Setup API canary

  1. In the AWS Management Console on the Services menu, click CloudWatch.
  2. On the left navigation menu under the Synthetics section, click Canaries.
  3. Click the create canary button.

New canary

Create an API Workflow canary

We are going to create a new canary that will test the PetSearch API responses.

  1. In a separate tab, navigate to Cloud9 in the AWS console.
  2. Click Open IDE on the observabilityworkshop Cloud9 instance.
  3. Open the file called syn-apicanary.js located at one-observability-demo/PetAdoptions/cdk/pet_stack/resources/syn-apicanary.js.
  4. Execute the following command in the terminal and copy the url that it returns:
aws ssm get-parameter --name '/petstore/searchapiurl'  | jq -r .Parameter.Value
  1. Take a look at the code below in the syn-apicanary.js file.
    const pettypes = ["fish", "bunny", "puppy", "kitten"];
    const position = Math.floor(Math.random() ` Math.floor(4));
    const requestOptions = {
        hostname: '<ALB_HOST_NAME>',
        // Example: hostname: '',
        port: 80,
        path: '/api/search?pettype='+pettypes[position],
        method: 'GET'

The PetAdoptions application does not support the PetType fish, however this code above randomly picks array entries from the pettypes array. There are good chances for it to pick fish once in a while.

  1. Replace the string <ALB_HOST_NAME> with the hostname from the PetSearch API URL that you copied in step 9 and save the file.

  2. Right click on the file, and select Download.

  3. Take a look at the code below which is also part of syn-apicanary.js.

        req.on('response', (res) => {
`Status Code: ${res.statusCode}`)
`Response Headers: ${JSON.stringify(res.headers)}`)
          if (res.statusCode !== 200) {
             reject("Failed: " + requestOption.path);
          res.on('data', (d) => {
  "Response: " + d.length);
            if(d.length <= 2)
                reject("PetType Invalid - : "+requestOption.path );
          res.on('end', () => {

In this code, you see that the response length is checked, and if the response length is short (<=2) we call the reject() function which indicates canary executing failure.

  1. Navigate back to the CloudWatch tab where you were creating your canary.
  2. Select Inline Editor.
  3. Name your canary ui-canary.
  4. In the Script editor section, select Upload Script.
  5. Click on Browse files, then navigate to and select the syn-canary.js file from your downloads folder.
  6. Type in exports.handler in the Script entry point textbox under Lambda handler

You can also optionally create an alarm based on the metrics created by Synthetics as shown below.

New canary2

Under VPC settings, you can also select the VPC under which you want the canary to be placed on. This is vital if you are testing a non-public facing endpoint. In our case the API endpoint is public facing, so you can leave it as it is.

  1. Click Create canary.

This will create the canary and start execution. You should be able to see the canary status on the canary home page as shown below.

New canary2

  1. Click on the name of the canary that you just created (it should be ui-canary).

You should see a screen with execution details for the past executions. The failure runs as in red dots for easier identification. You can select any one of them and go to Logs tab to see the execution logs.

Since this is an API testing canary which does not have UI, there were no screenshots captured.

  1. Navigate around the Metrics and Configuration tabs to see more details about the canary run.

New canary2

This concludes the Synthetics module.