我目前遇到一个问题，我们的生产站点主页的 Drupal 安装失败，出现“ERR_TOO_MANY_REDIRECTS”错误。
我们的设置的一些背景：在我们的服务器上，我们设置了不同的 VHost 来运行不同的应用程序。
其想法是每个安装都将在域名的子目录中提供服务，例如 subdomain.example.com/app1 和 subdomain.example.com/app2。
它已经运行了将近一年，突然间，只有 Drupal 安装的主页开始出现重定向循环 (subdomain.example.com/app)。临时环境的设置方式完全相同，不会出现此行为。此外，生产应用程序中的其他页面也没有任何问题 (subdomain.example.com/app/page)。
安装位于服务器上的 /var/www/app。当访问 subdomain.example.com/app/ 时，此位置应作为安装的文档根目录。
有问题的安装的 VHOST 如下所示：
<Directory "/var/www/app">
#
# Possible values for the Options directive are "None", "All",
# or any combination of:
# Indexes Includes FollowSymLinks SymLinksifOwnerMatch ExecCGI MultiViews
#
# Note that "MultiViews" must be named *explicitly* --- "Options All"
# doesn't give it to you.
#
# The Options directive is both complicated and important. Please see
# http://httpd.apache.org/docs/2.4/mod/core.html#options
# for more information.
#
Options Indexes FollowSymLinks
#
# AllowOverride controls what directives may be placed in .htaccess files.
# It can be "All", "None", or any combination of the keywords:
# Options FileInfo AuthConfig Limit
#
AllowOverride All
Order allow,deny
Allow from all
#
# Controls who can get stuff from this server.
#
Require all granted
RewriteEngine on
RewriteBase /
Include /var/www/app/.htaccess
</Directory>
NameVirtualHost *:80
<VirtualHost *:80>
ServerName subdomain.example.com
ServerPath /app
DocumentRoot /var/www/app
</VirtualHost>
# Set the Alias for the CLP installation
Alias "/app/" "/var/www/app/"
Alias "/app" "/var/www/app"
我还在每个 VHOSTS 内部都有一个 .htaccess 文件来驱动重定向：
#
# Apache/PHP/Drupal settings:
#
SetEnvIfNoCase X-Forwarded-Proto https HTTPS=on
# Protect files and directories from prying eyes.
<FilesMatch "\.(engine|inc|info|install|make|module|profile|test|po|sh|.*sql|theme|tpl(\.php)?|xtmpl)(~|\.sw[op]|\.bak|\.orig|\.save)?$|^(\..*|Entries.*|Repository|Root|Tag|Template|composer\.(json|lock))$|^#.*#$|\.php(~|\.sw[op]|\.bak|\.orig\.save)$">
Order allow,deny
</FilesMatch>
# Don't show directory listings for URLs which map to a directory.
Options -Indexes
# Follow symbolic links in this directory.
Options +FollowSymLinks
# Make Drupal handle any 404 errors.
# Relative to the DocumentRoot defined in httpd.conf
ErrorDocument 404 /app/index.php
# Set the default handler.
# Relative to the DocumentRoot defined in httpd.conf
DirectoryIndex /app/index.php /app/index.html /app/index.htm
# Override PHP settings that cannot be changed at runtime. See
# sites/default/default.settings.php and drupal_environment_initialize() in
# includes/bootstrap.inc for settings that can be changed at runtime.
php_value upload_max_filesize 500M
php_value post_max_size 500M
php_value memory_limit 500M
# PHP 5, Apache 1 and 2.
<IfModule mod_php5>
php_flag magic_quotes_gpc off
php_flag magic_quotes_sybase off
php_flag register_globals off
php_flag session.auto_start off
php_value mbstring.http_input pass
php_value mbstring.http_output pass
php_flag mbstring.encoding_translation off
</IfModule>
# Requires mod_expires to be enabled.
<IfModule mod_expires.c>
# Enable expirations.
ExpiresActive On
# Cache all files for 2 weeks after access (A).
ExpiresDefault A1209600
<FilesMatch \.php$>
# Do not allow PHP scripts to be cached unless they explicitly send cache
# headers themselves. Otherwise all scripts would have to overwrite the
# headers set by mod_expires if they want another caching behavior. This may
# fail if an error occurs early in the bootstrap process, and it may cause
# problems if a non-Drupal PHP file is installed in a subdirectory.
ExpiresActive Off
</FilesMatch>
</IfModule>
# Various rewrite rules.
<IfModule mod_rewrite.c>
RewriteEngine on
# Set "protossl" to "s" if we were accessed via https://. This is used later
# if you enable "www." stripping or enforcement, in order to ensure that
# you don't bounce between http and https.
RewriteRule ^ - [E=protossl]
RewriteCond %{HTTPS} on
RewriteRule ^ - [E=protossl:s]
# Make sure Authorization HTTP header is available to PHP
# even when running as CGI or FastCGI.
RewriteRule ^ - [E=HTTP_AUTHORIZATION:%{HTTP:Authorization}]
# Block access to "hidden" directories whose names begin with a period. This
# includes directories used by version control systems such as Subversion or
# Git to store control files. Files whose names begin with a period, as well
# as the control files used by CVS, are protected by the FilesMatch directive
# above.
#
# NOTE: This only works when mod_rewrite is loaded. Without mod_rewrite, it is
# not possible to block access to entire directories from .htaccess, because
# <DirectoryMatch> is not allowed here.
#
# If you do not have mod_rewrite installed, you should remove these
# directories from your webroot or otherwise protect them from being
# downloaded.
RewriteRule "/\.|^\.(?!well-known/)" - [F]
# If your site can be accessed both with and without the 'www.' prefix, you
# can use one of the following settings to redirect users to your preferred
# URL, either WITH or WITHOUT the 'www.' prefix. Choose ONLY one option:
#
# To redirect all users to access the site WITH the 'www.' prefix,
# (http://example.com/... will be redirected to http://www.example.com/...)
# uncomment the following:
# RewriteCond %{HTTP_HOST} .
# RewriteCond %{HTTP_HOST} !^www\. [NC]
# RewriteRule ^ http%{ENV:protossl}://www.%{HTTP_HOST}%{REQUEST_URI} [L,R=301]
#
# To redirect all users to access the site WITHOUT the 'www.' prefix,
# (http://www.example.com/... will be redirected to http://example.com/...)
# uncomment the following:
# RewriteCond %{HTTP_HOST} ^www\.(.+)$ [NC]
# RewriteRule ^ http%{ENV:protossl}://%1%{REQUEST_URI} [L,R=301]
# Modify the RewriteBase if you are using Drupal in a subdirectory or in a
# VirtualDocumentRoot and the rewrite rules are not working properly.
# For example if your site is at http://example.com/drupal uncomment and
# modify the following line:
RewriteBase /app/
#
# If your site is running in a VirtualDocumentRoot at http://example.com/,
# uncomment the following line:
#RewriteBase /
# Pass all requests not referring directly to files in the filesystem to
# index.php. Clean URLs are handled in drupal_environment_initialize().
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_URI} !=/favicon.ico
RewriteRule ^ index.php [L]
# Rules to correctly serve gzip compressed CSS and JS files.
# Requires both mod_rewrite and mod_headers to be enabled.
<IfModule mod_headers.c>
# Serve gzip compressed CSS files if they exist and the client accepts gzip.
RewriteCond %{HTTP:Accept-encoding} gzip
RewriteCond %{REQUEST_FILENAME}\.gz -s
RewriteRule ^(.*)\.css $1\.css\.gz [QSA]
# Serve gzip compressed JS files if they exist and the client accepts gzip.
RewriteCond %{HTTP:Accept-encoding} gzip
RewriteCond %{REQUEST_FILENAME}\.gz -s
RewriteRule ^(.*)\.js $1\.js\.gz [QSA]
# Serve correct content types, and prevent mod_deflate double gzip.
RewriteRule \.css\.gz$ - [T=text/css,E=no-gzip:1]
RewriteRule \.js\.gz$ - [T=text/javascript,E=no-gzip:1]
<FilesMatch "(\.js\.gz|\.css\.gz)$">
# Serve correct encoding type.
Header set Content-Encoding gzip
# Force proxies to cache gzipped & non-gzipped css/js files separately.
Header append Vary Accept-Encoding
</FilesMatch>
</IfModule>
RedirectMatch ^(.*)/app/course-page/CP([0-9]*)$ $1/app/course-page/$2
RedirectMatch ^(.*)/app/ramping-site/RS([0-9]*)$ $1/app/ramping-site/$2
RedirectMatch ^(.*)/app/content/BCTID([0-9]*)$ $1/app/content/$2
</IfModule>
# Add headers to all responses.
<IfModule mod_headers.c>
# Disable content sniffing, since it's an attack vector.
Header always set X-Content-Type-Options nosniff
</IfModule>
服务已经中断两天了，我却无法找到解决方案。
答案1
感谢大家的反馈。结果发现是虚拟机上的一个损坏的文件最终导致它崩溃。仍然不确定是什么原因。
如果我能弄清楚到底是什么损坏了，我会把它放在这里以供参考。
然而，在崩溃之前，Apache (HTTPD) 停止在浏览器中运行 PHP 7.0。它会在 CLI 中运行 PHP 脚本，但只会在 Web 浏览器中显示 PHP 文本。几个小时后，服务器崩溃了。