Ktor — HTTP Logging

OverviewRequestResponse

How It Works

WiretapKtorHttpPlugin hooks into three Ktor lifecycle points:

1. onRequest — Captures timestamps (ms + ns) for duration measurement
2. on(Send) — Intercepts the request before it reaches the network:
   • Evaluates mock/throttle rules via FindMatchingRuleUseCase
   • Logs the request immediately (visible in the UI while in-flight)
   • If a Mock rule matches, returns a fake HttpClientCall without network access
   • If a Throttle rule matches, delays with kotlinx.coroutines.delay() before proceeding
3. onResponse — Updates the log entry with response data (status, headers, body, duration, protocol)

Request Filtering

Use shouldLog to control which requests are captured:

install(WiretapKtorHttpPlugin) {
    shouldLog = { url, method ->
        url.contains("/api/") && method != "OPTIONS"
    }
}

Requests that don't pass shouldLog are still subject to rule evaluation (mock/throttle), but they won't appear in the log database.

Header Masking

Protect sensitive data in logs:

install(WiretapKtorHttpPlugin) {
    headerAction = { key ->
        when {
            key.equals("Authorization", ignoreCase = true) -> HeaderAction.Mask()
            key.equals("X-Api-Key", ignoreCase = true) -> HeaderAction.Mask("REDACTED")
            key.equals("Cookie", ignoreCase = true) -> HeaderAction.Skip
            else -> HeaderAction.Keep
        }
    }
}

Info

Header actions only affect logged data. The original request/response headers are never mutated.

Mock Rules

When a request matches a mock rule, Wiretap creates a full HttpClientCall with HttpResponseData and returns it without hitting the network. Mock responses appear in the inspector with a Mock badge and near-zero duration.

Mocked RequestsMocked ResponseMock Rule Setup

Throttle Rules

Throttle rules call kotlinx.coroutines.delay() before proceed(request). The real network call still happens — throttling only adds delay.

Throttle Rule SetupMock + Throttle

Error Handling

Wiretap logs exceptions and re-throws them so your error handling works normally:

Scenario	Response Code	Response Body
Network error	0	Exception message
Cancelled request	-1	"Canceled"
In-progress	-2	—

Log Retention

install(WiretapKtorHttpPlugin) {
    logRetention = LogRetention.Forever      // Keep all (default)
    logRetention = LogRetention.AppSession   // Clear on app restart
    logRetention = LogRetention.Days(7)      // Auto-prune after 7 days
}

Complete Example

class ApiClient(private val client: HttpClient) {

    suspend fun getUsers(): List<User> {
        return client.get("https://api.example.com/users").body()
    }

    suspend fun createUser(name: String): User {
        return client.post("https://api.example.com/users") {
            contentType(ContentType.Application.Json)
            setBody(mapOf("name" to name))
        }.body()
    }
}

All requests and responses are automatically captured — no additional instrumentation needed.