BoxLang MiniServer

Overview

BoxLang MiniServer is the official lightweight web server for BoxLang applications. It is built on Undertow and is NOT a servlet container — it is a purpose-built, fast web runtime for BoxLang. Use it for development servers and production deployments where a full Java EE container is not needed.

Binary: boxlang-miniserver (Windows: boxlang-miniserver.bat) Default behavior: binds 0.0.0.0:8080, uses current working directory as webroot.

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Quick Start

# Start in current directory on default port 8080
boxlang-miniserver

# Custom port and webroot
boxlang-miniserver --port 9000 --webroot ./public

# Enable URL rewrites (SPA or front-controller pattern)
boxlang-miniserver --rewrites

# Production with health checks
boxlang-miniserver --port 8080 --health-check --health-check-secure

---

CLI Flags

Flag	Short	Description
--port <n>	-p	Port to bind (default: 8080)
--host <ip>		Host/IP to bind (default: 0.0.0.0)
--webroot <path>	-w	Webroot directory (default: CWD)
--debug	-d	Enable debug mode
--rewrites	-r	Enable URL rewrites to index.bxm
--configPath <path>	-c	Path to JSON config file
--serverHome <path>	-s	Override server home directory
--health-check		Enable health check endpoints
--health-check-secure		Secure health checks (details localhost-only)
--version		Print version
--help		Print help

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Environment Variables

Environment variables are scanned before CLI arguments; CLI args take precedence.

Variable	Description
BOXLANG_CONFIG	Override boxlang.json path
BOXLANG_DEBUG	Enable/disable debug mode
BOXLANG_HOME	Override server HOME directory
BOXLANG_HOST	Override bind host
BOXLANG_PORT	Override bind port
BOXLANG_REWRITES	Enable/disable URL rewrites
BOXLANG_REWRITE_FILE	Rewrite target file (default: index.bxm)
BOXLANG_WEBROOT	Override webroot path
BOXLANG_HEALTH_CHECK	Enable health check endpoints
BOXLANG_HEALTH_CHECK_SECURE	Enable secure health checks
BOXLANG_MINISERVER_OPTS	Extra JVM options for startup

---

JSON Configuration (miniserver.json)

Create a miniserver.json file and pass it with --configPath (or use .boxlang.json project convention):

{
    "port": 8080,
    "host": "0.0.0.0",
    "webRoot": "./www",
    "debug": false,
    "configPath": "./.boxlang.json",
    "serverHome": "./.engine/boxlang",
    "rewrites": true,
    "rewriteFileName": "index.bxm",
    "healthCheck": true,
    "healthCheckSecure": true,
    "envFile": "./.env",
    "warmupURLs": ["/api/warmup", "/health/ready"],
    "undertow": {
        "ioThreads": 4,
        "workerThreads": 32,
        "bufferSize": 16384
    },
    "socket": {
        "tcpNoDelay": true,
        "reuseAddress": true
    },
    "websocket": {
        "maxFrameSize": 65536,
        "maxTextMessageSize": 65536
    }
}

Config Priority (high → low)

1. CLI arguments
2. JSON config file
3. Environment variables
4. Defaults

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.boxlang.json Project Convention

Place a .boxlang.json in your webroot for project-level BoxLang configuration. It is automatically merged with the global boxlang.json at startup — commit it to source control for portable config.

{
    "modules": {
        "bx-mysql": { "enabled": true },
        "bx-mail":  { "enabled": true }
    },
    "debugMode": false,
    "timezone": "UTC"
}

Pair with a miniserver.json that points to it:

{
    "port": 8080,
    "webRoot": "./www",
    "configPath": "./.boxlang.json"
}

---

Example Configurations

Development

{
    "port": 8080,
    "webRoot": "./public",
    "debug": true,
    "rewrites": true
}

Production

{
    "port": 8080,
    "host": "0.0.0.0",
    "webRoot": "/var/www/myapp",
    "rewrites": true,
    "healthCheck": true,
    "healthCheckSecure": true,
    "warmupURLs": ["/api/warmup/database", "/health/ready"],
    "undertow": {
        "ioThreads": 8,
        "workerThreads": 64
    }
}

Full Options

{
    "port": 8080,
    "host": "0.0.0.0",
    "webRoot": "./www",
    "debug": false,
    "rewrites": true,
    "rewriteFileName": "index.bxm",
    "serverHome": "./.engine/boxlang",
    "configPath": "./.boxlang.json",
    "envFile": ".env",
    "healthCheck": true,
    "healthCheckSecure": true,
    "warmupURLs": ["/api/warmup"],
    "undertow": { "ioThreads": 4, "workerThreads": 32, "bufferSize": 16384 },
    "socket": { "tcpNoDelay": true, "reuseAddress": true },
    "websocket": { "maxFrameSize": 65536, "maxTextMessageSize": 65536 }
}

---

Health Check Endpoints

Enable with --health-check. With --health-check-secure, remote callers get minimal info only.

Endpoint	Description
/health	Full JSON health info (status, uptime, JVM, memory)
/health/ready	Readiness probe — simple UP/DOWN
/health/live	Liveness probe — simple UP/DOWN

{
    "status": "UP",
    "timestamp": "2025-08-01T17:05:47Z",
    "uptime": "1m 47s",
    "uptimeMs": 107245,
    "version": "1.4.0",
    "javaVersion": "17.0.2",
    "memoryUsed": 152093696,
    "memoryMax": 4294967296
}

---

Environment Files (.env)

The MiniServer auto-loads .env from the webroot at startup. Variables are added to Java System Properties and accessible via getSystemSetting():

# .env
DATABASE_URL=jdbc:mysql://localhost:3306/mydb
API_KEY=secret
DEBUG_MODE=true

// Works in both local (.env) and production (real env var)
var apiKey = getSystemSetting( "API_KEY" )
var dbUrl  = getSystemSetting( "DATABASE_URL" )

Note: Use getSystemSetting() rather than server.system.environment — it works for both .env (system properties) and real environment variables.

---

Warmup URLs

Pre-request URLs on startup to warm caches and connections before serving traffic:

{
    "warmupURLs": [
        "/api/warmup/database",
        "/api/warmup/cache",
        "/health/ready"
    ]
}

Warmup runs sequentially after server init. Failures are logged but do not abort startup.

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Security Features

• Hidden file protection — any file or directory starting with . returns 404 automatically and cannot be disabled
• .env files are blocked from HTTP access even when healthCheck is enabled
• Health check endpoints never expose environment values

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Undertow Tuning

Setting	Default	Description
undertow.ioThreads	CPU count	I/O event threads
undertow.workerThreads	ioThreads * 8	Worker thread pool size
undertow.bufferSize	16384	Buffer size in bytes
socket.tcpNoDelay	true	Disable Nagle algorithm
socket.reuseAddress	true	Allow address reuse on restart
websocket.maxFrameSize	65536	Max WebSocket frame size
websocket.maxTextMessageSize	65536	Max text message size

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Checklist

• Use .boxlang.json in webroot for portable project-level config
• Enable --rewrites for SPA or front-controller apps (routes to index.bxm)
• Use getSystemSetting() to read env vars (works with both .env and real env vars)
• Enable --health-check --health-check-secure for container/load-balancer readiness probes
• Add warmupURLs for production to pre-load DB connections and caches
• Tune undertow.workerThreads based on expected concurrency
• Never rely on direct env var access for .env-sourced values