add replica connections for pg

server/db/pg/driver.ts

@@ -1,16 +1,32 @@
 import { drizzle as DrizzlePostgres } from "drizzle-orm/node-postgres";
 import { readConfigFile } from "@server/lib/readConfigFile";
+import { withReplicas } from "drizzle-orm/pg-core";
 
 function createDb() {
     const config = readConfigFile();
 
     const connectionString = config.postgres?.connection_string;
+    const replicaConnections = config.postgres?.replicas || [];
 
     if (!connectionString) {
-        throw new Error("Postgres connection string is not defined in the configuration file.");
+        throw new Error(
+            "A primary db connection string is required in the configuration file."
+        );
     }
 
-    return DrizzlePostgres(connectionString);
+    const primary = DrizzlePostgres(connectionString);
+    const replicas = [];
+
+    if (!replicaConnections.length) {
+        replicas.push(primary);
+    } else {
+        for (const conn of replicaConnections) {
+            const replica = DrizzlePostgres(conn.connection_string);
+            replicas.push(replica);
+        }
+    }
+
+    return withReplicas(primary, replicas as any);
 }
 
 export const db = createDb();

server/lib/readConfigFile.ts

@@ -121,9 +121,16 @@ export const configSchema = z.object({
     }),
     postgres: z
         .object({
-            connection_string: z.string().optional()
+            connection_string: z.string(),
+            replicas: z
+                .array(
+                    z.object({
+                        connection_string: z.string()
+                    })
+                )
+                .optional()
         })
-        .default({}),
+        .optional(),
     traefik: z
         .object({
             http_entrypoint: z.string().optional().default("web"),