If these are set, they are use to configure `wpa_supplicant.conf`, so that the Raspberry Pi can automatically connect to a wireless network on first boot. If `WPA_ESSID` is set and `WPA_PASSWORD` is unset an unprotected wireless network will be configured. If set, `WPA_PASSWORD` must be between 8 and 63 characters.
Setting to `1` will enable ssh server for remote log in. Note that if you are using a common password such as the defaults there is a high risk of attackers taking over you Raspberry Pi.
If set, then instead of working through the numeric stages in order, this list will be followed. For example setting to `"stage0 stage1 mystage stage2"` will run the contents of `mystage` before stage2. Note that quotes are needed around the list. An absolute or relative path can be given for stages outside the pi-gen directory.
A simple example for building Raspbian:
```bash
IMG_NAME='Raspbian'
```
The config file can also be specified on the command line as an argument the `build.sh` or `build-docker.sh` scripts.
```
./build.sh -c myconfig
```
This is parsed after `config` so can be used to override values set there.
## How the build process works
The following process is followed to build images:
* Loop through all of the stage directories in alphanumeric order
* Move on to the next directory if this stage directory contains a file called
"SKIP"
* Run the script ```prerun.sh``` which is generally just used to copy the build
directory between stages.
* In each stage directory loop through each subdirectory and then run each of the
install scripts it contains, again in alphanumeric order. These need to be named
with a two digit padded number at the beginning.
There are a number of different files and directories which can be used to
control different parts of the build process:
- **00-run.sh** - A unix shell script. Needs to be made executable for it to run.
- **00-run-chroot.sh** - A unix shell script which will be run in the chroot
of the image build directory. Needs to be made executable for it to run.
- **00-debconf** - Contents of this file are passed to debconf-set-selections
to configure things like locale, etc.
- **00-packages** - A list of packages to install. Can have more than one, space
separated, per line.
- **00-packages-nr** - As 00-packages, except these will be installed using
the ```--no-install-recommends -y``` parameters to apt-get.
- **00-patches** - A directory containing patch files to be applied, using quilt.
If a file named 'EDIT' is present in the directory, the build process will
be interrupted with a bash session, allowing an opportunity to create/revise
the patches.
* If the stage directory contains files called "EXPORT_NOOBS" or "EXPORT_IMAGE" then
add this stage to a list of images to generate
* Generate the images for any stages that have specified them
It is recommended to examine build.sh for finer details.
## Docker Build
Docker can be used to perform the build inside a container. This partially isolates
the build from the host system, and allows using the script on non-debian based
systems (e.g. Fedora Linux). The isolate is not complete due to the need to use
some kernel level services for arm emulation (binfmt) and loop devices (losetup).
To build:
```bash
vi config # Edit your config file. See above.
./build-docker.sh
```
If everything goes well, your finished image will be in the `deploy/` folder.
You can then remove the build container with `docker rm -v pigen_work`
If something breaks along the line, you can edit the corresponding scripts, and
continue:
```bash
CONTINUE=1 ./build-docker.sh
```
To examine the container after a failure you can enter a shell within it using:
```bash
sudo docker run -it --privileged --volumes-from=pigen_work pi-gen /bin/bash
```
After successful build, the build container is by default removed. This may be undesired when making incremental changes to a customized build. To prevent the build script from remove the container add
```bash
PRESERVE_CONTAINER=1 ./build-docker.sh
```
There is a possibility that even when running from a docker container, the
installation of `qemu-user-static` will silently fail when building the image
because `binfmt-support`_must be enabled on the underlying kernel_. An easy
fix is to ensure `binfmt-support` is installed on the host machine before
starting the `./build-docker.sh` script (or using your own docker build
solution).
## Stage Anatomy
### Raspbian Stage Overview
The build of Raspbian is divided up into several stages for logical clarity
and modularity. This causes some initial complexity, but it simplifies
maintenance and allows for more easy customization.
- **Stage 0** - bootstrap. The primary purpose of this stage is to create a
usable filesystem. This is accomplished largely through the use of
`debootstrap`, which creates a minimal filesystem suitable for use as a
base.tgz on Debian systems. This stage also configures apt settings and
installs `raspberrypi-bootloader` which is missed by debootstrap. The
minimal core is installed but not configured, and the system will not quite
boot yet.
- **Stage 1** - truly minimal system. This stage makes the system bootable by
installing system files like `/etc/fstab`, configures the bootloader, makes
the network operable, and installs packages like raspi-config. At this
stage the system should boot to a local console from which you have the
means to perform basic tasks needed to configure and install the system.
This is as minimal as a system can possibly get, and its arguably not
really usable yet in a traditional sense yet. Still, if you want minimal,
this is minimal and the rest you could reasonably do yourself as sysadmin.
- **Stage 2** - lite system. This stage produces the Raspbian-Lite image. It
installs some optimized memory functions, sets timezone and charmap
