Allow configuring max DB connection pool size via DATABASE_POOL_MAX (#5)

* add env validation utility

* make database pool size configurable

* rename DB_POOL_MAX to DATABASE_POOL_MAX

Author: stplasim

.env.example

@@ -2,3 +2,4 @@ SLACK_BOT_TOKEN=xoxb-
 SLACK_APP_TOKEN=xapp-
 GITHUB_TOKEN=github_pat_
 DATABASE_URL=postgres://root:password@localhost:5432/app
+# DATABASE_POOL_MAX=10

installation.md

@@ -46,6 +46,7 @@ DATABASE_URL=postgres://user:password@localhost/releases_db
 # Optional
 # POLL_CRON=0 * * * *        # How often to check releases (default: every hour)
 # DIGEST_CRON=30 7 * * *     # When to send the periodic digest in UTC (default: 07:30 UTC)
+# DATABASE_POOL_MAX=10       # Max connections in the DB connection pool (default: 10)
 ```
 
 All tables are created in the `main` PostgreSQL schema. To use a different schema, change the hardcoded value in `src/db/schema.ts` and `drizzle.config.ts`, then regenerate and re-apply migrations.

src/db/client.ts

@@ -1,7 +1,9 @@
 import { drizzle } from 'drizzle-orm/bun-sql'
+import { positiveInt, requiredString } from '@utils/env'
 
-if (!process.env.DATABASE_URL) {
-  throw new Error('DATABASE_URL is required')
-}
-
-export const db = drizzle(process.env.DATABASE_URL)
+export const db = drizzle({
+  connection: {
+    url: requiredString('DATABASE_URL'),
+    max: positiveInt('DATABASE_POOL_MAX', 10),
+  },
+})

src/env.d.ts

@@ -9,6 +9,7 @@ declare module 'bun' {
 
     // Database
     DATABASE_URL: string
+    DATABASE_POOL_MAX?: string
     // Jobs
     POLL_CRON?: string
     DIGEST_CRON?: string

src/slack/app.ts

@@ -1,7 +1,8 @@
 import { App } from '@slack/bolt'
+import { requiredString } from '@utils/env.ts'
 
 export const app = new App({
-  token: process.env.SLACK_BOT_TOKEN,
-  appToken: process.env.SLACK_APP_TOKEN,
+  token: requiredString('SLACK_BOT_TOKEN'),
+  appToken: requiredString('SLACK_APP_TOKEN'),
   socketMode: true,
 })

src/utils/env.ts

@@ -0,0 +1,24 @@
+type EnvVarName = keyof typeof process.env
+
+export function requiredString(name: EnvVarName): string {
+  const value = process.env[name]
+  if (!value) {
+    throw new Error(`${name} is required`)
+  }
+
+  return value
+}
+
+export function positiveInt(name: EnvVarName, defaultValue: number): number {
+  const raw = process.env[name]
+  if (!raw) {
+    return defaultValue
+  }
+
+  const value = Number(raw)
+  if (!Number.isInteger(value) || value < 1) {
+    throw new Error(`${name} must be a positive integer`)
+  }
+
+  return value
+}

tsconfig.json

@@ -13,11 +13,12 @@
     "noEmit": true,
     "skipLibCheck": true,
     "paths": {
-      "@db/*":       ["./src/db/*"],
-      "@forges/*":   ["./src/forges/*"],
-      "@bot/*":      ["./src/slack/*"],
-      "@jobs/*":     ["./src/jobs/*"],
-      "@classify/*": ["./src/classify/*"]
+      "@db/*": ["./src/db/*"],
+      "@forges/*": ["./src/forges/*"],
+      "@bot/*": ["./src/slack/*"],
+      "@jobs/*": ["./src/jobs/*"],
+      "@classify/*": ["./src/classify/*"],
+      "@utils/*": ["./src/utils/*"]
     }
   }
 }