Makes Docker image self-buildable

[EnigmaCurry]

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name: Pull request about: Pull request for this project title: "Makes Docker image self-buildable" labels: "" assignees: ""

Issue/Feature

I do not want to build s3-proxy on my host computer, but only as a docker image. This addition creates a multi-stage Dockerfile to build the s3-proxy binary and make an image in one step.

Additional Information

This does not require you to prebuild the s3-proxy binary. To build a Docker image from scratch, just run:

docker build -t s3-proxy .

Verification Steps

Checklist:

• [ ] Verified by team member
• [ ] Tests were added
• [ ] Comments where necessary
• [ ] Documentation changes if necessary