Add CLI examples for ubuntu-image.

doc/.custom_wordlist.txt

@@ -89,8 +89,10 @@ rsyslog
 runtime
 snapd
 stdin
+subdirectory
 subvolume
 subvolumes
+sudo
 superset
 sysfs
 TPM

doc/howto/index.rst

@@ -20,6 +20,7 @@ Getting started with autoinstall
    basic-server-installation
    configure-storage
    autoinstall-validation
+   Use ubuntu-image to build classical images <ubuntu-image-classic-examples>
 
 Found a problem?
 ----------------

doc/howto/ubuntu-image-classic-examples.rst

@@ -0,0 +1,269 @@
+.. _how-to-use-ubuntu-image-with-the-classic-command:
+
+How to use ``ubuntu-image`` with the ``classic`` command
+========================================================
+
+The :command:`classic` command in :command:`ubuntu-image` is used to create classical Ubuntu images based on traditional Ubuntu releases (like Desktop or Server images). The :command:`classic` command uses an **image definition** YAML file to define the image structure.
+
+.. note:: :command:`ubuntu-image` requires elevated permissions to run correctly. Use :command:`sudo` when running the command.
+
+
+.. _general-command-structure:
+
+General command structure
+-------------------------
+
+The general command to build a classical image is:
+
+.. code-block:: none
+
+    sudo ubuntu-image [options] classic <image-definition.yaml>
+
+Replace ``<image-definition.yaml>`` with the path to the image definition file.
+
+----
+
+
+.. _building-a-basic-ubuntu-image-for-a-pc:
+
+Building a basic Ubuntu image for a PC
+--------------------------------------
+
+In this example, you create a simple classical Ubuntu image for the **amd64** architecture.
+
+#. Create the image definition, :file:`classical-amd64.yaml`, with the following content:
+
+   .. code-block:: yaml
+
+    # Image metadata
+    name: ubuntu-classical-amd64
+    display-name: Ubuntu Classical Image for amd64
+    revision: 1
+    architecture: amd64
+    series: noble
+    class: preinstalled
+
+    # Optional kernel (defaults to 'linux' if omitted)
+    kernel: linux-image-generic
+
+    # Gadget snap
+    gadget:
+      url: https://github.com/canonical/pc-gadget
+      branch: classic
+      type: git
+
+    # Root filesystem definition
+    rootfs:
+      components:
+        - main
+        - restricted
+        - universe
+        - multiverse
+      archive: ubuntu
+      mirror: http://archive.ubuntu.com/ubuntu/
+      pocket: updates
+      seed:
+        urls:
+          - git://git.launchpad.net/~ubuntu-core-dev/ubuntu-seeds/+git/
+        names:
+          - server
+          - minimal
+        branch: noble
+        vcs: true
+      sources-list-deb822: true
+
+    # Required dependency
+    customization:
+      extra-snaps:
+        - name: snapd
+
+    # Artifacts to generate
+    artifacts:
+      img:
+        - name: ubuntu-classical-amd64.img
+      manifest:
+        name: ubuntu-classical-amd64.manifest
+
+#. Build the image by running the following command:
+
+   .. code-block:: none
+
+       sudo ubuntu-image classic classical-amd64.yaml
+
+   The expected output looks like this:
+
+   .. code-block:: none
+
+    WARNING: rootfs.sources-list-deb822 is set to true. The DEB822 format
+             will be used to manage sources list. Please make sure you are
+             not building an image older than noble.
+    [0] build_gadget_tree
+    [1] prepare_gadget_tree
+    [2] load_gadget_yaml
+    WARNING: volumes:pc:structure:2:filesystem_label used for defining partition roles; use role instead
+    [3] verify_artifact_names
+    [4] germinate
+    [5] create_chroot
+    [6] install_packages
+    [7] prepare_image
+    [8] preseed_image
+    [9] clean_rootfs
+    [10] customize_sources_list
+    [11] set_default_locale
+    [12] populate_rootfs_contents
+    [13] generate_disk_info
+    [14] calculate_rootfs_size
+    [15] populate_bootfs_contents
+    [16] populate_prepare_partitions
+    [17] make_disk
+    [18] update_bootloader
+    [19] generate_package_manifest
+    Build successful
+
+
+.. _building-a-basic-ubuntu-image-for-raspberry-pi:
+
+Building a basic Ubuntu image for Raspberry Pi
+----------------------------------------------
+
+In this example, you create a simple classical Ubuntu image for the Raspberry Pi board.
+
+#. Create the image definition, :file:`classical-raspi.yaml`, with the following content:
+
+   .. code-block:: yaml
+
+    # Image metadata
+    name: ubuntu-server-raspi-arm64
+    display-name: Ubuntu Server Raspberry Pi arm64
+    revision: 1
+    architecture: arm64
+    series: noble
+    class: preinstalled
+    kernel: linux-image-raspi
+
+    # Gadget snap
+    gadget:
+      url: https://git.launchpad.net/snap-pi
+      branch: "classic"
+      type: "git"
+
+    # Root filesystem definition
+    rootfs:
+      archive: ubuntu
+      sources-list-deb822: true
+      components:
+        - main
+        - restricted
+        - universe
+        - multiverse
+      mirror: http://ports.ubuntu.com/ubuntu-ports/
+      pocket: updates
+      seed:
+        urls:
+          - git://git.launchpad.net/~ubuntu-core-dev/ubuntu-seeds/+git/
+        branch: noble
+        names:
+          - server
+          - server-raspi
+          - raspi-common
+          - minimal
+          - standard
+          - cloud-image
+          - supported-raspi-common
+
+    # Additional settings
+    customization:
+      cloud-init:
+        user-data: |
+          #cloud-config
+          chpasswd:
+            expire: true
+            users:
+              - name: ubuntu
+                password: ubuntu
+                type: text
+      extra-snaps:
+        - name: snapd
+      fstab:
+        - label: "writable"
+          mountpoint: "/"
+          filesystem-type: "ext4"
+          dump: false
+          fsck-order: 1
+        - label: "system-boot"
+          mountpoint: "/boot/firmware"
+          filesystem-type: "vfat"
+          mount-options: "defaults"
+          dump: false
+          fsck-order: 1
+
+    # Artifacts to generate
+    artifacts:
+      img:
+        - name: ubuntu-24.04-preinstalled-server-arm64+raspi.img
+      manifest:
+        name: ubuntu-24.04-preinstalled-server-arm64+raspi.manifest
+
+
+#. Build the image by running the following command:
+
+   .. code-block:: none
+
+       sudo ubuntu-image classic classical-raspi.yaml
+
+
+.. _setting-image-size:
+
+Setting image size
+------------------
+
+To define a custom size for the generated image, use the ``--image-size`` option. For example, to set the image size to 8 GiB:
+
+.. code-block:: none
+
+    sudo ubuntu-image classic classical-amd64.yaml --image-size=8G
+
+This creates a classical Ubuntu image with a total size of 8 GiB. This is useful when intending to use the image on a medium with a specific capacity.
+
+.. note:: If the requested size is smaller than the minimum calculated size of the image, the ``--image-size`` option is ignored, and a warning is output.
+
+
+.. _specifying-working-and-output-directories:
+
+Specifying working and output directories
+-----------------------------------------
+
+To preserve all the downloaded and unpacked source files used for building the image after the build completes, specify a working directory using the ``--workdir`` option. The directory is created if it doesn't exist.
+
+The generated image is stored in the specified ``--workdir``, unless the ``--output-dir`` option is defined. By default, when neither of these options is used, a temporary working directory is used and deleted after the build, and the generated image is placed in the current directory.
+
+Example:
+
+.. code-block:: none
+
+    sudo ubuntu-image --workdir=/tmp/u-i --output-dir=images classic classical-raspi.yaml
+
+This command leaves all source files used to build the image in the :file:`/tmp/u-i/` directory, and places the generated image into the :file:`images` subdirectory within the current directory.
+
+
+.. _adding-a-disk-info-file-to-image:
+
+Adding a disk-info file to image
+--------------------------------
+
+To add an extra file with information to the generated image, use the ``--disk-info`` option. The file is included in the image as :file:`.disk/info`. This can be useful to store information, for example, about the name of the system, time of build, or other identifying data.
+
+For example, a :file:`disk.info` file could include the following content:
+
+.. code-block:: none
+   :caption: ``disk.info``
+
+    Built with: ubuntu-image 3.4.1
+    Time: Oct 14 2024, 13.27:11
+    Gadget: 64bit PC Gadget Snap
+
+To include it in an image, run:
+
+.. code-block:: none
+
+    sudo ubuntu-image --disk-info disk.info classic classical-amd64.yaml