moreload/docs/docker-swarm-usage.md

Docker Swarm Usage

Healthcheck

The Docker Image includes a Healthcheck with the following options:

--interval=30s

Specifies the time interval at which the health check should be performed. In this case, the health check will be performed every 30 seconds.

--timeout=10s

Specifies the amount of time to wait for a response from the health check command. If the response does not arrive within 10 seconds, the health check will be considered a failure.

--start-period=5s

Specifies the amount of time to wait before starting the health check process. In this case, the health check process will begin 5 seconds after the container is started.

--retries=3

Specifies the number of times Docker should retry the health check before considering the container to be unhealthy.

The CMD instruction is used to define the command that will be run as part of the health check. In this case, the command is wget --quiet --tries=1 --spider http://localhost:3000/ || exit 1. This command will attempt to connect to http://localhost:3000/ and if it fails it will exit with a status code of 1. If this command returns a status code other than 0, the health check will be considered a failure.

Overall, this HEALTHCHECK instruction is defining a health check process that will run every 30 seconds, wait up to 10 seconds for a response, begin 5 seconds after the container is started, and retry up to 3 times. The health check will consist of attempting to connect to http://localhost:3000/ and will consider the container to be unhealthy if it is unable to connect.