If you're installing the IMAP extension in your PHP docker image, it's possible that you get some errors like:
configure: error: utf8_mime2text() has new signature, but U8T_CANONICAL is missing. This should not happen. Check config.log for additional information.
and then:
configure: error: This c-client library is built with Kerberos support.
To solve this error:
configure: error: utf8_mime2text() has new signature, but U8T_CANONICAL is missing. This should not happen. Check config.log for additional information.
You just need to run the next command:
apt update && apt install -y libc-client-dev libkrb5-dev && rm -r /var/lib/apt/lists/*
So, now is probably that a new error appear:
configure: error: This c-client library is built with Kerberos support.
To solve this new error, you must install the extension with the next command:
docker-php-ext-configure imap --with-kerberos --with-imap-ssl && docker-php-ext-install imap