Geo-Location Scaling (Replication)

SSO Manager is built to be a self-contained identity provider, but if you have multiple physical sites, you may want a local copy of the directory at each site to ensure low latency and high availability.

Why and when to use this?

  • High Availability (HA): If your primary site goes completely offline, your other sites can still authenticate users locally without depending on a WAN link.
  • Low Latency: Applications at a remote site can bind directly to their local LDAP server (localhost or LAN IP) instead of traversing the internet to query the primary site, making logins blazing fast.
  • Independent Failure Domains: By replicating only the LDAP directory (the source of truth) and keeping session state (Redis) independent, you prevent complex “split-brain” scenarios in the web UI. A failure at Site A won’t bring down Site B.

By default, the sso-manager Docker container runs a single, independent OpenLDAP instance. However, you can enable N-Way Multi-Master Replication via environment variables.

How it works

In an N-Way Multi-Master setup, every site runs a fully active OpenLDAP server (slapd).

  • Reads and Writes anywhere: A user can change their password or update their profile at Site A, Site B, or Site C.
  • Conflict Resolution: OpenLDAP’s syncrepl engine uses Context Sequence Numbers (CSN) to track changes. If Site A goes offline and a user changes their password at Site B, Site A will automatically pull the newest changes the moment it rejoins the cluster.
  • Independent Redis: Session data, API Tokens, and OAuth Clients are stored in Redis. By design, Redis is NOT replicated in this geographic setup. This ensures that a failure at Site A never causes Site B’s Redis to become read-only, which would break the web UI at Site B. OAuth clients must be configured per-site.

Configuration

To enable replication, you must pass two environment variables to the sso-manager container:

  1. LDAP_SERVER_ID: A unique integer for this node (e.g., 1, 2, 3). This MUST be unique across the cluster.
  2. LDAP_REPLICATION_HOSTS: A space-separated list of the LDAP URLs of all other nodes in the cluster.

Example using theta-env / Docker Compose

Site 1 (setup.env or docker-compose.yml)

LDAP_SERVER_ID=1
LDAP_REPLICATION_HOSTS="ldaps://sso.site2.com:636 ldaps://sso.site3.com:636"

Site 2 (setup.env or docker-compose.yml)

LDAP_SERVER_ID=2
LDAP_REPLICATION_HOSTS="ldaps://sso.site1.com:636 ldaps://sso.site3.com:636"

Site 3 (setup.env or docker-compose.yml)

LDAP_SERVER_ID=3
LDAP_REPLICATION_HOSTS="ldaps://sso.site1.com:636 ldaps://sso.site2.com:636"

Once configured, the container’s entrypoint will automatically load the syncprov module, enable mirrormode, and generate the necessary syncrepl blocks in /etc/openldap/slapd.conf.

User Locations

When creating or editing a user, you can specify their Location (Site). This maps directly to the standard LDAP l (localityName) attribute, allowing you to track which physical site a user belongs to natively within the directory.