我有一个功能齐全的 ubuntu 14.04，其中 apache2 使用 Passenger Standalone 在反向代理中提供 ror 网站。升级到 16.04 后，一切都停止了，尽管我仍然可以使用“仅” Passenger Standalone 访问该网站。
经过大量“调查”，我得出结论，我的机器上的基本 apache2 安装存在问题。所以我回到了基础。
我创建了一个 VirtualHost，如下所示：
服务器名称 pd 文档根目录/home/purvez/www/testapp/public
我将其保存为/etc/apache2/sites-available/pd.conf
然后我运行sudo a2ensite pd.conf 将符号链接放入/etc/apache2/sites-enabled/pd.conf
我有一个非常简单的index.html，由一行组成，如下所示：
<h1>Test pd site</h1>
我在 hosts 中也有一个条目
127.0.0.1 pd
我已经重新启动了 apache 服务器并重新启动了机器。
然而，当我进入网页中的 pd 时，我得到的只是 Apache2 Ubuntu 默认页面（它的开头部分有此文本）...
Ubuntu 标志 Apache2 Ubuntu 默认页面 它起作用了！
这是在 Ubuntu 系统上安装 Apache2 服务器后，用来测试其是否正常运行的默认欢迎页面。它基于 Debian 上的等效页面，Ubuntu Apache 打包即源于此。如果您能读到此页面，则表示安装在该站点的 Apache HTTP 服务器正常运行。您应该先替换此文件（位于/var/www/html/index.html），然后再继续操作 HTTP 服务器。
如果您是本网站的普通用户，并且不知道此页面的内容，则可能意味着该网站目前因维护而无法使用。如果问题仍然存在，请联系网站管理员。配置概述
ETC。
另一件令人抓狂的事情是，即使我关闭了 apache 服务，我仍然会看到相同的页面。
目前在我看来 apache2 要么没有工作，要么即使工作也只是提供“默认页面”。
----------为想要完整 apache2.conf 的@eldergeek 编辑 1
#
# Based upon the NCSA server configuration files originally by Rob McCool.
#
# This is the main Apache server configuration file. It contains the
# configuration directives that give the server its instructions.
# See http://httpd.apache.org/docs/2.2/ for detailed information about
# the directives.
#
# Do NOT simply read the instructions in here without understanding
# what they do. They're here only as hints or reminders. If you are unsure
# consult the online docs. You have been warned.
#
# The configuration directives are grouped into three basic sections:
# 1. Directives that control the operation of the Apache server process as a
# whole (the 'global environment').
# 2. Directives that define the parameters of the 'main' or 'default' server,
# which responds to requests that aren't handled by a virtual host.
# These directives also provide default values for the settings
# of all virtual hosts.
# 3. Settings for virtual hosts, which allow Web requests to be sent to
# different IP addresses or hostnames and have them handled by the
# same Apache server process.
#
# Configuration and logfile names: If the filenames you specify for many
# of the server's control files begin with "/" (or "drive:/" for Win32), the
# server will use that explicit path. If the filenames do *not* begin
# with "/", the value of ServerRoot is prepended -- so "foo.log"
# with ServerRoot set to "/etc/apache2" will be interpreted by the
# server as "/etc/apache2/foo.log".
#
### Section 1: Global Environment
#
# The directives in this section affect the overall operation of Apache,
# such as the number of concurrent requests it can handle or where it
# can find its configuration files.
#
#
# ServerRoot: The top of the directory tree under which the server's
# configuration, error, and log files are kept.
#
# NOTE! If you intend to place this on an NFS (or otherwise network)
# mounted filesystem then please read the LockFile documentation (available
# at <URL:http://httpd.apache.org/docs/2.2/mod/mpm_common.html#lockfile>);
# you will save yourself a lot of trouble.
#
# Do NOT add a slash at the end of the directory path.
#
#ServerRoot "/etc/apache2"
#
# The accept serialization lock file MUST BE STORED ON A LOCAL DISK.
#
# LockFile ${APACHE_LOCK_DIR}/accept.lock
#
# PidFile: The file in which the server should record its process
# identification number when it starts.
# This needs to be set in /etc/apache2/envvars
#
PidFile ${APACHE_PID_FILE}
#
# Timeout: The number of seconds before receives and sends time out.
#
Timeout 300
#
# KeepAlive: Whether or not to allow persistent connections (more than
# one request per connection). Set to "Off" to deactivate.
#
KeepAlive On
#
# MaxKeepAliveRequests: The maximum number of requests to allow
# during a persistent connection. Set to 0 to allow an unlimited amount.
# We recommend you leave this number high, for maximum performance.
#
MaxKeepAliveRequests 100
#
# KeepAliveTimeout: Number of seconds to wait for the next request from the
# same client on the same connection.
#
KeepAliveTimeout 5
##
## Server-Pool Size Regulation (MPM specific)
##
# prefork MPM
# StartServers: number of server processes to start
# MinSpareServers: minimum number of server processes which are kept spare
# MaxSpareServers: maximum number of server processes which are kept spare
# MaxClients: maximum number of server processes allowed to start
# MaxRequestsPerChild: maximum number of requests a server process serves
<IfModule mpm_prefork_module>
StartServers 5
MinSpareServers 5
MaxSpareServers 10
MaxClients 150
MaxRequestsPerChild 0
</IfModule>
# worker MPM
# StartServers: initial number of server processes to start
# MinSpareThreads: minimum number of worker threads which are kept spare
# MaxSpareThreads: maximum number of worker threads which are kept spare
# ThreadLimit: ThreadsPerChild can be changed to this maximum value during a
# graceful restart. ThreadLimit can only be changed by stopping
# and starting Apache.
# ThreadsPerChild: constant number of worker threads in each server process
# MaxClients: maximum number of simultaneous client connections
# MaxRequestsPerChild: maximum number of requests a server process serves
<IfModule mpm_worker_module>
StartServers 2
MinSpareThreads 25
MaxSpareThreads 75
ThreadLimit 64
ThreadsPerChild 25
MaxClients 150
MaxRequestsPerChild 0
</IfModule>
# event MPM
# StartServers: initial number of server processes to start
# MinSpareThreads: minimum number of worker threads which are kept spare
# MaxSpareThreads: maximum number of worker threads which are kept spare
# ThreadsPerChild: constant number of worker threads in each server process
# MaxClients: maximum number of simultaneous client connections
# MaxRequestsPerChild: maximum number of requests a server process serves
<IfModule mpm_event_module>
StartServers 2
MinSpareThreads 25
MaxSpareThreads 75
ThreadLimit 64
ThreadsPerChild 25
MaxClients 150
MaxRequestsPerChild 0
</IfModule>
# These need to be set in /etc/apache2/envvars
User ${APACHE_RUN_USER}
Group ${APACHE_RUN_GROUP}
#
# AccessFileName: The name of the file to look for in each directory
# for additional configuration directives. See also the AllowOverride
# directive.
#
AccessFileName .htaccess
#
# The following lines prevent .htaccess and .htpasswd files from being
# viewed by Web clients.
#
<Files ~ "^\.ht">
Order allow,deny
Deny from all
Satisfy all
</Files>
#
# DefaultType is the default MIME type the server will use for a document
# if it cannot otherwise determine one, such as from filename extensions.
# If your server contains mostly text or HTML documents, "text/plain" is
# a good value. If most of your content is binary, such as applications
# or images, you may want to use "application/octet-stream" instead to
# keep browsers from trying to display binary files as though they are
# text.
#
# It is also possible to omit any default MIME type and let the
# client's browser guess an appropriate action instead. Typically the
# browser will decide based on the file's extension then. In cases
# where no good assumption can be made, letting the default MIME type
# unset is suggested instead of forcing the browser to accept
# incorrect metadata.
#
DefaultType None
#
# HostnameLookups: Log the names of clients or just their IP addresses
# e.g., www.apache.org (on) or 204.62.129.132 (off).
# The default is off because it'd be overall better for the net if people
# had to knowingly turn this feature on, since enabling it means that
# each client request will result in AT LEAST one lookup request to the
# nameserver.
#
HostnameLookups Off
# ErrorLog: The location of the error log file.
# If you do not specify an ErrorLog directive within a <VirtualHost>
# container, error messages relating to that virtual host will be
# logged here. If you *do* define an error logfile for a <VirtualHost>
# container, that host's errors will be logged there and not here.
#
ErrorLog ${APACHE_LOG_DIR}/error.log
#
# LogLevel: Control the number of messages logged to the error_log.
# Possible values include: debug, info, notice, warn, error, crit,
# alert, emerg.
#
LogLevel warn
# Include module configuration:
Include mods-enabled/*.load
Include mods-enabled/*.conf
# Include all the user configurations:
# Include httpd.conf
# Include ports listing
Include ports.conf
#
# The following directives define some format nicknames for use with
# a CustomLog directive (see below).
# If you are behind a reverse proxy, you might want to change %h into %{X-Forwarded-For}i
#
LogFormat "%v:%p %h %l %u %t \"%r\" %>s %O \"%{Referer}i\" \"%{User-Agent}i\"" vhost_combined
LogFormat "%h %l %u %t \"%r\" %>s %O \"%{Referer}i\" \"%{User-Agent}i\"" combined
LogFormat "%h %l %u %t \"%r\" %>s %O" common
LogFormat "%{Referer}i -> %U" referer
LogFormat "%{User-agent}i" agent
# Include of directories ignores editors' and dpkg's backup files,
# see README.Debian for details.
# Include generic snippets of statements
#Include conf.d/
# Include the virtual host configurations:
Include sites-enabled/
ServerName nexar
#LoadModule passenger_module /home/purvez/.rvm/gems/ruby-1.9.3-p0@global/gems/passenger-3.0.11/ext/apache2/mod_passenger.so
#PassengerRoot /home/purvez/.rvm/gems/ruby-1.9.3-p0@global/gems/passenger-3.0.11
#PassengerRuby /home/purvez/.rvm/wrappers/ruby-1.9.3-p0/ruby
----------------- 编辑 1 结束
======== 编辑 2：这是 cli 上命令的输出：
systemctl 状态 apache2.service
systemctl status apache2.service
● apache2.service - LSB: Apache2 web server
Loaded: loaded (/etc/init.d/apache2; bad; vendor preset: enabled)
Drop-In: /lib/systemd/system/apache2.service.d
└─apache2-systemd.conf
Active: inactive (dead) since Wed 2017-04-12 20:05:23 BST; 8min ago
Docs: man:systemd-sysv-generator(8)
Process: 15645 ExecStop=/etc/init.d/apache2 stop (code=exited, status=0/SUCCES
Process: 15628 ExecStart=/etc/init.d/apache2 start (code=exited, status=0/SUCC
Apr 12 20:05:23 127.0.1.1purvez-Aspire-5750 apache2[15628]: (98)Address already
Apr 12 20:05:23 127.0.1.1purvez-Aspire-5750 apache2[15628]: (98)Address already
Apr 12 20:05:23 127.0.1.1purvez-Aspire-5750 apache2[15628]: no listening sockets
Apr 12 20:05:23 127.0.1.1purvez-Aspire-5750 apache2[15628]: AH00015: Unable to o
Apr 12 20:05:23 127.0.1.1purvez-Aspire-5750 apache2[15628]: Action 'start' faile
Apr 12 20:05:23 127.0.1.1purvez-Aspire-5750 apache2[15628]: The Apache error log
Apr 12 20:05:23 127.0.1.1purvez-Aspire-5750 apache2[15628]: *
Apr 12 20:05:23 127.0.1.1purvez-Aspire-5750 apache2[15645]: * Stopping Apache h
Apr 12 20:05:23 127.0.1.1purvez-Aspire-5750 apache2[15645]: *
Apr 12 20:05:23 127.0.1.1purvez-Aspire-5750 systemd[1]: Started LSB: Apache2 web
purvez@127:~$
我不敢说我完全理解了，但看起来 Apache2 确实在运行。不过下面这行（命令开头第 5/6 行有点让人担心）：
活跃：自 2017-04-12 星期三 20:05:23 BST；8 分钟前开始不活跃（已死亡）
================= 编辑 2 结束
答案1
尝试将其作为 pd.conf
<VirtualHost *:80>
ServerName pd
DocumentRoot /home/purvez/www/testapp/public
<Directory /home/purvez/www/testapp/public>
Options Indexes FollowSymLinks
AllowOverride None
Require all granted
</Directory>
</VirtualHost>
重新启动 Apache 并尝试一下。
答案2
您要么在端口 80 上运行其他程序（以 root 身份运行 lsof -i :80），要么在各个配置文件中重叠 Listen 指令（针对端口 80）（grep -ri Listen /etc/apache2）