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HTTP Logging

Mockcat includes a persistent HTTP traffic logger that captures every request and response — including mocked ones — and presents them in a searchable list/detail UI.

Dependencies

app/build.gradle.kts
debugImplementation("com.mockcat:mockcat-logger-okhttp:0.1.0")  // OkHttp
debugImplementation("com.mockcat:mockcat-logger-ktor:0.1.0")    // Ktor
debugImplementation("com.mockcat:mockcat-logger-ui:0.1.0")      // UI viewer
releaseImplementation("com.mockcat:mockcat-noop-android:0.1.0")

Setup

import com.mockcat.logger.okhttp.MockcatLogging

val mockcatLogger = MockcatLogging(context)
val mockcatIntercept = MockcatIntercept(context)

val client = OkHttpClient.Builder()
    .addInterceptor(mockcatLogger)
    .addInterceptor(mockcatIntercept)
    .build()

import com.mockcat.logger.ktor.installMockcatKtorHttpLogging

val client = HttpClient(OkHttp) {
    installMockcatKtorHttpLogging(context)
    installMockcatKtorIntercept(context)
}

No other configuration is required. Logs are persisted in a Room database and survive process restarts.

Opening the log viewer

import com.mockcat.logger.ui.MockcatLoggerUi

startActivity(MockcatLoggerUi.createLaunchIntent(context))

The viewer opens in its own back-stack (singleTask with a dedicated taskAffinity). Calling createLaunchIntent while the viewer is already open brings it to the front rather than creating a new instance.

iOS

import MockcatLoggerUI

let logViewController = createHttpLogListViewController()
present(logViewController, animated: true)

What gets logged

Each captured call records:

Field Description
URL Full request URL including query string
Method GET, POST, etc.
Request headers All request headers
Status code HTTP response status
Response headers All response headers
Response body Up to the capture limit (see below)
Duration Time from request start to response end (ms)
Timestamps Request and response epoch times
Error Non-null if the request failed with an exception

Body capture limit

OkHttp uses response.peekBody() to read up to 256 KB of the response body without consuming it. Larger bodies are recorded as Omitted(reason = "body exceeds limit").

To change the limit for OkHttp:

import com.mockcat.logger.okhttp.MockcatHttpLoggingInterceptor

val logger = MockcatHttpLoggingInterceptor(
    writer = MockcatLogging.logReader(context),
    maxResponseBodyBytes = 1 * 1024 * 1024L // 1 MB
)

For Ktor, the logging plugin reads the full response body bytes and caches them in memory before re-delivering them to the caller. The captured body size is limited by available memory.

Log viewer features

List screen: - Every HTTP call sorted by time (newest first) - Status badge colour: green (2xx), orange (3xx), red (4xx/5xx/error) - Method, host, and path at a glance - Duration and response body size - Pull to clear all logs

Detail screen: - Full URL, method, status - Request headers (expandable) - Response headers (expandable) - Request and response body - Copy as cURL command - Share via system share sheet

Reading logs programmatically

import com.mockcat.logger.core.HttpLogReaderRegistry

val reader = HttpLogReaderRegistry.requireCurrent()

// Observe as a Flow
reader.observeLogs().collect { calls ->
    // calls: List<LoggedHttpCall>
}

// Get a specific call
val call = reader.getById(callId)

// Clear all logs
reader.clear()

LoggedHttpCall structure

data class LoggedHttpCall(
    val id: Long,
    val request: HttpRequestSnapshot,
    val response: HttpResponseSnapshot?,  // null if request failed
    val requestTimestampMs: Long,
    val responseTimestampMs: Long,
    val durationMs: Long?,
    val error: String?,  // non-null if request threw an exception
)

How the store is wired

MockcatLogging(context) and installMockcatKtorHttpLogging(context) both use ProcessHttpLogStore.get(context) — a process-wide singleton backed by a Room database. The log viewer reads from HttpLogReaderRegistry, which holds a reference to the same store.

If you need a custom log store (e.g., for testing or a multi-process app):

import com.mockcat.logger.core.InMemoryHttpLogStore
import com.mockcat.logger.core.HttpLogReaderRegistry

val store = InMemoryHttpLogStore()  // ring buffer, 200 entries max
HttpLogReaderRegistry.install(store)

val logger = MockcatHttpLoggingInterceptor(writer = store)

iOS bootstrap

Call once at app startup:

import MockcatLoggerUI

installHttpLogReaderForIos()

This initializes the Room-backed log store for iOS, registers it with HttpLogReaderRegistry, and shows a floating overlay button that opens the log viewer.