|
Пункт 2. New features with Apache 2.3/2.4
This document describes some of the major changes between the
2.2 and 2.4 versions of the Apache HTTP Server. For new features since
version 2.0, see the 2.2 new features
document.
Core Enhancements
- Run-time Loadable MPMs
- Multiple MPMs can now be built
as loadable modules at compile time.
The MPM of choice can be configured at run time via
LoadModule directive.
- Event MPM
- The Event MPM is no longer experimental
but is now fully supported.
- Asynchronous support
- Better support for asynchronous read/write for supporting MPMs and
platforms.
- Per-module and per-directory LogLevel configuration
- The
LogLevel can now be
configured per module and per directory. New levels trace1
to trace8 have been added above the debug log
level.
- Per-request configuration sections
-
<If> ,
<ElseIf> ,
and <Else>
sections can be used to set the configuration based on per-request
criteria.
- General-purpose expression parser
- A new expression parser allows to specify
complex conditions using a common syntax
in directives like
SetEnvIfExpr ,
RewriteCond ,
Header ,
<If> ,
and others.
- KeepAliveTimeout in milliseconds
- It is now possible to specify
KeepAliveTimeout in milliseconds.
- NameVirtualHost directive
- No longer needed and is now deprecated.
- Override Configuration
- The new
AllowOverrideList
directive allows more fine grained control which directives are
allowed in .htaccess files.
- Config file variables
- It is now possible to
Define
variables in the configuration, allowing a clearer representation
if the same value is used at many places in the configuration.
- Reduced memory usage
- Despite many new features, 2.4.x tends to use less memory than
2.2.x.
New Modules
-
mod_proxy_fcgi
- FastCGI Protocol backend for
mod_proxy
-
mod_proxy_scgi
- SCGI Protocol backend for
mod_proxy
-
mod_proxy_express
- Provides dynamically configured mass reverse proxies for
mod_proxy
-
mod_remoteip
- Replaces the apparent client remote IP address and hostname for the request
with the IP address list presented by a proxies or a load balancer via
the request headers.
-
mod_heartmonitor ,
mod_lbmethod_heartbeat
- Allow
mod_proxy_balancer to base loadbalancing decisions
on the number of active connections on the backend servers.
-
mod_proxy_html
- Formerly a third-party module, this supports fixing of HTML
links in a reverse proxy situation, where the backend generates
URLs that are not valid for the proxy's clients.
-
mod_sed
- An advanced replacement of
mod_substitute , allows
to edit the response body with the full power of sed.
-
mod_auth_form
- Enables form-based authentication.
-
mod_session
- Enables the use of session state for clients, using cookie or
database storage.
-
mod_allowmethods
- New module to restrict certain HTTP methods without interfering with
authentication or authorization.
-
mod_lua
- Embeds the Lua language into httpd,
for configuration and small business logic functions. (Experimental)
-
mod_log_debug
- Allows the addition of customizable debug logging at different phases of the
request processing.
-
mod_buffer
- Provides for buffering the input and output filter stacks
-
mod_data
- Convert response body into an RFC2397 data URL
-
mod_ratelimit
- Provides Bandwidth Rate Limiting for Clients
-
mod_request
- Provides Filters to handle and make available HTTP request bodies
-
mod_reflector
- Provides Reflection of a request body as a response via the output filter stack.
-
mod_slotmem_shm
- Provides a Slot-based shared memory provider (ala the scoreboard).
-
mod_xml2enc
- Formerly a third-party module, this supports internationalisation
in libxml2-based (markup-aware) filter modules.
-
mod_macro (available since 2.4.5)
- Provide macros within configuration files.
-
mod_proxy_wstunnel (available since 2.4.5)
- Support web-socket tunnels.
-
mod_authnz_fcgi (available since 2.4.10)
- Enable FastCGI authorizer applications to authenticate and/or
authorize clients.
-
mod_http2 (available since 2.4.17)
- Support for the HTTP/2 transport layer.
-
mod_proxy_hcheck (available since 2.4.21)
- Support independent dynamic health checks for remote proxiy backend servers.
Module Enhancements
-
mod_ssl
-
mod_ssl can now be configured to use an
OCSP server to check the validation status of a client
certificate. The default responder is configurable, along with
the decision on whether to prefer the responder designated in
the client certificate itself.
-
mod_ssl now also supports OCSP stapling, where the
server pro-actively obtains an OCSP verification of its certificate and
transmits that to the client during the handshake.
-
mod_ssl can now be configured to share SSL Session
data between servers through memcached
- EC keys are now supported in addition to RSA and DSA.
- Support for TLS-SRP (available in 2.4.4 and later).
-
mod_proxy
- The
ProxyPass directive
is now most optimally configured within a
Location or
LocationMatch
block, and offers a significant performance advantage over the traditional
two-parameter syntax when present in large numbers.
- The source address used for proxy requests is now configurable.
- Support for Unix domain sockets to the backend (available in 2.4.7
and later).
-
mod_proxy_balancer
- More runtime configuration changes for BalancerMembers via balancer-manager
- Additional BalancerMembers can be added at runtime via balancer-manager
- Runtime configuration of a subset of Balancer parameters
- BalancerMembers can be set to 'Drain' so that they only respond to existing sticky
sessions, allowing them to be taken gracefully offline.
- Balancer settings can be persistent after restarts.
-
mod_cache
- The
mod_cache CACHE filter can be optionally inserted
at a given point in the filter chain to provide fine control over caching.
-
mod_cache can now cache HEAD requests.
- Where possible,
mod_cache directives can now be set
per directory, instead of per server.
- The base URL of cached URLs can be customised, so that a cluster of
caches can share the same endpoint URL prefix.
-
mod_cache is now capable of serving stale cached
data when a backend is unavailable (error 5xx).
-
mod_cache can now insert HIT/MISS/REVALIDATE into
an X-Cache header.
-
mod_include
- Support for the 'onerror' attribute within an 'include' element,
allowing an error document to be served on error instead of the default
error string.
-
mod_cgi , mod_include ,
mod_isapi , ...
- Translation of headers to environment variables is more strict than
before to mitigate some possible cross-site-scripting attacks via header
injection. Headers containing invalid characters (including underscores)
are now silently dropped. Environment Variables
in Apache has some pointers on how to work around broken legacy
clients which require such headers. (This affects all modules which
use these environment variables.)
-
mod_authz_core Authorization Logic Containers
- Advanced authorization logic may now be specified using the
Require directive
and the related container directives, such as
<RequireAll> .
-
mod_rewrite
-
mod_rewrite adds the [QSD]
(Query String Discard) and [END] flags for
RewriteRule to
simplify common rewriting scenarios.
- Adds the possibility to use complex boolean expressions in
RewriteCond .
- Allows the use of SQL queries as
RewriteMap functions.
-
mod_ldap , mod_authnz_ldap
-
mod_authnz_ldap adds support for nested groups.
-
mod_ldap adds
LDAPConnectionPoolTTL ,
LDAPTimeout , and
other improvements in the handling of timeouts.
This is especially useful for setups where a
stateful firewall drops idle connections to the LDAP server.
-
mod_ldap adds
LDAPLibraryDebug to log
debug information provided by the used LDAP toolkit.
-
mod_info
-
mod_info can now dump the pre-parsed configuration
to stdout during server startup.
-
mod_auth_basic
- New generic mechanism to fake basic authentication (available in
2.4.5 and later).
Program Enhancements
-
fcgistarter
- New FastCGI daemon starter utility
-
htcacheclean
- Current cached URLs can now be listed, with optional metadata
included.
- Allow explicit deletion of individual cached URLs from the
cache.
- File sizes can now be rounded up to the given block size, making
the size limits map more closely to the real size on disk.
- Cache size can now be limited by the number of inodes, instead
of or in addition to being limited by the size of the files on
disk.
-
rotatelogs
- May now create a link to the current log file.
- May now invoke a custom post-rotate script.
-
htpasswd , htdbm
- Support for the bcrypt algorithm (available in 2.4.4 and later).
Documentation
- mod_rewrite
- The
mod_rewrite documentation has been
rearranged and almost completely rewritten, with a focus on
examples and common usage, as well as on showing you when other
solutions are more appropriate. The Rewrite
Guide is now a top-level section with much more detail and
better organization.
- mod_ssl
- The
mod_ssl documentation has been greatly
enhanced, with more examples at the getting started level, in
addition to the previous focus on technical details.
- Caching Guide
- The Caching Guide has been rewritten
to properly distinguish between the RFC2616 HTTP/1.1 caching
features provided by
mod_cache , and the generic
key/value caching provided by the socache
interface, as well as to cover specialised caching provided by
mechanisms such as mod_file_cache .
Module Developer Changes
- Check Configuration Hook Added
- A new hook,
check_config , has been added which runs
between the pre_config and open_logs
hooks. It also runs before the test_config hook
when the -t option is passed to
httpd . The check_config hook
allows modules to review interdependent configuration directive
values and adjust them while messages can still be logged to the
console. The user can thus be alerted to misconfiguration problems
before the core open_logs hook function redirects
console output to the error log.
- Expression Parser Added
- We now have a general-purpose expression parser, whose API is
exposed in ap_expr.h. This is adapted from the
expression parser previously implemented in
mod_ssl .
- Authorization Logic Containers
- Authorization modules now register as a provider, via
ap_register_auth_provider(), to support advanced authorization logic,
such as
<RequireAll> .
- Small-Object Caching Interface
- The ap_socache.h header exposes a provider-based
interface for caching small data objects, based on the previous
implementation of the
mod_ssl session cache.
Providers using a shared-memory cyclic buffer, disk-based dbm
files, and a memcache distributed cache are currently
supported.
- Cache Status Hook Added
- The
mod_cache module now includes a new
cache_status hook, which is called when the caching
decision becomes known. A default implementation is provided
which adds an optional X-Cache and
X-Cache-Detail header to the response.
The developer documentation contains a
detailed list of API changes.
|
 |
