apache/docs/manual/upgrading.xml

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<manualpage metafile="upgrading.xml.meta">

<title>Upgrading to 2.4 from 2.2</title>

<summary>
  <p>In order to assist folks upgrading, we maintain a document
  describing information critical to existing Apache HTTP Server users. These
  are intended to be brief notes, and you should be able to find
  more information in either the <a
  href="new_features_2_4.html">New Features</a> document, or in
  the <code>src/CHANGES</code> file.  Application and module developers
  can find a summary of API changes in the <a href="developer/new_api_2_4.html"
  >API updates</a> overview.</p>

  <p>This document describes changes in server behavior that might
  require you to change your configuration or how you use the server
  in order to continue using 2.4 as you are currently using 2.2.
  To take advantage of new features in 2.4, see the New Features
  document.</p>

  <p>This document describes only the changes from 2.2 to 2.4.  If you
  are upgrading from version 2.0, you should also consult the <a
  href="http://httpd.apache.org/docs/2.2/upgrading.html">2.0 to 2.2
  upgrading document.</a></p>

</summary>
<seealso><a href="new_features_2_4.html">Overview of new features in
  Apache HTTP Server 2.4</a></seealso>

  <section id="compile-time">
    <title>Compile-Time Configuration Changes</title>

    <p>The compilation process is very similar to the one used in
    version 2.2.  Your old <code>configure</code> command line (as
    found in <code>build/config.nice</code> in the installed server
    directory) can be used in most cases.  There are some changes in
    the default settings.  Some details of changes:</p>

    <ul>
      <li>These modules have been removed: mod_authn_default,
      mod_authz_default, mod_mem_cache.  If you were using
      mod_mem_cache in 2.2, look at <module>mod_cache_disk</module> in
      2.4.</li>

      <li>All load balancing implementations have been moved to
      individual, self-contained mod_proxy submodules, e.g.
      <module>mod_lbmethod_bybusyness</module>.  You might need
      to build and load any of these that your configuration
      uses.</li>

      <li>Platform support has been removed for BeOS, TPF, and
      even older platforms such as A/UX, Next, and Tandem.  These were
      believed to be broken anyway.</li>

      <li>configure: dynamic modules (DSO) are built by default</li>

      <li>configure: By default, only a basic set of modules is loaded. The
      other <directive>LoadModule</directive> directives are commented
      out in the configuration file.</li>

      <li>configure: the "most" module set gets built by default</li>

      <li>configure: the "reallyall" module set adds developer modules
      to the "all" set</li>
    </ul>

  </section>

  <section id="run-time">
    <title>Run-Time Configuration Changes</title>
    <p>There have been significant changes in authorization configuration,
    and other minor configuration changes, that could require changes to your 2.2
    configuration files before using them for 2.4.</p>

    <section id="authz">
      <title>Authorization</title>

      <p>Any configuration file that uses authorization will likely
      need changes.</p>

    <p>You should review the <a href="howto/auth.html">Authentication,
    Authorization and Access Control Howto</a>, especially the section
    <a href="howto/auth.html#beyond">Beyond just authorization</a>
    which explains the new mechanisms for controlling the order in
    which the authorization directives are applied.</p>

    <p>Directives that control how authorization modules respond when they don't match
    the authenticated user have been removed: This includes
    AuthzLDAPAuthoritative, AuthzDBDAuthoritative, AuthzDBMAuthoritative,
    AuthzGroupFileAuthoritative, AuthzUserAuthoritative,
    and AuthzOwnerAuthoritative.   These directives have been replaced by the
    more expressive <directive module="mod_authz_core">RequireAny</directive>,
    <directive module="mod_authz_core">RequireNone</directive>, and
    <directive module="mod_authz_core">RequireAll</directive>.</p>

    <p>If you use <module>mod_authz_dbm</module>, you must port your
    configuration to use <code>Require dbm-group ...</code> in place
    of <code>Require group ...</code>.</p>

    <section id="access">
      <title>Access control</title>

      <p>In 2.2, access control based on client hostname, IP address,
      and other characteristics of client requests was done using the
      directives <directive
      module="mod_access_compat">Order</directive>, <directive
      module="mod_access_compat">Allow</directive>, <directive
      module="mod_access_compat">Deny</directive>, and <directive
      module="mod_access_compat">Satisfy</directive>.</p>

      <p>In 2.4, such access control is done in the same way as other
      authorization checks, using the new module
      <module>mod_authz_host</module>.  The old access control idioms
      should be replaced by the new authentication mechanisms,
      although for compatibility with old configurations, the new
      module <module>mod_access_compat</module> is provided.</p>

      <note><title>Mixing old and new directives</title>
      <p>Mixing old directives like <directive
      module="mod_access_compat">Order</directive>, <directive
      module="mod_access_compat">Allow</directive> or <directive
      module="mod_access_compat">Deny</directive> with new ones like
      <directive
      module="mod_authz_core">Require</directive> is technically possible 
      but discouraged. <module>mod_access_compat</module> was created to support 
      configurations containing only old directives to facilitate the 2.4 upgrade. 
      Please check the examples below to get a better idea about issues that might arise.
      </p>
      </note>

      <p>Here are some examples of old and new ways to do the same
      access control.</p>

      <p>In this example, all requests are denied.</p>
      <example>
        <title>2.2 configuration:</title>
        <highlight language="config">
Order deny,allow
Deny from all
        </highlight>
      </example>
      <example>
        <title>2.4 configuration:</title>
        <highlight language="config">
        Require all denied
        </highlight>
      </example>

      <p>In this example, all requests are allowed.</p>
      <example>
        <title>2.2 configuration:</title>
        <highlight language="config">
Order allow,deny
Allow from all
        </highlight>
      </example>
      <example>
        <title>2.4 configuration:</title>
        <highlight language="config">
        Require all granted
        </highlight>
      </example>

      <p>In the following example, all hosts in the example.org domain
      are allowed access; all other hosts are denied access.</p>

      <example>
        <title>2.2 configuration:</title>
        <highlight language="config">
Order Deny,Allow
Deny from all
Allow from example.org
        </highlight>
      </example>
      <example>
        <title>2.4 configuration:</title>
        <highlight language="config">
        Require host example.org
        </highlight>
      </example>

      <p>In the following example, mixing old and new directives leads to 
      unexpected results.</p>
 
      <example>
        <title>Mixing old and new directives: NOT WORKING AS EXPECTED</title>
          <highlight language="config">
DocumentRoot "/var/www/html"

&lt;Directory "/"&gt;
    AllowOverride None
    Order deny,allow
    Deny from all
&lt;/Directory&gt;

&lt;Location "/server-status"&gt;
    SetHandler server-status
    Require 127.0.0.1
&lt;/Location&gt;

access.log - GET /server-status 403 127.0.0.1
error.log - AH01797: client denied by server configuration: /var/www/html/server-status
          </highlight>
      </example>
      <p>Why httpd denies access to servers-status even if the configuration seems to allow it?
        Because <module>mod_access_compat</module> directives take precedence
        over the <module>mod_authz_host</module> one in this configuration 
        <a href="sections.html#merging">merge</a> scenario.</p>

      <p>This example conversely works as expected:</p>

      <example>
        <title>Mixing old and new directives: WORKING AS EXPECTED</title>
        <highlight language="config">
DocumentRoot "/var/www/html"

&lt;Directory "/"&gt;
    AllowOverride None
    Require all denied
&lt;/Directory&gt;

&lt;Location "/server-status"&gt;
    SetHandler server-status
    Order deny,allow
    Deny from all
    Allow From 127.0.0.1
&lt;/Location&gt;

access.log - GET /server-status 200 127.0.0.1
        </highlight>
      </example> 
      <p>So even if mixing configuration is still
        possible, please try to avoid it when upgrading: either keep old directives and then migrate
        to the new ones on a later stage or just migrate everything in bulk.  
      </p>
    </section>

    </section>

    <section id="config">
      <title>Other configuration changes</title>

      <p>Some other small adjustments may be necessary for particular
      configurations as discussed below.</p>

      <ul>
        <li><directive>MaxRequestsPerChild</directive> has been renamed to
        <directive module="mpm_common">MaxConnectionsPerChild</directive>,
        describes more accurately what it does. The old name is still
        supported.</li>

        <li><directive>MaxClients</directive> has been renamed to
        <directive module="mpm_common">MaxRequestWorkers</directive>,
        which describes more accurately what it does. For async MPMs, like
        <module>event</module>, the maximum number of clients is not
        equivalent than the number of worker threads. The old name is still
        supported.</li>

        <li>The <directive module="core">DefaultType</directive>
        directive no longer has any effect, other than to emit a
        warning if it's used with any value other than
        <code>none</code>.  You need to use other configuration
        settings to replace it in 2.4.
        </li>

        <li><directive module="core">AllowOverride</directive> now
        defaults to <code>None</code>.</li>

        <li><directive module="core">EnableSendfile</directive> now
        defaults to Off.</li>

        <li><directive module="core">FileETag</directive> now
        defaults to "MTime Size" (without INode).</li>

        <li><module>mod_dav_fs</module>: The format of the <directive
        module="mod_dav_fs">DavLockDB</directive> file has changed for
        systems with inodes.  The old <directive
        module="mod_dav_fs">DavLockDB</directive> file must be deleted on
        upgrade.
        </li>

        <li><directive module="core">KeepAlive</directive> only
        accepts values of <code>On</code> or <code>Off</code>.
        Previously, any value other than "Off" or "0" was treated as
        "On".</li>

        <li>Directives AcceptMutex, LockFile, RewriteLock, SSLMutex,
        SSLStaplingMutex, and WatchdogMutexPath have been replaced
        with a single <directive module="core">Mutex</directive>
        directive.  You will need to evaluate any use of these removed
        directives in your 2.2 configuration to determine if they can
        just be deleted or will need to be replaced using <directive
        module="core">Mutex</directive>.</li>

        <li><module>mod_cache</module>: <directive
        module="mod_cache">CacheIgnoreURLSessionIdentifiers</directive>
        now does an exact match against the query string instead of a
        partial match.  If your configuration was using partial
        strings, e.g. using <code>sessionid</code> to match
        <code>/someapplication/image.gif;jsessionid=123456789</code>,
        then you will need to change to the full string
        <code>jsessionid</code>.
        </li>

        <li><module>mod_cache</module>: The second parameter to
        <directive module="mod_cache">CacheEnable</directive> only
        matches forward proxy content if it begins with the correct
        protocol. In 2.2 and earlier, a parameter of '/' matched all
        content.</li>

        <li><module>mod_ldap</module>: <directive
        module="mod_ldap">LDAPTrustedClientCert</directive> is now
        consistently a per-directory setting only.  If you use this
        directive, review your configuration to make sure it is
        present in all the necessary directory contexts.</li>

        <li><module>mod_filter</module>: <directive
        module="mod_filter">FilterProvider</directive> syntax has changed and
        now uses a boolean expression to determine if a filter is applied.
        </li>

        <li><module>mod_include</module>:
            <ul>
            <li>The <code>#if expr</code> element now uses the new <a
            href="expr.html">expression parser</a>. The old syntax can be
            restored with the new directive <directive module="mod_include"
            >SSILegacyExprParser</directive>.
            </li>
            <li>An SSI* config directive in directory scope no longer causes
            all other per-directory SSI* directives to be reset to their
            default values.</li>
            </ul>
        </li>

        <li><module>mod_charset_lite</module>: The <code>DebugLevel</code>
        option has been removed in favour of per-module <directive
        module="core">LogLevel</directive> configuration.
        </li>

        <li><module>mod_ext_filter</module>: The <code>DebugLevel</code>
        option has been removed in favour of per-module <directive
        module="core">LogLevel</directive> configuration.
        </li>

        <li><module>mod_proxy_scgi</module>: The default setting for
        <code>PATH_INFO</code> has changed from httpd 2.2, and
        some web applications will no longer operate properly with
        the new <code>PATH_INFO</code> setting.  The previous setting
        can be restored by configuring the <code>proxy-scgi-pathinfo</code>
        variable.</li>

        <li><module>mod_ssl</module>: CRL based revocation checking
        now needs to be explicitly configured through <directive
        module="mod_ssl">SSLCARevocationCheck</directive>.
        </li>

        <li><module>mod_substitute</module>: The maximum line length is now
        limited to 1MB.
        </li>

        <li><module>mod_reqtimeout</module>: If the module is loaded, it
        will now set some default timeouts.</li>

        <li><module>mod_dumpio</module>: <directive>DumpIOLogLevel</directive>
        is no longer supported.  Data is always logged at <directive
        module="core">LogLevel</directive> <code>trace7</code>.</li>

        <li>On Unix platforms, piped logging commands configured using
        either <directive module="core">ErrorLog</directive> or
        <directive module="mod_log_config">CustomLog</directive> were invoked using
        <code>/bin/sh -c</code> in 2.2 and earlier.  In 2.4 and later,
        piped logging commands are executed directly.  To restore the
        old behaviour, see the <a href="logs.html#piped">piped logging
        documentation</a>.</li>

      </ul>
    </section>
  </section>

  <section id="misc">
    <title>Misc Changes</title>

    <ul>
      <li><module>mod_autoindex</module>: will now extract titles and
      display descriptions for .xhtml files, which were previously
      ignored.</li>

      <li><module>mod_ssl</module>: The default format of the <code>*_DN</code>
      variables has changed. The old format can still be used with the new
      <code>LegacyDNStringFormat</code> argument to <directive
      module="mod_ssl">SSLOptions</directive>. The SSLv2 protocol is
      no longer supported. <directive module="mod_ssl">SSLProxyCheckPeerCN
	  </directive> and <directive module="mod_ssl">SSLProxyCheckPeerExpire
	  </directive> now default to On, causing proxy requests to HTTPS hosts
	  with bad or outdated certificates to fail with a 502 status code (Bad
	  gateway)</li>

      <li><program>htpasswd</program> now uses MD5 hash by default on
      all platforms.</li>

      <li>The <directive module="core">NameVirtualHost</directive>
      directive no longer has any effect, other than to emit a
      warning.  Any address/port combination appearing in multiple
      virtual hosts is implicitly treated as a name-based virtual host.
      </li>

      <li><module>mod_deflate</module> will now skip compression if it knows
      that the size overhead added by the compression is larger than the data
      to be compressed.
      </li>

      <li>Multi-language error documents from 2.2.x may not work unless
      they are adjusted to the new syntax of <module>mod_include</module>'s
      <code>#if expr=</code> element or the directive
      <directive module="mod_include">SSILegacyExprParser</directive> is
      enabled for the directory containing the error documents.
      </li>

      <li>The functionality provided by <code>mod_authn_alias</code>
      in previous versions (i.e., the <directive
      module="mod_authn_core">AuthnProviderAlias</directive> directive)
      has been moved into <module>mod_authn_core</module>.
      </li>

      <li><module>mod_cgid</module> uses the servers <directive module="core"
      >Timeout</directive> to limit the length of time to wait for CGI output.
      This timeout can be overridden with <directive module="mod_cgid">
      CGIDScriptTImeout</directive>.
      </li>

    </ul>

  </section>

  <section id="third-party">
    <title>Third Party Modules</title>
    <p>All modules must be recompiled for 2.4 before being loaded.</p>

    <p>Many third-party modules designed for version 2.2 will
    otherwise work unchanged with the Apache HTTP Server version 2.4.
    Some will require changes; see the <a href="developer/new_api_2_4.html">API
    update</a> overview.</p>
  </section>

  <section id="commonproblems">
    <title>Common problems when upgrading</title>
    <ul><li>Startup errors:
    <ul>
      <li><code>Invalid command 'User', perhaps misspelled or defined by a module not included in the server configuration</code> - load module <module>mod_unixd</module></li>
      <li><code>Invalid command 'Require', perhaps misspelled or defined by a module not included in the server configuration</code>, or
<code>Invalid command 'Order', perhaps misspelled or defined by a module not included in the server configuration</code>
 - load module <module>mod_access_compat</module>, or update configuration to 2.4 authorization directives.</li>
      <li><code>Ignoring deprecated use of DefaultType in line NN of /path/to/httpd.conf</code> - remove <directive module="core">DefaultType</directive>
      and replace with other configuration settings.</li>
      <li><code>Invalid command 'AddOutputFilterByType', perhaps misspelled
      or defined by a module not included in the server configuration
      </code> - <directive module="mod_filter">AddOutputFilterByType</directive>
      has moved from the core to mod_filter, which must be loaded.</li>
    </ul></li>
    <li>Errors serving requests:
    <ul>
      <li><code>configuration error:  couldn't check user: /path</code> -
      load module <module>mod_authn_core</module>.</li>
      <li><code>.htaccess</code> files aren't being processed - Check for an
      appropriate <directive module="core">AllowOverride</directive> directive;
      the default changed to <code>None</code> in 2.4.</li>
    </ul>
    </li>
</ul>
  </section>
</manualpage>