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Deploy and configure an OSTree commit

Project description

deploy-ostree: deploy and provision an OSTree commit

pipeline status PyPI python versions

deploy-ostree is a tool to deploy and configure an OSTree commit without user input from a simple configuration file. It will:

  • set up the remote
  • pull the commit
  • create the stateroot
  • check out and deploy the tree
  • run additional provisioners to make the deployed system useful

Its original intended use case was automatic tests; accordingly, it should not be seen as a replacement for an end-user installer. deploy-ostree can serve as a tool to install a regular system, but it may also take shortcuts and do things in a way that are fine for a disposable test environment, but might not be fine in long-lived system.

Requirements

  • Python 3.5 or newer
  • OSTree 2018.4 or newer (older versions may work, but weren't tested)

Running deploy-ostree from inside a libostree deployment requires no additional configuration (provided the bootloader is set up correctly). To run deploy-ostree on a system that's not using libostree, you need to first run ostree admin init-fs / to set up the libostree system repository and directory structure. In addition, you may need to set up the bootloader. How to do this depends on the OS, the architecture, and the bootloader in use.

Installation

You can install deploy-ostree using pip:

$ pip3 install deploy-ostree

Usage

# deploy-ostree <config path or HTTP URL>

This requires root permissions. If deploy-ostree exits successfully, your new OSTree deployment should be ready to boot.

Command-Line Arguments

  • --sysroot=SYSROOT: install into the specified target root directory, rather than /. Just like for /, the directory needs to exist and be initialized for libostree use with ostree admin init-fs <sysroot path>.
  • --karg-root=ROOT: set the kernel root boot parameter to the given value. By default, the root parameter of the current boot is used.
  • --fstab=FSTAB: copy the given file into the deployment as /etc/fstab. If this parameter is omitted, the system fstab (/etc/fstab) is used.

A Note on SELinux

While not recommended, certain combinations of SELinux-using host systems and SELinux-using deployed systems might require disabling SELinux before deploying to avoid clashes between the host's SELinux policies and the SELinux labels in the deployed tree. To temporarily disable SELinux:

# setenforce 0

Configuration Format

Configuration files must be either valid JSON or TOML files. The syntax of a configuration is determined by its file extension: if it's .toml (case-insensitive), it's parsed as a TOML file. Otherwise, it's considered a JSON file. While the syntax of the formats obviously differs, the structure used by deploy-ostree is the same for both, which means JSON configuration files can be converted to TOML using a generic JSON-to-TOML converter (and vice versa).

Both formats use the same top-level configuration keys:

  • url or path (required): path or URL to the OSTree repository to pull from. Exactly one of these must be specified. If a relative path is specified, it is interpreted relative to:
    • if the configuration is a local file: the directory of the configuration file.
    • the current working directory otherwise.
  • ref (required): OSTree commit to deploy.
  • remote: name for the OSTree remote. If this remote already exists, it it replaced. By default, a random name is used.
  • stateroot: name of the OSTree stateroot to use. By default, a random name is generated.
  • kernel-args: list of additional kernel arguments. The root partition is always determined and included in the kernel command line automatically.
  • provisioners: list of provisioners to run after the OSTree commit is checked out. This must be an array of objects. Each object defines a provisioner based on the keys it contains. Different kinds of provisioners are documented below.

Script Provisioners

Script provisioners allow you to run custom script snippets defined inline in your configuration file. These will be run in the deployment directory after deployment, with both /etc and /var available.

The script is specified with the script key. The script text will be fed to the interpreter over stdin. The interpreter is /bin/sh by default, but can be overridden using the interpreter key. Note that the interpreter needs to be able to consume a script from stdin with no further arguments. An optional description can be set with the description key. This line will be shown during deploying to describe the provisioning step.

The working directory of the script is set to the root directory of the deployment. Accordingly, any paths in the deployment should be relative to the current directory. Note that the script is not chrooted in any way. This means you can mess up the host system from your script if you're not careful!

If you need to run binaries from the deployed system, you can manually chroot into the deployment directory. Ultimately, you have to weigh depending on your usecase whether you want to rely on the host system for any tools you need, or whether you want to run things from the deployed system. Keep in mind that when deploying cross-architecture, running binaries from the deployed system may not work.

JSON example:

{
    "script": "echo my-system > ./etc/hostname",
    "interpreter": "/bin/bash",
    "description": "hostname"
}

TOML example:

[[provisioners]]
script = "echo my-system > ./etc/hostname"
interpreter = "/bin/bash"
description = "hostname"

Built-in Provisioners

These are the provisioners included with deploy-ostree. The name of the provisioner must be set with the key builtin on the configuration object. Any options documented below must also be specified in the provisioner configuration object.

JSON example:

{
    "builtin": "root-password",
    "password": "password"
}

TOML example:

[[provisioners]]
builtin = "root-password"
password = "password"

etc-network-interfaces

Set up the loopback interface and one other interface for DHCP with /etc/network/interfaces. This probably only applies to Debian-based systems and only for DHCP configuration. If you need different configuration, you will have to supply your own provisioner or use something like NetworkManager.

  • interface: name of the interface to configure. By default, the default network interface is retrieved from /proc/net/route. However, this might differ between systems (especially if only one is using predictable interface names) so it's not guaranteed to work.

root-password

Set the root password.

  • password (required): root password to set.

create-user

Create a user. This does try to create the home directory, but if your system requires anything more than the stateroot's /var being mounted, it may not work.

  • username (required): username of the user to create.
  • password (required): password of the user to create.
  • shell: shell for the user. If not specified, the default shell is used.

passwordless-sudo

Set up a user for passwordless sudo access. For this to have any effect, sudo must be installed on your system.

  • user (required): name of the user.

authorized-keys

Copy an SSH authorized_keys file from the host system into the deployed system. This is useful in Vagrant scenarios, as it allows you to copy the SSH key used by Vagrant into the deployed system.

  • path (required): path of the keys file to copy into the deployed system. This is a path on the system that is running deploy-ostree, not in the deployed system.
  • user (required): name of the user to receive the keys. This must be a user in the deployed system. The file is copied to .ssh/authorized_keys inside the user's home directory.

machine-id

Create an /etc/machine-id file containing a random UUID. If the file already exists, it's not overwritten. This is necessary to get D-Bus to work on systems that don't create a machine ID file on boot if missing.

  • path: alternative path to the file. If missing, /etc/machine-id is used. Any directories in the path that are missing will be created.

Example Config

This configuration will download and deploy CentOS Atomic Host, set up /etc/fstab, and create a user and set it up for passwordless sudo.

JSON:

{
    "url": "http://mirror.centos.org/centos/7/atomic/x86_64/repo/",
    "ref": "centos-atomic-host/7/x86_64/standard",
    "remote": "centos-atomic",
    "stateroot": "centos-atomic-host",
    "kernel-args": ["quiet", "splash"],

    "provisioners": [
        {
            "builtin": "create-user",
            "username": "atomic",
            "password": "atomic",
            "shell": "/usr/bin/bash"
        },
        {
            "script": "echo centos-atomic-host > etc/hostname",
            "description": "hostname"
        },
        {
            "builtin": "passwordless-sudo",
            "user": "atomic"
        }
    ]
}

TOML:

url = "http://mirror.centos.org/centos/7/atomic/x86_64/repo/"
ref = "centos-atomic-host/7/x86_64/standard"
remote = "centos-atomic"
stateroot = "centos-atomic-host"
kernel-args = ["quiet", "splash"]

[[provisioners]]
builtin = "create-user"
username = "atomic"
password = "atomic"
shell = "/usr/bin/bash"

[[provisioners]]
script = "echo centos-atomic-host > etc/hostname"
description = "hostname"

[[provisioners]]
builtin = "passwordless-sudo"
user = "atomic"

Note that CentOS Atomic Host includes cloud-init which means it will spend some time unsuccessfully doing its cloud setup. This is awkward, but there's not a lot of OSTree systems to demonstrate with so here we are.

Version History

See the changelog for a list of versions and their changes.

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