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Whaler is a Go program which is designed to reverse engineer docker images into the Dockerfile that created it. It currently performs the following actions

  • Generates a Dockerfile from an Image
  • Searches added filenames for potential secret files
  • Extracts files that were added by the Docker ADD/COPY Instructions
  • It also displays misc. information such as ports open, the user it runs as and environment variables.

How to run it

The easiest way is to run the tool in docker container:

docker pull pegleg/whaler
docker run -t --rm -v /var/run/docker.sock:/var/run/docker.sock:ro pegleg/whaler -sV=1.36 nginx:latest
docker build --rm -t pegleg/whaler .
alias whaler="docker run -t --rm -v /var/run/docker.sock:/var/run/docker.sock:ro pegleg/whaler"
whaler -sV=1.36 nginx:latest

This tool will pull target docker image automatically. Parameter -sV=1.36 is not always required.

How to build it

Git clone the project into your $GOPATH/src directory and perform the following command

go get -u
cd $GOPATH/src/
go build .

How to run it

Usage of ./Whaler:
  -f string
    	File containing images to analyze seperated by line
    	Filters filenames that create noise such as node_modules. Check ignore.go file for more details (default true)
  -sV string
    	Set the docker client ID to a specific version -sV=1.36
  -v	Print all details about the image
  -x	Save layers to current directory