Logging

LoggingMiddleware provides Morgan-style request logging with predefined and custom formats.

Basic Usage

// Default format (Dev)
server.use(LoggingMiddleware())

Configuration

server.use(LoggingMiddleware(LoggingMiddleware.Options(
  format = LoggingMiddleware.Format.Combined,
  immediate = false,
  skip = request => request.path.startsWith("/health"),
  handler = msg => println(msg),
  debug = false,
)))

Options

Option	Type	Default	Description
format	String	Format.Dev	Log format string
immediate	Boolean	false	Log on request (true) or response (false)
skip	Request => Boolean	_ => false	Skip logging for matching requests
handler	String => Unit	println	Custom log output handler
debug	Boolean	false	Enable debug output

Predefined Formats

Combined (Apache combined)

:remote-addr - :remote-user [:date] ":method :url HTTP/:http-version" :status :res[content-length] ":referrer" ":user-agent"

Common (Apache common)

:remote-addr - :remote-user [:date] ":method :url HTTP/:http-version" :status :res[content-length]

Dev

Concise colored output for development:

:method :url :status :response-time ms - :res[content-length]

Short

:remote-addr :remote-user :method :url HTTP/:http-version :status :res[content-length] - :response-time ms

Tiny

Minimal output:

:method :url :status :res[content-length] - :response-time ms

Format Tokens

Use these tokens in custom format strings:

Token	Description
:method	HTTP method
:url	Request URL
:status	Response status code
:response-time	Response time in milliseconds
:date	Timestamp
:remote-addr	Client IP address
:remote-user	Remote user
:http-version	HTTP version
:referrer	Referrer header
:user-agent	User-Agent header
:res[header]	Response header value

Custom Format

server.use(LoggingMiddleware(LoggingMiddleware.Options(
  format = ":method :url -> :status (:response-time ms)"
)))

Immediate vs Deferred Logging

• Deferred (default): Logs after the response is sent, includes status code and response time
• Immediate: Logs when the request arrives, no response data available

// Log immediately on request
server.use(LoggingMiddleware(LoggingMiddleware.Options(
  immediate = true
)))