OpenNebula Contextualization / OpenRC

This project provides “contextualization” scripts for Alpine Linux virtual machines running on OpenNebula.

The scripts are inspired by the official scripts from addon-context-linux, but rewritten from scratch to be more readable, robust and fully POSIX compatible. This is not yet another fork of these poor official scripts.

NOTE: Support for Gentoo has been removed in version 0.8.0. If you miss it, please let me know in the issues.

Scripts

00-network

Configures network interfaces (via /etc/network/interfaces) and (re)starts the networking service, if $NETWORK is YES. It supports the following variables:

$DNS — DNS servers (as space-separated addressess).
$SEARCH_DOMAIN — The domain search list.
$ETH<n>_MAC — Used to find the correct interface by MAC address.
$ETH<n>_IP — IPv4 address for the interface.
$ETH<n>_MASK — IPv4 network mask for the interface.
$ETH<n>_GATEWAY — Default IPv4 gateway for the interface.
$ETH<n>_IP6 (or legacy $ETH<n>_IPV6) — IPv6 address for the interface.
$ETH<n>_IP6_GATEWAY (or legacy $ETH<n>_GATEWAY6) — Default IPv6 gateway for the interface.
$ETH<n>_DNS — DNS servers for the network (as space-separated addressess).
$ETH<n>_SEARCH_DOMAIN — The domain search list for the network.

05-hostname

Sets the hostname to $SET_HOSTNAME, if provided. It should contain only alphanumeric ASCII characters and a hyphen ([a-zA-Z0-9-]), all other characters will be replaced with a hyphen (-).

10-hosts

Adds the following lines to /etc/hosts:

127.0.0.1  <fqdn> <hostname> localhost
::1        <fqdn> <hostname> localhost

<fqdn> is $SET_FQDN or, if not provided, $SET_HOSTNAME. It should contain only alphanumeric characters, a hyphen and a period ([a-zA-Z0-9.-]), all other characters will be replaced with a hyphen (-).

<hostname> is the system’s hostname (previously set to $SET_HOSTNAME).

15-ntp

Adds NTP servers specified in $NTP (as space-seperated addressess) to either /etc/ntpd.conf (OpenNTPD) or /etc/ntp.conf (ISC ntp), if $NTP is provided.

20-timezone

Changes the system timezone to $TIMEZONE (e.g. Europe/Prague, UTC), if provided.

50-sudo-user

Creates an user account named $USERNAME with primary group users, secondary group wheel, and shell $USERNAME_SHELL (defaults to /bin/sh). If $USERNAME_SUDO isn’t provided or it’s YES, it also creates a doas or sudo (if doas is not installed) rule in /etc/doas.d/wheel.conf or /etc/sudoers.d/wheel, respectively, to permit the created user to run any command as any user (i.e. gives them the root access).

If $USERNAME is not provided, this script is skipped.

55-ssh-public-key

Adds an SSH public key provided in $SSH_PUBLIC_KEY to authorized_keys of the user specified by $USERNAME (or root if not set), if $SSH_PUBLIC_KEY is provided.

60-grow-fs

Extends all mounted filesystems to the maximum disk capacity, unless $GROWFS_DISABLE is YES. Only ext3, ext4, and btrfs are currently supported.

If the filesystem resides on a partition (GPT or DOS) and it’s the last partition, it will be expanded before resizing the filesystem.

Note: It’s completely unnecessary and pointless to use partitions on virtual disks, it just adds more complexity and complications, but some broken platforms and tools require it.

65-ssmtp

Updates /etc/ssmtp/ssmtp.conf, if exists:

Root to $ROOT_EMAIL (if provided)
Mailhub to $SMTP (if provided)

90-start-script

Executes the script provided in $START_SCRIPT_BASE64 (base64-encoded) or $START_SCRIPT. If the script doesn’t start with a shebang, it’s executed with /bin/sh.

Requirements

POSIX-compatible shell (e.g. ash, bash, dash)
core *nix utils (awk, grep, sed…)
OpenRC
blkid from util-linux (for OpenRC runscript)
btrfs utility and/or resize2fs from e2fsprogs (only for growfs script)
partx and sfdisk from util-linux (only for grow-fs script if you use partitions)
ifup (only for network scripts)
kernel with support for mounting CD-ROM with ISO 9660 filesystem ^[1]

Installation

Alpine Linux

Install one-context from the Alpine’s main repository:
```
apk add one-context
```

Manually

Clone this repository and jump in:

git clone https://github.com/jirutka/one-context.git
cd one-context

Install init script, contextualization scripts and symlinks (you may need to run this with sudo)…
```
make install
```
You may use variables DESTDIR and PREFIX to specify the target directories.
rc-update add vmcontext boot

Directory Structure

The scripts are installed into /usr/share/one-context/scripts (depends on DESTDIR and PREFIX variables, see above) and symlinked into /etc/one-context.d with a numeric prefix to specify the execution order. The runscript is installed into /etc/init.d/vmcontext.

License

This project is licensed under MIT License.

1. This is the way how OpenNebula passes configuration variables into VM.