How to use
- Copy the installation command and review the source package before installing it in your own agent environment.
- Check the source document for required tools, credentials and supported hosts.
- Describe your input and desired deliverable; review the output against the source material.
npx skills add https://github.com/j4flmao/agent_skills_nodejs_nestjs --skill logging-and-observabilityBefore you start
- Installation does not include a model subscription, API allowance or permission to access your files.
- Repository stars and installation counts describe activity, not an independent quality or security test.
Original skill document
Rendered from the source repository. Headings, examples, code, tables, links, and referenced images are preserved.
Logging and Observability
When to use
- Wiring observability for a new service
- Debugging cross-service requests
- Removing
console.logfrom production code
Core rules
- Structured JSON logs in production, pretty in development
- Every log entry has
timestamp,level,message,traceId - No
console.login production code - Correlation/trace ID passed through async context
- Health endpoint (
/health) and readiness endpoint (/ready)
Reference shape (TypeScript)
Logger Interface (Port)
typescript
export interface Logger {
info(message: string, meta?: Record<string, unknown>): void;
warn(message: string, meta?: Record<string, unknown>): void;
error(message: string, meta?: Record<string, unknown>): void;
debug(message: string, meta?: Record<string, unknown>): void;
}JSON Logger Implementation
typescript
export class JsonLogger implements Logger {
constructor(private traceId?: string) {}
info(message: string, meta?: Record<string, unknown>): void {
this.log('info', message, meta);
}
private log(level: string, message: string, meta?: Record<string, unknown>): void {
const entry = {
timestamp: new Date().toISOString(),
level,
message,
traceId: this.traceId,
...meta,
};
console.log(JSON.stringify(entry));
}
}Examples — Do
typescript
this.logger.info('User created', { userId: user.id, email: user.email.value });Examples — Don't
typescript
// ❌ Console.log in production code
console.log('User created:', user);
// ❌ No trace ID
logger.info('Request processed');Checklist
- [ ] Structured JSON logger implemented
- [ ] Trace/correlation ID in every log entry
- [ ] Health and readiness endpoints created
- [ ] No
console.login production code
See reference/logging-patterns.md for full patterns.
