Comment 9 for bug 2011716

This error happen because the file /tmp/dhparams.pem already exist.
So when the script /usr/local/bin/kolla_httpd_setup trigger the script /usr/libexec/httpd-ssl-gencerts,
he try to generate again the file but fail:

sscg -q \
     --cert-file /etc/pki/tls/certs/localhost.crt \
     --cert-key-file /etc/pki/tls/private/localhost.key \
     --ca-file /etc/pki/tls/certs/localhost.crt \
     --dhparams-file /tmp/dhparams.pem \
     --lifetime 365 \
     --hostname $FQDN \
     --email root@$FQDN

Not really sure what this file is about and why it has already been generated.

So we can add the -f option to the sscg call or in /usr/local/bin/kolla_httpd_setup we add this part:
rm -rf /var/run/httpd/* /run/httpd/* /tmp/httpd* /tmp/dhparams.pem

(at the start of the kolla script there is this information:
    # NOTE(pbourke): httpd will not clean up after itself in some cases which
    # results in the container not being able to restart. (bug #1489676, 1557036))