Configuring LDAP failover

# openshift start \
    --public-master=https://openshift.example.com:8443 \
    --write-config=/etc/origin/

# mkdir -p /etc/origin/remote-basic/
# oc adm ca create-server-cert \
    --cert='/etc/origin/remote-basic/remote-basic.example.com.crt' \
    --key='/etc/origin/remote-basic/remote-basic.example.com.key' \
    --hostnames=remote-basic.example.com \ (1)
    --signer-cert='/etc/origin/master/ca.crt' \
    --signer-key='/etc/origin/master/ca.key' \
    --signer-serial='/etc/origin/master/ca.serial.txt'

# scp /etc/origin/master/ca.crt \
      root@remote-basic.example.com:/etc/pki/CA/certs/

# scp /etc/origin/remote-basic/remote-basic.example.com.crt \
      root@remote-basic.example.com:/etc/pki/tls/certs/

# scp /etc/origin/remote-basic/remote-basic.example.com.key \
      root@remote-basic.example.com:/etc/pki/tls/private/

# yum install -y sssd \
                 sssd-dbus \
                 realmd \
                 httpd \
                 mod_session \
                 mod_ssl \
                 mod_lookup_identity \
                 mod_authnz_pam \
                 php \
                 mod_php

# realm join ldap.example.com

[domain/example.com]
...
ldap_user_extra_attrs = mail (1)

domains = example.com

[ifp]
user_attributes = +mail
allowed_uids = apache, root

$ systemctl restart sssd.service

$ getent passwd <username>
username:*:12345:12345:Example user:/home/username:/usr/bin/bash

# dbus-send --print-reply --system --dest=org.freedesktop.sssd.infopipe \
    /org/freedesktop/sssd/infopipe org.freedesktop.sssd.infopipe.GetuserAttr \
    string:username \ (1)
    array:string:mail (2)

method return time=1528091855.672691 sender=:1.2787 -> destination=:1.2795 serial=13 reply_serial=2
   array [
      dict entry(
         string "mail"
         variant             array [
               string "username@example.com"
            ]
      )
   ]

auth required pam_sss.so
account required pam_sss.so

LoadModule authnz_pam_module modules/mod_authnz_pam.so

LoadModule request_module modules/mod_request.so
LoadModule php7_module modules/libphp7.so

# Nothing needs to be served over HTTP.  This virtual host simply redirects to
# HTTPS.
<VirtualHost *:80>
  DocumentRoot /var/www/html
  RewriteEngine              On
  RewriteRule     ^(.*)$     https://%{HTTP_HOST}$1 [R,L]
</VirtualHost>

<VirtualHost *:443>
  # This needs to match the certificates you generated.  See the CN and X509v3
  # Subject Alternative Name in the output of:
  # openssl x509 -text -in /etc/pki/tls/certs/remote-basic.example.com.crt
  ServerName remote-basic.example.com

  DocumentRoot /var/www/html

  # Secure all connections with TLS
  SSLEngine on
  SSLCertificateFile /etc/pki/tls/certs/remote-basic.example.com.crt
  SSLCertificateKeyFile /etc/pki/tls/private/remote-basic.example.com.key
  SSLCACertificateFile /etc/pki/CA/certs/ca.crt

  # Require that TLS clients provide a valid certificate
  SSLVerifyClient require
  SSLVerifyDepth 10

  # Other SSL options that may be useful
  # SSLCertificateChainFile ...
  # SSLCARevocationFile ...

  # Send logs to a specific location to make them easier to find
  ErrorLog logs/remote_basic_error_log
  TransferLog logs/remote_basic_access_log
  LogLevel warn

  # PHP script that turns the Apache REMOTE_user env var
  # into a JSON formatted response that OpenShift understands
  <Location /check_user.php>
    # all requests not using SSL are denied
    SSLRequireSSL
    # denies access when SSLRequireSSL is applied
    SSLOptions +StrictRequire
    # Require both a valid basic auth user (so REMOTE_user is always set)
    # and that the CN of the TLS client matches that of the OpenShift master
    <RequireAll>
      Require valid-user
      Require expr %{SSL_CLIENT_S_DN_CN} == 'system:openshift-master'
    </RequireAll>
    # Use basic auth since OpenShift will call this endpoint with a basic challenge
    AuthType Basic
    AuthName openshift
    AuthBasicProvider PAM
    AuthPAMService openshift

    # Store attributes in environment variables. Specify the email attribute that
    # you confirmed.
    LookupOutput Env
    LookupuserAttr mail REMOTE_user_MAIL
    LookupuserGECOS REMOTE_user_DISPLAY_NAME

    # Other options that might be useful

    # While REMOTE_user is used as the sub field and serves as the immutable ID,
    # REMOTE_user_PREFERRED_userNAME could be used to have a different username
    # LookupuserAttr <attr_name> REMOTE_user_PREFERRED_userNAME

    # Group support may be added in a future release
    # LookupuserGroupsIter REMOTE_user_GROUP
  </Location>

  # Deny everything else
  <Location ~ "^((?!\/check_user\.php).)*$">
      Deny from all
  </Location>
</VirtualHost>

<?php
// Get the user based on the Apache var, this should always be
// set because we 'Require valid-user' in the configuration
$user = apache_getenv('REMOTE_user');

// However, we assume it may not be set and
// build an error response by default
$data = array(
    'error' => 'remote PAM authentication failed'
);

// Build a success response if we have a user
if (!empty($user)) {
    $data = array(
        'sub' => $user
    );
    // Map of optional environment variables to optional JSON fields
    $env_map = array(
        'REMOTE_user_MAIL' => 'email',
        'REMOTE_user_DISPLAY_NAME' => 'name',
        'REMOTE_user_PREFERRED_userNAME' => 'preferred_username'
    );

    // Add all non-empty environment variables to JSON data
    foreach ($env_map as $env_name => $json_name) {
        $env_data = apache_getenv($env_name);
        if (!empty($env_data)) {
            $data[$json_name] = $env_data;
        }
    }
}

// We always output JSON from this script
header('Content-Type: application/json', true);

// Write the response as JSON
echo json_encode($data);
?>

LoadModule lookup_identity_module modules/mod_lookup_identity.so

# setsebool -P httpd_dbus_sssd on

# setsebool -P allow_httpd_mod_auth_pam on

# systemctl start httpd.service

  identityProviders:
  - name: sssd
    challenge: true
    login: true
    mappingMethod: claim
    provider:
      apiVersion: v1
      kind: BasicAuthPasswordIdentityProvider
      url: https://remote-basic.example.com/check_user.php
      ca: /etc/origin/master/ca.crt
      certFile: /etc/origin/master/openshift-master.crt
      keyFile: /etc/origin/master/openshift-master.key

# systemctl restart atomic-openshift-master-api

# systemctl restart atomic-openshift-master-controllers

$ oc login https://openshift.example.com:8443

$ oc get identity -o yaml