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<?xml version='1.0' encoding='utf-8'?>
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd" [
]>
<refentry>
<refentryinfo>
<title>httpd systemd units</title>
<productname>httpd</productname>
<author><contrib>Author</contrib><surname>Orton</surname><firstname>Joe</firstname><email>jorton@redhat.com</email></author>
</refentryinfo>
<refmeta>
<refentrytitle>httpd.service</refentrytitle>
<manvolnum>5</manvolnum>
</refmeta>
<refnamediv>
<refname>httpd.service</refname>
<refname>httpd.socket</refname>
<refpurpose>httpd unit files for systemd</refpurpose>
</refnamediv>
<refsynopsisdiv>
<para>
<filename>/usr/lib/systemd/system/httpd.service</filename>,
<filename>/usr/lib/systemd/system/httpd.socket</filename>
</para>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para>This manual page describes the <command>systemd</command>
unit files used to integrate the <command>httpd</command> daemon
with <command>systemd</command>. Two unit files are available:
<command>httpd.service</command> allows the
<command>httpd</command> daemon to be run as a system service, and
<command>httpd.socket</command> allows httpd to be started via
socket-based activation. Most systems will use
<command>httpd.service</command>.</para>
<refsect2>
<title>Changing default behaviour</title>
<para>To change the default behaviour of the httpd service, an
<emphasis>over-ride</emphasis> file should be created, rather
than changing
<filename>/usr/lib/systemd/system/httpd.service</filename>
directly, since such changes would be lost over package
upgrades. Running <command>systemctl edit
httpd.service</command> or <command>systemctl edit
httpd.socket</command> as root will create a drop-in file in
<filename>/etc/systemd/system/httpd.service.d</filename> which
over-rides the system defaults.</para>
<para>For example, to set the <literal>LD_LIBRARY_PATH</literal>
environment variable for the daemon, run <command>systemctl edit
httpd.service</command> and enter:
<programlisting>[Service]
Environment=LD_LIBRARY_PATH=/opt/vendor/lib</programlisting></para>
</refsect2>
<refsect2>
<title>Starting the service at boot time</title>
<para>The httpd.service and httpd.socket units are
<emphasis>disabled</emphasis> by default. To start the httpd
service at boot time, run: <command>systemctl enable
httpd.service</command>. In the default configuration, the
httpd daemon will accept connections on port 80 (and, if mod_ssl
is installed, TLS connections on port 443) for any configured
IPv4 or IPv6 address.</para>
<para>If httpd is configured to depend on any specific IP
address (for example, with a "Listen" directive), which may only
become available during startup, or if httpd depends on other
services (such as a database daemon), the service
<emphasis>must</emphasis> be configured to ensure correct
startup ordering.</para>
<para>For example, to ensure httpd is only running after all
configured network interfaces are configured, create a drop-in
file (as described above) with the following:
<programlisting>[Unit]
After=network-online.target
Wants=network-online.target</programlisting>
See <ulink
url="https://www.freedesktop.org/wiki/Software/systemd/NetworkTarget/"/>
for more information on startup ordering with systemd.</para>
</refsect2>
<refsect2>
<title>Reloading and stopping the service</title>
<para>When running <command>systemctl reload
httpd.service</command>, a "<emphasis>graceful</emphasis>"
restart is used, which sends a signal to the httpd parent
process to reload the configuration and re-open log files. Any
children with open connections at the time of reload will
terminate only once they have completed serving requests. This
prevents users of the server seeing errors (or potentially
losing data) due to the reload, but means some there is some
delay before any configuration changes take effect for all
users.</para>
<para>Similarly, a "<emphasis>graceful stop</emphasis>" is used
when <command>systemctl stop httpd.service</command> is run,
which terminates the server only once active connections have
been processed.</para>
</refsect2>
<refsect2>
<title>systemd integration and mod_systemd</title>
<para>httpd.service uses the "<option>notify</option>" systemd
service type. The <literal>mod_systemd</literal> module must be
loaded (as in the default configuration) for this to work
correctly - the service will fail if this module is not
loaded. <literal>mod_systemd</literal> also makes worker and
request statistics available when running <command>systemctl status
httpd</command>. See
<citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
for more information on systemd service types.</para>
</refsect2>
<refsect2>
<title>Security and SELinux</title>
<para>The default SELinux policy restricts the httpd service in
various ways. The ports to which httpd can bind (using the
<literal>Listen</literal> directive), which parts of the
filesystem can be accessed, whether outgoing TCP connections are
possible, are limited by default, for example. Many of these
restrictions can be lifted using SELinux booleans and port
types. See
<citerefentry><refentrytitle>httpd_selinux</refentrytitle><manvolnum>8</manvolnum></citerefentry>
for more information.</para>
<para>The httpd service enables <emphasis>PrivateTmp</emphasis>
by default. The <filename>/tmp</filename> and
<filename>/var/tmp</filename> directories available within the
httpd process (and CGI scripts, etc) are not shared by other
processes. See
<citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
for more information.</para>
</refsect2>
</refsect1>
<refsect1>
<title>Files</title>
<para><filename>/usr/lib/systemd/system/httpd.service</filename>,
<filename>/usr/lib/systemd/system/httpd.socket</filename>,
<filename>/etc/systemd/systemd/httpd.service.d</filename></para>
</refsect1>
<refsect1>
<title>See also</title>
<para>
<citerefentry><refentrytitle>httpd</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
<citerefentry><refentrytitle>httpd_selinux</refentrytitle><manvolnum>8</manvolnum></citerefentry>
</para>
</refsect1>
</refentry>
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