime": "1970-01-01T00:00:00.000Z",
"userIdentity": {
"principalId": "EXAMPLE"
},
"eventSource": "aws:s3",
"requestParameters": {
"sourceIPAddress": "127.0.0.1"
},
"s3": {
"configurationId": "testConfigRule",
"object": {
"eTag": "0123456789abcdef0123456789abcdef",
"key": "lambda-test.txt",
"sequencer": "0A1B2C3D4E5F678901",
"size": 1024
},
"bucket": {
"ownerIdentity": {
"principalId": "EXAMPLE"
},
"name": "test4lambda",
"arn": "arn:aws:s3:::test4lambda"
},
"s3SchemaVersion": "1.0"
},
"responseElements": {
"x-amz-id-2": "EXAMPLE123/5678abcdefghijklambdaisawesome/mnopqrstuvwxyzABCDEFGH",
"x-amz-request-id": "EXAMPLE123456789"
},
"awsRegion": "us-east-1"
}
]
}
4. 编写 yaml 配置文件
当然, 不需要手写, 可以到 lambda 后台导出.
4.1 导出函数
4.2 下载 AWS SAM 文件
4.3 得到的配置文件如下
AWSTemplateFormatVersion: '2010-09-09'
Transform: 'AWS::Serverless-2016-10-31'
Description: >-
An Amazon S3 trigger that retrieves metadata for the object that has been
updated.
Resources:
myTest1:
Type: 'AWS::Serverless::Function'
Properties:
Handler: lambda_function.lambda_handler
Runtime: python2.7
CodeUri: .
Description: >-
An Amazon S3 trigger that retrieves metadata for the object that has
been updated.
MemorySize: 128
Timeout: 3
Role: 'arn:aws:iam::851829110870:role/service-role/lambdaTest'
Events:
BucketEvent1:
Type: S3
Properties:
Bucket:
Ref: Bucket1
Events:
- 's3:ObjectCreated:*'
Tags:
'lambda-console:blueprint': s3-get-object-python
Bucket1:
Type: 'AWS::S3::Bucket'
4.4 最终的三个文件如下:
运行
sam local invoke myTest1 -e event.json -t myTest1.yaml
竟然提示 "time out after 3 seconds"
解决方法: 在 myTest1.yaml 找到 Timeout 字段, 改成 30
再次运行, 成功输出 "text/plain", 也就是 python 代码那句 print 语句的结果
结语
一个本地调试 lambda 的环境就这样完成了. sam 还有很多功能, 更多学习, 可以执行以下两个命令
➜ sam --help
Usage: sam [OPTIONS] COMMAND [ARGS]...
AWS Serverless Application Model (SAM) CLI
The AWS Serverless Application Model extends AWS CloudFormation to provide
a simplified way of defining the Amazon API Gateway APIs, AWS Lambda
functions, and Amazon DynamoDB tables needed by your serverless
application. You can find more in-depth guide about the SAM specification
here: https://github.com/awslabs/serverless-application-model.
Options:
--debug Turn on debug logging
--version Show the version and exit.
--help Show this message and exit.
Commands:
init Initialize a serverless application with a...
package Package an AWS SAM application. This is an alias for 'aws
cloudformation package'.
local Run your Serverless application locally for...
validate Validate an AWS SAM template.
deploy Deploy an AWS SAM application. This is an alias for 'aws
cloudformation deploy'.
➜ sam local generate-event --help
Usage: sam local generate-event [OPTIONS] COMMAND [ARGS]...
Generate an event
Options:
--help Show this message and exit.
Commands:
api Generates a sample Amazon API Gateway event
dynamodb Generates a sample Amazon DynamoDB event
kinesis Generates a sample Amazon Kinesis event
s3 Generates a sample Amazon S3 event
schedule Generates a sample scheduled event
sns Generates a sample Amazon SNS event
