Docker Health Check Server

A simple utility that can be configured to perform basic health checks for Docker containers. It runs a very simplified web interface on port 80 and responds with a HTTP code based on the health of the configured health checks.

This is intended to be a small, fast health check server. As such, the dependency requirements must be kept to a minimum for this core software. If additional dependencies are required, especially for heath check logic, those should be kept in separate projects.

Requirements

• Maven 3.6 or later
• Java 8

Supported Health Checks

Any custom health check can be used, as long as it is a subclass of AbstractCheck. Below is a list of built-in health checks.

• TCP Check
  • Performs a simple TCP connection to a specified host and port. If the connection is successful then the health check passes

Building

This project is built using Maven. Below is an example of how to build this repository

$ git clone https://github.com/willchapman/docker-health-check.git
$ cd docker-health-check
$ mvn package

The resulting docker-health-check*.jar file can be executed using the java -jar <jarfile> command.

Configuration

The server loads a properties file on start up that will read the configured health checks. If all of them pass, then the health check will respond with a HTTP 200 code with a simple text string of how many checks passed. The format is simple the class name of the check as the key, and a configuration String the check will parse to perform its task. Below is an example of checking a TCP connection to google.com

com.raxware.healthCheck.checks.SimpleTCPHealthCheck=google.com:443

It will default to the config/checks.properties file but can be overridden by setting the HEALTH_CHECK_CONFIG environment variable.

Roadmap

Future improvements will be added as time allows.

• Configuration of web service ports
• Customize text output of web service response
  • A summary report of each health check as an option
• Additional generic health checks
• Improve customization of logging
• Add unit testing

Contributing

If you would like to submit any improvements to this code base, please fork the code and submit a pull request. I will review and patch as time permits.

License

The MIT License (MIT)

Copyright (c) 2022 Will Chapman

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.