Logging and Observability

[BravinR]

logging pattern configuration using

%d{yyyy-MM-dd HH:mm:ss.SSS} ${LOG_LEVEL_PATTERN:%5level} log_level="%level" ${PID:- } --- [thread="%thread", httpMethod="%X{httpMethod:-null}", httpRequestURI="%X{httpRequestURI-null}", X-Request-ID="%X{requestId:-null}"] [%15.15t] %-40.40logger{39} : %replace(%msg){'\r\n|\n', '\u2028'} %replace(%Exception){'\r\n|\n', '\u2028'}%nopex

Components:

• %d{yyyy-MM-dd HH:mm:ss.SSS}: Date and time in the format yyyy-MM-dd HH:mm:ss.SSS.
• ${LOG_LEVEL_PATTERN:%5level}: Log level with a minimum width of 5 characters, using a custom variable LOG_LEVEL_PATTERN if defined.
• log_level="%level": The log level again, enclosed in quotes.
• ${PID:- }: Process ID, if available, otherwise a space.
• ---: A static string separator.
• [thread="%thread": Name of the thread that logs the message.
• httpMethod="%X{httpMethod:-null}": HTTP method from the MDC (Mapped Diagnostic Context) or null if not available.
• httpRequestURI="%X{httpRequestURI-null}": HTTP request URI from the MDC or null if not available.
• X-Request-ID="%X{requestId:-null}"]: X-Request-ID from the MDC or null if not available.
• [%15.15t]: Thread name truncated to 15 characters.
• %-40.40logger{39}: Logger name, with a minimum width of 40 characters, truncated to 39 characters if longer.
• : %replace(%msg){'\r\n|\n', '\u2028'}: The log message, replacing new line characters with Unicode line separator.
• %replace(%Exception){'\r\n|\n', '\u2028'}: The exception stack trace, replacing new line characters with Unicode line separator.
• %nopex: Prevents evaluation of exception output (used to avoid recursion issues in logging).

[BravinR]

Example Log Output

2024-06-15 10:00:00.000  INFO log_level="INFO" --- [thread="http-nio-8080-exec-1", httpMethod="GET", httpRequestURI="/api/resource", X-Request-ID="123e4567-e89b-12d3-a456-426614174000"] [http-nio-8080-exec-1] com.example.logging.LoggingInterceptor : START requestId=123e4567-e89b-12d3-a456-426614174000 method=GET uri=/api/resource