Monitor Your AWS Lambda Capabilities (or Any Different AWS Service) in Slack | by Ben Bogart | Jul, 2022

Stepping via the code:

API Gateway forwards question string parameters to our Lambda operate via the occasion parameter.

The above code first units the variable x to occasion['queryStringParameters']['x']. Each aspect in occasion['queryStringParameters'] is a string, so to make use of x for any numeric calculations, we should forged it to a numeric knowledge kind. We do this with x = float(x). floatis an information kind representing a floating-point quantity, so making an attempt to forged something that isn’t a quantity to floatwill trigger our Lambda to throw an exception. Lastly, we double x and return it within the physique of our response.

Create the API Gateway Endpoint

Notifications would work with out this step, however organising an API is comparatively easy and supplies our MonitorMe Lambda with a practical occasion variable to course of.

1. Go to the API gateway service and choose Construct on the HTTP API panel.

2. Join our MonitorMe Lambda operate as an API integration.

Click on Add integration

• Choose Lambda as the mixing kind
• Make sure that the right area is chosen (this could match the AWS area your Lambda is hosted in,) then seek for the MonitorMe Lambda operate we created above.
• Present a reputation for the API. I am calling my API MyAPI. (intelligent, I do know)
• Click on Subsequent

3. Now we want a route. A route assigns an motion to a URL path. The motion we’re going to arrange forwards a request to our MonitorMeLambda operate.

• Enter a logical path for the Useful resource path. I’m utilizing the title of our Lambda operate MonitorMe, however you should utilize something
• Choose MonitorMe because the Integration goal.
• Click on Subsequent.

4. On the following display screen, settle for the defaults.

Make sure that Auto-deploy is turned on. With out it, we’ve to deploy any adjustments to our API manually. This could be helpful if we would have liked to deploy to a growth API for testing earlier than deploying into the manufacturing API. We need to hold issues easy for this instance.

The API is deployed. Let’s Take a look at it!

1. Discover the Invoke URL on the MyAPI web page for the $default stage. That is our base URL. Copy it.

2. Add the route path we created in API creation step 3 to the bottom URL. Substitute {YOUR API BASE URL} with base URL you copied within the earlier step. (The URL is case insensitive, however I’ve capitalized it for readability):

https://{YOUR API BASE URL}/MonitorMe

3. Add the question to the URL by appending a ?x= adopted by the worth to check. That is the place we ship parameters to the MonitorMe Lambda operate. For instance:

https://{YOUR API BASE URL}/MonitorMe?x=2

4. Plug this into your browser, and vualá. 2×2= 4.0

That is one tremendous helpful mannequin. 😉

Finally, we begin to get into the meat of the mission. We are going to ship messages to Slack by the use of a webhook.

1. Create a channel in your notifications. I am calling mine aws-notifications

2. Go to api.slack.com/apps. If you’re not signed in, you will note a message asking you to register to your Slack account to create an utility. Do it.

3. As soon as you’re signed in, you’ll as a substitute see a button labeled Create an App. Click on it.

4. We need to create our app from scratch.

5. On the following display screen, add an app title, choose your workspace, and click on Create App.

6. When you create the app, the Slack API web site conveniently suggests some options. We wish Incoming Webhooks, so discover that field and click on it.

7. On the incoming webhooks web page, click on the slider within the higher proper nook to show webhooks on. This will even broaden a settings part on the backside of the web page.

8. Click on the Add New Webhook to Workspacebutton within the settings part on the backside of the web page.

9. Choose the channel we created earlier and Enable.

10. Now, you will note that you’ve created a webhook URL. The curl instance updates so we will check it out on the command line.

Merely seize the Pattern curl request to publish to channelcode and paste it into your terminal like so (If you’re on an older model of Home windows, you’ll be able to set up cURL by following the instructions in this StackOverflow reply):

It’s going to return okay. Test your slack channel, and you will note a publish from AWS Notifier that claims Hiya, World!.

Yay! We will now publish to our slack channel.

11. Copy the Webhook URL. We’re going to want it later.

On this part, we’ll arrange a Lambda operate that, when triggered, will ship us the Slack message with the error particulars.

Identical to earlier than, create a brand new Lambda operate:

1. Go to the Lambda service within the AWS console.
2. Choose Capabilities from the sidebar.
3. Choose Create operate to — you guessed it once more — create a brand new operate.

4. Select Creator from Scratch, enter a reputation in your operate, after which choose the runtime. For this step, I’ll name the operate Notifyand use Python 3.8 because the runtime. Settle for the remainder of the default settings and click on Create operate.

5. Copy and paste the next code into your new Lambda operate.

Let’s step via the code

• Set SLACK_WEBHOOK to the slack webhook URL you created earlier. You could replace this to the URL of the webhook you created.
• AWS calls the lambda_handler operate when the Lambda is invoked. AWS passes in occasionandcontext as parameters. occasion comprises the encoded error message.
• Subsequent, Lambda callsdecode_logpayload to decode the error message. This operate does three issues:
  1. Use base64decode to decode the error string.
  2. Use gzip to decompress the decoded error string.
  3. Convert the ensuing JSON to a Python dictionary and return it.
• Then we construct the slack message. Particulars on Slack message development can be found in Creating wealthy message layouts within the Slack API documentation.
  • We add every logEvent to an attachments listing. This ensures we get your entire log message.
  • Then, we construct the message with the primary textual content equal to the log group title, which identifies the Lambda that threw the error, and the listing of logEvents, which comprises the error log.
• Lastly, we create a request object with urllib’sRequest class and ship it to the SLACK_ENDPOINT with’s geturl methodology.

There’s one element right here that is essential. We create the set off on Notify Lambda, not the Lambda throwing the error. Because of this if that you must monitor a number of lambda capabilities, you add one set off for every to the Notify Lambda. Fortuitously, AWS doesn’t impose a restrict on the variety of triggers for a single Lambda operate.

Establishing the set off

1. Whereas nonetheless in our Notify Lambda, choose Add set off from the highest of the web page.

2. This can carry up the Set off configuration dialog.
• Choose CloudWatch Logs because the set off kind.
• Choose the Log group comparable to the Lambda’s logs you need to monitor. If you’re following alongside, this shall be /aws/lambda/MonitorMe.
• Title the filter. This may be something. Go wild.
• The filter sample will decide which logs set off the notification Lambda. Right here I’ll merely enter ERROR which is able to match any logs that comprise the textual content ERROR.

You will discover extra details about CloudWatch Filters on the Filter and sample syntax web page within the CloudWatch Documentation.

• Click on Add within the decrease proper of the dialog.

And we’re completed! 🌴

Let’s be sure that this all works as anticipated. We’ve two instances to check:

1. We should always not get a notification in Slack if the MonitorMe Lambda logs a message that’s not an error.
2. We should always get a helpful message if the MonitorMe Lambda does log an error.

Case 1: Profitable MonitorMe execution

To check this, we hit our API endpoint with the identical URL we used to check the endpoint initially:

https://{YOUR API BASE URL}/MonitorMe?x=2

And we confirm that no messages had been despatched to Slack:

Nothing occurred. Success!

Case 2: Unsuccessful MonitorMe execution

Let’s modify the API name to ship a string as a substitute of a quantity. This can trigger the Lambda to throw an error.

https://{YOUR API BASE URL}/MonitorMe?x=wompwomp

Glorious. An error. Let’s take a look at Slack.

Wonderful! Not solely did we get a notification in Slack, the notification got here full with the error traceback! We will see that it was line 7 of lambda_function.pyand that the error comes from making an attempt to forged wompwomp to drift.

There are different methods to seize and ship errors to Slack from any AWS service. I listed some articles at the start of this publish, however whenever you anticipate a low quantity of errors, this strategy is superior as a result of it’s extra easy and provides you your entire error message proper in Slack.

At Komaza, we use this strategy to observe pipelines in proof-of-concept tasks, knowledge high quality checks, and a few Lambda capabilities manually triggered by considered one of our inner net functions. We have caught errors like database schema adjustments, expired tokens, and varied different points instantly and had been in a position to deploy fixes in beneath 24 hours in all instances. This comparatively easy strategy to Lambda monitoring has improved our stakeholder expertise by guaranteeing greater high quality knowledge and serving to us reply sooner to system failures.

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Now go do some good.