Can I get information about AWS Lambda request IDs, e.g. the trigger?

Question

In my logs I find

START RequestId: 123a1a12-1234-1234-1234-123456789012 Version: $LATEST

for every invocation of AWS lambda. Is it possible to get more information about a request, e.g. what triggered it?

Answer 1

You can get the request id and other information from the context object.

When Lambda runs your function, it passes a context object to the handler. This object provides methods and properties that provide information about the invocation, function, and execution environment. https://docs.aws.amazon.com/lambda/latest/dg/nodejs-context.html

You can get further information from the process.env variable.

I wrote a short lambda function (node.js) which logs these information to the console and ends up in aws cloud watch

exports.handler = async (event, context) => {
    console.log('context:', JSON.stringify(context));
    console.log('process.env:', JSON.stringify(process.env));

    return {statusCode: 200, body: 'Hello World'};
};

Log output:

START RequestId: 6f3c103e-f0a5-4982-934c-dabedda0065e Version: $LATEST
context:
{
    "callbackWaitsForEmptyEventLoop": true,
    "functionVersion": "$LATEST",
    "functionName": "my_lambda_function_name",
    "memoryLimitInMB": "128",
    "logGroupName": "/aws/lambda/my_lambda_function_name",
    "logStreamName": "2020/10/01/[$LATEST]8adb13668eed4ac8b3e7f8d796fe4d49",
    "invokedFunctionArn": "arn:aws:lambda:us-east-1:636121343751:function:my_lambda_function_name",
    "awsRequestId": "6f3c103e-f0a5-4982-934c-dabedda0065e"
}
process.env:
{
    "AWS_LAMBDA_FUNCTION_VERSION": "$LATEST",
    "AWS_SESSION_TOKEN": "IZZ3eS6vFF...",
    "LD_LIBRARY_PATH": "/var/lang/lib:/lib64:/usr/lib64:/var/runtime:/var/runtime/lib:/var/task:/var/task/lib:/opt/lib",
    "LAMBDA_TASK_ROOT": "/var/task",
    "AWS_LAMBDA_LOG_GROUP_NAME": "/aws/lambda/my_lambda_function_name",
    "AWS_LAMBDA_RUNTIME_API": "127.0.0.1:9001",
    "AWS_LAMBDA_LOG_STREAM_NAME": "2020/10/01/[$LATEST]8adb13668eed4ac8b3e7f8d796fe4d49",
    "AWS_EXECUTION_ENV": "AWS_Lambda_nodejs12.x",
    "AWS_LAMBDA_FUNCTION_NAME": "my_lambda_function_name",
    "AWS_XRAY_DAEMON_ADDRESS": "169.254.79.2:2000",
    "PATH": "/var/lang/bin:/usr/local/bin:/usr/bin/:/bin:/opt/bin",
    "AWS_DEFAULT_REGION": "us-east-1",
    "PWD": "/var/task",
    "AWS_SECRET_ACCESS_KEY": "5nQrpKhBwF...",
    "LAMBDA_RUNTIME_DIR": "/var/runtime",
    "LANG": "en_US.UTF-8",
    "NODE_PATH": "/opt/nodejs/node12/node_modules:/opt/nodejs/node_modules:/var/runtime/node_modules:/var/runtime:/var/task",
    "AWS_REGION": "us-east-1",
    "TZ": ":UTC",
    "AWS_ACCESS_KEY_ID": "ASIAZNANWY3473BTADSB",
    "SHLVL": "0",
    "_AWS_XRAY_DAEMON_ADDRESS": "169.254.79.2",
    "_AWS_XRAY_DAEMON_PORT": "2000",
    "AWS_XRAY_CONTEXT_MISSING": "LOG_ERROR",
    "_HANDLER": "index.handler",
    "AWS_LAMBDA_FUNCTION_MEMORY_SIZE": "128",
    "_X_AMZN_TRACE_ID": "Root=1-6f75f4e5-5801599f17fd63e74ecd0833;Parent=73fb93812cdbf83f;Sampled=0"
}
END RequestId: 6f3c103e-f0a5-4982-934c-dabedda0065e
REPORT RequestId: 6f3c103e-f0a5-4982-934c-dabedda0065e
Duration: 21.71 ms  Billed Duration: 100 ms 
Memory Size: 128 MB Max Memory Used: 64 MB  Init Duration: 132.35 ms    

Answer 2

You need to get this information from your lambda function context .

    RequestId=context.aws_request_id

You will get following result RequestId- "00cfaafe-5018-4be0-9668-b98daf5a7312" Version: $LATEST

Answer 3

Not sure I understand what you mean by what triggered it? If it's connected to the API Gateway, then requests are proxied through the Gateway to your Lambda. In that case the Gateway triggered it, even though it was a proxied request.

Additionally and you can augment your Gateway to pass additional request info to your Lambda. See how

And also, to attach the request details to the RequestID you're seeing, you can check the context.awsRequestId.

I'd assume you want to do some form of log monitoring, in which case I think you can bundle up these request information(headers, query, params, body) and send to your log aggregator along with the awsRequestId. Let me know if that helps

Further reference

Answer 4

A lambda function has two parameters: Event and context.

A normal invocation looks like this:

{
    "event": {
        "version": "0",
        "id": "abcdefgh-1234-5678-1234-abcdefghijkl",
        "detail-type": "Scheduled Event",
        "source": "aws.events",
        "account": "123456789012",
        "time": "2018-01-01T12:00:00Z",
        "region": "us-east-1",
        "resources": [
            "arn:aws:events:us-east-1:123456788901:rule/foo"
        ],
        "detail": {}
    },
    "context": "<__main__.LambdaContext object at 0x123456ax1234>"
}

The test invocation has the elements you get.