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CI Modules 0.53.1Last updated in version 0.50.11

Check Url

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This folder contains a script called check-url. This script can be used to repeatedly test a URL until either it returns an expected response, and the script exits successfully, or the max number of retries is exceeded, and the script exits with an error.

Installing the script in your code

You can install these scripts using the Gruntwork Installer:

gruntwork-install --module-name "check-url" --repo "https://github.com/gruntwork-io/terraform-aws-ci" --tag "v0.3.6"

Example usage

One place this script is useful is as part of a CI job that automatically deploys a Docker container using Amazon's EC2 Container Service. When you deploy a service with ECS (e.g. by running Terraform or making an API call to AWS), the ECS scheduler will always return a "success" response. However, it's possible the scheduler won't actually be able to deploy your Docker container, either because there is no room left for it in your ECS cluster or because there is a bug in the container itself that prevents it from booting correctly. Unfortunately, there is no way for your CI job to know about that, so it'll exit successfully, even though the deployment actually failed.

The check-url script can help you verify your container actually deployed successfully, assuming that container exposes an endpoint this script can test. For example, imagine you added a /version endpoint to your Docker container that returns the currently running version:

> curl http://www.my-company.com/version

version = 1.0.0

After telling ECS to deploy version 2.0.0 of your container, you can use the check-url to repeatedly test the /version URL until it returns 2.0.0, which means your new container deployed successfully, or the maximum retries are exceeded (default is to keep retrying for 5 minutes), which means the container failed to deploy:

> check-url --url http://www.my-company.com/version --expected-body 2.0.0

Making a request to URL http://www.my-company.com/version
Response code: 200
Response body:
version = 1.0.0
Body did not contain expected text '1.0.0'
Sleeping for 10 seconds before trying again.

Making a request to URL http://www.my-company.com/version
Response code: 200
Response body:
version = 1.0.0
Body did not contain expected text '1.0.0'
Sleeping for 10 seconds before trying again.

Making a request to URL http://www.my-company.com/version
Response code: 200
Response body:
version = 2.0.0
Success! Got expected status code '200' and text '2.0.0' from URL http://www.my-company.com/version.