Using Sentry for Lambda Functions

ajjindal — Fri, 02 Oct 2020 22:23:52 +0000

Here's how I instrumented my Python Lambda function. If you are using Node environment, there are parallel docs.

Step 1: Create a dummy function - I created a simple function that tries Division By Zero. (Skip this if you already have your function)

import json

def lambda_handler(event, context):

    message = 'Hello {} {}!'.format(event['first_name'], 
                                    event['last_name'])  

    x=3/0

    return { 
        'message' : message
    }

Step 2: Add Sentry to the Python function folder using pip

pip install --upgrade sentry-sdk

Step 3: Initialize Sentry - This required me to import Sentry's serverless package and wrap my handler.

import json
import sentry_sdk
from sentry_sdk.integrations.aws_lambda import AwsLambdaIntegration

sentry_sdk.init(
    dsn="Your dsn from sentry.io",
    integrations=[AwsLambdaIntegration()],
    traces_sample_rate=1.0,
)

def lambda_handler(event, context):

    message = 'Hello {} {}!'.format(event['first_name'], 
                                    event['last_name'])  

    x=3/0

    return { 
        'message' : message
    }

That's it. I now have complete visibility into my Lambda functions.

The stack traces are detailed and point me to the line of code that's causing the exception.

Sentry captured my function transactions automatically (although, the transaction is pretty empty because my function doesn't do much)

Function context like aws_request_id and remaining_time_in_milis are super helpful. In addition, I have deep links to CloudWatch logs.

In addition, I made couple customizations to my error reporting:

I really care about timeout issues. They end up bleeding into unknown issues that are difficult to debug. So, I enabled timeout_warning.

sentry_sdk.init(
    dsn="Your dsn from sentry.io",
    integrations=[AwsLambdaIntegration(timeout_warning=True)],
    traces_sample_rate=1.0,
)

Also, while Sentry automatically captured tons of context, I did want to look at my payload to the function. So, I enabled send_default_pii

python
sentry_sdk.init(
    dsn="Your dsn from sentry.io",
    integrations=[AwsLambdaIntegration(timeout_warning=True)],
    traces_sample_rate=1.0,
        send_default_pii=True,
)

With this instrumentation, I have visibility that's unparalleled to any other out there. I can quickly debug issues and identify root causes for slow executing functions. Thus, saving tons of time and unnecessary lambda cost.

How to debug errors in Lambda functions

ajjindal — Wed, 23 Sep 2020 23:21:32 +0000

Troubleshooting production issues in Lambda environments is often challenging. CloudWatch is not easy to use to quickly identify and resolve issues. CloudWatch requires me to go into logs, search for relevant terms that I may not always know and has hard to consume stack traces.

I am using Sentry to instrument my Lambda Functions code in order to report error stack traces and associated debugging context.

Here's how I instrumented my Node function. If you are using Python environment, there are parallel docs.

Step 1: Create a dummy function to test the error reporting - I created a simple function that calls an unknown function.

const mySyncHandler = (event, context, callback) => {

  notDefinedFunc();
};

Step 2: Add Sentry to the Node folder - I used npm for this but you can use yarn as well

npm install --save @sentry/serverless

Step 3: Initialize Sentry in my Lambda function - This required me to import Sentry's serverless package and wrap. my handler.

const Sentry = require("@sentry/serverless");

Sentry.init({
  dsn:
    "Get your dsn by creating a free account with Sentry",
});

const mySyncHandler = (event, context, callback) => {

  notDefinedFunc();
};

exports.handler = Sentry.AWSLambda.wrapHandler(mySyncHandler);

That's it. I now have visibility into errors from my lambda functions.

The stack traces are detailed and point me to the line of code that's causing the exception.

Function context like aws_request_id and remaining_time_in_milis are super helpful. In addition, I have deep links to CloudWatch logs.

In addition, I made couple customizations to my error reporting:

I really care about timeout issues. They end up bleeding into unknown issues that are difficult to debug. So, I enabled timeout warnings.
```
exports.handler =     Sentry.AWSLambda.wrapHandler(yourHandler, {
  captureTimeoutWarning: false,
});
```
Also, while Sentry automatically captured breadcrumbs from console logs, I added some of my own

Sentry.addBreadcrumb({
  category: "auth",
  message: "Authenticated user " + user.email,
  level: Sentry.Severity.Info,
});

With this instrumentation, I have visibility that's unparalleled to any other solution out there. I can quickly identify issues, reproduce issues in my local environment and get to root cause of the problem.

Please share if you have used a better way to monitor errors for your Lambda functions.

DEV Community: ajjindal

Using Sentry for Lambda Functions

How to debug errors in Lambda functions