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Description

Enabling the log_connections setting causes each attempted connection to the server to be logged, along with successful completion of client authentication. This parameter cannot be changed after the session starts.

Rationale​

PostgreSQL does not log attempted connections by default. Enabling the log_connections setting will create log entries for each attempted connection as well as successful completion of client authentication which can be useful in troubleshooting issues and to determine any unusual connection attempts to the server. This recommendation is applicable to PostgreSQL database instances.

Impact​

Turning on logging will increase the required storage over time. Mismanaged logs may cause your storage costs to increase. Setting custom flags via command line on certain instances will cause all omitted flags to be reset to defaults. This may cause you to lose custom flags and could result in unforeseen complications or instance restarts. Because of this, it is recommended you apply these flags changes during a period of low usage.

Audit​

From Google Cloud Console​

  1. Go to the Cloud SQL Instances page in the Google Cloud Console by visiting https://console.cloud.google.com/sql/instances.
  2. Select the instance to open its Instance Overview page.
  3. Go to the Configuration card.
  4. Under Database flags, check the value of log_connections flag to determine if it is configured as expected.

From Google Cloud CLI​

  1. Ensure the below command returns on for every Cloud SQL PostgreSQL database instance:

         gcloud sql instances describe [INSTANCE_NAME] --format=json | jq '.settings.databaseFlags[] | select(.name=="log_connections")|.value'

In the output, database flags are listed under the settings as the collection databaseFlags.

Default Value​

By default log_connections is off.

References​

  1. https://cloud.google.com/sql/docs/postgres/flags
  2. https://www.postgresql.org/docs/9.6/runtime-config-logging.html#RUNTIME-CONFIG-LOGGING-WHAT

Additional Information​

WARNING: This patch modifies database flag values, which may require your instance to be restarted. Check the list of supported flags - https://cloud.google.com/sql/docs/postgres/flags - to see if your instance will be restarted when this patch is submitted.

Note: some database flag settings can affect instance availability or stability and remove the instance from the Cloud SQL SLA. For information about these flags, see the Operational Guidelines.

Note: Configuring the above flag does not require restarting the Cloud SQL instance.