# 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

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

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

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

Don't forget to add Port 443 to your listen ports in `/etc/httpd/conf/httpd.conf`

    Listen 443

For TLS/SSL, you will need a key and certificate. If you own a public domain, you can use Let's Encrypt to obtain a certificate for free, otherwise follow #Create a key and (self-signed) certificate.

After obtaining a key and certificate, make sure the `SSLCertificateFile` and `SSLCertificateKeyFile` lines in `/etc/httpd/conf/extra/httpd-ssl.conf` point to the key and certificate.

Finally, restart `httpd.service` to apply any changes.

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.

#### Create a key and (self-signed) certificate

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 server.key -out server.crt -days 1095
    # chmod 400 server.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 server.key
    # chmod 400 server.key
    # openssl req -new -sha256 -key server.key -out server.csr
    # openssl x509 -req -days 1095 -in server.csr -signkey server.key -out server.crt

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

### 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.

In `/etc/httpd/conf/httpd.conf`, comment the line:

    #LoadModule mpm_event_module modules/mod_mpm_event.so

and uncomment the line:

    LoadModule mpm_prefork_module modules/mod_mpm_prefork.so

Note: The above is required, because `libphp7.so` included with php-apache does not work with `mod_mpm_event`, but will only work `mod_mpm_prefork` instead. (FS#39218)

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 an alternative, you can use `mod_proxy_fcgi` (see #Using 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 php7_module modules/libphp7.so

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

    Include conf/extra/php7_module.conf

- And the handler at the end of the `LoadModule`:

    AddHandler php7-script php

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 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 libphp7, 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.

Enable proxy modules:

    /etc/httpd/conf/httpd.conf

    LoadModule proxy_module modules/mod_proxy.so
    LoadModule proxy_fcgi_module modules/mod_proxy_fcgi.so

Create `/etc/httpd/conf/extra/php-fpm.conf` with the following content:

    /etc/httpd/conf/extra/php-fpm.conf

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

And include it at the bottom of `/etc/httpd/conf/httpd.conf`:

    Include conf/extra/php-fpm.conf

Note: The pipe between `sock` and `fcgi` is not allowed to be surrounded by a space! `localhost` can be replaced by any string. More here

You can configure PHP-FPM in `/etc/php/php-fpm.d/www.conf`, but the default setup should work fine.

Note:

If you have added the following lines to `httpd.conf`, remove them, as they are no longer needed:

    LoadModule php7_module modules/libphp7.so
    Include conf/extra/php7_module.conf

Restart `httpd.service` and `php-fpm.service`.

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

Install the mod_fcgid and php-cgi packages.

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

Create `/etc/httpd/conf/extra/php-fcgid.conf` with the following content:

    /etc/httpd/conf/extra/php-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>

Edit `/etc/httpd/conf/httpd.conf`, enabling the actions module:

    LoadModule actions_module modules/mod_actions.so

And add the following lines:

    LoadModule fcgid_module modules/mod_fcgid.so
    Include conf/extra/httpd-mpm.conf
    Include conf/extra/php-fcgid.conf

Note:

If you have added the following lines to `httpd.conf`, remove them, as they are no longer needed:

    LoadModule php7_module modules/libphp7.so
    Include conf/extra/php7_module.conf

Restart `httpd.service`.

#### MySQL/MariaDB

Follow the instructions in PHP#MySQL/MariaDB.

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

### HTTP2

To enable HTTP/2 support, install the nghttp2 package.

Then uncomment the following line in `httpd.conf`:

    LoadModule http2_module modules/mod_http2.so

And add the following line:

    Protocols h2 http/1.1

For more information, see the mod_http2 documentation.

## 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` line in `httpd.conf`: `#LoadModule unique_id_module modules/mod_unique_id.so`

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

If when loading `php7_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`.

### AH00534: httpd: Configuration error: No MPM loaded.

You might encounter this error after a recent upgrade. This is only the result of a recent change in `httpd.conf` that you might not have reproduced in your local configuration. To fix it, uncomment the following line.

    /etc/httpd/conf/httpd.conf

    LoadModule mpm_prefork_module modules/mod_mpm_prefork.so

Also check the above if more errors occur afterwards.

### Changing the max_execution_time in php.ini has no effect

If you changed the `max_execution_time` in `php.ini` to a value greater than 30 (seconds), you may still get a `503 Service Unavailable` response from Apache after 30 seconds. To solve this, add a `ProxyTimeout` directive to your http configuration right before the `<FilesMatch \.php$>` block:

    /etc/httpd/conf/httpd.conf

    ProxyTimeout 300

and restart `httpd.service`.

## See also

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

Category:

- Web server

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