Call logging
Ktor provides the capability to log application events using the SLF4J library. You can learn about general logging configuration from the Logging topic.
The CallLogging
plugin allows you to log incoming client requests.
Add dependencies
To use CallLogging
, you need to include the ktor-server-call-logging
artifact in the build script:
Install CallLogging
To install the CallLogging
plugin to the application, pass it to the install
function in the specified module. The code snippets below show how to install CallLogging
...
... inside the
embeddedServer
function call.... inside the explicitly defined
module
, which is an extension function of theApplication
class.
Configure logging settings
You can configure CallLogging
in multiple ways: specify a logging level, filter requests based on a specified condition, customize log messages, and so on. You can see the available configuration settings at CallLoggingConfig.
Set the logging level
By default, Ktor uses the Level.INFO
logging level. To change it, use the level
property:
Filter log requests
The filter
property allows you to add conditions for filtering requests. In the example below, only requests made to /api/v1
get into a log:
Customize a log message format
By using the format
function, you can put any data related to a request/response into a log. The example below shows how to log a response status, a request HTTP method, and the User-Agent
header value for each request.
You can find the full example here: logging.
Put call parameters in MDC
The CallLogging
plugin supports MDC (Mapped Diagnostic Context). You can put a desired context value with the specified name to MDC using the mdc
function. For example, in the code snippet below, a name
query parameter is added to MDC:
You can access the added value during an ApplicationCall
lifetime: