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<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>8</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>

    <para>The <command>apachectl</command> command has been modified

    to invoke <command>systemctl</command> for most uses, so for

    example, running <command>apachectl start</command> is equivalent

    to running <command>systemctl start httpd.service</command>.  This

    ensures that the running httpd daemon is tracked and managed by

    <command>systemd</command>.  In contrast, running

    <command>httpd</command> directly from a root shell will start the

    service outside of <command>systemd</command>; in this case,

    default security restrictions described below (including, but not

    limited to, SELinux) will not be enforced.</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 <option>LD_LIBRARY_PATH</option>

      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 section:

      <programlisting>[Unit]

After=network-online.target

Wants=network-online.target</programlisting>

      See 

      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>The 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. For example, the default policy limits the ports

      to which httpd can bind (using the <literal>Listen</literal>

      directive), which parts of the filesystem can be accessed, and

      whether outgoing TCP connections are possible. Many of these

      restrictions can be adjusted using <command>semanage</command>

      to change booleans or other 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>,

    <citerefentry><refentrytitle>semanage</refentrytitle><manvolnum>8</manvolnum></citerefentry>

    </para>

  </refsect1>

</refentry>