# Apache HTTP Server

Related articles

- PHP
- MySQL
- PhpMyAdmin
- Adminer
- Xampp
- mod_perl

The Apache HTTP Server, or Apache for short, is a very popular web server, developed by the Apache Software Foundation.

Apache is often used together with a scripting language such as PHP and database such as MySQL. This combination is often referred to as a LAMP stack (Linux, Apache, MySQL, PHP). This article describes how to set up Apache and how to optionally integrate it with PHP and MySQL.

## Installation

Install the apache package.

## Configuration

Apache configuration files are located in `/etc/httpd/conf`. The main configuration file is `/etc/httpd/conf/httpd.conf`, which includes various other configuration files. The default configuration file should be fine for a simple setup. By default, it will serve the directory `/srv/http` to anyone who visits your website.

To start Apache, start `httpd.service` using systemd.

Apache should now be running. Test by visiting http://localhost/ in a web browser. It should display a simple index page.

For optional further configuration, see the following sections.

### Advanced options

These options in `/etc/httpd/conf/httpd.conf` might be interesting for you:

    User http

  For security reasons, as soon as Apache is started by the root user (directly or via startup scripts) it switches to this UID. The default user is http, which is created automatically during installation.

    Listen 80

  This is the port Apache will listen to. For Internet-access with router, you have to forward the port.

  If you want to setup Apache for local development you may want it to be only accessible from your computer. Then change this line to `Listen 127.0.0.1:80`.

    ServerAdmin you@example.com

  This is the admin's email address which can be found on e.g. error pages.

    DocumentRoot "/srv/http"

  This is the directory where you should put your web pages.

  Change it, if you want to, but do not forget to also change `<Directory "/srv/http">` to whatever you changed your `DocumentRoot` to, or you will likely get a 403 Error (lack of privileges) when you try to access the new document root. Do not forget to change the `Require all denied` line to `Require all granted`, otherwise you will get a 403 Error. Remember that the DocumentRoot directory and its parent folders must allow execution permission to others (can be set with `chmod o+x /path/to/DocumentRoot`), otherwise you will get a 403 Error.

    AllowOverride None

  This directive in `<Directory>` sections causes Apache to completely ignore `.htaccess` files. Note that this is now the default for Apache 2.4, so you need to explicitly allow overrides if you plan to use `.htaccess` files. If you intend to use `mod_rewrite` or other settings in `.htaccess` files, you can allow which directives declared in that file can override server configuration. For more info refer to the Apache documentation.

Tip: If you have issues with your configuration you can have Apache check the configuration with: `apachectl configtest`

More settings can be found in `/etc/httpd/conf/extra/httpd-default.conf`:

To turn off your server's signature:

    ServerSignature Off

To hide server information like Apache and PHP versions:

    ServerTokens Prod

### User directories

User directories are available by default through http://localhost/~yourusername/ and show the contents of `~/public_html` (this can be changed in `/etc/httpd/conf/extra/httpd-userdir.conf`).

If you do not want user directories to be available on the web, comment out the following line in `/etc/httpd/conf/httpd.conf`:

    Include conf/extra/httpd-userdir.conf

The factual accuracy of this article or section is disputed.

Reason: It is not necessary to set `+x` for every users, setting it only for the webserver via ACLs suffices (see Access Control Lists#Granting execution permissions for private files to a Web Server). (Discuss in Talk:Apache HTTP Server#)

You must make sure that your home directory permissions are set properly so that Apache can get there. Your home directory and `~/public_html` must be executable for others ("rest of the world"):

    $ chmod o+x ~
    $ chmod o+x ~/public_html
    $ chmod -R o+r ~/public_html

Restart `httpd.service` to apply any changes. See also Umask#Set the mask value.

### TLS/SSL

openssl provides TLS/SSL support and is installed by default on Arch installations.

Create a private key and self-signed certificate. This is adequate for most installations that do not require a CSR:

    # cd /etc/httpd/conf
    # openssl req -new -x509 -nodes -newkey rsa:4096 -keyout apache.key -out apache.crt -days 1095
    # chmod 400 apache.key
    # chmod 444 apache.crt

Then edit `/etc/httpd/conf/extra/httpd-ssl.conf` to reflect the new key and certificate:

- `SSLCertificateFile "/etc/httpd/conf/server.crt" => SSLCertificateFile "/etc/httpd/conf/apache.crt",`,
- `SSLCertificateKeyFile "/etc/httpd/conf/server.key" => SSLCertificateKeyFile "/etc/httpd/conf/apache.key",`

Note: The -days switch is optional and RSA keysize can be as low as 2048 (default).

If you need to create a CSR, follow these keygen instructions instead of the above:

    # openssl genpkey -algorithm RSA -pkeyopt rsa_keygen_bits:4096 -out apache.key
    # chmod 400 apache.key
    # openssl req -new -sha256 -key apache.key -out apache.csr
    # openssl x509 -req -days 1095 -in apache.csr -signkey apache.key -out apache.crt

Note: For more openssl options, read the man page or peruse openssl's extensive documentation.

Then, in `/etc/httpd/conf/httpd.conf`, uncomment the following three lines:

    LoadModule ssl_module modules/mod_ssl.so
    LoadModule socache_shmcb_module modules/mod_socache_shmcb.so
    Include conf/extra/httpd-ssl.conf

Warning: If you plan on implementing SSL/TLS, know that some variations and implementations are still vulnerable to attack. For details on these current vulnerabilities within SSL/TLS and how to apply appropriate changes to the web server, visit http://disablessl3.com/ and https://weakdh.org/sysadmin.html
Tip: Mozilla has a useful SSL/TLS article which includes Apache specific configuration guidelines as well as an automated tool to help create a more secure configuration.

Restart `httpd.service` to apply any changes.

### Virtual hosts

Note: You will need to add a separate <VirtualHost dommainame:443> section for virtual host SSL support. See #Managing many virtual hosts for an example file.

If you want to have more than one host, uncomment the following line in `/etc/httpd/conf/httpd.conf`:

    Include conf/extra/httpd-vhosts.conf

In `/etc/httpd/conf/extra/httpd-vhosts.conf` set your virtual hosts. The default file contains an elaborate example that should help you get started.

To test the virtual hosts on you local machine, add the virtual names to your `/etc/hosts` file:

    127.0.0.1 domainname1.dom
    127.0.0.1 domainname2.dom

Restart `httpd.service` to apply any changes.

#### Managing many virtual hosts

If you have a huge amount of virtual hosts, you may want to easily disable and enable them. It is recommended to create one configuration file per virtual host and store them all in one folder, eg: `/etc/httpd/conf/vhosts`.

First create the folder:

    # mkdir /etc/httpd/conf/vhosts

Then place the single configuration files in it:

    # nano /etc/httpd/conf/vhosts/domainname1.dom
    # nano /etc/httpd/conf/vhosts/domainname2.dom
    ...

In the last step, `Include` the single configurations in your `/etc/httpd/conf/httpd.conf`:

    #Enabled Vhosts:
    Include conf/vhosts/domainname1.dom
    Include conf/vhosts/domainname2.dom

You can enable and disable single virtual hosts by commenting or uncommenting them.

A very basic vhost file will look like this:

    /etc/httpd/conf/vhosts/domainname1.dom

    <VirtualHost domainname1.dom:80>
        ServerAdmin webmaster@domainname1.dom
        DocumentRoot "/home/user/http/domainname1.dom"
        ServerName domainname1.dom
        ServerAlias domainname1.dom
        ErrorLog "/var/log/httpd/domainname1.dom-error_log"
        CustomLog "/var/log/httpd/domainname1.dom-access_log" common

        <Directory "/home/user/http/domainname1.dom">
            Require all granted
        </Directory>
    </VirtualHost>

    <VirtualHost domainname1.dom:443>
        ServerAdmin webmaster@domainname1.dom
        DocumentRoot "/home/user/http/domainname1.dom"
        ServerName domainname1.dom:443
        ServerAlias domainname1.dom:443
        ErrorLog "/var/log/httpd/domainname1.dom-error_log"
        CustomLog "/var/log/httpd/domainname1.dom-access_log" common

        <Directory "/home/user/http/domainname1.dom">
            Require all granted
        </Directory>

        SSLEngine on
        SSLCertificateFile "/etc/httpd/conf/apache.crt"
        SSLCertificateKeyFile "/etc/httpd/conf/apache.key"
    </VirtualHost>

## Extensions

### PHP

To install PHP, first install the php and php-apache packages.

Note: `libphp5.so` included with php-apache does not work with `mod_mpm_event` (FS#39218). You will have to use `mod_mpm_prefork` instead. Otherwise you will get the following error:

    Apache is running a threaded MPM, but your PHP Module is not compiled to be threadsafe.  You need to recompile PHP.
    AH00013: Pre-configuration failed
    httpd.service: control process exited, code=exited status=1

As the configuration of `/etc/httpd/conf/httpd.conf` has for standard the `mod_mpm_event` you will have to use `mod_mpm_prefork` in order to `libphp5.so` work properly, so open `/etc/httpd/conf/httpd.conf` and replace:

    LoadModule mpm_event_module modules/mod_mpm_event.so

with

    LoadModule mpm_prefork_module modules/mod_mpm_prefork.so

As an alternative, you can use `mod_proxy_fcgi` (see #Using php5 with php-fpm and mod proxy fcgi below).

To enable PHP, add these lines to `/etc/httpd/conf/httpd.conf`:

- Place this in the `LoadModule` list anywhere after `LoadModule dir_module modules/mod_dir.so`:

    LoadModule php5_module modules/libphp5.so

- Place this at the end of the `Include` list:

    Include conf/extra/php5_module.conf

If your `DocumentRoot` is not `/srv/http`, add it to `open_basedir` in `/etc/php/php.ini` as such:

    open_basedir=/srv/http/:/home/:/tmp/:/usr/share/pear/:/path/to/documentroot

Restart `httpd.service` using systemd

To test whether PHP was correctly configured: create a file called `test.php` in your Apache `DocumentRoot` directory (e.g. `/srv/http/` or `~/public_html`) with the following contents:

    <?php phpinfo(); ?>

To see if it works go to: http://localhost/test.php or http://localhost/~myname/test.php

For advanced configuration and extensions, please read PHP.

#### Using php5 with php-fpm and mod_proxy_fcgi

Note: Unlike the widespread setup with ProxyPass, the proxy configuration with SetHandler respects other Apache directives like DirectoryIndex. This ensures a better compatibility with software designed for libphp5, mod_fastcgi and mod_fcgid. If you still want to try ProxyPass, experiment with a line like this:

    ProxyPassMatch ^/(.*\.php(/.*)?)$ unix:/run/php-fpm/php-fpm.sock|fcgi://localhost/srv/http/$1

- Install the php-fpm package.

- Set `listen` in `/etc/php/php-fpm.conf` like this (these values are currently the defaults):

    ;listen = 127.0.0.1:9000
    listen = /run/php-fpm/php-fpm.sock
    listen.owner = http
    listen.group = http

- Append following to `/etc/httpd/conf/httpd.conf`:

    <FilesMatch \.php$>
        SetHandler "proxy:unix:/run/php-fpm/php-fpm.sock|fcgi://localhost/"
    </FilesMatch>
    <IfModule dir_module>
        DirectoryIndex index.php index.html
    </IfModule>

The pipe between sock and fcgi is not allowed to be surrounded by a space!

- If you have it added, remove the php module, as this is no longer needed.

    LoadModule php5_module modules/libphp5.so

- Restart the apache php-fpm daemon again.

#### Using php5 with apache2-mpm-worker and mod_fcgid

- Uncomment following in `/etc/conf.d/apache`:

    HTTPD=/usr/bin/httpd.worker

- Uncomment following in `/etc/httpd/conf/httpd.conf`:

    Include conf/extra/httpd-mpm.conf

- Install the mod_fcgid and php-cgi packages from the official repositories.

- Create `/etc/httpd/conf/extra/php5_fcgid.conf` with following content:

    /etc/httpd/conf/extra/php5_fcgid.conf

    # Required modules: fcgid_module

    <IfModule fcgid_module>
        AddHandler php-fcgid .php
        AddType application/x-httpd-php .php
        Action php-fcgid /fcgid-bin/php-fcgid-wrapper
        ScriptAlias /fcgid-bin/ /srv/http/fcgid-bin/
        SocketPath /var/run/httpd/fcgidsock
        SharememPath /var/run/httpd/fcgid_shm
            # If you don't allow bigger requests many applications may fail (such as WordPress login)
            FcgidMaxRequestLen 536870912
            # Path to php.ini – defaults to /etc/phpX/cgi
            DefaultInitEnv PHPRC=/etc/php/
            # Number of PHP childs that will be launched. Leave undefined to let PHP decide.
            #DefaultInitEnv PHP_FCGI_CHILDREN 3
            # Maximum requests before a process is stopped and a new one is launched
            #DefaultInitEnv PHP_FCGI_MAX_REQUESTS 5000
            <Location /fcgid-bin/>
            SetHandler fcgid-script
            Options +ExecCGI
        </Location>
    </IfModule>

- Create the needed directory and symlink it for the PHP wrapper:

    # mkdir /srv/http/fcgid-bin
    # ln -s /usr/bin/php-cgi /srv/http/fcgid-bin/php-fcgid-wrapper

- Edit `/etc/httpd/conf/httpd.conf`:

    #LoadModule php5_module modules/libphp5.so
    LoadModule fcgid_module modules/mod_fcgid.so
    Include conf/extra/php5_fcgid.conf

and restart httpd.

Note: As of Apache 2.4 you can now use mod_proxy_fcgi (part of the official distribution) with PHP-FPM (and the new event MPM). See this configuration example.

#### MySQL/MariaDB

Follow the instructions in PHP#MySQL/MariaDB.

When configuration is complete, restart the `httpd` service to apply all the changes.

#### SPDY

mod_spdy is a SPDY module for Apache 2.2 that allows your web server to take advantage of SPDY features like stream multiplexing and header compression.

Follow the instructions in Apache and spdy.

## Troubleshooting

### Apache Status and Logs

See the status of the Apache daemon with systemctl.

Apache logs can be found in `/var/log/httpd/`

### Error: PID file /run/httpd/httpd.pid not readable (yet?) after start

Comment out the unique_id_module: `#LoadModule unique_id_module modules/mod_unique_id.so`

### Upgrading Apache to 2.4 from 2.2

If you use `php-apache`, follow the introductory note to Apache with PHP above.

Access Control has changed. Convert all `Order`, `Allow`, `Deny` and `Satisfy` directives to the new `Require` syntax. mod_access_compat allows you to use the deprecated format during a transition phase.

More information: Upgrading to 2.4 from 2.2

### Apache is running a threaded MPM, but your PHP Module is not compiled to be threadsafe.

If when loading `php5_module` the `httpd.service` fails, and you get an error like this in the journal:

    Apache is running a threaded MPM, but your PHP Module is not compiled to be threadsafe.  You need to recompile PHP.

you need to replace `mpm_event_module` with `mpm_prefork_module`:

    /etc/httpd/conf/httpd.conf

    LoadModule mpm_event_module modules/mod_mpm_event.so
    LoadModule mpm_prefork_module modules/mod_mpm_prefork.so

and restart `httpd.service`.

## See also

- Apache Official Website
- Tutorial for creating self-signed certificates
- Apache Wiki Troubleshooting

Category:

- Web server