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refactoring 2021-05 #19

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refactoring 2021-05 #19

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236 changes: 123 additions & 113 deletions bin/strip-docker-image
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Original file line number Diff line number Diff line change
@@ -1,154 +1,164 @@
#!/bin/bash
#!/usr/bin/env bash

# NAME
# strip-docker-image - strips the bare essentials from an image and exports them
# strip-docker-image - strips the bare essentials from an image and exports them
#
# SYNOPSIS
# strip-docker-image -i image-name -t target-image-name -t [-p package | -f file] [-d Dockerfile] [-x expose-port] [-v]
# strip-docker-image -i image-name -t target-image-name -t [-p package | -f file] [-d Dockerfile] [-x expose-port] [-v] [-k]
#
#
# OPTIONS
# -i image-name to strip
# -t target-image-name the image name of the stripped image
# -p package package to include from image, multiple -p allowed.
# -f file file to include from image, multiple -f allowed.
# -x port to expose.
# -d Dockerfile to incorporate in the stripped image.
# -v verbose
# -i image-name - name of the image to strip
# -t target-image-name - name of the image after stripping
# -p package - package to include from image, multiple parameters allowed
# -f file - file to include from image, multiple parameters allowed
# -x port - port to expose
# -d Dockerfile - Dockerfile to incorporate in the stripped image
# -v - verbose output
# -k - keep stripped container files incl. Dockerfile (for manual editing)
#
# DESCRIPTION
# creates a new Docker image based on the scratch which contains
# only the the source image of selected packages and files.
# "strip-docker-image" creates a new Docker image based on the scratch which contains
# only the the source image of selected packages and files.
#
# EXAMPLE
# The following example strips the nginx installation from the default NGiNX docker image,
# The following example strips the nginx installation from the default NGiNX docker image,
#
# strip-docker-image -i nginx -t stripped-nginx \
# -v \
# -p nginx \
# -f /bin/cat \
# -f /bin/ls \
# -f /bin/mkdir \
# -f /bin/ps \
# -f /bin/sh \
# -f /etc/group \
# -f /etc/nsswitch.conf \
# -f /etc/passwd \
# -f /var/cache/nginx \
# -f /var/log/nginx \
# -f /var/run \
# -f '/lib/*/libnss*'
#
# strip-docker-image -i nginx -t stripped-nginx \
# -p nginx \
# -f /etc/passwd \
# -f /etc/group \
# -f '/lib/*/libnss*' \
# -f /bin/ls \
# -f /bin/cat \
# -f /bin/sh \
# -f /bin/mkdir \
# -f /bin/ps \
# -f /var/run \
# -f /var/log/nginx
# CAVEATS
# requires an image that has awk, bash, grep, ldd, readlink, sort & tar installed.
#
# AUTHOR
# Mark van Holsteijn
# Mark van Holsteijn
#
# COPYRIGHT
#
# Copyright 2015 Xebia Nederland B.V.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
# Copyright 2015 Xebia Nederland B.V.
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

function usage() {
echo "usage: $(basename $0) -i image-name -t stripped-image-name [-d Dockerfile] [-p package | -f file] [-v]" >&2
echo " $@" >&2
echo "usage: ${BASH_SOURCE[0]} -i image-name -t stripped-image-name [-d Dockerfile] [-p package | -f file] [-v] [-k]" >&2
echo " $@" >&2
}

function parse_commandline() {

while getopts "vi:t:p:f:x:d:" OPT; do
case "$OPT" in
v)
VERBOSE=-v
;;
p)
PACKAGES="$PACKAGES -p $OPTARG"
;;
f)
FILES="$FILES -f $OPTARG"
;;
i)
IMAGE_NAME="$OPTARG"
;;
t)
TARGET_IMAGE_NAME="$OPTARG"
;;
x)
EXPOSE_PORTS="$EXPOSE_PORTS $OPTARG"
;;
d)
DOCKERFILES="$DOCKERFILES \"$OPTARG\""
;;
*)
usage
exit 1
;;
esac
done
shift $((OPTIND-1))

if [ -z "$IMAGE_NAME" ] ; then
usage "image name is missing."
exit 1
fi

if [ -z "$TARGET_IMAGE_NAME" ] ; then
usage "target image name -t missing."
exit 1
fi

if [ -z "$PACKAGES" -a -z "$FILES" ] ; then
usage "Missing -p or -f options"
exit 1
fi
export PACKAGES FILES VERBOSE
while getopts "vki:t:p:f:x:d:" OPT; do
case "$OPT" in
v)
VERBOSE=-v
;;
k)
KEEP=1
;;
p)
PACKAGES+=(-p "$OPTARG")
;;
f)
FILES+=(-f "$OPTARG")
;;
i)
IMAGE_NAME="$OPTARG"
;;
t)
TARGET_IMAGE_NAME="$OPTARG"
;;
x)
EXPOSE_PORTS+=("$OPTARG")
;;
d)
DOCKERFILES+=("$OPTARG")
;;
*)
usage
exit 1
;;
esac
done
shift $((OPTIND-1))

if [ -z "$IMAGE_NAME" ]; then
usage "Image name -i is missing."
exit 1
fi

if [ -z "$TARGET_IMAGE_NAME" ]; then
usage "Target image name -t missing."
exit 1
fi

if ! (( "${#PACKAGES[@]}" + "${#FILES[@]}" )); then
usage "Missing options -p or -f"
exit 1
fi
}

parse_commandline "$@"

DIR=strip-docker-image-$$
mkdir -p $DIR/export
SCRIPT_DIR=$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )
mkdir -p "$DIR"/export
SCRIPT_DIR="$PWD"

docker run -v $PWD/$DIR/export:/export \
-v $SCRIPT_DIR:/mybin \
--entrypoint="/bin/bash" \
$IMAGE_NAME \
/mybin/strip-docker-image-export -d /export $VERBOSE $PACKAGES $FILES
docker run --rm -v "$PWD"/"$DIR"/export:/export \
-v "$SCRIPT_DIR":/mybin \
--entrypoint="/bin/bash" \
"$IMAGE_NAME" \
/mybin/strip-docker-image-export -d /export \
"$VERBOSE" "${PACKAGES[@]}" "${FILES[@]}"

cat > $DIR/Dockerfile <<!
cat << EOF > "$DIR"/Dockerfile
FROM scratch
ADD export /
!
EOF

for DOCKERFILE in $DOCKERFILES ; do
sed ':x; /\\$/ { N; s/\\\n//; tx }' "$(eval echo $DOCKERFILE)" \
| grep -v '^\(FROM\|RUN\|ADD\|COPY\)' \
>> $DIR/Dockerfile
for DOCKERFILE in "${DOCKERFILES[@]}"; do
sed ':x; /\\$/ { N; s/\\\n//; tx }' "$DOCKERFILE" \
| grep -v '^\(FROM\|RUN\|ADD\|COPY\)' \
>> "$DIR"/Dockerfile
done

for PORT in $EXPOSE_PORTS ; do
echo EXPOSE $PORT >> $DIR/Dockerfile
for PORT in "${EXPOSE_PORTS[@]}"; do
echo "EXPOSE ${PORT#" "}" >> "$DIR"/Dockerfile
done

EXPOSE=$(docker inspect -f '{{range $key, $value := .Config.ExposedPorts}}{{$key}} {{end}}' $IMAGE_NAME | sed -e 's/\/[a-z]* / /g')
ENTRYPOINT=$(docker inspect --format='{{if .Config.Entrypoint}}ENTRYPOINT {{json .Config.Entrypoint}}{{end}}' $IMAGE_NAME)
CMD=$(docker inspect --format='{{if .Config.Cmd}}CMD {{json .Config.Cmd}}{{end}}' $IMAGE_NAME)
EXPOSE=$(docker inspect --format='{{range $key, $value := .Config.ExposedPorts}}{{$key}} {{end}}' "$IMAGE_NAME" | sed -e 's/\/[a-z]* / /g')
ENTRYPOINT=$(docker inspect --format='{{if .Config.Entrypoint}}ENTRYPOINT {{json .Config.Entrypoint}}{{end}}' "$IMAGE_NAME")
CMD=$(docker inspect --format='{{if .Config.Cmd}}CMD {{json .Config.Cmd}}{{end}}' "$IMAGE_NAME")

[ -z "$EXPOSE" ] || echo "EXPOSE $EXPOSE" >> $DIR/Dockerfile
[ -z "$ENTRYPOINT" ] || echo $ENTRYPOINT >> $DIR/Dockerfile
[ -z "$CMD" ] || echo $CMD >> $DIR/Dockerfile
[ -z "$EXPOSE" ] || echo "EXPOSE $EXPOSE" >> "$DIR"/Dockerfile
[ -z "$ENTRYPOINT" ] || echo "$ENTRYPOINT" >> "$DIR"/Dockerfile
[ -z "$CMD" ] || echo "$CMD" >> "$DIR"/Dockerfile

(
cd $DIR
docker build --no-cache -t $TARGET_IMAGE_NAME .
)
pushd "$DIR" &>/dev/null && {
docker build --no-cache -t "$TARGET_IMAGE_NAME" .
popd &>/dev/null
}

rm -rf $DIR
if [ -z "$KEEP" ]; then
rm -rf "$DIR"
fi
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