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@lirazsiri @jeroenpeters1986 @OnGle
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Playing in the sandbox

The root.sandbox environment can be used to accelerate development with quick and dirty manual prototyping of changes to the root filesystem.

This makes it easier to test changes without having to edit source code and then rebuild from scratch.

fab-chroot will help you switch to the sandbox environment by executing::
root@tkldev products/core# fab-chroot build/root.sandbox/

root.sandbox is implemented as a copy-on-write filesystem that branches off from root.patched. If you dirty the sandbox by making changes inside it, then your changes get saved to a separate overlay in product.iso.

Note that before we start playing in the sandbox the overlay does not exist:

root@tkldev products/core# ls -la build/cdroot/casper/*sandbox*
ls: cannot access build/cdroot/casper/*sandbox*: No such file or directory

Now let's make a small "hello world" change inside the sandbox:

root@tkldev products/core# fab-chroot build/root.sandbox/
root@tkldev /# hello
bash: hello: command not found

root@tkldev /# apt-get install hello
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following NEW packages will be installed:
  hello
0 upgraded, 1 newly installed, 0 to remove and 0 not upgraded.
Need to get 0 B/68.7 kB of archives.
After this operation, 566 kB of additional disk space will be used.
debconf: delaying package configuration, since apt-utils is not installed
Selecting previously unselected package hello.
(Reading database ... 22578 files and directories currently installed.)
Unpacking hello (from .../archives/hello_2.8-2_amd64.deb) ...
Processing triggers for man-db ...
Setting up hello (2.8-2) ...

root@tkldev /# hello
Hello, world!

root@tkldev /# echo hello > /root/.bashrc.d/hello
root@tkldev /# chmod +x /root/.bashrc.d/hello
root@tkldev /# exit
exit

The result of this small change is that root shells will now say hello:

root@tkldev products/core# fab-chroot build/root.sandbox/
Hello, world!
root@tkldev /# exit
exit
root@tkldev products/core#

Usually building a new ISO from scratch would take about 5 minutes.

But repacking a new ISO for testing only takes about 5 seconds because we don't need to rebuild everything from scratch, just save the changes made to the copy-on-write sandbox:

root@tkldev products/core# time make
cp build/root.sandbox/usr/lib/syslinux/isolinux.bin build/cdroot/isolinux
cp build/root.sandbox/boot/vmlinuz-3.2.0-4-amd64 build/cdroot/casper/vmlinuz
cp build/root.sandbox/boot/initrd.img-3.2.0-4-amd64 build/cdroot/casper/initrd.gz
rm -f build/cdroot/casper/20sandbox.squashfs
mksquashfs $(deck --get-level=last build/root.sandbox) build/cdroot/casper/20sandbox.squashfs
Parallel mksquashfs: Using 1 processor
Creating 4.0 filesystem on build/cdroot/casper/20sandbox.squashfs, block size 131072.
[===========================================================================================|] 5/5 100%
Exportable Squashfs 4.0 filesystem, gzip compressed, data block size 131072
    compressed data, compressed metadata, compressed fragments, compressed xattrs
    duplicates are removed
Filesystem size 0.85 Kbytes (0.00 Mbytes)
    45.09% of uncompressed filesystem size (1.89 Kbytes)
Inode table size 232 bytes (0.23 Kbytes)
    38.03% of uncompressed inode table size (610 bytes)
Directory table size 249 bytes (0.24 Kbytes)
    66.05% of uncompressed directory table size (377 bytes)
Number of duplicate files found 4
Number of inodes 19
Number of files 8
Number of fragments 1
Number of symbolic links  0
Number of device nodes 0
Number of fifo nodes 0
Number of socket nodes 0
Number of directories 11
Number of ids (unique uids + gids) 1
Number of uids 1
    root (0)
Number of gids 1
    root (0)
genisoimage -o build/product.iso -r -J -l -V core -b isolinux/isolinux.bin -c isolinux/boot.cat -no-emul-boot -boot-load-size 4 -boot-info-table build/cdroot/
Size of boot image is 4 sectors -> No emulation
  6.68% done, estimate finish Fri Jul 11 16:27:37 2014
 13.34% done, estimate finish Fri Jul 11 16:27:37 2014
 20.01% done, estimate finish Fri Jul 11 16:27:37 2014
 26.67% done, estimate finish Fri Jul 11 16:27:37 2014
 33.35% done, estimate finish Fri Jul 11 16:27:37 2014
 40.01% done, estimate finish Fri Jul 11 16:27:37 2014
 46.68% done, estimate finish Fri Jul 11 16:27:37 2014
 53.34% done, estimate finish Fri Jul 11 16:27:37 2014
 60.02% done, estimate finish Fri Jul 11 16:27:37 2014
 66.68% done, estimate finish Fri Jul 11 16:27:37 2014
 73.35% done, estimate finish Fri Jul 11 16:27:38 2014
 80.01% done, estimate finish Fri Jul 11 16:27:38 2014
 86.69% done, estimate finish Fri Jul 11 16:27:39 2014
 93.36% done, estimate finish Fri Jul 11 16:27:39 2014
Total translation table size: 2048
Total rockridge attributes bytes: 1902
Total directory bytes: 4096
Path table size(bytes): 40
Max brk space used 0
74991 extents written (146 MB)

real        0m4.980s
user        0m1.496s
sys 0m0.716s

How the sandbox works: a peak under the hood

Now that we've "dirtied" the sandbox and rebuilt the product.iso, the overlay does exist:

root@tkldev products/core# ls -la build/cdroot/casper/*sandbox*
-rw-r--r-- 1 root root 3297280 Jul 13 11:09 build/cdroot/casper/20sandbox.squashfs

Let's unpack it to look inside:

root@tkldev products/core# unsquashfs -dest sandbox-squashfs build/cdroot/casper/20sandbox.squashfs
Parallel unsquashfs: Using 2 processors
2224 inodes (188 blocks) to write

[=======================================================================================|] 188/188 100%
created 82 files
created 332 directories
created 0 symlinks
created 0 devices
created 0 fifos

The sandbox overlay is only 10MB because copy-on-write only saves filesystem changes (relative to root.patched):

root@tkldev products/core# du -s sandbox-squashfs/
10556       sandbox-squashfs/

root@tkldev products/core# ls -l sandbox-squashfs/root/.bashrc.d/ sandbox-squashfs/usr/bin/
sandbox-squashfs/root/.bashrc.d/:
total 4
-rwxr-xr-x 1 root root    6 Jul 13 11:00 hello

sandbox-squashfs/usr/bin/:
total 32
-rwxr-xr-x 1 root root 31232 Jun  7  2012 hello

Hacking Core by example: Hello world!

We'll now throw away our sandbox and re-implement "hello world" in source code.

First, we throw away the sandbox:

deck -D build/root.sandbox

Note that before we implement this, we don't get a hello world when we chroot into root.patched:

root@tkldev products/core# fab-chroot build/root.patched/
root@tkldev /#  exit

Implement hello world change:

root@tkldev products/core# echo hello >> plan/main
root@tkldev products/core# cat plan/main
#include <turnkey/base>
hello
root@tkldev products/core# mkdir -p overlay/root/.bashrc.d
root@tkldev products/core# echo hello > overlay/root/.bashrc.d/hello
root@tkldev products/core# chmod +x overlay/root/.bashrc.d/hello

Rebuild:

root@tkldev products/core# make clean
root@tkldev products/core# make

Now we do get "hello world":

root@tkldev products/core# fab-chroot build/root.patched/
Hello, world!
root@tkldev /# exit

Hacking root.patched without rebuilding from scratch

Note that changing the package installation plan like we did above (I.e., by adding hello) requires us to "make clean" first.

That can take a few minutes because we need to reinstall all the packages into the root.build target.

However, we can save time and skip this step if we don't need to change the package plan. This is the case if we're only making changes to scripts in conf.d/ or files in overlay/

For example, let's say we want the root shell to print "hello universe" instead of "hello world".

So we'll edit the root bashrc.d configuration:

root@tkldev products/core# cat overlay/root/.bashrc.d/hello
hello
root@tkldev products/core# echo echo hello universe > overlay/root/.bashrc.d/hello

And we'll rebuild root.patched:

root@tkldev products/core# make root.patched
make: Nothing to be done for `root.patched'.

Woops. That didn't work because we forgot to tell "make" it needed to rebuild the already existing root.patched target.

We do that by removing the root.patched "build stamp":

root@tkldev products/core# rm build/stamps/root.patched

It only takes 12 seconds to rebuild root.patched:

root@tkldev products/core# time make root.patched
deck -D build/root.patched
deck build/root.build build/root.patched
# apply the common overlays
fab-apply-overlay /turnkey/fab/common/overlays/turnkey.d/apt build/root.patched
fab-apply-overlay /turnkey/fab/common/overlays/turnkey.d/autologin build/root.patched
fab-apply-overlay /turnkey/fab/common/overlays/turnkey.d/bashrc build/root.patched
fab-apply-overlay /turnkey/fab/common/overlays/turnkey.d/etckeeper build/root.patched
fab-apply-overlay /turnkey/fab/common/overlays/turnkey.d/grub build/root.patched
fab-apply-overlay /turnkey/fab/common/overlays/turnkey.d/interfaces build/root.patched
fab-apply-overlay /turnkey/fab/common/overlays/turnkey.d/ntp build/root.patched
fab-apply-overlay /turnkey/fab/common/overlays/turnkey.d/profile build/root.patched
fab-apply-overlay /turnkey/fab/common/overlays/turnkey.d/rcS-sulogin build/root.patched
fab-apply-overlay /turnkey/fab/common/overlays/turnkey.d/resolvconf build/root.patched
fab-apply-overlay /turnkey/fab/common/overlays/turnkey.d/ssh-emptypw build/root.patched
fab-apply-overlay /turnkey/fab/common/overlays/turnkey.d/sslcert build/root.patched
fab-apply-overlay /turnkey/fab/common/overlays/turnkey.d/turnkey-init-fence build/root.patched
fab-apply-overlay /turnkey/fab/common/overlays/turnkey.d/webmin build/root.patched
# run the common configuration scripts
$(call run-conf-scripts, /turnkey/fab/common/conf/turnkey.d)
fab-chroot build/root.patched --script /turnkey/fab/common/conf/turnkey.d/apt
fab-chroot build/root.patched --script /turnkey/fab/common/conf/turnkey.d/busybox
fab-chroot build/root.patched --script /turnkey/fab/common/conf/turnkey.d/console-setup
fab-chroot build/root.patched --script /turnkey/fab/common/conf/turnkey.d/cronapt
fab-chroot build/root.patched --script /turnkey/fab/common/conf/turnkey.d/etckeeper
fab-chroot build/root.patched --script /turnkey/fab/common/conf/turnkey.d/hostname
fab-chroot build/root.patched --script /turnkey/fab/common/conf/turnkey.d/locale
Generating locales (this might take a while)...
Generation complete.
fab-chroot build/root.patched --script /turnkey/fab/common/conf/turnkey.d/motd
fab-chroot build/root.patched --script /turnkey/fab/common/conf/turnkey.d/persistent-net
fab-chroot build/root.patched --script /turnkey/fab/common/conf/turnkey.d/roothome
fab-chroot build/root.patched --script /turnkey/fab/common/conf/turnkey.d/rootpass
fab-chroot build/root.patched --script /turnkey/fab/common/conf/turnkey.d/shellinabox
Adding group `certssl' (GID 1000) ...
Done.
fab-chroot build/root.patched --script /turnkey/fab/common/conf/turnkey.d/sshd
fab-chroot build/root.patched --script /turnkey/fab/common/conf/turnkey.d/sslcert
fab-chroot build/root.patched --script /turnkey/fab/common/conf/turnkey.d/sysctl
fab-chroot build/root.patched --script /turnkey/fab/common/conf/turnkey.d/vim.tiny
fab-chroot build/root.patched --script /turnkey/fab/common/conf/turnkey.d/webmin-cats
fab-chroot build/root.patched --script /turnkey/fab/common/conf/turnkey.d/webmin-deftab
fab-chroot build/root.patched --script /turnkey/fab/common/conf/turnkey.d/webmin-fw
fab-chroot build/root.patched --script /turnkey/fab/common/conf/turnkey.d/webmin-history
fab-chroot build/root.patched --script /turnkey/fab/common/conf/turnkey.d/webmin-port
fab-chroot build/root.patched --script /turnkey/fab/common/conf/turnkey.d/webmin-theme
fab-chroot build/root.patched --script /turnkey/fab/common/conf/turnkey.d/webmin-updates
# apply the common removelists
fab-apply-removelist /turnkey/fab/common/removelists/turnkey build/root.patched;
# apply the product-local root overlay
if [ -d overlay ]; then fab-apply-overlay overlay build/root.patched; fi
# run the product-local configuration scripts
# apply the product-local removelist
# update initramfs (handle reconfigured initramfs scripts)
fab-chroot build/root.patched "update-initramfs -u"
update-initramfs: Generating /boot/initrd.img-3.2.0-4-amd64
fab-chroot build/root.patched "rm -rf /boot/*.bak"
#
# tagging package management system with release package
# setting /etc/turnkey_version and apt user-agent
#
/usr/share/fab/make-release-deb.py /turnkey/fab/products/core/changelog build/root.patched
dpkg-deb: building package `turnkey-core-13.0' in `build/root.patched/turnkey-core-13.0_1_all.deb'.
/usr/share/fab/make-release-deb.py ./changelog build/root.patched
dpkg-deb: building package `turnkey-core-13.0' in `build/root.patched/turnkey-core-13.0_1_all.deb'.
fab-chroot build/root.patched "dpkg -i *.deb && rm *.deb && rm -f /var/log/dpkg.log"
Selecting previously unselected package turnkey-core-13.0.
(Reading database ... 22631 files and directories currently installed.)
Unpacking turnkey-core-13.0 (from turnkey-core-13.0_1_all.deb) ...
Setting up turnkey-core-13.0 (1) ...
fab-chroot build/root.patched "which insserv >/dev/null && insserv"
fab-chroot build/root.patched "which postsuper >/dev/null && postsuper -d ALL || true"
fab-chroot   build/root.patched "rm -f /var/cache/debconf/*-old"; fab-chroot   build/root.patched "rm -f /var/log/dpkg.log"; fab-chroot   build/root.patched "rm -f /var/log/apt/*"; fab-chroot   build/root.patched "rm -f /var/cache/apt/*.bin"; fab-chroot   build/root.patched "rm -f /var/cache/apt/archives/*.deb"; fab-chroot   build/root.patched "rm -rf /var/lib/apt/lists/*"; fuser -k  build/root.patched || true;
touch build/stamps/root.patched

real        0m11.819s
user        0m3.284s
sys 0m3.176s

Now a root shell launched inside root.patched says hello universe instead of hello world:

root@tkldev products/core# fab-chroot build/root.patched/
hello universe
root@tkldev /# exit

We can test the integration by chrooting into root.patched, or we can continue with the build and test the product.iso image (e.g., in a VM)

The default make target is product.iso so if we run make with no target it will just continue from where it left off (root.patched in this example):

root@tkldev products/core# time make
if [ -e build/cdroot ]; then rm -rf build/cdroot; fi
cp -a /turnkey/fab/cdroots/gfxboot-turnkey build/cdroot
mkdir build/cdroot/casper
if [ -d cdroot.overlay ]; then fab-apply-overlay cdroot.overlay build/cdroot; fi
/usr/bin/mksquashfs build/root.patched build/cdroot/casper/10root.squashfs -no-sparse
Parallel mksquashfs: Using 2 processors
Creating 4.0 filesystem on build/cdroot/casper/10root.squashfs, block size 131072.
[=====================================================================================================|] 24754/24754 100%
Exportable Squashfs 4.0 filesystem, gzip compressed, data block size 131072
    compressed data, compressed metadata, compressed fragments, compressed xattrs
    duplicates are removed
Filesystem size 135873.83 Kbytes (132.69 Mbytes)
    38.36% of uncompressed filesystem size (354167.31 Kbytes)
Inode table size 296013 bytes (289.08 Kbytes)
    29.63% of uncompressed inode table size (998902 bytes)
Directory table size 284687 bytes (278.01 Kbytes)
    46.79% of uncompressed directory table size (608393 bytes)
Number of duplicate files found 1213
Number of inodes 29458
Number of files 23630
Number of fragments 1584
Number of symbolic links  2770
Number of device nodes 38
Number of fifo nodes 0
Number of socket nodes 0
Number of directories 3020
Number of ids (unique uids + gids) 18
Number of uids 6
    root (0)
    man (6)
    libuuid (100)
    ntp (101)
    proxy (13)
    shellinabox (103)
Number of gids 17
    root (0)
    tty (5)
    kmem (15)
    disk (6)
    shadow (42)
    certssl (1000)
    bin (2)
    utmp (43)
    crontab (102)
    ssh (104)
    staff (50)
    libuuid (101)
    proxy (13)
    ntp (103)
    shellinabox (105)
    adm (4)
    mail (8)
touch build/stamps/cdroot
deck -D build/root.sandbox
deck build/root.patched build/root.sandbox
touch build/stamps/root.sandbox
cp build/root.sandbox/usr/lib/syslinux/isolinux.bin build/cdroot/isolinux
cp build/root.sandbox/boot/vmlinuz-3.2.0-4-amd64 build/cdroot/casper/vmlinuz
cp build/root.sandbox/boot/initrd.img-3.2.0-4-amd64 build/cdroot/casper/initrd.gz
rm -f build/cdroot/casper/20sandbox.squashfs
genisoimage -o build/product.iso -r -J -l -V core -b isolinux/isolinux.bin -c isolinux/boot.cat -no-emul-boot -boot-load-size 4 -boot-info-table build/cdroot/
Size of boot image is 4 sectors -> No emulation
  6.67% done, estimate finish Sun Jul 13 14:24:22 2014
 13.35% done, estimate finish Sun Jul 13 14:24:22 2014
 20.00% done, estimate finish Sun Jul 13 14:24:22 2014
 26.68% done, estimate finish Sun Jul 13 14:24:22 2014
 33.34% done, estimate finish Sun Jul 13 14:24:22 2014
 40.01% done, estimate finish Sun Jul 13 14:24:22 2014
 46.67% done, estimate finish Sun Jul 13 14:24:22 2014
 53.34% done, estimate finish Sun Jul 13 14:24:22 2014
 60.00% done, estimate finish Sun Jul 13 14:24:22 2014
 66.67% done, estimate finish Sun Jul 13 14:24:22 2014
 73.33% done, estimate finish Sun Jul 13 14:24:22 2014
 80.00% done, estimate finish Sun Jul 13 14:24:22 2014
 86.66% done, estimate finish Sun Jul 13 14:24:22 2014
 93.32% done, estimate finish Sun Jul 13 14:24:22 2014
Total translation table size: 2048
Total rockridge attributes bytes: 1816
Total directory bytes: 4574
Path table size(bytes): 40
Max brk space used 0
75014 extents written (146 MB)
isohybrid build/product.iso

real        0m51.614s
user        1m30.394s
sys 0m4.080s

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