从lambda函数中的dynamodb获取时缺少凭据错误

Question

docClient.query(params, function(err, data) {
        if (err) {
            console.error("Unable to query. Error:", JSON.stringify(err, null, 2));
        } else {
            console.log("Query succeeded.");
}
});

得到类似这样的错误。我已正确设置lambda的角色以允许dynamodbaccess。我有适当的表和密钥配置来获取详细信息。

{
    "message": "Missing credentials in config",
    "code": "CredentialsError",
    "time": "2017-11-29T22:27:08.406Z",
    "requestId": "6f897dab-d554-11e7-8215-01d4f4e39dee",
    "statusCode": 400,
    "retryable": false,
    "retryDelay": 25.21987048923635,
    "originalError": {
        "message": "Could not load credentials from CognitoIdentityCredentials",
        "code": "CredentialsError",
        "time": "2017-11-29T22:27:08.406Z",
        "requestId": "6f897dab-d554-11e7-8215-01d4f4e39dee",
        "statusCode": 400,
        "retryable": false,
        "retryDelay": 25.21987048923635,
        "originalError": {
            "message": "Invalid login token. Token expired: 1511994128 >= 1511993457",
            "code": "NotAuthorizedException",
            "time": "2017-11-29T22:27:08.392Z",
            "requestId": "6f897dab-d554-11e7-8215-01d4f4e39dee",
            "statusCode": 400,
            "retryable": false,
            "retryDelay": 25.21987048923635
        }
    }
}