From 680393de3dc47a4ad7ee3bd6342c951f576ef625 Mon Sep 17 00:00:00 2001 From: "Brian C. Lane" Date: Fri, 11 May 2018 17:17:26 -0700 Subject: [PATCH] Add documentation for lorax-composer and composer-cli --- docs/composer-cli.rst | 62 +++++++++++ docs/index.rst | 7 ++ docs/lorax-composer.rst | 235 ++++++++++++++++++++++++++++++++++++++++ 3 files changed, 304 insertions(+) create mode 100644 docs/composer-cli.rst create mode 100644 docs/lorax-composer.rst diff --git a/docs/composer-cli.rst b/docs/composer-cli.rst new file mode 100644 index 00000000..7cde6feb --- /dev/null +++ b/docs/composer-cli.rst @@ -0,0 +1,62 @@ +composer-cli +============ + +:Authors: + Brian C. Lane + +``composer-cli`` is used to interact with the ``lorax-composer`` API server, managing blueprints, exploring available packages, and building new images. + +It requires `lorax-composer `_ to be installed on the +local system, and the user running it needs to be a member of the ``weldr`` +group. They do not need to be root, but all of the `security precautions +`_ apply. + +composer-cli cmdline arguments +------------------------------ + +.. argparse:: + :ref: composer.cli.cmdline.composer_cli_parser + :prog: composer-cli + +Edit a Blueprint +---------------- + +Start out by listing the available blueprints using ``composer-cli blueprints +list``, pick one and save it to the local directory by running ``composer-cli +blueprints save http-server``. If there are no blueprints available you can +copy one of the examples `from the test suite +`_. + +Edit the file (it will be saved with a .toml extension) and chance the +description, add a package or module to it. Send it back to the server by +running ``composer-cli blueprints push http-server.toml``. You can verify that it was +saved by viewing the changelog - ``composer-cli blueprints changes http-server``. + +Build an image +---------------- + +Build a ``qcow2`` disk image from this blueprint by running ``composer-cli +compose start http-server qcow2``. It will print a UUID that you can use to +keep track of the build. You can also cancel the build if needed. + +The available types of images is displayed by ``composer-cli compose types``. +Currently this consists of: ext4-filesystem, live-iso, partitioned-disk, qcow2, +tar + +Monitor the build status +------------------------ + +Monitor it using ``composer-cli compose status``, which will show the status of +all the builds on the system. You can view the end of the anaconda build logs +once it is in the ``RUNNING`` state using ``composer-cli compose log UUID`` +where UUID is the UUID returned by the start command. + +Once the build is in the ``FINISHED`` state you can download the image. + +Download the image +------------------ + +Downloading the final image is done with ``composer-cli compose image UUID`` and it will +save the qcow2 image as ``UUID-disk.qcow2`` which you can then use to boot a VM like this:: + + qemu-kvm --name test-image -m 1024 -hda ./UUID-disk.qcow2 diff --git a/docs/index.rst b/docs/index.rst index c9b962d8..40acd5a6 100644 --- a/docs/index.rst +++ b/docs/index.rst @@ -14,9 +14,16 @@ Contents: intro lorax livemedia-creator + lorax-composer + composer-cli product-images modules +Documentation for other Lorax Branches +====================================== + +* `Fedora 28 `_ +* `RHEL7 lorax-composer `_ Indices and tables ================== diff --git a/docs/lorax-composer.rst b/docs/lorax-composer.rst new file mode 100644 index 00000000..70fb5818 --- /dev/null +++ b/docs/lorax-composer.rst @@ -0,0 +1,235 @@ +lorax-composer +============== + +:Authors: + Brian C. Lane + +``lorax-composer`` is an API server that allows you to build disk images using +`Blueprints`_ to describe the package versions to be installed into the image. +It is compatible with the Weldr project's bdcs-api REST protocol. More +information on Weldr can be found `on the Weldr blog `_. + +Behind the scenes it uses `livemedia-creator `_ and +`Anaconda `_ to handle the +installation and configuration of the images. + +Installation +------------ + +The best way to install ``lorax-composer`` is to use ``sudo dnf install +lorax-composer composer-cli``, this will setup the weldr user and install the +systemd socket activation service. You will then need to enable it with ``sudo +systemctl enable lorax-composer.socket``. This will leave the server off until +the first request is made. Systemd will then launch the server and it will +remain running until the system is rebooted. + +Quickstart +---------- + +1. Create a ``weldr`` user and group by running ``useradd weldr`` +2. Remove any pre-existing socket directory with ``rm -rf /run/weldr/`` + A new directory with correct permissions will be created the first time the server runs. +3. Enable the socket activation with ``systemctl enable lorax-composer.socket`` or + run it directly with ``lorax-composer /path/to/blueprints/`` + +The ``/path/to/blueprints/`` directory is where the blueprints' git repo will +be created, and all the blueprints created with the ``/api/v0/blueprints/new`` +route will be stored. If there are blueprint ``.toml`` files in the top level +of the directory they will be imported into the blueprint git storage when +``lorax-composer`` starts. + +Logs +---- + +Logs are stored under ``/var/log/lorax-composer/`` and include all console +messages as well as extra debugging info and API requests. + +Security +-------- + +Some security related issues that you should be aware of before running ``lorax-composer``: + +* One of the API server threads needs to retain root privileges in order to run Anaconda. +* SELinux must be set to Permissive or disabled to allow ``livemedia-creator`` to run Anaconda. +* Only allow authorized users access to the ``weldr`` group and socket. + +Since Anaconda kickstarts are used there is the possibility that a user could +inject commands into a blueprint that would result in the kickstart executing +arbitrary code on the host. Only authorized users should be allowed to build +images using ``lorax-composer``. + +lorax-composer cmdline arguments +-------------------------------- + +.. argparse:: + :ref: pylorax.api.cmdline.lorax_composer_parser + :prog: lorax-composer + + +How it Works +------------ + +The server runs as root, and as ``weldr``. Communication with it is via a unix +domain socket (``/run/weldr/api.socket`` by default). The directory and socket +are owned by ``root:weldr`` so that any user in the ``weldr`` group can use the API +to control ``lorax-composer``. + +At startup the server will check for the correct permissions and +ownership of a pre-existing directory, or it will create a new one if it +doesn't exist. The socket path and group owner's name can be changed from the +cmdline by passing it the ``--socket`` and ``--group`` arguments. + +It will then drop root privileges for the API thread and run as the ``weldr`` +user. The queue and compose thread still runs as root because it needs to be +able to mount/umount files and run Anaconda. + +Composing Images +---------------- + +The `welder-web `_ GUI project can be used to construct +blueprints and create composes using a web browser. + +Or use the command line with `composer-cli `_. + +Blueprints +---------- + +Blueprints are simple text files in `TOML `_ format that describe +which packages, and what versions, to install into the image. They can also define a limited set +of customizations to make to the final image. + +Example blueprints can be found in the ``lorax-composer`` `test suite +`_, with a simple one +looking like this:: + + name = "base" + description = "A base system with bash" + version = "0.0.1" + + [[packages]] + name = "bash" + version = "4.4.*" + +The ``name`` field is the name of the blueprint. It can contain spaces, but they will be converted to ``-`` +when it is written to disk. It should be short and descriptive. + +``description`` can be a longer description of the blueprint, it is only used for display purposes. + +``version`` is a `semver compatible `_ version number. If +a new blueprint is uploaded with the same ``version`` the server will +automatically bump the PATCH level of the ``version``. If the ``version`` +doesn't match it will be used as is. eg. Uploading a blueprint with ``version`` set to ``0.0.1`` when the existing blueprint ``version`` is ``0.0.1`` will result in the new blueprint being stored as ``version 0.0.1``. + +[[packages]] and [[modules]] +~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +These entries describe the package names and matching version glob to be installed into the image. + +The names must match the names exactly, and the versions can be an exact match +or a filesystem-like glob of the version using ``*`` wildcards and ``?`` +character matching. + +NOTE: As of lorax-composer-29.2-1 the versions are not used for depsolving, +that is planned for a future release. And currently there are no differences +between ``packages`` and ``modules`` in ``lorax-composer``. + +Customizations +~~~~~~~~~~~~~~ + +The ``[[customizations]]`` section can be used to configure the hostname of the final image. eg.:: + + [[customizations]] + hostname = "baseimage" + + +[[customizations.sshkey]] +************************* + +Set an existing user's ssh key in the final image:: + + [[customizations.sshkey]] + user = "root" + key = "PUBLIC SSH KEY" + +The key will be added to the user's authorized_keys file. + + +[[customizations.user]] +*********************** + +Add a user to the image, and/or set their ssh key. +All fields for this section are optional except for the ``name``, here is a complete example:: + + [[customizations.user]] + name = "admin" + description = "Administrator account" + password = "$6$CHO2$3rN8eviE2t50lmVyBYihTgVRHcaecmeCk31L..." + key = "PUBLIC SSH KEY" + home = "/srv/widget/" + shell = "/usr/bin/bash" + groups = ["widget", "users", "wheel"] + uid = 1200 + gid = 1200 + +If the password starts with ``$6$``, ``$5$``, or ``$2b$`` it will be stored as +an encrypted password. Otherwise it will be treated as a plain text password. + + +[[customizations.group]] +************************ + +Add a group to the image. ``name`` is required and ``gid`` is optional:: + + [[customizations.group]] + name = "widget" + gid = 1130 + + +Adding Output Types +------------------- + +``livemedia-creator`` supports a large number of output types, and only some of +these are currently available via ``lorax-composer``. To add a new output type to +lorax-composer a kickstart file needs to be added to ``./share/composer/``. The +name of the kickstart is what will be used by the ``/compose/types`` route, and the +``compose_type`` field of the POST to start a compose. It also needs to have +code added to the :py:func:`pylorax.api.compose.compose_args` function. The +``_MAP`` entry in this function defines what lorax-composer will pass to +:py:func:`pylorax.installer.novirt_install` when it runs the compose. When the +compose is finished the output files need to be copied out of the build +directory (``/var/lib/lorax/composer/results//compose/``), +:py:func:`pylorax.api.compose.move_compose_results` handles this for each type. +You should move them instead of copying to save space. + +If the new output type does not have support in livemedia-creator it should be +added there first. This will make the output available to the widest number of +users. + +Example: Add partitioned disk support +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +Partitioned disk support is something that livemedia-creator already supports +via the ``--make-disk`` cmdline argument. To add this to lorax-composer it +needs 3 things: + +* A ``partitioned-disk.ks`` file in ``./share/composer/`` +* A new entry in the _MAP in :py:func:`pylorax.api.compose.compose_args` +* Add a bit of code to :py:func:`pylorax.api.compose.move_compose_results` to move the disk image from + the compose directory to the results directory. + +The ``partitioned-disk.ks`` is pretty similar to the example minimal kickstart +in ``./docs/fedora-minimal.ks``. You should remove the ``url`` and ``repo`` +commands, they will be added by the compose process. Make sure the bootloader +packages are included in the ``%packages`` section at the end of the kickstart, +and you will want to leave off the ``%end`` so that the compose can append the +list of packages from the blueprint. + +The new ``_MAP`` entry should be a copy of one of the existing entries, but with ``make_disk`` set +to ``True``. Make sure that none of the other ``make_*`` options are ``True``. The ``image_name`` is +what the name of the final image will be. + +``move_compose_results()`` can be as simple as moving the output file into +the results directory, or it could do some post-processing on it. The end of +the function should always clean up the ``./compose/`` directory, removing any +unneeded extra files. This is especially true for the ``live-iso`` since it produces +the contents of the iso as well as the boot.iso itself.