track()
Attribute API costs to specific features in your app. This lets you see “my chat feature costs $8/day” instead of just “OpenAI costs $8/day”.
Usage
import { track } from '@burn0/burn0'
// Wrap any async function that makes API calls
await track('chat', { userId: 'user123' }, async () => {
const response = await openai.chat.completions.create({
model: 'gpt-4o-mini',
messages: [{ role: 'user', content: 'Hello' }],
})
return response
})
track() callback are tagged with the feature name and metadata.
Parameters
track(feature: string, metadata: Record<string, string | number | boolean>, fn: () => Promise<void>): Promise<void>
| Parameter | Type | Description |
|---|
feature | string | Feature name (e.g., 'chat', 'summarize', 'search') |
metadata | object | Key-value pairs (e.g., { userId: 'u123', tier: 'pro' }) |
fn | async function | The function that makes API calls |
Alternative: startSpan
For cases where a callback wrapper doesn’t fit, use startSpan:
import { startSpan } from '@burn0/burn0'
const span = startSpan('chat', { userId: 'user123' })
// ... make API calls ...
span.end()
Always call span.end() when done. Forgetting to end a span means subsequent API calls may be attributed to the wrong feature.
Examples
Per-user cost tracking
app.post('/api/chat', async (req, res) => {
const { userId, message } = req.body
await track('chat', { userId }, async () => {
const response = await openai.chat.completions.create({
model: 'gpt-4o-mini',
messages: [{ role: 'user', content: message }],
})
res.json({ response: response.choices[0].message.content })
})
})
Per-feature breakdown
// Summarize feature
await track('summarize', { documentId: doc.id }, async () => {
await anthropic.messages.create({ ... })
})
// Search feature
await track('search', { query: q }, async () => {
await openai.embeddings.create({ ... })
await pinecone.query({ ... })
})
Viewing tracked data
Feature and metadata are stored with each event and visible in:
- The dashboard event detail view
burn0 report (coming soon: per-feature breakdown)
