feat: add multi-master replication support

- Add syncprov module to init-config.sh
- Create init-replication.sh for configuring N-way multi-master
- Update entrypoint to handle replication configuration
- Support LDAP_REPLICATION_ENABLED, LDAP_SERVER_ID, LDAP_REPLICATION_HOSTS
- Replica servers can sync DIT from existing masters

docker-entrypoint.sh

@@ -44,6 +44,12 @@ export LDAP_TLS_VERIFY_CLIENT="${LDAP_TLS_VERIFY_CLIENT:-try}"
 export LDAP_LOG_LEVEL="${LDAP_LOG_LEVEL:-256}"
 export LDAP_READONLY="${LDAP_READONLY:-false}"
 
+# Replication settings
+export LDAP_REPLICATION_ENABLED="${LDAP_REPLICATION_ENABLED:-false}"
+export LDAP_SERVER_ID="${LDAP_SERVER_ID:-1}"
+export LDAP_REPLICATION_HOSTS="${LDAP_REPLICATION_HOSTS:-}"
+export LDAP_BOOTSTRAP_PRIMARY="${LDAP_BOOTSTRAP_PRIMARY:-false}"
+
 log_info "OpenLDAP Container Starting"
 log_info "Domain: $LDAP_DOMAIN"
 log_info "Base DN: $LDAP_BASE_DN"
@@ -53,36 +59,43 @@ log_info "Organisation: $LDAP_ORGANISATION"
 if [ ! -f /var/lib/openldap/openldap-data/data.mdb ]; then
     log_info "First run - initializing OpenLDAP..."
 
-    # Initialize cn=config
+    # Initialize cn=config (always needed)
     /scripts/init-config.sh
 
-    # Load schemas in order
+    # Load schemas in order (always needed)
     /scripts/init-schemas.sh
 
-    # Configure overlays
+    # Configure overlays (always needed)
     /scripts/init-overlays.sh
 
-    # Create base DIT
-    /scripts/init-dit.sh
+    # Determine if we should initialize DIT or replicate from peer
+    # If replication is enabled and we're not the bootstrap primary, skip DIT init
+    if [ "$LDAP_REPLICATION_ENABLED" = "true" ] && [ "$LDAP_BOOTSTRAP_PRIMARY" != "true" ]; then
+        log_info "Replication enabled - this server will sync DIT from peers"
+        log_info "Skipping local DIT initialization..."
+    else
+        # Create base DIT
+        /scripts/init-dit.sh
 
-    # Configure ACLs
-    /scripts/init-acls.sh
+        # Configure ACLs
+        /scripts/init-acls.sh
 
-    # Create service accounts if requested
-    if [ "$LDAP_CREATE_SERVICE_ACCOUNTS" = "true" ]; then
-        /scripts/init-services.sh
-    fi
+        # Create service accounts if requested
+        if [ "$LDAP_CREATE_SERVICE_ACCOUNTS" = "true" ]; then
+            /scripts/init-services.sh
+        fi
 
-    # Process custom LDIF files if present
-    if [ -d /ldif/custom ] && [ "$(ls -A /ldif/custom 2>/dev/null)" ]; then
-        log_info "Processing custom LDIF files..."
-        for ldif in /ldif/custom/*.ldif; do
-            if [ -f "$ldif" ]; then
-                log_info "Loading: $ldif"
-                ldapadd -x -H "$LDAPI_SOCKET" -D "cn=admin,$LDAP_BASE_DN" -w "$LDAP_ADMIN_PASSWORD" -f "$ldif" || \
-                    log_warn "Failed to load $ldif (may already exist)"
-            fi
-        done
+        # Process custom LDIF files if present
+        if [ -d /ldif/custom ] && [ "$(ls -A /ldif/custom 2>/dev/null)" ]; then
+            log_info "Processing custom LDIF files..."
+            for ldif in /ldif/custom/*.ldif; do
+                if [ -f "$ldif" ]; then
+                    log_info "Loading: $ldif"
+                    ldapadd -x -H "$LDAPI_SOCKET" -D "cn=admin,$LDAP_BASE_DN" -w "$LDAP_ADMIN_PASSWORD" -f "$ldif" || \
+                        log_warn "Failed to load $ldif (may already exist)"
+                fi
+            done
+        fi
     fi
 
     log_info "Initialization complete."
@@ -108,7 +121,38 @@ fi
 
 log_info "Starting slapd with URLs: $SLAPD_URLS"
 
-# Start slapd
+# If replication is enabled, start slapd in background first to configure replication
+if [ "$LDAP_REPLICATION_ENABLED" = "true" ]; then
+    log_info "Starting slapd in background for replication configuration..."
+
+    /usr/sbin/slapd -h "$SLAPD_URLS" \
+        -F /etc/openldap/slapd.d \
+        -u ldap -g ldap &
+
+    SLAPD_PID=$!
+
+    # Wait for slapd to be ready
+    log_info "Waiting for slapd to be ready..."
+    sleep 2
+    for i in $(seq 1 30); do
+        if ldapsearch -x -H ldap://localhost -b "" -s base "objectClass=*" >/dev/null 2>&1; then
+            log_info "slapd is ready"
+            break
+        fi
+        sleep 1
+    done
+
+    # Configure replication
+    /scripts/init-replication.sh
+
+    # Stop background slapd gracefully
+    log_info "Restarting slapd in foreground mode..."
+    kill $SLAPD_PID 2>/dev/null || true
+    wait $SLAPD_PID 2>/dev/null || true
+    sleep 1
+fi
+
+# Start slapd in foreground (final)
 exec /usr/sbin/slapd -h "$SLAPD_URLS" \
     -F /etc/openldap/slapd.d \
     -u ldap -g ldap \

scripts/init-config.sh

@@ -31,6 +31,7 @@ olcModuleLoad: memberof.so
 olcModuleLoad: refint.so
 olcModuleLoad: unique.so
 olcModuleLoad: ppolicy.so
+olcModuleLoad: syncprov.so
 
 dn: cn=schema,cn=config
 objectClass: olcSchemaConfig

scripts/init-replication.sh

@@ -0,0 +1,129 @@
+#!/bin/sh
+set -e
+
+. /scripts/utils.sh
+
+# Skip if replication not enabled
+if [ "$LDAP_REPLICATION_ENABLED" != "true" ]; then
+    log_info "Replication not enabled, skipping..."
+    exit 0
+fi
+
+# Validate required variables
+if [ -z "$LDAP_SERVER_ID" ]; then
+    log_error "LDAP_SERVER_ID is required for replication"
+    exit 1
+fi
+
+if [ -z "$LDAP_REPLICATION_HOSTS" ]; then
+    log_error "LDAP_REPLICATION_HOSTS is required for replication"
+    exit 1
+fi
+
+# Use admin credentials for replication if not specified
+LDAP_REPLICATION_DN="${LDAP_REPLICATION_DN:-cn=admin,$LDAP_BASE_DN}"
+LDAP_REPLICATION_PASSWORD="${LDAP_REPLICATION_PASSWORD:-$LDAP_ADMIN_PASSWORD}"
+
+log_info "Configuring multi-master replication..."
+log_info "Server ID: $LDAP_SERVER_ID"
+log_info "Replication hosts: $LDAP_REPLICATION_HOSTS"
+
+# Wait for slapd to be ready
+wait_for_slapd 30 "$LDAPI_SOCKET"
+
+# Configure serverID in cn=config
+log_info "Setting serverID..."
+cat > /tmp/repl-serverid.ldif << EOF
+dn: cn=config
+changetype: modify
+replace: olcServerID
+olcServerID: ${LDAP_SERVER_ID}
+EOF
+
+ldapmodify -Y EXTERNAL -H "$LDAPI_SOCKET" -f /tmp/repl-serverid.ldif 2>/dev/null || \
+    log_warn "ServerID may already be set"
+
+# Configure syncprov overlay on the database
+log_info "Configuring syncprov overlay..."
+cat > /tmp/repl-syncprov.ldif << EOF
+dn: olcOverlay=syncprov,olcDatabase={1}mdb,cn=config
+changetype: add
+objectClass: olcOverlayConfig
+objectClass: olcSyncProvConfig
+olcOverlay: syncprov
+olcSpCheckpoint: 100 10
+olcSpSessionlog: 100
+EOF
+
+ldapmodify -Y EXTERNAL -H "$LDAPI_SOCKET" -f /tmp/repl-syncprov.ldif 2>/dev/null || \
+    log_warn "syncprov overlay may already exist"
+
+# Build syncrepl configuration for each peer
+# Format: LDAP_REPLICATION_HOSTS="ldap://server1.example.com,ldap://server2.example.com"
+REPLICA_NUM=0
+SYNCREPL_CONFIG=""
+
+# Parse the comma-separated list of hosts
+OLD_IFS="$IFS"
+IFS=','
+for host in $LDAP_REPLICATION_HOSTS; do
+    REPLICA_NUM=$((REPLICA_NUM + 1))
+
+    # Trim whitespace
+    host=$(echo "$host" | sed 's/^[[:space:]]*//;s/[[:space:]]*$//')
+
+    log_info "Adding replication peer $REPLICA_NUM: $host"
+
+    SYNCREPL_CONFIG="${SYNCREPL_CONFIG}
+olcSyncRepl: rid=$(printf '%03d' $REPLICA_NUM)
+  provider=${host}
+  bindmethod=simple
+  binddn=\"${LDAP_REPLICATION_DN}\"
+  credentials=${LDAP_REPLICATION_PASSWORD}
+  searchbase=\"${LDAP_BASE_DN}\"
+  scope=sub
+  schemachecking=on
+  type=refreshAndPersist
+  retry=\"60 +\"
+  timeout=1"
+done
+IFS="$OLD_IFS"
+
+# Configure syncrepl and mirrormode on the database
+log_info "Configuring syncrepl and mirrormode..."
+cat > /tmp/repl-syncrepl.ldif << EOF
+dn: olcDatabase={1}mdb,cn=config
+changetype: modify
+replace: olcSyncRepl
+${SYNCREPL_CONFIG}
+-
+replace: olcMirrorMode
+olcMirrorMode: TRUE
+EOF
+
+ldapmodify -Y EXTERNAL -H "$LDAPI_SOCKET" -f /tmp/repl-syncrepl.ldif || {
+    log_error "Failed to configure syncrepl"
+    cat /tmp/repl-syncrepl.ldif
+    exit 1
+}
+
+# Add additional indexes for replication
+log_info "Adding replication indexes..."
+cat > /tmp/repl-indexes.ldif << EOF
+dn: olcDatabase={1}mdb,cn=config
+changetype: modify
+add: olcDbIndex
+olcDbIndex: entryCSN eq
+-
+add: olcDbIndex
+olcDbIndex: entryUUID eq
+EOF
+
+ldapmodify -Y EXTERNAL -H "$LDAPI_SOCKET" -f /tmp/repl-indexes.ldif 2>/dev/null || \
+    log_warn "Indexes may already exist"
+
+# Cleanup
+rm -f /tmp/repl-*.ldif
+
+log_info "Multi-master replication configured successfully"
+log_info "This server (ID=$LDAP_SERVER_ID) will replicate with $REPLICA_NUM peer(s)"