🗃️ Custom Logger

The App will provide a default logger, but you can also provide your own. The default Logger instance will be set to ConsoleLogger from the @microsoft/teams.common package.

import { App } from '@microsoft/teams.apps';
import { ConsoleLogger } from '@microsoft/teams.common';

// initialize app with custom console logger
// set to debug log level
const app = new App({
  logger: new ConsoleLogger('echo', { level: 'debug' }),
});

app.on('message', async ({ send, activity, log }) => {
  log.debug(activity);
  await send({ type: 'typing' });
  await send(`you said "${activity.text}"`);
});

(async () => {
  await app.start();
})();

Log Levels

Available levels, from most to least severe: error, warn, info, debug, trace. The default is info. Setting level: 'debug' emits error, warn, info, and debug — but not trace.

Filtering by Logger Name

Each logger is created with a name. You can filter which loggers emit output by providing a name pattern, using * as a wildcard.

Each logger has a name. The pattern option filters which loggers emit, with * as a wildcard. Prefix a pattern with - to exclude. Combine with commas.

new ConsoleLogger('my-app', { pattern: '@teams*' });        // only SDK loggers
new ConsoleLogger('my-app', { pattern: '*,-@teams/http*' }); // everything except HTTP

Environment Variables

The TypeScript SDK's ConsoleLogger reads two environment variables at construction:

Variable	Purpose	Example
LOG_LEVEL	Minimum severity	LOG_LEVEL=debug
LOG	Logger name pattern (wildcards)	LOG=@teams*

Env vars override options passed to the constructor. If you do not pass a logger to App, the SDK creates a default ConsoleLogger named @teams/app — so LOG_LEVEL=debug alone is enough to enable debug output.

Gotcha: LOG is a name filter, not a toggle. Setting LOG to a pattern that doesn't match the default @teams/app (for example LOG=my-app*) silences the default logger. If in doubt, unset LOG to match everything.

Child Loggers

Call log.child('scope') on an existing logger to get a scoped logger. Its name is parent/scope, and pattern/level are inherited.

app.on('message', async ({ log }) => {
  const msgLog = log.child('message-handler');
  msgLog.debug('processing'); // logged as "@teams/app/message-handler"
});