Could not reliably determine the server's fully qualified domain name … How to solve it in Docker?

Question

I am just starting in Docker and I was following that tutorial that shows basically these steps:

1. Create a Dockerfile like this:

   From php:7.0-apach

Answer 1

This is not an error it is just a warning and you can safely ignore it. What it is saying is that ServerName is not set so it will assume machine IP as the same.

If you look at the default configs present inside /etc/apache2/sites-available, you will find 000-default.conf and default-ssl.conf

root@d591ab6febff:/etc/apache2/sites-available# cat 000-default.conf

    # The ServerName directive sets the request scheme, hostname and port that
    # the server uses to identify itself. This is used when creating
    # redirection URLs. In the context of virtual hosts, the ServerName
    # specifies what hostname must appear in the request's Host: header to
    # match this virtual host. For the default virtual host (this file) this
    # value is not decisive as it is used as a last resort host regardless.
    # However, you must set it for any further virtual host explicitly.
    #ServerName www.example.com

    ServerAdmin webmaster@localhost
    DocumentRoot /var/www/html

    # Available loglevels: trace8, ..., trace1, debug, info, notice, warn,
    # error, crit, alert, emerg.
    # It is also possible to configure the loglevel for particular
    # modules, e.g.
    #LogLevel info ssl:warn

    ErrorLog ${APACHE_LOG_DIR}/error.log
    CustomLog ${APACHE_LOG_DIR}/access.log combined

    # For most configuration files from conf-available/, which are
    # enabled or disabled at a global level, it is possible to
    # include a line for only one particular virtual host. For example the
    # following line enables the CGI configuration for this host only
    # after it has been globally disabled with "a2disconf".
    #Include conf-available/serve-cgi-bin.conf

The ServerName directive is commented in the config

#ServerName www.example.com

So if you are worried about the warning you should change it to the value you want like below

ServerName www.tarunlalwani.com
ServerAlias tarunlalwani.com

You would need to create a config in your folder and then overwrite the files from default config using Dockerfile. Then the warning would be gone.