Writing a custom health check

Another critical feature needed when we take our application to production is monitoring it. In the olden days, people would set up a CRON job to ping a server and see if it was up. More intricate systems would track disk usage, memory usage, and ideally page someone when the database was at 95%, so it could be saved before falling over.

Spring Boot provides a new era in health check monitoring. To kick things off, launch the application and visit /application/health:

    {
        status: "UP",
        diskSpace: {
            status: "UP",
            total: 498937626624,
            free: 96519303168,
            threshold: 10485760
        },
        mongo: {
            status: "UP",
            version: "3.4.6"
        }
    }  

Out of the box, this provides us with an endpoint we can ping and additionally...