Mounton - Chroot Script for Chromebooks

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#1 Fri, 2015-01-09 05:35

jrcowart

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Last seen: 3 years 2 months ago
Joined: 2015-01-09

Hey everybody! I've been impressed with how lightweight this linux distro is and I thought it would be perfect to use as developer environment under ChromeOS. Creating a chroot wasn't to terribly difficult to do, however, I've made a script intended to facilitate the process for other users. The script can be found on my github account at https://github.com/jrcowart/Mounton. It is incredibly bare bones at the moment, having no fail safes of any kind, but it is still a work in progress. I hope to eventually add some fail safes (checking directory existence, handling of download failure, etc.) and some of the nice features that crouton has (such as backups and install from a backup, multiple chroots, etc.).

Disclaimer: This script is still in testing, so I do not expect it to run flawlessly for everybody. However, feedback would be very helpful for getting this script polished into a safe and user friendly tool. Please look over the script before running and if you find any issues or have suggestions for the code, let me know!

The script:

#!/bin/bash
CHROOT_DIR=/usr/local/chroots/alpine
MIRROR=http://nl.alpinelinux.org/alpine
TEMP=/usr/local/chroots/tmp
 
#making a temporary directory to keep files which can be safely deleted after completion
mkdir $TEMP
 
#setting up chroot directory
mkdir $CHROOT_DIR
 
#change to $TEMP directory
cd $TEMP
 
#get list of packages from $MIRROR
curl "$MIRROR/edge/main/x86_64/" -o packages.tmp
 
#get name of current apk-tools-static and download
CURRENT_APK=$(grep -o "apk-tools-static-[[:alnum:]/._-]*" packages.tmp | head -1)
wget $MIRROR/edge/main/x86_64/$CURRENT_APK
 
#extract apk
tar -xzf $CURRENT_APK
 
#install base system
./sbin/apk.static -X $MIRROR/edge/main/ -U --allow-untrusted --root $CHROOT_DIR --initdb add alpine-base
 
#mounting system proc,sys,dev in chroot
mount -t proc none $CHROOT_DIR/proc
mount -o bind /sys $CHROOT_DIR/sys
mount -o bind /dev $CHROOT_DIR/dev
 
#update apk repository list
echo "$MIRROR/edge/main" > $CHROOT_DIR/etc/apk/repositories
 
#copying system resolv.conf to alpine chroot for internet access
cp /etc/resolv.conf $CHROOT_DIR/etc/resolv.conf
 
#remove $TEMP
cd /
rm -rf $TEMP
 
#creates easy way to enter chroot: type 'climb' at command line
cd /usr/local/bin/
 
echo "chroot /usr/local/chroots/alpine /bin/sh -l" > climb
chmod ugo+x climb
 
#creates easy way to 'nuke' the chroot: type 'avalanche' at command line
echo "#!/bin/bash
 
echo -n \"Running avalanche will delete your Alpine chroot. Are you sure you want to continue (type 'YES' in all capital letters to do so)\":
 
read CONTINUE
 
if [ \$CONTINUE == \"YES\" ]
then
    umount /usr/local/chroots/alpine/proc
    umount /usr/local/chroots/alpine/sys
    umount -l /usr/local/chroots/alpine/dev
    rm -rf /usr/local/chroots/alpine
    rm /usr/local/bin/climb
    rm /usr/local/bin/avalanche
    exit 1
else
    echo \"Canceling operation.\"
    exit 1
fi" > avalanche
 
chmod ugo+x avalanche
 
echo "\n\nYour Alpine Linux chroot is ready to use! Type 'climb' at the command line to start using or type 'avalanche' to delete the chroot and any related file."

Usage is pretty straight forward, do the following after downloading the script:

cd ~/Downloads
sudo sh -e mounton.sh

This will install an Alpine Linux (running on Edge) chroot under /usr/local/chroots/alpine, and two helper scripts (climb and avalanche) to /usr/local/bin.

The following will run the helper scripts:

sudo climb #easy way to enter the chroot
sudo avalanche #will delete chroot and helper scripts

Again, I'm more the open to any questions, comments, suggestions, and criticisms related to this script! I think that we can make this distribution an incredibly viable choice for Chromebook users, as many use their Chromebooks for development work on the go.

I hope you like it!

P.S.
A big thanks to the dev team of Alpine Linux for making such an awesome distribution!