Ensure server parameter 'logfiles.retention_days' is greater than 3 days for PostgreSQL flexible servers

Overview

Ensure logfiles.retention_days on PostgreSQL flexible servers is set to an appropriate value.

Rationale

Configuring logfiles.retention_days determines the duration in days that Azure Database for PostgreSQL retains log files. Query and error logs can be used to identify, troubleshoot, and repair configuration errors and sub-optimal performance.

Impact

Configuring this setting will result in logs being retained for the specified number of days. If this is configured on a high traffic server, the log may grow quickly to occupy a large amount of disk space. In this case you may want to set this to a lower number.

Default Value

By default, logfiles.retention_days is set to 3.

Remediation guidance

Remediate from Azure Portal

Open the server using the Open in Azure button
Under Settings, click Server parameters.
In the filter bar, type logfiles.retention_days.
Set the VALUE for logfiles.retention_days to ON.
Click Save.

Remediate from Azure CLI

Use the below command to update logfiles.retention_days:

az postgres flexible-server parameter set --resource-group <resourceGroup> --server-name <serverName> --name logfiles.retention_days --value <4-7>

Remediate from PowerShell

Use the below command to update logfiles.retention_days:

Update-AzPostgreSqlFlexibleServerConfiguration -ResourceGroupName <resourceGroup> -ServerName <serverName> -Name logfiles.retention_days -Value <4-7>

Multiple Remediation Paths

Azure

SERVICE-WIDE (RECOMMENDED when many resources are affected): Assign Azure Policy initiatives at management group/subscription scope and trigger remediation tasks.

az policy assignment create --name <assignment-name> --scope /subscriptions/<subscription-id> --policy-set-definition <initiative-id>
az policy remediation create --name <remediation-name> --policy-assignment <assignment-id>

ASSET-LEVEL: Apply the resource-specific remediation steps above to the listed non-compliant resources.

PREVENTIVE: Embed Azure Policy checks into landing zones and IaC workflows to block or auto-remediate drift.

References for Service-Wide Patterns

Azure Policy overview: https://learn.microsoft.com/en-us/azure/governance/policy/overview
Azure Policy remediation: https://learn.microsoft.com/en-us/azure/governance/policy/how-to/remediate-resources
Azure Policy initiative structure: https://learn.microsoft.com/en-us/azure/governance/policy/concepts/initiative-definition-structure

Operational Rollout Workflow

Use this sequence to reduce risk and avoid repeated drift.

1. Contain at Service-Wide Scope First (Recommended)

Azure: assign policy initiatives at management group/subscription scope and run remediation tasks.

az policy assignment create --name <assignment-name> --scope /subscriptions/<subscription-id> --policy-set-definition <initiative-id>
az policy remediation create --name <remediation-name> --policy-assignment <assignment-id>

2. Remediate Existing Affected Assets

Execute the control-specific Console/CLI steps documented above for each flagged resource.
Prioritize internet-exposed and production assets first.

3. Validate and Prevent Recurrence

Re-scan after each remediation batch.
Track exceptions with owner and expiry date.
Add preventive checks in IaC/CI pipelines.

Query logic

These are the stored checks tied to this control.

Azure PostgreSQL Flex Servers with low logfiles retention days

Connectors

Microsoft Azure

Covered asset types

PostgreSQLFlexibleServer

Expected check: eq []

{
  postgreSqlFlexibleServers(
    where: {
      configurations_SOME: {
        name: "logfiles.retention_days"
        value_MATCHES: "[0-3]"
      }
    }
  ) {
    ...AssetFragment
  }
}