Postgres Pro Enterprise Manager : Documentation: 2: 4.2. Installation in the High Availability Mode : Postgres Professional

4.2. Installation in the High Availability Mode
Prev	Up	Chapter 4. Installation and Setup	Home	Next

4.2. Installation in the High Availability Mode #

This section provides an example of installing and setting up PPEM in the high availability mode. The following software is used in the example:

Debian Linux 12 OS
HAProxy 2.6.12 (included in the Debian repository)
keepalived 2.2.7 (included in the Debian repository)
Postgres Pro Enterprise 17.2.2 + BiHA (included in the postgrespro-ent-17-contrib package)

The recommended high availability PPEM architecture includes the following components:

High availability cluster based on the BiHA solution available in Postgres Pro Enterprise 16 and higher.
BiHA cluster consists of three or more nodes. One of the nodes acts as the leader. The manager automatically connects to the leader. If the leader fails, one of the remaining nodes automatically becomes the new leader.
Cluster of HAProxy servers + keepalived.
A virtual IP address is automatically activated on one of the servers using the keepalived service. Users and agents interact with managers using this virtual IP address. If the server with the virtual IP address fails, the virtual IP address is activated on one of the remaining servers.
HAProxy also balances client HTTP requests between available managers. For sending requests of a specific client to the same manager, the HAProxy IP-based stickiness or cookie session stickiness functionality is used.
You can deploy this component on separate servers and managers.
Manager.
Two or more servers in the active mode.

The components required for implementation of the recommended architecture are described in the table below.

Component	Amount	Minimum Requirements
Manager server + HAProxy + keepalived	2	2 CPU, 4 GB RAM, 20 GB HDD.
Postgres Pro BiHA server	3	2 CPU, 4 GB RAM, 20 GB HDD.
Virtual static IP address	1	The IP address must be excluded from the DHCP pool. You can also create a DNS A record for this IP address.

To install PPEM in the high availability mode:

Install Postgres Pro Enterprise with the BiHA solution.

To provide PPEM servers with access to DBMS, edit the pg_hba.conf configuration file, for example:

# cat /var/lib/pgpro/ent-17/data/pg_hba.conf

host    all     all     192.168.1.0/24      scram-sha-256

Configure the manager:
```
# cat /etc/ppem-manager.yml
http:
  server:
    address: "network_address_for_incoming_connections"
    port: "port_for_incoming_connections"
repo:
  url: postgres://ppem:DBMS_user_password@biha-server-1/ppem
  fallback_addresses:
    - biha_server_2
    - biha_server_3
  target_session_attrs: read-write
```
Where:
- http.server.address and http.server.port: The network address of the server and the port number for incoming network connections.
  In terms of HAProxy these are backend parameters.
- repo.url: The network address of the first BiHA cluster node.
- fallback_addresses: The network addresses of the remaining BiHA cluster nodes.
- target_session_attrs: The session attribute condition that determines when the manager can automatically connect to the BiHA cluster leader.
  Specify read-write.
On HAProxy servers, install haproxy, keepalived, and the required tools:
```
sudo apt-get install haproxy keepalived psmisc
```

Configure HAProxy using the haproxy.cfg configuration file, for example:

global
  log /dev/log  local0
  log /dev/log  local1 notice
  stats socket /var/lib/haproxy/stats level admin
  chroot /var/lib/haproxy
  user haproxy
  group haproxy
  daemon

defaults
  log global
  mode  http
  option  httplog
  option  dontlognull
  timeout connect 5000
  timeout client 50000
  timeout server 50000
  errorfile 400 /etc/haproxy/errors/400.http
  errorfile 403 /etc/haproxy/errors/403.http
  errorfile 408 /etc/haproxy/errors/408.http
  errorfile 500 /etc/haproxy/errors/500.http
  errorfile 502 /etc/haproxy/errors/502.http
  errorfile 503 /etc/haproxy/errors/503.http
  errorfile 504 /etc/haproxy/errors/504.http

frontend hafrontend
  bind *:80
  mode http
  default_backend habackend

backend habackend
  mode http
  balance roundrobin
  option forwardfor
  option httpchk
  http-check send meth HEAD uri /
  cookie SERVERID insert indirect
  server ppem-server-1 PPEM_server_address-1:8080 cookie ppem-server-1 check
  server ppem-server-2 PPEM_server_address-2:8080 cookie ppem-server-2 check

The cookie-based persistence method is used in the example. It assigns a cookie with the PPEM server name to users. This is required for sending all queries within the HTTP session to a single manager server.

Configure the HAProxy-1 server using the keepalived.conf configuration file:

global_defs {
  enable_script_security
}

vrrp_script chk_haproxy {
  script "/usr/bin/killall -0 haproxy"
  interval 3
  fall 2
  rise 3
  timeout 3
  user root
}

vrrp_instance internal {
  interface interface
  state MASTER
  virtual_router_id 124
  priority 100

  unicast_src_ip HAproxy-1_server_IP_address
  unicast_peer {
    HAproxy-2_server_IP_address
  }
  virtual_ipaddress {
    virtual_IP_address/subnet_class_(for_example_16_or_24) dev interface
  }
  track_script {
    chk_haproxy
  }
}

The configuration is the same for the HAProxy-2 server, but the IP addresses in the unicast_src_ip and unicast_peer parameters are switched.

On all BiHA servers, configure agents.
The connection to the manager must be configured via a virtual IP address.
Perform healthcheck by ensuring that:
- The BiHA cluster database is available on all PPEM servers.
- The ppem system server is running on all PPEM servers:
```
systemctl status ppem
```
- The web application is available on all PPEM servers:
  - on port 8080:
    curl http://PPEM_server_IP_address:8080
  - on port 80 via HAProxy:
    curl http://PPEM_server_IP_address:80
  - via a virtual IP address:
    curl http://virtual_IP_address:80
- The HAProxy and keepalived services are running on all PPEM servers:
```
systemctl status haproxy
systemctl status keepalived
```

Prev	Up	Next
4.1. Installation in Secure Environments	Home	4.3. Installation and Configuration of Backup and Restore Tools

epub pdf