Contexts

Contexts are available since LogTape 0.5.0.

LogTape provides a context system to reuse the same properties across log messages. A context is a key-value map. You can set a context for a logger and log messages with() the context. Here's an example of setting a context for a logger:

const logger = getLogger(["my-app", "my-module"]);
const ctx = logger.with({ userId: 1234, requestId: "abc" });
ctx.info `This log message will have the context (userId & requestId).`;
ctx.warn("Context can be used inside message template: {userId}, {requestId}.");

The context is inherited by child loggers. Here's an example of setting a context for a parent logger and logging messages with a child logger:

const logger = getLogger(["my-app"]);
const parentCtx = logger.with({ userId: 1234, requestId: "abc" });
const childCtx = parentCtx.getLogger(["my-module"]);
childCtx.debug("This log message will have the context: {userId} {requestId}.");

Contexts are particularly useful when you want to do structured logging.