docs/linux/using_a_chroot.md

# Using a chroot

If you want to run web tests and you're not running Lucid, you'll get errors
due to version differences in libfreetype. To work around this, you can use a
chroot.

## Basic Instructions

*   Run `build/install-chroot.sh`. On the prompts, choose to install a 64-bit
    Lucid chroot and activate all your secondary mount points.
*   sudo edit `/etc/schroot/mount-lucid64bit` and uncomment `/run` and
    `/run/shm`.  Verify that your mount points are correct and uncommented: for
    example, if you have a second hard drive at `/src`, you should have an entry
    like `/src /src none rw,bind 0 0`.
*   Enter your chroot as root with `sudo schroot -c lucid64`.
    Run `build /install-build-deps.sh`, then exit the rooted chroot.
*   Delete your out/ directory if you had a previous non-chrooted build.
*   To enter your chroot as normal user, run `schroot -c lucid64`.
*   Now compile and run DumpRenderTree within chroot.

## Tips and Tricks

### NFS home directories

The chroot install will be installed by default in /home/$USER/chroot. If your
home directory is inaccessible by root (typically because it is mounted on NFS),
then move this directory onto your local disk and change the corresponding entry
in `/etc/schroot/mount-lucid64bit`.

### Goma builds

If you get mysterious compile errors (glibconfig.h or dbus header error), make
sure that goma is running in the chroot, or don't use goma for builds inside the
chroot.

### Different color prompt

I use the following code in my .zshrc file to change the color of my prompt in
the chroot.

```shell
# load colors
autoload colors zsh/terminfo
if [[ "$terminfo[colors]" -ge 8 ]]; then
  colors
fi
for color in RED GREEN YELLOW BLUE MAGENTA CYAN WHITE; do
  eval PR_$color='%{$terminfo[bold]$fg[${(L)color}]%}'
  eval PR_LIGHT_$color='%{$fg[${(L)color}]%}'
done
PR_NO_COLOR="%{$terminfo[sgr0]%}"

# set variable identifying the chroot you work in (used in the prompt below)
if [ -z "$debian_chroot" ] && [ -r /etc/debian_chroot ]; then
  debian_chroot=$(cat /etc/debian_chroot)
fi

if [ "xlucid64" = "x$debian_chroot" ]; then
    PS1="%n@$PR_GREEN% lucid64$PR_NO_COLOR %~ %#"
else
    PS1="%n@$PR_RED%m$PR_NO_COLOR %~ %#"
fi
```

### Running X apps

I also have `DISPLAY=:0` in my `$debian_chroot` section so I can run test_shell
or web tests without manually setting my display every time.  Your display
number may vary (`echo $DISPLAY` outside the chroot to see what your display
number is).

You can also use `Xvfb` if you only want to
[run tests headless](web_tests_linux.md#Using-an-embedded-X-server).

### Having web test results open in a browser

After running web tests, you should get a new browser tab or window that
opens results.html.  If you get an error "Failed to open
file:///path/to/results.html, check the
following conditions.

1.  Make sure `DISPLAY` is set. See the
    [Running X apps](#Running-X-apps) section above.
1.  Install `xdg-utils`, which includes `xdg-open`, a utility for finding the
    right application to open a file or URL with.
1.  Install [Chrome](https://www.google.com/intl/en/chrome/browser/).