docker-health-go

docker-health-go (htcheck)

Special-purpose HTTP client for light-weight health check for use in docker

Why this program? When using docker directly or via docker-compose, you can and should define a health check, so that docker knows that the process it is running is doing well. There are a couple of libraries to provide a HTTP health endpoints for Go, such as [https://github.com/docker/go-healthcheck] and also Java offers with Spring Boot Actuator corresponding frameworks.

But on the client side, you still need to use curl or the outdated wget to perform the check. If you ever checked, which dependencies curl and thus libcurl4 brings with it, you might wonder if this is worth the balast just to do a simple HTTP get with an exit code. Libcurl brings openldap libraries into the image and what not. So this little decent project provides a special-purpose HTTP client to use for health checks in docker or elsewhere instead of throwing a general-purpose HTTP client at the job.

Build

Set GOPATH Get depenencies:

# go get github.com/spf13/pflag
# go get github.com/savaki/jq
# go get github.com/jarcoal/httpmock

Build binary and test:

# go build -o htcheck
# go test

when you would like to get rid of a bit fat from the statically linked binary, use the flags

go build -o htcheck -ldflags="-s -w"

Usage

Simple sample usage in a Dockerfile:

COPY ./htcheck /usr/bin/

HEALTHCHECK --interval=5m --timeout=3s CMD htcheck -u http://localhost/ || exit 1

Sample usage for Spring Boot actuator health endpoint:

COPY ./htcheck /usr/bin/

HEALTHCHECK --interval=5m --timeout=3s CMD htcheck -u http://localhost/health -p .status -v UP || exit 1

Internals

Dependencies used by the project:

• pflag: posix-compatible command line flags (https://github.com/spf13/pflag) - BSD 3-clause license
• jq: jq-style JSON path (https://github.com/savaki/jq) - Apache 2 license

Testing only:

• httpmock: HTTP server mocking test library (https://github.com/jarcoal/httpmock) - MIT license
• gotesttools: asserts for go (https://godoc.org/gotest.tools) - Apache 2 license

Copyright & License

Docker Health Go is Copyright (c) Peter Klotz. All Rights Reserved.

Permission to modify and redistribute is granted under the terms of the Apache 2.0 license. See the LICENSE file for the full license.