DISCLAIMER:
I'm not responsible if You brick Your Onion following this tutorial. I'm Linux newbie so follow this tutorial on Your own reponsibillity

I tested it on 0.0.4 (b220) firmware.

Hi,
in this tutorial I'll show you how to install LAMP, FTP and PhpMyAdmin on your Onion Omega. In this tutorial I'll use nano for editing text (yes I'm newbie who deosen't use vi:) and you can install it with:

opkg update
opkg install nano

Make Your Onion to boot from USB storage

Apache as other packages requires a lot of space so first thing You will have to do is to extend your storage. I did this by following this tutorial. To do that you will have to format your USB storage into ext4 filesystem. You can do this by following commands:

opkg update
opkg install e2fsprogs
mkfs.ext4 /dev/<your partition>

(your partition is the same You got from fdisk command in the tutorial above)

Install SFTP
To install sftp use opkg install openssh-sftp-server command.

Install Apache server

opkg update
opkg install apache

Then edit httpd.conf:

nano /etc/apache/httpd.conf

Find Listen part in the file and change it into:

Listen <ip You use to connect to Your console>:<port number other than 80>

Also find ServerName and change it into:

ServerName <name for Your server>:<same port as in Listen>

Then you should find:

LogLevel debug

and change it into

LogLevel error

To start Apache server You hould execute:

apachectl start

Address of Your Apache server is : <Onion Console IP adress>:<Your chosen port>

Install PHP
Since I had some problems with PhpMyAdmin I installed all this packages for php (all of them are not required but those were that I installed)

opkg install php5 php5-cgi php5-fastcgi php5-mod-json php5-mod-session php5-mod-zip libsqlite3 zoneinfo-core php5-mod-pdo php5-mod-pdo-sqlite php5-mod-ctype php5-mod-mbstring php5-mod-gd sqlite3-cli php5-mod-sqlite3 php5-mod-curl curl php5-mod-xml php5-mod-simplexml php5-mod-hash php5-mod-dom php5-mod-iconv

Type:

ln -s /usr/bin/php-cgi /usr/share/cgi-bin/

and then add folowing lines into httpd.conf:

<Directory "/usr/share/cgi-bin">
    AllowOverride None
    Options FollowSymLinks
    Order allow,deny
    Allow from all
</Directory>

<Directory "/usr/bin">
    AllowOverride None
    Options none
    Order allow,deny
    Allow from all
</Directory>

Find ScriptAlias /cgi-bin/ "/usr/share/cgi-bin" and affter that line add ScriptAlias /php/ "/usr/bin" so you should have:

ScriptAlias /cgi-bin/ "/usr/share/cgi-bin"
ScriptAlias /php/ "/usr/bin"

Find <IfModule mime_module> section and add AddType application/x-httpd-php .php and Action application/x-httpd-php "/php/php-cgi"' into that section (before </IfModule>)so you should have:

AddType application/x-httpd-php .php
Action application/x-httpd-php "/php/php-cgi"
</IfModule> 

To change Directory Index, change DirectoryIndex index.html to DirectoryIndex index.php index.html.

Open php.ini:

nano /etc/php.ini

And uncomment (remove ; ) on lines:

extension  = gd.so
extension = mbstring.so
extension = pdo-mysql.so
extension = pdo_sqlite.so
extension = socket.so

Also do not specify doc_root so change doc_root into doc_root =

After that restart apache server: apachectl restart

Install mysql

opkg install mysql-server

Create two folders:

mkdir /mnt/data/mysql
mkdir /mnt/data/tmp

Use command:

mysql_install_db --force

Ok, nex step is to create root user (when I installed mysql, table with users was empty, if that's also Your case use this steps). Execute:

/usr/bin/mysqld --skip-grant-tables --skip-networking &
mysql -u root
use mysql;
FLUSH PRIVILEGES;
INSERT into user (Host, User,Password) values ('localhost','root',' ');
UPDATE user SET Password=PASSWORD('password you want') WHERE User='root';

update user set Select_priv='Y',Insert_priv='Y',Update_priv='Y',Delete_priv='Y',Create_priv='Y',Drop_priv='Y',Reload_priv='Y',Shutdown_priv='Y',Process_priv='Y',File_priv='Y',Grant_priv='Y',References_priv='Y',Index_priv='Y',Alter_priv='Y',Show_db_priv='Y',Super_priv='Y',Create_tmp_table_priv='Y',Lock_tables_priv='Y',Execute_priv='Y',Repl_slave_priv='Y',Repl_client_priv='Y',Create_view_priv='Y',Show_view_priv='Y',Create_routine_priv='Y',Alter_routine_priv='Y',Create_user_priv='Y' where user='root';

FLUSH PRIVILEGES;

To start mysql server you should type:

/etc/init.d/mysqld start

Install PhpMyAdmin
To install PhpMyAdmin you should download it from link and extract it to /usr/share/htdocs (Apache server root) and rename root folder of PhpMyAdmin (PhpMyAdmin-4..-allLanguages) to phpmyadmin.
You should copy the content of config.sample.inc.php to config.inc.php and edit it:

cp usr/share/htdocs/phpmyadmin/config.sample.inc.php usr/share/htdocs/phpmyadmin/config.inc.php
nano usr/share/htdocs/phpmyadmin/config.inc.php

Change Authentication type and Servers parameters into:

$cfg['Servers'][$i]['auth_type'] = 'cookie';

$cfg['Servers'][$i]['host'] = '127.0.0.1';
$cfg['Servers'][$i]['connect_type'] = 'tcp';
$cfg['Servers'][$i]['compress'] = false;
$cfg['Servers'][$i]['extension'] = 'mysql';
$cfg['Servers'][$i]['AllowNoPassword'] = true;

After that open /usr/share/htdocs/phpmyadmin/libraries/common.inc.php with nano (or whatever You use) and comment following part:

 #if (PMA_MYSQL_INT_VERSION < $cfg['MysqlMinVersion']['internal'] {
    #    PMA_fatalError(
    #        __('You should upgrade to %s %s or later.'),
    #        array('MySQL', $cfg['MysqlMinVersion']['human'])
    #    );
    #}

And that's it:)
You can access PhpMyAdmin on <Onion Console IP adress>:<Your chosen port>/phpmyadmin

UPDATE (ty to @Chris-MacKay)
If you get some permission errors change ScriptAlias /php/ "/usr/bin" to ScriptAlias /php/ "/usr/bin/" in httpd.conf .

However, following the instructions you referenced from https://samhobbs.co.uk/2013/11/more-space-for-packages-with-extroot-on-your-openwrt-router I now have my Omega running entirely from USB without any problems.

Consequently, I am now able to install jamvm (which I need for a compact Java VM on the Omega) though I did need to use the --force-depends option on opkg because of kernel/repo version mismatches - though it is in fact not causing any problems.

@Boken-Lin While I don't understand your reference to pivot-overlay vs pivot-root, if it makes an important difference, I will await your updates and re-do the loading on to USB

While the pivot-root method as referenced by @Josip-Mlakar in https://samhobbs.co.uk/2013/11/more-space-for-packages-with-extroot-on-your-openwrt-router appears to work well, i think I will change to the overlay-root method.

Will let you know if I hit any problems. And again thanks for the info

• mount /dev/sda1 /mnt ; tar -C /overlay -cvf - . | tar -C /mnt -xf - ; umount /mnt

I get the messages

• tar: empty archive
  tar: short read

I think this may be related to the fact that Step 2 said:

• mount /dev/sda1 /mnt/sda1

I think there is some issue as to where /dev/sda1 is mounted.
I am confused - can you clarify please. Thanks.

mount /dev/sda1 /mnt

then

tar -C /overlay -cvf - . | tar -C /mnt -xf -

Finally,

umount /mnt

mount /dev/sda1 /mnt ; tar -C /overlay -cvf - . | tar -C /mnt -xf - ; umount /mnt

via PuTTY I continued to get the same error. However using MobaXTerm it worked.
Now, my /mnt/sda1 directory has a copy of my /overlay directory.

So I proceeded with the subsequent steps:

block detect > /etc/config/fstab

Edited /etc/config/fstab to set enabled to '1'

reboot

But nothing seems to have changed on my Omega.
Sorry to swamp you with lots of information, but after the reboot, I have:

Output from df -h

root@Omega-0A97:/# df -h
Filesystem                Size      Used Available Use% Mounted on
rootfs                    8.4M    376.0K      8.1M   4% /
/dev/root                 6.5M      6.5M         0 100% /rom
tmpfs                    29.9M    456.0K     29.4M   1% /tmp
/dev/mtdblock3            8.4M    376.0K      8.1M   4% /overlay
overlayfs:/overlay        8.4M    376.0K      8.1M   4% /
tmpfs                   512.0K         0    512.0K   0% /dev
/dev/sda1                29.2G     44.0M     27.7G   0% /mnt/sda1
root@Omega-0A97:/#

Output from mount

root@Omega-0A97:/# mount
rootfs on / type rootfs (rw)
/dev/root on /rom type squashfs (ro,relatime)
proc on /proc type proc (rw,nosuid,nodev,noexec,noatime)
sysfs on /sys type sysfs (rw,nosuid,nodev,noexec,noatime)
tmpfs on /tmp type tmpfs (rw,nosuid,nodev,noatime)
/dev/mtdblock3 on /overlay type jffs2 (rw,noatime)
overlayfs:/overlay on / type overlay (rw,noatime,lowerdir=/,upperdir=/overlay/upper,workdir=/overlay/work)
tmpfs on /dev type tmpfs (rw,nosuid,relatime,size=512k,mode=755)
devpts on /dev/pts type devpts (rw,nosuid,noexec,relatime,mode=600)
/dev/sda1 on /mnt/sda1 type ext4 (rw,relatime,data=ordered)
debugfs on /sys/kernel/debug type debugfs (rw,noatime)
root@Omega-0A97:/#

Contents of /etc/config/fstab

root@Omega-0A97:/# cat /etc/config/fstab
config 'global'
        option  anon_swap       '0'
        option  anon_mount      '0'
        option  auto_swap       '1'
        option  auto_mount      '1'
        option  delay_root      '5'
        option  check_fs        '0'

config 'mount'
        option  target  '/mnt/sda1'
        option  uuid    'cad99fb9-c045-467a-b629-3acd4c170ae3'
        option  enabled '1'

root@Omega-0A97:/#

It looks like my USB is not getting mounted on /overlay.

Do you see anything wrong? Is there some step I have missed? Is there any other info I can supply that might help?

config 'mount'
        option  target  '/mnt/sda1'
        option  uuid    'cad99fb9-c045-467a-b629-3acd4c170ae3'
        option  enabled '1'

from /etc/config/fstab to:

config 'mount'
        option  target  '/overlay'
        option  uuid    'cad99fb9-c045-467a-b629-3acd4c170ae3'
        option  enabled '1'

While adapting @Josip-Mlakar 's guide to the Wiki, this step was missed.

Seems simple enough of a step, but it is assumed the drive is formatted as ext4 in further steps.

Thanks for both of yours' work!

@Josip-Mlakar said:

To do that you will have to format your USB storage into ext4 filesystem. You can do this by following commands:

opkg update
opkg install e2fsprogs
mkfs.ext4 /dev/<your partition>

#!/bin/sh /etc/rc.common
START=95
start() {
	apachectl start
}
restart() {
	apachectl restart
}
stop() {
	apachectl stop
}

made it executable with chmod +x /etc/init.d/apache
and then executed /etc/init.d/apache enable. It gets enabled and I can start it with /etc/init.d/apache startbut script doesen't start on boot I'll keep You updated if I find the solution:)

• A symlink in /etc/rc.d named S95apache that references your /etc/init.d/apache file
  Files named like S<nn>Xxxx in /etc/rc.d are executed in order of the <nn> at system boot time as S<nn>Xxxx start thus starting the referenced file
  Files named like K<nn>Xxxx in /etc/rc.d are executed in order of the <nn> at system shutdown time as K<nn>Xxxx stop thus stopping the referenced file

One small thing I would check though is your use of START=95 (and corresponding usage of 95 in S95apache and K95apache) - as far as I can see 95 is currently being used by /etc/init.d/done and /etc/rc.d/S95done and I am unsure about the effects of resuing the same number.

Just for the record, after some quick testing, i can confirm that the symlinks in /etc/rc.d do work as I expected and also that the START value (and the <nn> values) can be reused - I created a test file in /etc/init.d with START=95 and set up the S95 and K95 links which duplicate the 95 used by /etc/init.d/done and all worked fine,

Create a file /etc/init.d/apache, add the following content:

#!/bin/sh /etc/rc.common

START=12

USE_PROCD=1
NAME=apache
PROG=/usr/sbin/apachectl

start_service() {
        procd_open_instance
        procd_set_param command "$PROG" start
        procd_close_instance
}

stop() {
        /usr/sbin/apachectl stop
}

reload() {
        /usr/sbin/apachectl reload
}

Make the file executable:

chmod +x /etc/init.d/apache

Reboot again.

Please let me know if this works