Using Let's Encrypt inside Docker's official Wordpress container

I believe this could be the issue with TERM, because the client uses some terminal user interface,
but even after fixing this with export TERM=xterm, you'll hit the issue with apache restart, when the letsencrypt client restarts apache and the wordpress container has been killed immediately. Thanks to the answer How to automatically start a service when running a docker container? I've overcome this in my custom WordPress image with the tail approach, you can have a look for more ideas there, as you can see from the screenshot, it works))

update

the following steps help to fix the issue with lines in the dialog (in addition to previously applied export TERM=xterm)

apt-get install locales
locale-gen "en_US.UTF-8"
localedef -v -c -i en_US -f UTF-8 en_US.UTF-8
export LC_ALL="en_US.UTF-8"
export NCURSES_NO_UTF8_ACS=1

You can also run the client in 2 other modes

• -t text UI mode
• -n, --non-interactive, --noninteractive Run without ever asking for user input. This may require additional command line flags; the client will try to explain which ones are required if it finds one missing