[LEGACY] Ensure server parameter 'log_disconnections' is set to 'ON' for PostgreSQL single server

Overview

Enable log_disconnections on PostgreSQL Servers.

NOTE: This recommendation currently only applies to Single Server, not Flexible Server. See additional information below for details about the planned retirement of Azure PostgreSQL Single Server.

Rationale

Enabling log_disconnections helps PostgreSQL Database to Logs end of a session, including duration, which generates query and error logs. Query and error logs can be used to identify, troubleshoot, and repair configuration errors and sub-optimal performance.

Impact

Enabling this setting will enable a log of all disconnections. If this is enabled for a high traffic server, the log may grow exponentially.

Default Value

By default, log_disconnections is disabled (set to off).

Additional Information

RETIREMENT of Azure PostgreSQL Single Server: Azure PostgreSQL Single Server is slated for retirement by March 25, 2025. Please use these resources to consider and prepare for migration:

https://learn.microsoft.com/en-us/azure/postgresql/single-server/whats-happening-to-postgresql-single-server
https://learn.microsoft.com/en-us/azure/postgresql/migrate/concepts-single-to-flexible

Remediation guidance

Remediate from Azure Portal

Open the server using the Open in Azure button
Under Settings, click Server parameters.
Search for log_disconnections.
Set log_disconnections to ON.
Click Save.

Remediate from Azure CLI

Use the below command to update log_disconnections configuration.

az postgres server configuration set --resource-group <resourceGroupName> --server-name <serverName> --name log_disconnections --value on

Remediate from PowerShell

Use the below command to update log_disconnections configuration.

Update-AzPostgreSqlConfiguration -ResourceGroupName  -ServerName  -Name log_disconnections -Value on

Service-wide remediation

Recommended when many resources are affected: fix the platform baseline first so new resources inherit the secure setting, then remediate the existing flagged resources in batches.

Azure

Use management group or subscription Azure Policy assignments, remediation tasks where supported, landing-zone standards, and IaC modules so drift is prevented at scale.

Operational rollout

Fix the baseline first at the account, subscription, project, cluster, or tenant scope that owns this control.
Remediate the currently affected resources in batches, starting with internet-exposed and production assets.
Re-scan and track approved exceptions with an owner and expiry date.

Query logic

These are the stored checks tied to this control.

Server parameter 'log_disconnections' is set to 'ON' for PostgreSQL Database Server

Connectors

Microsoft Azure

Covered asset types

PostgreSQLServer

Expected check: eq []

{
  postgreSqlServers(
    where: {
      configurations_SOME: {
        name: "log_disconnections"
        value_MATCHES: "(?i)off"
      }
    }
  ) {
    ...AssetFragment
  }
}