Certbot Apache error "Name duplicates previous WSGI daemon definition."

Question

On my Ubuntu 16.04 server, I have an Apache conf file at /etc/apache2/sites-enabled/000-default.conf, which looks like this (abbreviated):

WSGIApplicationGroup %{GLOBAL}

<VirtualHost *:80>
    ServerName example.com
    WSGIDaemonProcess myprocess user=ubuntu group=ubuntu threads=10 home=/home/ubuntu/myapp
    WSGIProcessGroup myprocess
    ...
</VirtualHost>

It works fine in HTTP mode, but when I run $ sudo certbot --apache to set up HTTPS, it fails with the error Syntax error on line 7 of /etc/apache2/sites-enabled/000-default.conf: Name duplicates previous WSGI daemon definition. Line 7 is the line beginning with WSGIDaemonProcess.

Answer 1

It turns out that if my Apache conf file 000-default.conf only declares <VirtualHost *:80>...</VirtualHost>, then Certbot duplicates it and creates a second Apache conf file called 000-default-le-ssl.conf to define <VirtualHost *:443>...</VirtualHost>.

The Name duplicates previous WSGI daemon definition error appears because both Apache conf files have the same line defining WSGIDaemonProcess myprocess.... This appears to be a known Certbot bug.

The workaround I've found is to define both VirtualHosts (80 and 443) in the same Apache conf file (so that Certbot doesn't create a second file), and to define WSGIDaemonProcess outside both VirtualHosts, like this:

WSGIApplicationGroup %{GLOBAL}
WSGIDaemonProcess myprocess user=ubuntu group=ubuntu threads=10 home=/home/ubuntu/myapp
WSGIProcessGroup myprocess

<VirtualHost *:80>
    ServerName example.com
    ...
</VirtualHost>
<VirtualHost *:443>
    ServerName example.com
    ...
</VirtualHost>

Answer 2

As the error says, you cannot use the same name for a WSGIDaemonProcess definition more than once. They have to be unique for the whole Apache instance.

If you have both 80 and 443 instances of the VirtualHost for same ServerName, you shouldn't create a separate WSGIDaemonProcess in the 443 instance. Define it in the 80 instance and reference by name from the 443 instance. That way you share the same daemon process group between 80 and 443 instances of the VirtualHost for the same ServerName.

WSGIApplicationGroup %{GLOBAL}
WSGIRestrictEmbedded On

<VirtualHost *:80>
ServerName example.com
WSGIDaemonProcess myprocess threads=10 home=/home/ubuntu/myapp
WSGIProcessGroup myprocess
...
</VirtualHost>

<VirtualHost *:443>
ServerName example.com
WSGIProcessGroup myprocess
...
</VirtualHost>