Securely serving webapps using uWSGI

David Runge

2016-10-08 09:00

Ever since I have been running my own Arch Linux box to serve my services, I used nginx in conjunction with uWSGI.
So instead of using php-fpm and be limited to just PHP, I can use a single application server to do all of them (CGI, Python, PHP and even the stuff I don't use, such as Ruby Rack, Mono, Java, Lua, Perl, WebDAV). They are all separately installable as plugins.
Static sites, such as this, default to being served by nginx directly of course.
Over time I found uWSGI to be a very versatile and powerful piece of software that has many advantages (over e.g. Apache):

socket activation
webapp encapsulation and jailing
self-healing
being able to separetely manage services
exit after idle

I'll explain the services I use (MantisBT, roundcube, ownCloud, Mailman, Stikked, Wordpress, Postfixadmin, phpMyAdmin, cgit, MediaWiki, Etherpad ) along with configuration examples and their possible pitfalls.

In my last post about Let's Encrypt I already showed some examples on how to configure nginx for the use with uWSGI. Let's jump right in.

Preparing nginx

nginx can serve dynamic websites only indirectly, because it is a web server for static content (HTML, CSS, JavaScript, images, videos, compressed files, etc.), unlike Apache, which uses plugins to take care of many scripting languages (PHP and the like).
In combination with uWSGI you are able to direct calls to dynamic content to something that handles those best: an application server. Meanwhile nginx will keep on serving the remaining static content.
This form of encapsulation has some noticeable security advantages, as every webapp is handled by a separate instance of that application server (and not your web server, which is less likely to blow up in your face because of security flaws in the used scripting language), and that in turn is only accessible through your web server.
Obviously this also makes it possible to use nginx as a load balancer and proxy, as you can have one machine serve your domains and just redirect the traffic to other machines plainly serving the webapps.
I will keep to examples using a single machine (for brevity).


nginx ships with /etc/nginx/uwsgi_params holding a set of parameters for the application server, that are set to some of the web server's internally used variables.

uWSGI uses a list of modifiers, that are explained in more detail in the list of packet descriptions and of which some correspond to the usage of certain script languages.
When redirecting to a webapp nginx uses uwsgi_pass in conjunction with the uwsgi_modifier1 stating the type of application:

include uwsgi_params;
uwsgi_modifier1 14;
uwsgi_pass unix:/run/uwsgi/mywebapp.sock;

Hardening uWSGI

uWSGI is quite a complex piece of software, but fortunately has a pretty well documented feature set and code base.
The way it is used in a systemd context on Arch Linux can be improved though (and will hopefully in the future).
I'm currently only using socket activation for my webapps (not in Emperor mode), so all examples will be about how to set that up correctly.
Following are the current service and socket file shipped with the package in the community repository.

/usr/lib/systemd/system/uwsgi-secure@.service

[Unit]
Description=uWSGI service unit
After=syslog.target

[Service]
ExecStart=/usr/bin/uwsgi --ini /etc/uwsgi/%I.ini
ExecReload=/bin/kill -HUP $MAINPID
ExecStop=/bin/kill -INT $MAINPID
Restart=always
Type=notify
StandardError=syslog
NotifyAccess=all
KillSignal=SIGQUIT

[Install]
WantedBy=multi-user.target

/usr/lib/systemd/system/uwsgi-secure@.socket

[Unit]
Description=Socket for uWSGI %I

[Socket]
# Change this to your uwsgi application port or unix socket location
ListenStream=/run/uwsgi/%I.sock

[Install]
WantedBy=sockets.target

As the @ in the service/socket files already suggest: You start them using a configuration file (to be found in /etc/uwsgi/) name as parameter, similar to:

systemctl start uwsgi-secure@mywebapp

When using socket activation, you would do

systemctl start uwsgi-secure@mywebapp.socket

which will then start the uwsgi@mywebapp.service automatically, once the socket is accessed by your web server.
Starting your webapp in this context generally means, using a configuration file for uwsgi, found in /etc/uwsgi/mywebapp.ini.
Let's pretend that mywebapp is a PHP application. This is an abbreviated example of how your configuration might look like:

/etc/uwsgi/mywebapp.ini

[uwsgi]
# name the process
procname-master = mywebapp
# define the plugin
plugins = php
# define a master process for this app
master = true
# this is where the socket resides
socket = /run/uwsgi/%n.sock
# we want to use this user and group (or any other)
uid = http
gid = http
# give this application a maximum of 10 processes
processes = 10

# dynamic scaling
# minimum amount of workers/processes to keep at all times
cheaper = 2
# increase workers/processes by step
cheaper-step = 1

# mark as idle after 10 minutes
idle = 600
# kill the webapp when it is idle
die-on-idle = true

# allow no other extenseion than .php
php-allowed-ext = .php
# fix our application in this directory
php-docroot = /usr/share/webapps/mywebapp
# set the standard index
php-index = index.php
php-set = date.timezone=Europe/Berlin
# the application needs access to the following directories
php-set = open_basedir=/tmp/:/usr/share/webapps/mywebapp:/etc/webapps/mywebapp
# this is where we save our sessions
php-set = session.save_path=/tmp

# mywebapp needs the following PHP extensions
php-set = extension=curl.so
php-set = extension=gd.so
php-set = extension=imagick.so
php-set = extension=intl.so
php-set = extension=mysqli.so
php-set = extension=pdo_mysql.so

As you can see: You can (and should) setup your own PHP environment for your webapp. All settings will only be available to that specific app (alongside global settings found in /etc/php/php.ini, /etc/php/conf.d/).
My suggestion is to disable all system-wide PHP settings and then start to build settings for all your applications. This is much safer, than e.g. an extensive open_basedir for all applications. On top: Many applications will not need all the extensions enabled, so just enable the ones they need!

You probably also noticed the idle and die-on-idle settings here. This will make uWSGI exit itself, when it is not needed after a given time. This feature will not work with the provided service files however, because systemd will restart the service automatically (given the above service files). Once uWSGI is running, it might exit, but will start again immediately, which is not a resource gentle approach at all.
The application server provides a non-zero, non-one exit code upon exiting by itself. To systemd this by default means failure though. So, how do we fix that and what kind of exit codes does uWSGI actually give?
To find out about that, let's dig into uwsgi.h in the uWSGI source code (at the time of writing version 2.0.14), where we will find the following:

uwsgi-2.0.14/uwsgi.h

#define UWSGI_RELOAD_CODE 17
#define UWSGI_END_CODE 30
#define UWSGI_EXILE_CODE 26
#define UWSGI_FAILED_APP_CODE 22
#define UWSGI_DE_HIJACKED_CODE 173
#define UWSGI_EXCEPTION_CODE 5
#define UWSGI_QUIET_CODE 29
#define UWSGI_BRUTAL_RELOAD_CODE 31
#define UWSGI_GO_CHEAP_CODE 15

As you can see, we have exit code 15, 17, 29 and 30 reserved for non-failing exits, while 26 is used in Emperor mode and 22, 5, 173, 31 are used for failed exits or even worse.

systemd however treats every non-zero exit code in its services as a failure and therefore would not start the service again, once it killed itself and was started by socket activation again afterwards.
Luckily, the many configuration possibilities of service files come to help. Here is what I came up with (with added hardening):

/etc/systemd/system/uwsgi-private@.service

[Unit]
Description=uWSGI service unit
After=syslog.target

[Service]
ExecStart=/usr/bin/uwsgi --ini /etc/uwsgi/%I.ini
Type=notify
SuccessExitStatus=15 17 29 30
StandardError=syslog
NotifyAccess=all
KillSignal=SIGQUIT
PrivateDevices=yes
PrivateTmp=yes
ProtectSystem=full
ReadWriteDirectories=/etc/webapps /var/lib/
ProtectHome=yes
NoNewPrivileges=yes

[Install]
WantedBy=multi-user.target

/etc/systemd/system/uwsgi-private@.service

[Unit]
Description=Socket for uWSGI %I

[Socket]
# Change this to your uwsgi application port or unix socket location
ListenStream=/run/uwsgi/%I.sock

[Install]
WantedBy=sockets.target

While the socket file is just a copy of the original, I have tweaked the service.
This way the above mentioned exit codes are treated as success, instead of failure by systemd and each uWSGI instance will get its own private temporary directory below /tmp/.
Additionally, the /home, /root and /run/user directories appear empty and system directories, such as /boot, /usr and /etc are read-only to the service.
Because of configuration and temporary data, I excluded /etc/webapps and /var/lib from the above rules.
For further information on these settings, have a look at the systemd.exec manual.

Now a proper starting via socket activation, (harmless) suicide of the service and a re-activation (again via socket) can take place!

Webapps

I will go through many examples, that facilitate this setup (some with varying backends though).
For brevity and due to my earlier post I will only explain whatever happens within nginx's server directive (whether you choose to serve your webapps encrypted or not, is not up to me, although I would always encourage encryption!).

MantisBT

For a couple of weeks now, I have been maintaining MantisBT in the AUR, since it was dropped from the community repository earlier and I always wanted to try a self-hosted bug tracker. It is a PHP based application, that is actively maintained, but ironically also still features many bugs (and then there was that change to PHP7).
It is non-trivial to setup, but once you get the grip on it, it's actually quite nice and has a bunch of interesting features.

Here is, how I serve it on a subdomain

/etc/nginx/mantisbt.conf

# ...

location ~ ^/(admin|core|doc|lang) {
  deny all;
  access_log off;
  log_not_found off;
}

location / {
  index index.php;
  try_files $uri $uri/ @mantisbt;
}

location @mantisbt {
  include uwsgi_params;
  uwsgi_modifier1 14;
  uwsgi_pass unix:/run/uwsgi/mantisbt.sock;
}

location ~  \.php?$ {
  include uwsgi_params;
  uwsgi_modifier1 14;
  uwsgi_pass unix:/run/uwsgi/mantisbt.sock;
}

# Deny serving files beginning with a dot, but allow letsencrypt acme-challenge
location ~ /\.(?!well-known/acme-challenge) {
  access_log off;
  log_not_found off;
  deny all;
}

# ...

/etc/uwsgi/mantisbt.ini

[uwsgi]
procname-master = mantisbt
plugins = php
master = true
socket = /run/uwsgi/%n.sock
uid = http
gid = http
processes = 10
cheaper = 2
cheaper-step = 1
idle = 600
die-on-idle = true

php-allowed-ext = .php
php-docroot = /usr/share/webapps/mantisbt
php-index = index.php
php-set = date.timezone=Europe/Berlin
php-set = open_basedir=/tmp/:/usr/share/fonts/TTF:/usr/share/webapps/mantisbt:/usr/share/webapps/mantisbt/core:/etc/webapps/mantisbt
php-set = session.save_path=/tmp
php-set = session.gc_maxlifetime 21600
php-set = session.gc_divisor 500
php-set = session.gc_probability 1
php-set = post_max_size=64M
php-set = upload_max_filesize=64M
php-set = always_populate_raw_post_data=-1

php-set = extension=curl.so
php-set = extension=gd.so
php-set = extension=imagick.so
php-set = extension=intl.so
php-set = extension=mysqli.so
php-set = extension=pdo_mysql.so

Roundcube

I have used the excellent webmail frontend for many years now and it just keeps getting better, I think. I would not want to miss its nice features ranging from sieve and GnuPG integration, to password reset and simple folder management.

/etc/nginx/roundcube.conf

# ...

location / {
  index index.php;
  try_files $uri $uri/$args @roundcubemail;
}

location @roundcubemail {
  include uwsgi_params;
  uwsgi_modifier1 14;
  uwsgi_pass unix:/run/uwsgi/roundcubemail.sock;
}

location ~ ^/favicon.ico$ {
  root /usr/share/webapps/roundcubemail/skins/classic/images;
  log_not_found off;
  access_log off;
  expires max;
}

location = /robots.txt {
  allow all;
  log_not_found off;
  access_log off;
  expires 30d;
}

# Deny serving some files
location ~ ^/(composer\.json-dist|composer\.json|package\.xml|CHANGELOG|INSTALL|LICENSE|README\.md|UPGRADING|bin|config|installer|program\/(include|lib|localization|steps)|SQL|tests)$ {
  deny all;
}

# Deny serving files beginning with a dot, but allow letsencrypt acme-challenge
location ~ /\.(?!well-known/acme-challenge) {
  deny all;
  access_log off;
  log_not_found off;
}

# ...

/etc/uwsgi/roundcubemail.ini

[uwsgi]
procname-master = roundcubemail
plugins = php
socket = /run/uwsgi/%n.sock
master = true
uid = http
gid = http
processes = 10
cheaper = 2
cheaper-step = 1
idle = 60
die-on-idle = true
; create a cache with 1000 items named roundcube
cache2 = name=roundcube,items=1000

php-allowed-ext = .php
php-docroot = /usr/share/webapps/roundcubemail
php-index = index.php
php-set = date.timezone=Europe/Berlin
php-set = session.save_path=/tmp
php-set = session.save_handler=uwsgi
php-set = session.gc_maxlifetime 21600
php-set = session.gc_divisor 500
php-set = session.gc_probability 1
php-set = open_basedir=/tmp/:/usr/share/webapps/roundcubemail/:/etc/webapps/roundcubemail/:/var/cache/roundcubemail/:/var/log/roundcubemail/:/secure/location/of/gnupg/keys/for/enigma:/usr/bin/gpg:/usr/bin/gpg-agent
php-set = post_max_size=64M
php-set = upload_max_filesize=64M
php-set = error_reporting=E_ALL
php-set = log_errors=On
php-set = extension=exif.so
php-set = extension=iconv.so
php-set = extension=intl.so
php-set = extension=imap.so
php-set = extension=mcrypt.so
php-set = extension=pdo_mysql.so
php-set = extension=pspell.so
php-set = extension=zip.so

ownCloud

I guess the open-source cloud solution ownCloud has by now reached many homes and work places. It has so many useful features (extended by apps), that it is hard to keep track.
In any case it is very useful for synchronizing your contacts, calendars and files between many devices and enables you to share files with other ownCloud users or the general public.

/etc/nginx/owncloud.conf

# ...

location = /robots.txt {
  allow all;
  log_not_found off;
  access_log off;
}

location ~ ^/(?:\.htaccess|data|config|db_structure\.xml|README) {
  deny all;
  log_not_found off;
  access_log off;
}

location ~ ^(.+\.php)(.*)$ {
  include uwsgi_params;
  uwsgi_modifier1 14;
  uwsgi_pass unix:/run/uwsgi/owncloud.sock;
  uwsgi_intercept_errors on;
}

location / {
  root /usr/share/webapps/owncloud;
  index index.php;
  rewrite ^/.well-known/host-meta /public.php?service=host-meta last;
  rewrite ^/.well-known/host-meta.json /public.php?service=host-meta-json last;
  rewrite ^/.well-known/carddav /remote.php/dav/ redirect;
  rewrite ^/.well-known/caldav /remote.php/dav/ redirect;
  rewrite ^(/core/doc/[^\/]+/)$ $1/index.html;
  rewrite ^/caldav(.*)$ /remote.php/dav$1 redirect;
  rewrite ^/carddav(.*)$ /remote.php/dav$1 redirect;
  rewrite ^/webdav(.*)$ /remote.php/dav$1 redirect;
  try_files $uri $uri/ /index.php;
}

location ~ ^/.(?:jpg|jpeg|gif|bmp|ico|png|css|js|swf)$ {
  expires 30d;
  access_log off;
}

# ...

/etc/uwsgi/owncloud.ini

[uwsgi]
procname-master = owncloud
plugins = php
master = true
socket = /run/uwsgi/%n.sock
uid = http
gid = http
processes = 10
cheaper = 2
cheaper-step = 1
idle = 600
die-on-idle = true

owncloud_data_dir = /absolute/path/to/where/your/data/resides
owncloud_writable_apps_dir = /absolute/path/to/writable/apps
chdir = %(owncloud_data_dir)

php-allowed-ext = .php
php-docroot = /usr/share/webapps/owncloud
php-index = index.php
php-set = date.timezone=Europe/Berlin
php-set = open_basedir=%(owncloud_data_dir):%(owncloud_writable_apps_dir):/tmp/:/usr/share/webapps/owncloud:/etc/webapps/owncloud:/dev/urandom:/run/redis/redis.sock
php-set = session.save_path=/tmp
php-set = session.gc_maxlifetime 21600
php-set = session.gc_divisor 500
php-set = session.gc_probability 1
php-set = post_max_size=1000M
php-set = upload_max_filesize=1000M
php-set = always_populate_raw_post_data=-1
php-set = max_input_time=120
php-set = max_execution_time=60
php-set = memory_limit=256M

php-set = extension=bz2.so
php-set = extension=curl.so
php-set = extension=exif.so
php-set = extension=gd.so
php-set = extension=imagick.so
php-set = extension=intl.so
php-set = extension=gmp.so
php-set = extension=iconv.so
php-set = extension=mcrypt.so
php-set = extension=pdo_mysql.so
php-set = extension=redis.so
php-set = extension=sockets.so
php-set = extension=xmlrpc.so
php-set = extension=xsl.so
php-set = extension=zip.so

cron = -15 -1 -1 -1 -1 curl --silent https://owncloud.domain.tld/cron.php 1>/dev/null

You can see here, that uWSGI is also able to launch a timed command through its cron directive. In this case I am using it to have the call to cron.php also be handled by the application server, instead of writing a timer service or using crontab.

Mailman

The mailing list software Mailman has been around for ages. The Python-based scripts, templates and CGI frontend are used all around the globe in small to large-scale setups.
Due to its age and the sometimes very quirky adoptation of the software by several Linux distributions, Mailman has a not so trivial setup (after all you have to connect it to your MTA and serve its web-frontend).
It was slightly annoying to set it up in my case, but eventually it all worked out.

/etc/nginx/mailman.conf

# ...

# Send all access to / to uwsgi
location / {
  gzip off;
  include uwsgi_params;
  uwsgi_modifier1 9;
  uwsgi_pass unix:/run/uwsgi/mailman.sock;
}

# Set alias for accessing /icons
location /icons {
  alias /usr/lib/mailman/icons;
  autoindex on;
}

# Set alias for accessing /archives
location /archives {
  alias /var/lib/mailman/archives/public;
  autoindex on;
}

# Deny serving files beginning with a dot, but allow letsencrypt acme-challenge
location ~ /\.(?!well-known/acme-challenge) {
  access_log off;
  log_not_found off;
  deny all;
}

# ...

You might wonder about the /archives location at this point. I setup my Mailman instance to serve the archive there, instead of pipermail:

/etc/mailman/mm_cfg.py

# ...

DEFAULT_URL_PATTERN = 'https://%s/'
PUBLIC_ARCHIVE_URL = 'https://%(hostname)s/archives/%(listname)s'

# ...

I am also removing the useless /mailman/cgi-bin/ suffix, because I can.

/etc/uwsgi/mailman.ini

[uwsgi]
procname-master = mailman
master = true
plugins = cgi
socket = /run/uwsgi/%n.sock
processes = 1
threads = 2
cheaper-step = 1
idle = 120
die-on-idle = true
uid = http
gid = http
cgi = /=/usr/lib/mailman/cgi-bin
cgi-index = listinfo

As you can see, the frontend does not require a lot of special treatment at all.

There is one pitfall however, which leads us right back to the above proposed systemd service file. It does not allow the changing of users or rather acquiring of new privilegdes.
Unfortunately, that is just what Mailman does...

/etc/systemd/system/uwsgi@.service

[Unit]
Description=uWSGI service unit
After=syslog.target

[Service]
ExecStart=/usr/bin/uwsgi --ini /etc/uwsgi/%I.ini
Type=notify
SuccessExitStatus=15 17 29 30
StandardError=syslog
NotifyAccess=all
KillSignal=SIGQUIT
PrivateDevices=yes
PrivateTmp=yes
ProtectSystem=full
ReadWriteDirectories=/etc/webapps
ProtectHome=yes

[Install]
WantedBy=multi-user.target

My proposed fix for this is to leave out NoNewPrivileges=yes for now, as ugly as this may seem. Mailman seems to be the only webapp I have encountered so far, that requires this.

Stikked

The PHP-based little webapp Stikked is able to be your own little pastebin replacement. There are also some nice cli's around for it.

/etc/nginx/stikked.conf

# ...

location / {
  index index.php;
  try_files $uri $uri/ @stikked;
}

location @stikked {
  rewrite ^/(.*)$ /index.php?/$1 last;
}

location ~ \.php?$ {
  include uwsgi_params;
  uwsgi_modifier1 14;
  uwsgi_pass unix:/run/uwsgi/stikked.sock;
}

# Deny serving some directories
location ^~ ^/(application|system)/ {
  deny all;
}

# Serve some static files
location ~* ^.+(favicon.ico|static|robots.txt) {
  expires 30d;
}

# Deny serving files beginning with a dot, but allow letsencrypt acme-challenge
location ~ /\.(?!well-known/acme-challenge) {
  access_log off;
  log_not_found off;
  deny all;
}

# ...

/etc/uwsgi/stikked.ini

[uwsgi]
procname-master = stikked
plugins = php
master = true
socket = /run/uwsgi/%n.sock
uid = http
gid = http
processes = 10
cheaper = 2
cheaper-step = 1
idle = 120
die-on-idle = true
cache2 = name=stikked,items=1000

php-allowed-ext = .php
php-index = index.php
php-docroot = /usr/share/webapps/Stikked
php-set = date.timezone=Europe/Berlin
php-set = open_basedir=/tmp/:/usr/share/webapps/Stikked/:/etc/webapps/stikked/
php-set = session.save_path=stikked
php-set = session.save_handler=uwsgi
php-set = session.gc_maxlifetime 21600
php-set = session.gc_divisor 500
php-set = session.gc_probability 1
php-set = extension=gd.so
php-set = extension=mysqli.so

# cleanup pastes every 5 minutes
cron = -5 -1 -1 -1 -1 curl --silent https://stikked.domain.tld/index.php/cron/stringFromConfig

Again, I am using uWSGI's cron functionality. This time to call Stikked to make it delete old pastes from time to time.

Wordpress

Although I try really hard to get around Wordpress wherever I can by now, it is used by many for their websites and I am also still responsible for a few instances myself. According to its Wikipedia article, the PHP-based CMS has reached a worldwide coverage of more than 25%.

That's pretty crazy, considering its long history of vulnerabilities.

/etc/nginx/wordpress.conf

# ...

index index.php;

## Global restrictions
location = /favicon.ico {
  log_not_found off;
  access_log off;
}

location = /robots.txt {
  allow all;
  log_not_found off;
  access_log off;
}

# Deny all attempts to access hidden files such as .htaccess, .htpasswd, .DS_Store (Mac).
# Keep logging the requests to parse later (or to pass to firewall utilities such as fail2ban)
location ~ /\. {
  deny all;
}

# Deny access to any files with a .php extension in the uploads directory
# Works in sub-directory installs and also in multisite network
# Keep logging the requests to parse later (or to pass to firewall utilities such as fail2ban)
location ~* /(?:uploads|files)/.*\.php$ {
  deny all;
}

## WordPress multisite subdirectory rules.
# This order might seem weird - this is attempted to match last if rules below fail.
# http://wiki.nginx.org/HttpCoreModule
location / {
  try_files $uri $uri/ /index.php?$args;
}

# Directives to send expires headers and turn off 404 error logging.
location ~* \.(js|css|png|jpg|jpeg|gif|ico)$ {
  expires 24h;
  log_not_found off;
}

# Add trailing slash to */wp-admin requests.
rewrite /wp-admin$ $scheme://$host$uri/ permanent;

# Directives to send expires headers and turn off 404 error logging.
location ~* ^.+\.(ogg|ogv|svg|svgz|eot|otf|woff|mp4|ttf|rss|atom|jpg|jpeg|gif|png|ico|zip|tgz|gz|rar|bz2|doc|xls|exe|ppt|tar|mid|midi|wav|bmp|rtf)$ {
  access_log off;
  log_not_found off;
  expires max;
}

# Uncomment one of the lines below for the appropriate caching plugin (if used).
#include global/wordpress-ms-subdir-wp-super-cache.conf;
#include global/wordpress-ms-subdir-w3-total-cache.conf;

# Rewrite multisite '.../wp-.*' and '.../*.php'.
if (!-e $request_filename) {
  rewrite /wp-admin$ $scheme://$host$uri/ permanent;
  rewrite ^/[_0-9a-zA-Z-]+(/wp-.*) $1 last;
  rewrite ^/[_0-9a-zA-Z-]+(/.*\.php)$ $1 last;
}

# Pass all .php files on to uwsgi
location ~ \.php$ {
  include uwsgi_params;
  uwsgi_modifier1 14;
  uwsgi_pass unix:/run/uwsgi/wordpress.sock;
}

## Errors
# redirect server error pages to the static page /50x.html
error_page   500 502 503 504  /50x.html;
location = /50x.html {
  root   /usr/share/nginx/html;
}

# ...

This setup is also ready for Wordpress' multisite feature.

/etc/uwsgi/wordpress.ini

[uwsgi]
procname-master = wordpress
plugins = php
master = true
socket = /run/uwsgi/%n.sock
uid = http
gid = http
processes = 10
cheaper = 2
cheaper = 1
idle = 360
die-on-idle = true
cache2 = name=wordpress,items=1000

php-allowed-ext = .php
php-docroot = /srv/http/websites/domain.tld
php-index = index.php
php-set = date.timezone=Europe/Berlin
php-set = open_basedir=/srv/http/websites/domain.tld:/tmp/:/usr/share/pear/
php-set = upload_max_filesize=24M
php-set = post_max_filesize=64M
php-set = post_max_size=64M
php-set = session.save_path=/tmp
php-set = session.save_handler=uwsgi
php-set = session.gc_maxlifetime 21600
php-set = session.gc_divisor 500
php-set = session.gc_probability 1

php-set = extension=gd.so
php-set = extension=iconv.so
php-set = extension=mysqli.so

; run wp-cron.php job for wordpress every 10 minutes
cron = -10 -1 -1 -1 -1 curl --silent https://domain.tld/wp-cron.php 1>/dev/null

Yet again, the calling of wp-cron.php is taken care of by uWSGI directly.

PostfixAdmin

When using Postfix as your MTA and MariaDB as a backend for your user data, Postfixadmin is a very nice and easy choice to add, delete and change accounts, forwards, etc. for all the domains you run.

Nevertheless, this is most likely one of those webapps you might want to hide behind a geoblocker and use a VPN to access it.

/etc/nginx/postfixadmin.conf

# ...

location / {
  index index.php;
}

# pass all .php or .php/path urls to uWSGI
location ~ ^(.+\.php)(.*)$ {
  include uwsgi_params;
  uwsgi_modifier1 14;
  uwsgi_pass unix:/run/uwsgi/postfixadmin.sock;
}

location ~ ^/(config|installer|composer.json-dist|.htaccess|CHANGELOG|INSTALL|LICENSE|README.md|UPGRADING) {
  access_log off;
  log_not_found off;
  deny all;
}

# Serve some static files
location ~* ^.+(robots.txt) {
  allow all;
  log_not_found off;
  access_log off;
  expires 30d;
}

# Deny serving files beginning with a dot, but allow letsencrypt acme-challenge
location ~ /\.(?!well-known/acme-challenge) {
  access_log off;
  log_not_found off;
  deny all;
}

# ...

/etc/uwsgi/postfixadmin.ini

[uwsgi]
procname-master = postfixadmin
master = true
plugins = php
socket = /run/uwsgi/%n.sock
uid = http
gid = http
processes = 10
cheaper = 2
cheaper-step = 1
idle = 120
die-on-idle = true

php-allowed-ext = .php
php-docroot = /usr/share/webapps/postfixAdmin
php-index = index.php
php-set = date.timezone=Europe/Berlin
php-set = open_basedir=/tmp/:/usr/share/webapps/postfixAdmin/:/etc/webapps/postfixadmin/:/usr/share/doc/postfixadmin/
php-set = session.save_path=/tmp
php-set = session.gc_maxlifetime 21600
php-set = session.gc_divisor 500
php-set = session.gc_probability 1
php-set = extension=mysqli.so
php-set = extension=imap.so

As you would suspect, what this application needs, is not much.
I recommend having a very close look at the configuration file though!

phpMyAdmin

If you don't feel like writing SQL statements to modify your databases, there is phpMyAdmin available to offer a pretty extensive administrative backend.
This PHP webapp is another one I would not necessarily offer for public access (especially not over plain http).

/etc/nginx/phpmyadmin.conf

# ...

client_max_body_size 200M;

location / {
  index index.php;
}

location ~ ^(.+\.php)(.*)$ {
  include uwsgi_params;
  uwsgi_modifier1 14;
  uwsgi_pass unix:/run/uwsgi/phpmyadmin.sock;
}

# Serve some static files
location ~* ^.+(print.css|favicon.ico|robots.txt) {
  expires 30d;
}

location ~ ^/(setup|CONTRIBUTING.md|ChangeLog|DCO|LICENSE|README|RELEASE-DATE*|composer.json) {
  deny all;
}

# Deny serving files beginning with a dot, but allow letsencrypt acme-challenge
location ~ /\.(?!well-known/acme-challenge) {
  access_log off;
  log_not_found off;
  deny all;
}

# ...

/etc/uwsgi/phpmyadmin.ini

[uwsgi]
procname-master = phpmyadmin
plugins = php
master = true
socket = /run/uwsgi/%n.sock
uid = http
gid = http
processes = 10
cheaper = 2
cheaper-step = 1
idle = 600
die-on-idle = true

php-allowed-ext = .php
php-docroot = /usr/share/webapps/phpMyAdmin
php-index = index.php
php-set = date.timezone=Europe/Berlin
php-set = open_basedir=/tmp/:/usr/share/webapps/phpMyAdmin:/etc/webapps/phpmyadmin
php-set = session.save_path=/tmp
php-set = session.gc_maxlifetime 21600
php-set = session.gc_divisor 500
php-set = session.gc_probability 1
php-set = post_max_size=64M
php-set = upload_max_filesize=64M
php-set = extension=bz2.so
php-set = extension=mysqli.so
php-set = extension=mcrypt.so
php-set = extension=zip.so

cgit

The blazingly fast CGI web-interface for git - the amazing VCS - is a must for everyone self-hosting some repositories.

cgit does not require a database, is themeable and very configurable. In conjunction with lightweight access control systems, such as gitosis, you get a very fast and flexible setup.

/etc/nginx/cgit.conf

# ...

location ~* ^.+(cgit.(css|png)|favicon.ico|robots.txt|\.well-known/acme-challenge) {
  expires 30d;
}

location / {
  try_files $uri @cgit;
}

location @cgit {
  gzip off;
  include uwsgi_params;
  uwsgi_modifier1 9;
  uwsgi_pass unix:/run/uwsgi/cgit.sock;
}

location = /50x.html {
  root /usr/share/nginx/html;
}

# ...

/etc/uwsg/cgit.ini

[uwsgi]
procname-master = cgit
master = true
plugins = cgi
socket = /run/uwsgi/%n.sock
uid = http
gid = http
processes = 1
threads = 2
cheaper-step = 1
idle = 120
die-on-idle = true
cgi = /usr/lib/cgit/cgit.cgi

Mediawiki

The well-known wiki software MediaWiki is used in a variety of projects and useful in many contexts.
I use it mainly for personal documentation, but it is of course also a great tool for collaborative knowledge representation (e.g. Wikipedia, Arch Linux Wiki) and planning (e.g. 32C3, LAC2016).

/etc/nginx/mediawiki.conf

# ...

location / {
  index index.php;
  try_files $uri $uri/ @mediawiki;
}
location @mediawiki {
  rewrite ^/(.*)$ /index.php?title=$1&$args;
}
location ~ \.php5?$ {
  include uwsgi_params;
  uwsgi_modifier1 14;
  uwsgi_pass unix:/run/uwsgi/mediawiki.sock;
}
location ~* \.(js|css|png|jpg|jpeg|gif|ico)$ {
  try_files $uri /index.php;
  expires max;
  log_not_found off;
}
# Restrictions based on the .htaccess files
location ^~ ^/(cache|includes|maintenance|languages|serialized|tests|images/deleted)/ {
  deny all;
}
location ^~ ^/(bin|docs|extensions|includes|maintenance|mw-config|resources|serialized|tests)/ {
  internal;
}
location ^~ /images/ {
  try_files $uri /index.php;
}
# Deny serving files beginning with a dot, but allow letsencrypt acme-challenge
location ~ /\.(?!well-known/acme-challenge) {
  access_log off;
  log_not_found off;
  deny all;
}

# ...

/etc/uwsgi/mediawiki.ini

[uwsgi]
procname-master = mediawiki
plugins = php
master = true
socket = /run/uwsgi/%n.sock
uid = http
gid = http
processes = 10
cheaper = 2
cheaper-step = 1
idle = 360
die-on-idle = true
cache2 = name=mediawiki,items=1000

php-allowed-ext = .php
php-docroot = /usr/share/webapps/mediawiki
php-index = index.php
php-set = date.timezone=Europe/Berlin
php-set = open_basedir=/tmp/:/usr/share/pear/:/usr/share/webapps/mediawiki/:/etc/webapps/mediawiki/:/var/lib/mediawiki/:/usr/bin/
php-set = include_path=.:/usr/share/pear
php-set = log_errors=On
php-set = display_errors=Off
php-set = error_reporting=E_ALL
php-set = upload_max_filesize=128M
php-set = post_max_filesize=128M
php-set = post_max_size=128M
php-set = session.save_path=/tmp
php-set = session.gc_maxlifetime 21600
php-set = session.gc_divisor 500
php-set = session.gc_probability 1
php-set = extension=gd.so
php-set = extension=iconv.so
php-set = extension=intl.so
php-set = extension=mysqli.so
php-set = extension=redis.so

MediaWiki instances need proper spam protection, especially, if you want to run them in the wild.
It is no fun to delete hundreds of spam bot users and pages (been there, done that, good times).
Make sure to spend some time with your configuration and monitor the wiki instance closely!

Etherpad

Etherpad is a beast of its own, because it is a NodeJS application, so it does not require any application server.
Although it is a very useful tool for collaborative work, I am suspicious of its code base, that builds upon a comparibly young JavaScript framework with sometimes questionable decision making.
Anyways, it is served similarly to serving a uWSGI application:

/etc/nginx/etherpad-lite.conf

location ~ ^/p/lac2016(.*) {
  include pad.sleepmap-auth-lac2016.conf;
  try_files $uri @etherpad-lite;
}

location / {
  try_files $uri @etherpad-lite;
}

location @etherpad-lite {
  proxy_pass http://localhost:9001;
  proxy_redirect off;
  proxy_buffering on;
  proxy_request_buffering on;
  proxy_read_timeout 150;
  proxy_set_header Host $host;
  proxy_set_header X-Real-IP $remote_addr;
  proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
}

As you can see, this is a proxy setup for all traffic going towards the location, which is then served by the etherpad-lite.service listening on port 9001.

Sidenotes

You may have noticed the redis extension used in some of the webapps. The in-memory data structure store can be used to speed up (common) queries to your application.

The shown processes, cheaper, cheaper-step, idle and die-on-idle, along with language specific settings (e.g. PHP) in the uWSGI configurations might of course require tweaking, depending on your setup and throughput.
Not all PHP webapps work with session.save_handler=uwsgi.
Make sure to tail your nginx access and error logs and follow the journal of any webapp you start using.

tail -f /var/log/nginx/access.domain.tld.log /var/log/nginx/error.domain.tld.log
journalctl -f -u uwsgi-secure@mywebapp -u uwsgi-secure@mywebapp2

All in all I hope this article will be somewhat helpful in setting up some (or all) of the above mentioned applications within the given framework of tools.

Enjoy a setup, where your webapps work on demand and you can selectively pull the plug on any of them, without touching your web server.