chezmoi/bin/executable_docker-traverse.sh

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#!/bin/bash
set -euo pipefail
# Parse command line arguments
while [[ $# -gt 0 ]]; do
key="$1"
case "$key" in
--image)
IMAGE_NAME="$2"
shift
shift
;;
*)
echo "Error: Unknown option: $key"
echo "Usage: $0 --image IMAGE_NAME"
exit 1
;;
esac
done
# Define the path to the temporary directory where the files will be extracted
DESTINATION="/tmp/docker_images/${IMAGE_NAME}"
MANIFEST="${DESTINATION}/manifest.json"
# Define a function to download and extract the Docker image layers
function extract_docker_image {
# Pull image to make sure we have it before we save it.
docker pull "$IMAGE_NAME"
# Save the Docker image as a tar file
echo "Saving Docker image as a tar file..." >&2
docker save "$1" -o "${DESTINATION}/${IMAGE_NAME}.tar"
# Extract the Docker image layers to the destination directory
echo "Extracting Docker image layers..." >&2
mkdir -p "${DESTINATION}/layers"
tar -xf "${DESTINATION}/${IMAGE_NAME}.tar" -C "${DESTINATION}/"
# Rename the layer directories to their respective layer IDs
LAYERS=$(jq -r '.[0].Layers[]' "${MANIFEST}")
# Extract each layer
for LAYER in ${LAYERS}; do
BLOB="${LAYER}"
# Extract the layer tar file to the destination directory
echo "Extracting layer ${LAYER}..." >&2
mkdir -p "${DESTINATION}/$(dirname ${BLOB})"
tar -xf "${DESTINATION}/${BLOB}" -C "${DESTINATION}/layers"
echo "Layer ${LAYER} extracted" >&2
done
}
# Ensure that the user has provided the Docker image name using the --image flag
if [ -z "$IMAGE_NAME" ]; then
echo "Error: Docker image name not provided." >&2
echo "Usage: $0 --image IMAGE_NAME" >&2
exit 1
fi
# Create the destination directory if it doesn't already exist
rm -rf "${DESTINATION}"
mkdir -p "${DESTINATION}"
# Call the function to download and extract the Docker image layers
extract_docker_image "$IMAGE_NAME"