concourse-resource

a Go module to simplify the development of concourse resources

Features

minimal dependencies

Only github.com/stretchr/testify and github.com/go-playground/validator/v10 are directly required by this module.

config validation

To validate your input, simply add the correct validator tags

flexible

Use whatever library you want, do what ever you want. This module takes only care about the communication with concourse. No assumptions beyond that are made.

testable

Test your resources with go test. A full set of testing helpers and a testify suite are provided.

Usage

To develop a new resource, you must provide a type, that fulfills at least one of the following interfaces:

• types.CheckResource
• types.InResource
• types.OutResource

If your resource takes parameters for in or out, the type must implement the types.ParametrizedResource interface.

In addition, a factory function must be provided.

While all arguments to check, in and out are provided by the resource at runtime, the configuration (source) must be provided statically.

All communication with concourse is done by the Handler. For an example of a resource, have a look at the test/dummy implementation.

Inside your main, put all the stuff together and call the Run method.

package main

import (
	"log"

	resource "pkg.loki.codes/concourse-resource"

	"your/resource/implementation"
)

func main() {
	if err := resource.New[implementation.Config](implementation.New).Run(); err != nil {
		log.Fatal(err)
	}
}

Environment variables (metadata)

The Concourse metadata can be accessed with the help of some wrappers.

See metadata

Container build

To build your container image, you may just symlink the binary to the correct locations. For example:

FROM golang:alpine AS builder

RUN apk update && apk add --no-cache git ca-certificates && update-ca-certificates

ADD . /app/
WORKDIR /app
RUN CGO_ENABLED=0 go build -ldflags="-w -s" -o resource .
RUN mkdir -p /target/opt/resource/
RUN cp resource /target/opt/resource/
RUN ln -s resource /target/opt/resource/in
RUN ln -s resource /target/opt/resource/out
RUN ln -s resource /target/opt/resource/check


FROM scratch
COPY --from=builder /etc/ssl/certs/ca-certificates.crt /etc/ssl/certs/
COPY --from=builder /target/opt /opt

See also

• Concourse Documentation

Testing

There is an extensive test framework. See test