132 lines
4.3 KiB
Markdown
132 lines
4.3 KiB
Markdown
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The Devuan SDK more in-depth
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============================
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The following parts will explain the Devuan SDK more technically. It
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will show its configuration, important functions, and show how it all
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glues together.
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Configuration
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-------------
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Much of the _libdevuansdk_ configuration is done in
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`libdevuansdk/config`. Here you can edit the defaults if you wish to
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do something your needs are expressing. However, overriding these
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through upper levels is recommended.
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### `config` file
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`vars` and `arrs` are global arrays for holding other global variables
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and arrays, respectively. This is required for `zuper` and helps a lot
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with debugging. If you declare new variables or arrays, add them to the
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aforementioned variables.
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* `os` holds the name of the distribution being worked on.
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* `release` holds the release codename of the distribution. Used for apt
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repositories mostly.
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* `version` is the version of the distribution being worked on.
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* `mirror` is a mirror holding the required packages for `debootstrap`.
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* `section` are the sections of the repository. For adding in
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`/etc/apt/sources.list`. Separate them with whitespaces.
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* `image_name` is the output name of the raw image. If you declare a
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blend or a device name (arm-sdk), they will be appended to this name.
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* `rootcredentials` and `usercredentials` are currently placeholders.
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* `core_packages` is an array holding the core packages that will be
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installed in the bootstrap process.
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* `base_packages` is an array holding the base packages that will be
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installed at a later point in the bootstrap process.
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* `purge_packages` is an array of packages that will get purged at the
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end of the bootstrap process.
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Helper functions
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----------------
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You can find useful helper functions in `libdevuansdk/zlibs/helpers`.
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They are intended to help when it comes to writing wrappers, as well
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as making the developers' jobs easier for developing
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_libdevuansdk_. Some of these functions are required for
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_libdevuansdk_ to work properly as well.
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### `build_image_dist()`
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This function is a kind of a wrapper function. It's used in _arm-sdk_
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to build a complete dd-able image from start to end. To run, it
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requires `$arch`, `$size`, `$parted_type`, `$workdir`, `$strapdir`,
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and `$image_name` to be declared. See the section dedicated to
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"Creating wrappers" for insight on these variables.
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The workflow of this function is bootstrapping a complete _rootfs_,
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creating a raw image, installing/compiling a kernel, rsyncing
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everything to the raw image, and finally compressing the raw image.
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This same workflow is applied in the next two functions in this file,
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which are `build_iso_dist` and `build_vagrant_dist`. To get a better
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understanding of _libdevuansdk_, it's recommended to go through one of
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these functions and following it deeper to find and figure out the
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other functions and how they work together.
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### `devprocsys()`
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This function is a simple helper function that takes two arguments. It
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mounts or unmounts `/dev`, `/proc`, and `/sys` filesystems to or from
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wherever you tell it to. For example:
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```
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$ devprocsys mount $strapdir
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$ devprocsys umount $strapdir
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```
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It is very necessary to use this if one wants to do anything requiring
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access to hardware or the system's resources, i.e. cryptography.
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### `dpkgdivert()`
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This function, like `devprocsys` takes two arguments and will create
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or remove a dpkg diversion in the place you tell it to and remove
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`invoke-rc.d` so that _apt_ does not autostart daemons when they are
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installed.
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### `chroot-script()`
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This very useful functions allows you to _chroot_ into `$strapdir` and
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execute the script/binary that's passed as a parameter to this
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function. It also takes an optional argument `-d` that will call
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`dpkgdivert` on and off before and after execution.
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The `chroot-script` is also an example on its own that shows how to use
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the `chroot-script` function.
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Mandatory variables
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-------------------
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* `$R` is the root directory of a wrapper. It's defined already in all
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the existing ones. In almost evert situation it can be `$PWD`.
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* `$workdir` is the working directory of the current build. A sane
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default is `$R/tmp/workdir`
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* `$strapdir` is the bootstrap directory of the build. It holds the
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rootfs when you debootstrap it, and customize it further on. Default
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is `$workdir/rootfs`.
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* `$arch` is the CPU architecture of the build. I.e. `amd64`, `armhf`,
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etc.
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