Introduction

A virtual appliance can be used to deploy a PostgreSQL cluster.
This PostgreSQL cluster is typically operated with Cyberelements Cleanroom platforms with cluster architecture to ensure end-to-end redundancy.

Note

Please note that the operation and updating of virtual appliances provided by Systancia are the responsibility of the Customer as defined in the product lifecycle.

The virtual appliance includes all the components needed to deploy a PostgreSQL cluster, as well as a utility to facilitate its installation. It can be downloaded from the Systancia Marketplace (requires creation of a customer account): Systancia Marketplace

The PostgreSQL cluster is based on three PostgreSQL nodes and the use of a virtual IP address.
The use of three nodes ensures service resilience even if one node is lost (two active nodes being the minimum). This works using the following components:

• Patroni
• Etcd
• Keepalived

Together, they allow automated management of virtual IP and replication.

This PostgreSQL cluster does not have a node that is always designated as LEADER; the LEADER alternates depending on the circumstances encountered by the cluster. If the LEADER were to fail, a new LEADER would be elected by absolute majority and the virtual IP would switch to the latter. Note that it takes approximately 20 seconds to reliably identify the loss of the LEADER and switch the virtual IP to the new LEADER.
The LEADER node is the only one with read/write access to the PostgreSQL database; the REPLICA nodes are read-only.

The typical architecture of a cyberelements Cleanroom cluster based on a PostgreSQL cluster is as follows:

flowchart LR
    subgraph Cloud or DMZ
        MED-M(Mediation Controller<br/>MASTER)
        MED-S(Mediation Controller<br/>SLAVE)
    end
    subgraph LAN
        GW-1(Edge Gateway 1)
        GW-2(Edge Gateway 2)
        subgraph PSQL [PostgreSQL Cluster]
            direction TB
            PSQL-1(PostgreSQL<br/>node 1)
            PSQL-2(PostgreSQL<br/>node 2)
            PSQL-3(PostgreSQL<br/>node 3)
        end
    end

    MED-M <--> |Cluster interconnection| MED-S
    GW-1 & GW-2 --> |TLS| MED-M & MED-S
    MED-M & MED-S ~~~ GW-1 & GW-2
    GW-1 & GW-2 -..-> |SQL| PSQL

    PSQL-1 <--> |Cluster interconnection| PSQL-2 <--> |Cluster interconnection| PSQL-3 <--> |Cluster interconnection| PSQL-1

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To install a PostgreSQL cluster with Systancia virtual appliances, please follow the steps below:

• Prerequisites

  ---

  Defining the prerequisites for the PostgreSQL cluster.

  See more

• Importing the virtual appliance

  ---

  The virtual appliance must be imported three times to prepare for the installation of the PostgreSQL cluster.

  See more

• Installing the PostgreSQL cluster

  ---

  Instructions for configuring and installing the PostgreSQL cluster.

  See more