Docker + K8s Workshop - chroot example

Create a chroot jail

mkdir jail

Create directories for system binaries

mkdir jail/bin

Copy the bash binary from the host

cp -v /bin/bash jail/bin

Create a list of libraries needed for the binary to work

list_of_libs="$(ldd /bin/bash | egrep -o '/lib.*\.[0-9]')"
echo $list_of_libs

Copy the libraries recursively

for i in $list_of_libs; do cp  -v --parents "$i" `pwd`/jail; done

Create a demo script

let i=0;
while :
do
        let i++
        echo "Last value of i is ${i}"
        read -rep $'Pausing for 5 seconds\n' -t 5
done

Copy the demo script to the jail

chmod +x demos.sh
cp demo.sh jail/

Enter the chroot

sudo chroot `pwd`/jail /bin/bash

In the chroot, execute the shell script

/bin/bash -c ./demo.sh