无法可靠地确定服务器的标准域名...如何在Docker中解决? [英] Could not reliably determine the server's fully qualified domain name ... How to solve it in Docker?
问题描述
我刚刚开始使用Docker，我一直在关注教程，该教程基本上显示了这些内容步骤:
I am just starting in Docker and I was following that tutorial that shows basically these steps:
-
像这样创建一个Dockerfile:
Create a Dockerfile like this:
From php:7.0-apache
copy src/ /var/www/html
EXPOSE 80
From php:7.0-apache
copy src/ /var/www/html
EXPOSE 80
从我拥有dockerfile的位置构建容器:
Build the container from where I have my dockerfile:
$ docker build -t mytest .
生成图像"mytest"后，我使用以下命令运行它:
After the image "mytest" is generated I run it with:
$ docker run -p 80 mytest
这就是我得到的错误:
AH00558: apache2: Could not reliably determine the server's fully qualified domain name, using 172.17.0.2. Set the 'ServerName' directive globally to suppress this message
AH00558: apache2: Could not reliably determine the server's fully qualified domain name, using 172.17.0.2. Set the 'ServerName' directive globally to suppress this message
[Sun Sep 17 16:25:12.340564 2017] [mpm_prefork:notice] [pid 1] AH00163: Apache/2.4.10 (Debian) PHP/7.0.23 configured -- resuming normal operations
[Sun Sep 17 16:25:12.340666 2017] [core:notice] [pid 1] AH00094: Command line: 'apache2 -D FOREGROUND'
所以，我不知道如何解决.有帮助吗?
So, I dont know how to solve it. Any help?
推荐答案
我想提供另一种(可能更多的Docker-ish)解决警告消息的方法.但是首先，在盲目地设置ServerName之前，先了解 Apache实际上正在弄清楚域名的意义. http://ratfactor.com/apache-fqdn.html 上有一篇很好的文章，其中解释了过程.
I'd like to offer another (maybe more Docker-ish) way of solving the warning message. But first, it makes sense to understand what Apache is actually doing to figure out the domain name before just blindly setting ServerName. There is a good article at http://ratfactor.com/apache-fqdn.html which explains the process.
一旦我们可以确认getnameinfo是Apache用于查找名称的对象，并且可以使用/etc/nsswitch.conf确定首先查找的位置，我们就可以找出要修改的内容.
Once we can confirm that getnameinfo is what Apache uses to lookup the name and that it uses /etc/nsswitch.conf to determine where to go first for the lookup, we can figure out what to modify.
如果我们检查容器内的nsswitch.conf，我们可以看到它在外部DNS之前的/etc/hosts文件中查找主机:
If we check out the nsswitch.conf inside the container we can see that it looks up hosts in the /etc/hosts file before external DNS:
# cat /etc/nsswitch.conf | grep hosts
hosts: files dns
知道了这一点，也许我们可以在Docker运行时影响文件，而不是将其添加到我们的配置文件中?
Knowing this, maybe we can influence the file at Docker runtime instead of adding it to our configuration files?
如果我们查看Docker运行参考文档，则/etc/hosts文件上的
If we take a look at the Docker run reference documentation there is a section on the /etc/hosts file at https://docs.docker.com/engine/reference/run/#managing-etchosts. It mentions:
您的容器将在/etc/hosts中包含几行，这些行定义了容器本身的主机名以及localhost和其他一些常见的东西.
Your container will have lines in /etc/hosts which define the hostname of the container itself as well as localhost and a few other common things.
因此，如果我们仅设置容器主机名，它将被添加到/etc/hosts中，这将解决Apache警告.幸运的是，使用--hostname或-h选项很容易做到这一点.如果我们将其设置为完全限定的域名，则Docker将在我们的/etc/hosts文件中对其进行设置，而Apache将对其进行提取.
So, if we just set the container hostname, it will get added to /etc/hosts which will solve the Apache warning. Fortunately, this is very easy to do with the --hostname or -h option. If we set this to a fully qualified domain name, Docker will set it in our /etc/hosts file and Apache will pick it up.
尝试一下很容易.警告示例(无主机名):
It is pretty easy to try this out. Example with the warning (no hostname):
$ docker run --rm php:7.0-apache
AH00558: apache2: Could not reliably determine the server's fully qualified domain name, using 172.17.0.2. Set the 'ServerName' directive globally to suppress this message
AH00558: apache2: Could not reliably determine the server's fully qualified domain name, using 172.17.0.2. Set the 'ServerName' directive globally to suppress this message
[Sun Sep 17 19:00:32.919074 2017] [mpm_prefork:notice] [pid 1] AH00163: Apache/2.4.10 (Debian) PHP/7.0.23 configured -- resuming normal operations
[Sun Sep 17 19:00:32.919122 2017] [core:notice] [pid 1] AH00094: Command line: 'apache2 -D FOREGROUND'
现在将-h选项设置为完全限定的域名:
Now with the -h option set to a fully qualified domain name:
$ docker run --rm -h myapp.mydomain.com php:7.0-apache
[Sun Sep 17 19:01:27.968915 2017] [mpm_prefork:notice] [pid 1] AH00163: Apache/2.4.10 (Debian) PHP/7.0.23 configured -- resuming normal operations
[Sun Sep 17 19:01:27.968968 2017] [core:notice] [pid 1] AH00094: Command line: 'apache2 -D FOREGROUND'
希望这有助于回答问题，并提供有关Apache和完全限定域名的一些知识.
Hope this helps answer the question and provide some learning about Apache and fully qualified domain names.
这篇关于无法可靠地确定服务器的标准域名...如何在Docker中解决?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
