错误:: ResourceNotFoundException: 在 AWS.config.credentials.refresh 中找不到请求的资源

Question

我正在尝试执行 dynamodb db 操作并生成一个运行良好的报告，但在生产中有时会看到错误 - CredentialsError: Missing credentials in config, if using AWS_CONFIG_FILE, set AWS_SDK_LOAD_CONFIG=1 using identity poolid。因此，我更新了代码以刷新令牌，如下所示 -

<script src="https://sdk.amazonaws.com/js/aws-sdk-2.789.0.min.js"></script>

var GetWallboardx = () => {

    AWS.config.region = 'eu-west-2';
    AWS.config.credentials = new AWS.CognitoIdentityCredentials({
        IdentityPoolId: 'eu-west-2:xxxxxxxxxxxxxxxxx0e8',
    });
    
    //refreshes credentials using AWS.CognitoIdentity.getCredentialsForIdentity()
    AWS.config.credentials.refresh(error => {
      if (error) {
        console.error(error);
      } else {;
        var docClient = new AWS.DynamoDB.DocumentClient();
      }
    });
    
    docClient.scan(params, function(err, data) {
        -- some db operation --
    })
    
    setTimeout(GetWallboardx,RefreshInterval)// run this every 5 seconds
}

GetWallboardx()

如果我尝试使用这种“刷新方法”，看起来就像错误所说的无法访问发电机数据库 - 错误:: ResourceNotFoundException: 未找到请求的资源。谁能帮帮我吗。当我之前没有像这样使用“刷新”时，我没有得到这个异常 -

var docClient;

AWS.config.region = 'eu-west-2';
AWS.config.credentials = new AWS.CognitoIdentityCredentials({
    IdentityPoolId: 'eu-west-2:xxxxxxxxxxxxxxxxx0e8',
});

docClient = new AWS.DynamoDB.DocumentClient();

Answer 1

因为 refresh() 是 promise 方法，这意味着它正在异步运行。你可能需要一些关于 javascript 的异步承诺的知识。您应该参考此链接的另一件事是如何使用凭据刷新（）

Users should call get / getPromise before using refresh

请参阅下面的示例来解决您的问题：

var GetWallboardx = async () => {
     try {
         // whether the credentials object should call refresh()
         if (AWS.config.credentials.needRefresh()) {
              await refreshCredentials();
         }

         let data = await docClient.scan(params).promise();
         // some db operation

         setTimeout(GetWallboardx(),5000) // run this every 5 seconds
     } catch(e) {
         // Error handler
     }
}

var refreshCredentials = async () => {
    await AWS.config.credentials.refreshPromise();
}

var getCredentials = async () => {
    try {
        AWS.config.region = 'eu-west-2';
        AWS.config.credentials = new AWS.CognitoIdentityCredentials({
            IdentityPoolId: 'eu-west-2:xxxxxxxxxxxxxxxxx0e8',
        });
    
        // Should call this method to have ability using refresh()
        await AWS.config.credentials.getPromise();

        // once users get the credential identity, it is able to do refresh()
        console.log('getCredentials done: ',AWS.config.credentials.identityId)
        // await refreshCredentials()

        var docClient = new AWS.DynamoDB.DocumentClient();
        
        GetWallboardx();
    } catch(e) {
        // Error handler
    }
}

getCredentials()

我还没有尝试过该代码，但我认为它应该可以按预期工作。如果您有任何问题，请告诉我。