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Celix Logging Facilities

The Celix Logging facility is service oriented and logging technology-agnostic logging solution.

Bundles can request (services on demand) and use celix_log_service_t services to log events. Logging support the following log levels: trace, debug, info, error, fatal.

Bundles can provide celix_log_sink_t services to sink log message to different logging backends (e.g. syslog, log4c, etc)

The Celix::log_admin bundle facilitates the celix_log_service_t services and ‘connects’ these to the available celix_log_sink_t services. If there is no celix_log_sink_t service available, log messages will be printed on stdout/stderr.

The Celix shell command celix::log_admin can be used to view the existing log services and sinks, changed the active log level per log services and enable/disable log sinks. For example:

  • celix::log_admin list the available log services and log sinks.
  • celix::log_admin log error Set the active log level for all log services to error.
  • celix::log_admin log celix_ trace Set the active log level for all log services starting with ‘celix_’ to trace.
  • celix::log_admin sink false Disables all available log sinks.
  • celix::log_admin sink celix_syslog true Enables all log sinks starting with ‘celix_syslog’.

The Celix::log_helper static library can be used to more easily request a celix_log_service_t. An additional benefit of the Celix:log_helper is that if the Celix::log_admin is not installed, log messages will be printed on stdout/stderr.

Logging Properties

Properties shared among the logging bundles

CELIX_LOGGING_DEFAULT_ACTIVE_LOG_LEVEL The default active log level for created log services. Default is "info".

Log Admin Properties

Properties specific for the Celix Log Admin (Celix::log_admin bundle)

CELIX_LOG_ADMIN_FALLBACK_TO_STDOUT If set to true, the log admin will log to stdout/stderr if no celix log writers are available. Default is true
CELIX_LOG_ADMIN_ALWAYS_USE_STDOUT If set to true, the log admin will always log to stdout/stderr after forwaring log statements to the available celix log writers. Default is false.
CELIX_LOG_ADMIN_LOG_SINKS_DEFAULT_ENABLED Whether discovered log sink are default enabled. Default is true.

CMake option

BUILD_LOG_SERVICE=ON

Using info

If the Celix Log Service is installed, ‘find_package(Celix)’ will set:

  • The Celix::log_service_api interface (i.e. header only) library target (v2 and v3 api)
  • The Celix::log_admin bundle target. The log admin will create log services on demand and forward log message to the available log sinks.
  • The Celix::log_helper static library target. Helper library with common logger functionality and helpers to setup logging
  • The Celix::log_writer_syslog bundle target. A bundle which provides a celix_log_sink_t service for syslog.

Also the following deprecated bundle will be set:

  • The Celix::log_service bundle target. The log service bundle. Deprecated, use Celix::log_admin instead.
  • The Celix::log_writer_stdout bundle target. Deprecated bundle. Logging to stdout is now an integral part of the log admin.