An internal PostgreSQL requires one variable to be available during installation or upgrade. If it is not set by the user, a random 10 character alphanumeric string will be set instead; therefore, it recommended for the user to set this explicitly during installation and upgrade.
--set postgresql.postgresqlPassword=<value> \
The values should remain same between upgrades. If this was autogenerated during helm install, the same password will have to be passed on future upgrades.
To read the current password, use the following command (for more information on reading a secret value, see Kubernetes: Decoding a Secret).
POSTGRES_PASSWORD=$(kubectl get secret -n <namespace><release_name>-postgresql -o jsonpath="{.data.postgresql-password}" | base64 --decode)The following parameter can be set during upgrade.
--set postgresql.postgresqlPassword=${POSTGRES_PASSWORD} \