This image is built from the tool called Whaler from https://github.com/P3GLEG/Whaler

Features

• support multi-platforms, such as linux/arm/v7,linux/arm64/v8,linux/arm/v6,linux/amd64,linux/ppc64le,linux/s390x

Github Repo

https://github.com/alpine-docker/dfimage

build logs

https://app.circleci.com/pipelines/github/alpine-docker/dfimage

Docker image tags

https://hub.docker.com/r/alpine/dfimage/tags/

Whaler

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 this image

It will pull the target docker image automaticlaly. Parameter -sV=1.36 is not always required.

$ alias dfimage="docker run -v /var/run/docker.sock:/var/run/docker.sock --rm alpine/dfimage"
$ dfimage -sV=1.36 nginx:latest

Analyzing nginx:latest
Docker Version: 18.09.7
GraphDriver: overlay2
Environment Variables
|PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
|NGINX_VERSION=1.19.0
|NJS_VERSION=0.4.1
|PKG_RELEASE=1~buster

Open Ports
|80

Image user
|User is root

Potential secrets:
Dockerfile:
CMD ["bash"]
LABEL maintainer=NGINX Docker Maintainers <docker-maint@nginx.com>
ENV NGINX_VERSION=1.19.0
ENV NJS_VERSION=0.4.1
ENV PKG_RELEASE=1~buster
RUN set -x  \
	&& addgroup --system --gid 101 nginx  \
	&& adduser --system --disabled-login --ingroup nginx --no-create-home --home /nonexistent --gecos "nginx user" --shell /bin/false --uid 101 nginx  \
	&& apt-get update  \
	&& apt-get install --no-install-recommends --no-install-suggests -y gnupg1 ca-certificates  \
	&& NGINX_GPGKEY=573BFD6B3D8FBC641079A6ABABF5BD827BD9BF62; found=''; for server in ha.pool.sks-keyservers.net hkp://keyserver.ubuntu.com:80 hkp://p80.pool.sks-keyservers.net:80 pgp.mit.edu ; do echo "Fetching GPG key $NGINX_GPGKEY from $server"; apt-key adv --keyserver "$server" --keyserver-options timeout=10 --recv-keys "$NGINX_GPGKEY"  \
	&& found=yes  \
	&& break; done; test -z "$found"  \
	&& echo >&2 "error: failed to fetch GPG key $NGINX_GPGKEY"  \
	&& exit 1; apt-get remove --purge --auto-remove -y gnupg1  \
	&& rm -rf /var/lib/apt/lists/*  \
	&& dpkgArch="$(dpkg --print-architecture)"  \
	&& nginxPackages=" nginx=${NGINX_VERSION}-${PKG_RELEASE} nginx-module-xslt=${NGINX_VERSION}-${PKG_RELEASE} nginx-module-geoip=${NGINX_VERSION}-${PKG_RELEASE} nginx-module-image-filter=${NGINX_VERSION}-${PKG_RELEASE} nginx-module-njs=${NGINX_VERSION}.${NJS_VERSION}-${PKG_RELEASE} "  \
	&& case "$dpkgArch" in amd64|i386) echo "deb https://nginx.org/packages/mainline/debian/ buster nginx" >> /etc/apt/sources.list.d/nginx.list  \
	&& apt-get update ;; *) echo "deb-src https://nginx.org/packages/mainline/debian/ buster nginx" >> /etc/apt/sources.list.d/nginx.list  \
	&& tempDir="$(mktemp -d)"  \
	&& chmod 777 "$tempDir"  \
	&& savedAptMark="$(apt-mark showmanual)"  \
	&& apt-get update  \
	&& apt-get build-dep -y $nginxPackages  \
	&& ( cd "$tempDir"  \
	&& DEB_BUILD_OPTIONS="nocheck parallel=$(nproc)" apt-get source --compile $nginxPackages )  \
	&& apt-mark showmanual | xargs apt-mark auto > /dev/null  \
	&& { [ -z "$savedAptMark" ] || apt-mark manual $savedAptMark; }  \
	&& ls -lAFh "$tempDir"  \
	&& ( cd "$tempDir"  \
	&& dpkg-scanpackages . > Packages )  \
	&& grep '^Package: ' "$tempDir/Packages"  \
	&& echo "deb [ trusted=yes ] file://$tempDir ./" > /etc/apt/sources.list.d/temp.list  \
	&& apt-get -o Acquire::GzipIndexes=false update ;; esac  \
	&& apt-get install --no-install-recommends --no-install-suggests -y $nginxPackages gettext-base curl  \
	&& apt-get remove --purge --auto-remove -y  \
	&& rm -rf /var/lib/apt/lists/* /etc/apt/sources.list.d/nginx.list  \
	&& if [ -n "$tempDir" ]; then apt-get purge -y --auto-remove  \
	&& rm -rf "$tempDir" /etc/apt/sources.list.d/temp.list; fi  \
	&& ln -sf /dev/stdout /var/log/nginx/access.log  \
	&& ln -sf /dev/stderr /var/log/nginx/error.log  \
	&& mkdir /docker-entrypoint.d
COPY file:d68fadb480cbc781c3424ce3e42e1b5be80133bdcce2569655e90411a4045da2 in /
	docker-entrypoint.sh

COPY file:b96f664d94ca7bbe69241468d85ee421e9d310ffa36f3b04c762dcce9a42c7f1 in /docker-entrypoint.d
	docker-entrypoint.d/
	docker-entrypoint.d/10-listen-on-ipv6-by-default.sh

COPY file:cc7d4f1d03426ebd11e960d6a487961e0540059dcfad14b33762f008eed03788 in /docker-entrypoint.d
	docker-entrypoint.d/
	docker-entrypoint.d/20-envsubst-on-templates.sh

ENTRYPOINT ["/docker-entrypoint.sh"]
EXPOSE 80
STOPSIGNAL SIGTERM
CMD ["nginx" "-g" "daemon off;"]