Add support for HANA active/read-enabled system replication in Pacemaker cluster

[hjstam]

Problem

• SAP allows active/read-enabled setups for SAP HANA System Replication, where the secondary systems of SAP HANA System Replication can be used actively for read-intense workloads. SDAF currently has no support for this.
• The sapadm user isn't created with the sapadm_uid as specified in the ansible-input-api variable which was only observed on HANA systems. For (A)SCS, ERS and PAS/APP the generic user creation took care of the creation of the sapadm user with the right uid.

Solution

• Add support for HANA active/read-enabled system replication in Pacemaker cluster. A second front-end is added to the HDB load balancer with a seperate health probe and load balancer rule. It re-uses the same back-end. HANA replication is set-up with the operation mode logreplay_readaccess and pacemaker is configured with an additional resource g_secip_.
• Create the sapadm user like it was before version 3.7 of SDAF. This seems like a bug that was introduced in 5884945#diff-d3129e54dc1d8b4502da8ee28296a38f7b058bdff58ce55ecc9a8f72f3d10ddcR102

Tests

Deployed a high available HANA cluster on RHEL 8.10 with the database_active_active variable set to true.

[root@hana01] root # pcs status
Cluster name: SID_cluster
Cluster Summary:
  * Stack: corosync (Pacemaker is running)
  * Current DC: hana01 (version 2.1.7-5.2.el8_10-0f7f88312) - partition with quorum
  * Last updated: Mon Nov  4 17:08:03 2024 on hana02
  * Last change:  Mon Nov  4 16:21:58 2024 by root via root on hana02
  * 2 nodes configured
  * 9 resource instances configured

Node List:
  * Online: [ hana01 hana02 ]

Full List of Resources:
  * rsc_st_azure        (stonith:fence_azure_arm):       Started hana01
  * Clone Set: SAPHanaTopology_SID_00-clone [SAPHanaTopology_SID_00]:
    * Started: [ hana01 hana02 ]
  * Clone Set: SAPHana_SID_00-clone [SAPHana_SID_00] (promotable):
    * Masters: [ hana02 ]
    * Slaves: [ hana01 ]
  * Resource Group: g_ip_SID_00:
    * nc_SID_00 (ocf::heartbeat:azure-lb):       Started hana02
    * vip_SID_00        (ocf::heartbeat:IPaddr2):        Started hana02	
  * Resource Group: g_secip_SID_00 :
    * secnc_SID_00      (ocf::heartbeat:azure-lb):       Started hana01
    * secvip_SID_00     (ocf::heartbeat:IPaddr2):        Started hana01

Daemon Status:
  corosync: active/enabled
  pacemaker: active/enabled
  pcsd: active/enabled

sidadm@hana01:/usr/sap/sid/HDB00> hdbnsutil -sr_state | grep "operation mode"
operation mode: logreplay_readaccess
Performing Final Memory Release with 9 threads.
Finished Final Memory Release successfuly.

Notes

https://learn.microsoft.com/en-us/azure/sap/workloads/sap-hana-high-availability-rhel?tabs=lb-portal#configure-hana-activeread-enabled-system-replication-in-pacemaker-cluster
https://learn.microsoft.com/en-us/azure/sap/workloads/sap-hana-high-availability?tabs=lb-portal%2Csaphanasr#configure-hana-activeread-enabled-system-replication-in-a-pacemaker-cluster

[hdamecharla]

Approved #660