PostgreSQL SCRAM: Migrate Passwords with Client Evidence

Context

PostgreSQL SCRAM authentication changes how a client proves knowledge of a password and how the server stores its verifier. It requires compatible clients. A migration therefore involves drivers, poolers, administrative tools, and password rotation, not simply a configuration edit. Established connections can hide an incompatible client until its next restart.

Prepare the migration inventory

Record the PostgreSQL major version, all login roles, driver versions, poolers, backup clients, scheduled jobs, and administrator tools. Identify credential owners and a tested recovery access path. Current PostgreSQL documentation deprecates MD5-encrypted passwords, but the supported migration sequence must still match the installed version. Use a representative staging environment and avoid copying password verifiers into tickets or shared documents.

Stage the transition

1. Confirm SCRAM support for every client that opens a database connection, including infrequent jobs. Test the real packaged runtime rather than a developer's newer local tool. For poolers, examine both client-to-pooler and pooler-to-server authentication, since one compatible hop does not establish compatibility for the other.
2. Inspect the effective password_encryption setting and selected HBA rules. This setting controls newly assigned passwords; changing it does not convert existing verifiers. Use an authorized administrative review to classify verifier types without printing the verifier values. Keep role ownership and rotation readiness in the migration record.
3. Rotate a dedicated staging role to a SCRAM-backed password through the approved secret workflow. Test all intended clients with new sessions. Be aware that an HBA entry labeled md5 can still select SCRAM when the stored verifier is SCRAM, so leaving that label unchanged is not a way to preserve old-driver compatibility after rotation.
4. Roll out by owned role or service cohort. Update secret consumers and their rotation procedure, recycle pools deliberately, and apply the intended HBA method after compatibility is established. Use secure interactive or managed credential tools; avoid embedding example passwords into shell history or deployment logs. Preserve a controlled administrative access route throughout the transition.

Diagnostic table

Illustrative scenario

A nightly export uses an older bundled client library. Interactive application tests pass after the database configuration changes, but the export fails only after its role password is rotated. The team upgrades the export package in staging and tests its full connection workflow before continuing the cohort rollout. The missing inventory item, rather than the password value, caused the failure.

Correct and verify

When a client fails, identify the exact incompatible component and upgrade or reconfigure it through its supported path. Do not weaken the entire server's authentication policy to accommodate an unidentified dependency. Verify fresh sessions from every client class, including after process restart, then confirm that secret rotation and rollback procedures remain usable. Test TLS identity separately because authentication compatibility does not establish transport verification.

Maintain the evidence

Track migrated roles, tested client versions, rotation dates, and owners without storing secrets in the checklist. Monitor connection failures during scheduled-job windows and after deployments. Add SCRAM support to the acceptance criteria for new tools. Rehearse a future credential rotation so the migration's success is demonstrated by repeatable access, not by one long-lived connection that happened to remain open.

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Technical reference

• www.postgresql.org documentation
• www.postgresql.org documentation