Supabase边缘函数调用AWS SES报错：仍尝试读取文件系统配置

问题描述 #

在Supabase边缘函数里用AWS SES发邮件，已经配置了这些AWS环境变量：

AWS_ACCESS_KEY_ID=key
AWS_SECRET_ACCESS_KEY=secret
AWS_REGION=us-east-2
AWS_DEFAULT_REGION=us-east-2
AWS_DEFAULT_PROFILE=default
AWS_SDK_LOAD_CONFIG=

虽然执行下面的代码能正常打印出凭证信息：

import { SESClient } from "npm:@aws-sdk/client-ses";
const client = new SESClient();
console.log(await client.config.credentialDefaultProvider()());

但运行时还是会因为SDK尝试读取文件系统（边缘运行时没有文件系统）抛出错误：

runtime has escaped from the event loop unexpectedly: event loop error: TypeError [ERR_INVALID_ARG_TYPE]" argument must be of type string. Received null
    at assertPath (ext:deno_node/path/_util.ts:10:11)
    at join (ext:deno_node/path/_posix.ts:77:5)
    at getCredentialsFilepath (file:///tmp/sb-compile-edge-runtime/node_modules/localhost/@smithy/shared-ini-file-loader/2.3.1/dist-cjs/index.js:75:117)
    at loadSharedConfigFiles (file:///tmp/sb-compile-edge-runtime/node_modules/localhost/@smithy/shared-ini-file-loader/2.3.1/dist-cjs/index.js:132:22)
    at file:///tmp/sb-compile-edge-runtime/node_modules/localhost/@smithy/node-config-provider/2.2.1/dist-cjs/index.js:51:105
    at file:///tmp/sb-compile-edge-runtime/node_modules/localhost/@smithy/property-provider/2.1.1/dist-cjs/index.js:79:33
    at eventLoopTick (ext:core/01_core.js:183:11)
    at async coalesceProvider (file:///tmp/sb-compile-edge-runtime/node_modules/localhost/@smithy/property-provider/2.1.1/dist-cjs/index.js:106:18)
    at async file:///tmp/sb-compile-edge-runtime/node_modules/localhost/@smithy/property-provider/2.1.1/dist-cjs/index.js:117:20

就算直接给SESClient传凭证也解决不了这个问题。

原因分析 #

AWS SDK v3的默认配置加载逻辑是按优先级依次尝试获取配置：先环境变量，再本地配置文件。但在Supabase边缘运行时这种无文件系统的环境里，SDK尝试构建本地配置文件路径时，因为系统路径变量是null，触发了类型错误。哪怕环境变量里的凭证已经能正常读取，这个文件系统读取的尝试还是会中断执行。

解决办法 #

方法1：手动指定配置，跳过文件系统加载 #

直接从环境变量读取凭证和区域，同时禁用SDK的配置文件加载逻辑：

import { SESClient } from "npm:@aws-sdk/client-ses";
import { fromEnv } from "npm:@aws-sdk/credential-provider-env";

const sesClient = new SESClient({
  region: Deno.env.get("AWS_REGION"),
  credentials: fromEnv(),
  // 阻止SDK尝试读取本地配置文件
  configFileSelector: () => Promise.reject("No config files available in edge runtime"),
});

方法2：自定义配置加载链 #

如果需要更灵活的配置，可以只保留环境变量加载器，跳过所有文件系统相关的加载逻辑：

import { SESClient } from "npm:@aws-sdk/client-ses";
import { fromEnv } from "npm:@aws-sdk/credential-provider-env";
import { regionProvider } from "npm:@aws-sdk/node-config-provider";

const sesClient = new SESClient({
  region: await regionProvider(fromEnv)(),
  credentials: fromEnv(),
});

方法3：用环境变量强制禁用配置文件加载 #

把AWS_SDK_LOAD_CONFIG设为false，强制SDK只从环境变量读取配置，不再尝试加载本地文件：

AWS_SDK_LOAD_CONFIG=false

然后初始化客户端时不用额外传参数：

import { SESClient } from "npm:@aws-sdk/client-ses";
const sesClient = new SESClient({});

验证 #

修改后运行发送邮件的代码，确认不再出现文件系统相关的类型错误，同时邮件能正常发送。

内容的提问来源于stack exchange，提问作者Inquisitor