logger

@workkit/logger

Structured logging for Cloudflare Workers with automatic request context and Hono middleware

Install

bun add @workkit/logger

Usage

Before (raw console.log)

// No structure, no levels, no request context
console.log("processing request", request.url)
console.log("user found", JSON.stringify(user))
console.error("something failed", error.message)

After (workkit logger)

import { createLogger } from "@workkit/logger"

const log = createLogger({ service: "api", level: "debug" })
log.info("processing request", { url: request.url })
log.info("user found", { userId: user.id })
log.error("something failed", { error })
// {"level":"info","msg":"processing request","ts":1234567890,"service":"api","url":"/users"}

Hono Middleware

import { Hono } from "hono"
import { logger, getLogger } from "@workkit/logger"

const app = new Hono()

// Auto-logs request start/complete with timing and requestId
app.use(logger({ exclude: ["/health"], fields: { service: "api" } }))

app.get("/users", (c) => {
  const log = getLogger(c)
  log.info("fetching users", { count: 50 })
  return c.json(users)
})

Child Loggers

const log = createLogger({ service: "worker" })
const batchLog = log.child({ batchId: "abc-123" })

batchLog.info("processing item", { itemId: 1 })
// {"level":"info","msg":"processing item","ts":...,"service":"worker","batchId":"abc-123","itemId":1}

Redaction

app.use(
  logger({
    redact: ["authorization", "cookie", "x-api-key"],
  }),
)
// Fields matching redacted keys are replaced with "[REDACTED]"

// Or use a custom redactor function
app.use(
  logger({
    redact: (key, value) =>
      key.toLowerCase().includes("secret") ? "[REDACTED]" : value,
  }),
)

Request Context (AsyncLocalStorage)

import { getRequestContext } from "@workkit/logger"

// Inside a request handled by the logger middleware:
const ctx = getRequestContext()
if (ctx) {
  console.log(ctx.requestId) // "a1b2c3d4e5f67890"
  console.log(ctx.method) // "GET"
  console.log(ctx.path) // "/users"
}

API

Standalone Logger

• createLogger(options?) -- Create a structured logger
  • options.level -- Minimum log level ("debug", "info", "warn", "error"). Default: "info"
  • options.fields -- Base fields attached to every log entry
  • Returns Logger with .debug(), .info(), .warn(), .error(), .child()

Hono Middleware

• logger(options?) -- Hono middleware for structured request logging

  • options.level -- Minimum log level. Default: "info"
  • options.exclude -- Routes to skip (exact match or prefix)
  • options.requestId -- Header name to use as requestId (default: auto-generate)
  • options.fields -- Base fields on every entry
  • options.timing -- Auto-log request duration. Default: true
  • options.redact -- Field names or custom function for redacting sensitive data

• getLogger(c) -- Get a logger from Hono context (includes requestId, method, path)

Request Context

• getRequestContext() -- Get the current request context from AsyncLocalStorage

Types

• LogLevel -- "debug" | "info" | "warn" | "error"
• LogFields -- Record<string, unknown>
• LogEntry -- { level, msg, ts, ...fields }
• Logger -- Logger interface with level methods and .child()
• RequestContext -- { requestId, method, path, startTime, fields }

License

MIT