working docker image for extracting ubuntu iso kernel

docker/estenrye/ubuntu-pxe-image-mirror/Dockerfile

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+FROM debian:stable-slim
+RUN apt update \
+  && apt install -y \
+    p7zip-full \
+    rsync \
+  && apt clean \
+  && rm -rf /var/lib/apt/lists/*
+
+VOLUME /tftp
+COPY scripts /scripts
+
+ENTRYPOINT ["bash", "/scripts/ubuntu.sh"]

docker/estenrye/ubuntu-pxe-image-mirror/scripts/date-script.sh

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+#!/bin/sh
+echo "Current date and time is " "$(date +%D-%H:%M)"

docker/estenrye/ubuntu-pxe-image-mirror/scripts/extract.ubuntu.sh

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+#!/bin/bash
+
+fatal() {
+  echo "$1"
+  exit 1
+}
+
+warn() {
+  echo "$1"
+}
+
+LIVE_KERNEL_ROOT='/tftp/live/ubuntu/live-server-amd64'
+IMAGE_ROOT='/tftp/images/ubuntu'
+VERSION_PATTERN='[0-9][0-9]\.[0-9][0-9]$'
+ISO_PATTERN='live-server-amd64\.iso$'
+
+for ISOFILE in `ls ${IMAGE_ROOT} | grep ${VERSION_PATTERN} | xargs -I% find ${IMAGE_ROOT}/%/ -print | grep ${ISO_PATTERN}`
+do
+  VERSION=`basename $(dirname $ISOFILE)`
+
+  echo "Creating directory ${LIVE_KERNEL_ROOT}/${VERSION}"
+  mkdir -p "${LIVE_KERNEL_ROOT}/${VERSION}"
+  rm -f ${LIVE_KERNEL_ROOT}/${VERSION}/ubuntu-live-server-amd64.iso
+
+  echo "Linking ${ISOFILE} to ${LIVE_KERNEL_ROOT}/${VERSION}/ubuntu-live-server-amd64.iso"
+  ln -s ${ISOFILE} ${LIVE_KERNEL_ROOT}/${VERSION}/ubuntu-live-server-amd64.iso
+
+  echo "Copying ${ISO_MNT_ROOT}/${VERSION}/casper to directory ${LIVE_KERNEL_ROOT}/${VERSION}"
+  7z e -tiso -o/${LIVE_KERNEL_ROOT}/${VERSION} -i\!casper/initrd -i\!casper/vmlinuz ${ISOFILE}
+done

docker/estenrye/ubuntu-pxe-image-mirror/scripts/rsync.ubuntu.sh

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+#!/bin/bash
+
+fatal() {
+  echo "$1"
+  exit 1
+}
+
+warn() {
+  echo "$1"
+}
+
+# Find a source mirror near you which supports rsync on
+# https://launchpad.net/ubuntu/+cdmirrors
+# rsync://<iso-country-code>.rsync.releases.ubuntu.com/releases should always work
+RSYNCSOURCE=rsync://mirror.math.princeton.edu/pub/ubuntu-iso/
+
+# Define where you want the mirror-data to be on your mirror
+BASEDIR=/tftp/images/ubuntu/
+
+if [ ! -d ${BASEDIR} ]; then
+  warn "${BASEDIR} does not exist yet, trying to create it..."
+  mkdir -p ${BASEDIR} || fatal "Creation of ${BASEDIR} failed."
+  mkdir -p ${BASEDIR}/.trace || fatal "Creation of ${BASEDIR}/.trace failed."
+fi
+
+rsync --verbose --recursive --times --links --safe-links --hard-links \
+  --stats --delete-after \
+  ${RSYNCSOURCE} ${BASEDIR} || fatal "Failed to rsync from ${RSYNCSOURCE}."
+
+date -u > ${BASEDIR}/.trace/$(hostname -f)

docker/estenrye/ubuntu-pxe-image-mirror/scripts/ubuntu.sh

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+#!/bin/bash
+
+fatal() {
+  echo "$1"
+  exit 1
+}
+
+warn() {
+  echo "$1"
+}
+
+SCRIPT_DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" >/dev/null 2>&1 && pwd )"
+
+${SCRIPT_DIR}/date-script.sh || fatal "Failed to run date-script.sh."
+${SCRIPT_DIR}/rsync.ubuntu.sh || fatal "Failed to rsync from ${RSYNCSOURCE}."
+${SCRIPT_DIR}/extract.ubuntu.sh || fatal "Failed to extract from ${RSYNCSOURCE}."