Module logging

From modules you can log messages at the resource level or at the machine level.

Resource-level logging

The following log severity levels are available for resource logs:

# Within some method, log information:
self.logger.debug("debug info")
self.logger.info("info")
self.logger.warn("warning info")
self.logger.error("error info")
self.logger.exception("error info", exc_info=True)
self.logger.critical("critical info")

fn (c *component) someFunction(ctx context.Context, a int) {
  // Log with severity info:
  c.logger.CInfof(ctx, "performing some function with a=%v", a)
  // Log with severity debug (using value wrapping):
  c.logger.CDebugw(ctx, "performing some function", "a" ,a)
  // Log with severity warn:
  c.logger.CWarnw(ctx, "encountered warning for component", "name", c.Name())
  // Log with severity error without a parameter:
  c.logger.CError(ctx, "encountered an error")
}

Resource-level logs are recommended instead of global logs for modular resources, because they make it easier to determine which component or service an error is coming from. Resource-level error logs appear in the ERROR LOGS section of each resource’s configuration card in the app.

Machine-level logging

If you need to publish to the global machine-level logs instead of using the recommended resource-level logging, you can follow this example:

# In your import block, import the logging package:
from viam.logging import getLogger

# Before your first class or function, define the LOGGER variable:
LOGGER = getLogger(__name__)

# in some method, log information
LOGGER.debug("debug info")
LOGGER.info("info info")
LOGGER.warn("warn info")
LOGGER.error("error info")
LOGGER.exception("error info", exc_info=True)
LOGGER.critical("critical info")