Alpine local backup: Difference between revisions

Revision as of 05:52, 29 March 2013

Alpine itself only loads a few required packages when you boot a clean Alpine Linux.
But you probably want to do some personal adjustments (e.g installing a package or doing some configuration).
Because Alpine runs on RAM (normally), and everything in RAM will get lost next time the box is rebooted or shut down, you will need to permanently save your modifications and adjustments to Alpine. This is where 'lbu' comes in handy!

Note: If you installed Alpine on HDD you don't need to use 'lbu'. All your modifications would be permanently stored on your HDD.

First thing you need to know is this: As default 'lbu' only cares about modifications in /etc/ and it's subfolders, with the exception of /etc/init.d/!
Please have a look at 'lbu include' to save files/folders located elsewhere than in /etc/.

Alpine has the following tools for permanently storing your modifications:

lbu
lbu_commit (Same as 'lbu commit')
lbu_exclude (Same as 'lbu exclude')
lbu_include (Same as 'lbu include')
lbu_status (Same as 'lbu status')
lbu_update (Same as 'lbu update')

In the below examples you will find some characters with special meaning

| = or ('lbu commit|ci' means that you can type ether 'lbu commit' or 'lbu ci')
[ ] = optional (In 'lbu commit|ci [-nv]' you can just skip the '-n', '-v' or '-nv' part if you don't want it)

Saving your changes

When you save your changes you will get a file that is named like 'myboxname.apkovl.tar.gz' ('myboxname' will be the same as the hostname).
This file (that contains your modifications) is called 'apkovl'.
You will need to save your 'apkovl' on some suitable media (floppy, usb, cf, other).

usage: lbu commit|ci [-nv] [<media>]

Options:
  -d	Remove old apk overlay files.
  -e	Protect configuration with a password.
  -n	Don't commit, just show what would have been committed.
  -p <password>	Give encryption password on the command-line
  -v	Verbose mode.

The following values for <media> is supported: floppy usb
If <media> is not specified, the environment variable LBU_MEDIA will be used.

Password protection will use aes-256-cbc encryption. Other ciphers can be
used by setting the DEFAULT_CIPHER or ENCRYPTION environment variables.
For possible ciphers, try: openssl -v

The password used to encrypt the file, can either be specified with the -p
option or using the PASSWORD environment variable.

The environment variables can also be set in /etc/lbu/lbu.conf

Include special files/folders to the apkovl

Assume that you have some files that you want to permanently save, but they are located somewhere else than in /etc/.
It could be /root/.ssh/authorized_keys (used by 'sshd' to authenticate ssh-users).
Such files/folders can be added to the /etc/lbu/include list by manually editing the file or using the following command:

usage: lbu include|inc|add [-rv] <file> ...
       lbu include|inc|add [-v] -l

Options:
  -l	List contents of include list.
  -r	Remove specified file(s) from include list instead of adding.
  -v	Verbose mode.

Note: This command only modifies some lbu-related config files. You will need to run 'lbu commit' to actually create/modify your apkovl.

Exclude specific files/folders from the apkovl

Assume that you have some files located in /etc/ or one of it's subfolders that you do not want to permanently save.
It could be some log file or status file that for some reason is elsewhere than in /var/log.
Such files/folders can be added to the /etc/lbu/exclude list by manually editing the file or using the following command:

usage: lbu exclude|ex|delete [-rv] <file> ...
       lbu exclude|ex|delete [-v] -l

Options:
  -l	List contents of exclude list.
  -r	Remove specified file(s) from exclude list instead of adding.
  -v	Verbose mode.

Note: This command only modifies some lbu-related config files. You will need to run 'lbu commit' to actually create/modify your apkovl.

Execute a script as part of a backup

Sometimes it is necessary to run a script before or after a backup. Scripts in two optional directories allow for this:

/etc/lbu/pre-package.d
/etc/lbu/post-package.d

Files in those directories are run using run-script rules (meaning they must have the executable bit set, they are run in alphabetical order, and cannot contain an "extension" e.g. runme works, runme.sh does not.)

The scripts in pre-package.d are run before the apkovl is created; scripts inpost-package.d are run after the apkovl is created.

Example

Rather than adding the raw database directories to /etc/lbu/include, you can do a "database dump". For purposes of example, we use postgresql:

Add the database dump file to the list of files to back up: lbu include root/pgdatabases.gz
Create /etc/lbu/pre-package.d/sqldump with the following contents: pg_dumpall -U postgres | gzip -c >/root/pgdatabases.gz
Mark the file executable: chmod +x /etc/lbu/pre-package.d/sqldump
Create /etc/lbu/post-package.d/sqldumpdelete with the following contents: rm -f /root/pgdatabases.gz
Mark the file executable: chmod +x /etc/lbu/post-package.d/sqldumpdelete

Now whenever you do a lbu commit, the sql databases are dumped and gzipped to /root/pgdatabases.gz, and then the temporary file is deleted at the end of the lbu commit.

On a catastrophic restore, the databases are not automatically restored (that's not lbu's responsibility), but you will find a complete database dump in the /root directory, where it can be restored manually.

Check what will be added to your apkovl

Sometimes it would be handy to know what files will be permanently saved next time you run 'lbu commit'. Here you have your help:

usage: lbu list|ls

Create a apkovl elsewhere than on some specific media

usage: lbu package|pkg -v [<dirname>|<filename>]

Options:
  -v	Verbose mode.

If <dirname> is a directory, a package named <hostname>.apkovl.tar.gz will
be created in the specified directory.

If <filename> is specified, and is not a directory, a package with the
specified name will be created.

If <dirname> nor <filename> is not specified, a package named
<hostname>.apkovl.tar.gz will be created in current work directory.

Use SSH to create an apkovl on a different host

To create an apkovl of client on a centralized server, use "-" as the apkovl name:

On the server:

ssh root@client "lbu package -" >client.apkovl.tar.gz

Check what files have been changed since last commit

usage: lbu status|st [-av]

Options:
  -a	Compare all files, not just since last commit.
  -v	Also show include and exclude lists.

Multiple Backups

Lbu can now keep backups so you can revert to older, good known config. Set BACKUP_LIMIT in /etc/lbu/lbu.conf to the number of backups you want to keep.

You can list the current backups with:

lbu list-backup [<media>]

and you can revert to an older with:

lbu revert <filename> [<media>]

Note that when you revert, the current apkovl on media will be backed up.