Docker healthchecks using healthchecks.io

May 15 2021

I'm currently in the midst of improving the monitoring of my infrastructure. I make heavy use of docker and docker-compose for my hosting, so it's vital to add monitoring for most of the containers.

I'm hosting my own instance of healthchecks.io. Their solution to monitoring involves you having to ping them, instead of the other way around. This let's you add healthchecks to virtually anything that can ping a http-endpoint.

docker-compose let's you define healthchecks to your config that, when completing sucessfully, mark the container as "healthy". The process of adding such a healthcheck is simple. First, create a new check in your healthchecks.io account and set the ping interval to 1 minute, or a value you prefer. Then, add this snippet to your docker-compose file:

app:
    image: nextcloud
    ports:
        - 127.0.0.1:8080:80
    healthcheck:
        test:
            [
                "CMD",
                "curl",
                "-f",
                "https://app-endpoint.tld",
                "&&",
                "curl",
                "-fsS",
                "-m",
                "10",
                "--retry",
                "5",
                "-o",
                "/dev/null",
                "https://healthchecks.io/ping/<UUID>",
            ]
        interval: 60s
        timeout: 10s
        retries: 6

Change the first url to the url of your app. The second URL is the endpoint of your healthchecks.io instance. You can obtain it from the check you configured earlier.

This configuration will try to ping your application and, if successful, notify the healthcheck that the application is healthy. If the app is not reachable or the container is down, the latter request will not be executed and your service is marked as "down".

In addition to the healthchecks of my docker containers, I also added basic healthchecks to my servers cronfiles and its backup-commands.

Do you have any suggestions regarding this topic? Feel free to reach out to me via Matrix or email!

This is post 017 of #100DaysToOffload.


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