rust

如何用Rust快速构建AWS Lambda Function

文章目录

  1. 1. cargo-lambda
  2. 2. 运行
  3. 3. 打包
  4. 4. 部署

AWS Lambda Function是轻量级的计算服务。优势是按需付费，专注于功能，服务本身如何构建暴露都有AWS都不需要自己操心。

而按需付费基本就是服务使用时长和内存占用了，这个优化的话那妥妥的是Rust的拿手好戏, 所以现在有好多Serverless服务都用Rust构建的Lambda Function来搞。

今天简单看下如何用Rust快速构建Lambda Function（别担心没aws环境，往下看，有本地沙箱可尝试）

cargo-lambda

cargo-lambda这个库可以用来构建Lambda Function （也是官方推荐的工具）

如下代码安装：

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brew tap cargo-lambda/cargo-lambda
brew install cargo-lambda

然后初始化一个demo

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cargo lambda new lambda-demo
> Is this function an HTTP function? Yes

会自动生成初始化项目，引入相关依赖及运行时：lambda-http和tokio依赖

功能部分代码如下，提供一个hello world式请求处理：

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use lambda_http::{run, service_fn, tracing, Body, Error, Request, RequestExt, Response};

async fn function_handler(event: Request) -> Result<Response<Body>, Error> {
    let who = event
        .query_string_parameters_ref()
        .and_then(|params| params.first("name"))
        .unwrap_or("world");
    let message = format!("Hello {who}, this is an AWS Lambda HTTP request");

    let resp = Response::builder()
        .status(200)
        .header("content-type", "text/html")
        .body(message.into())
        .map_err(Box::new)?;
    Ok(resp)
}

#[tokio::main]
async fn main() -> Result<(), Error> {
    tracing::init_default_subscriber();

    run(service_fn(function_handler)).await
}

题外话，有没有感觉这个service_fn很眼熟?

这个接的handler也要求实现Service trait， 跟tower service一样。为啥呢，用了hyper库！
都说hyper基本就是Rust服务框架的基石不假。

运行

开发中用watch就能本地运行调试，支持变更重编译

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cargo lambda watch
#  INFO invoke server listening on [::]:9000

也可以命令行调用

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cargo lambda invoke lambda-demo --data-ascii "?name=newbmiao"

打包

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cargo lambda build --release --arm64

这样会将执行文件编译到./target/lambda/lambda-demo/bootstrap

(注意：如果是workspace, 则需要去workspace下target目录找)

可执行文件压缩一下就可以用来部署了

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zip bootstrap.zip bootstrap

部署

(这部分会设计比较多infrastructure，感兴趣的同学可以继续往下)

部署也很方便，不过难在不是所有人都有aws账户啊。

也好解决，localstack可以本地模拟aws环境

用docker-compose up起个localstack

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version: "3.8"

services:
  localstack:
    container_name: "${LOCALSTACK_DOCKER_NAME:-localstack-main}"
    image: localstack/localstack
    ports:
      - "127.0.0.1:4566:4566" # LocalStack Gateway
      - "127.0.0.1:4510-4559:4510-4559" # external services port range
    environment:
      # LocalStack configuration: https://docs.localstack.cloud/references/configuration/
      - DEBUG=${DEBUG:-0}
    volumes:
      - "${LOCALSTACK_VOLUME_DIR:-./volume}:/var/lib/localstack"
      - "/var/run/docker.sock:/var/run/docker.sock"

然后用terraform构建部署流程, 核心部分就是：

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# 构建
resource "aws_lambda_function" "lambda_demo" {
  filename         = "bootstrap.zip"
  function_name    = "lambda_demo"
  role             = aws_iam_role.iam_for_lambda_tf.arn
  handler          = "bootstrap"
  source_code_hash = filebase64sha256("bootstrap.zip")
  runtime          = "provided.al2"
  architectures    = ["arm64"]
}

剩下就是权限以及获取lambda function地址

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resource "aws_lambda_function_url" "lambda_demo_url" {
  function_name      = aws_lambda_function.lambda_demo.arn
  authorization_type = "NONE"
}

output "function_url" {
  description = "Function URL."
  value       = aws_lambda_function_url.lambda_demo_url.function_url
}

resource "aws_iam_role" "iam_for_lambda_tf" {
  name = "iam_for_lambda_tf"

  assume_role_policy = <<EOF
{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Action": "sts:AssumeRole",
      "Principal": {
        "Service": "lambda.amazonaws.com"
      },
      "Effect": "Allow",
      "Sid": ""
    }
  ]
}
EOF
}

这样从terraform apply 部署结果中能拿到访问地址, 比如

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...
Apply complete! Resources: 3 added, 0 changed, 0 destroyed.

Outputs:

function_url = "http://h6v7ozz6ay3h6apr2hi5edsmnc0wpz80.lambda-url.us-east-1.localhost.localstack.cloud:4566/

想上手试下的话，详细代码见lambda-demo, build.sh有详细打包流程

如有疑问，请文末留言交流或邮件：newbvirgil@gmail.com 本文链接 : https://newbmiao.github.io/2024/03/10/rust-lambda.html