httpd.conf

...
############## CUSTOM CONFIG #################
LogLevel debug

LoadModule auth_cas_module modules/mod_auth_cas.so

CASCookiePath /var/cache/httpd/mod_auth_cas/
CASLoginURL https://alfresco.<hostname>.com/auth/realms/master/protocol/cas/login
CASValidateURL https://alfresco.<hostname>.com/auth/realms/master/protocol/cas/serviceValidate
CASProxyValidateURL https://alfresco.<hostname>.com/auth/realms/master/protocol/cas/proxyValidate
CASDebug On

<Location /share>
#### CAS Auth ######
    AuthType CAS
    AuthName 'CAS'
    require valid-user
    CASAuthNHeader X-Alfresco-Remote-User
    CASScope /share
#### CAS Auth END

#### Basic Auth #####
#    RequestHeader set X-Alfresco-Remote-User admin
#    AllowOverride AuthConfig
#    AuthType Basic
#    AuthName "Authentication Required from Apache"
#    AuthUserFile "/etc/htpasswd/.htpasswd"
#### Basic Auth END #####

  Require valid-user
  Order allow,deny
  Allow from all
</Location>

ProxyPass               /auth            http://ec2-3-124-5-4.eu-central-1.compute.amazonaws.com:8080/auth
ProxyPassReverse        /auth            http://ec2-3-124-5-4.eu-central-1.compute.amazonaws.com:8080/auth

ProxyPass               /share           http://ec2-18-157-161-63.eu-central-1.compute.amazonaws.com:8080/share
ProxyPassReverse        /share           http://ec2-18-157-161-63.eu-central-1.compute.amazonaws.com:8080/share