Have you ever needed to save your Android Logcat logs for later analysis?
I recently built a service-based Android app, and I needed to monitor its activity to validate its correctness. For that I could not sit in front of the computer monitor for 24+ hours, I needed a way to store the logs with app behavior to validate it’s performing as it should.
I leveraged the following 2 tools to accomplish this task
- Timber: A logger with a small, extensible API which provides utility on top of Android’s normal Log class.
- Airtable: Airtable is a hybrid solution that mixes the intuitiveness of spreadsheets and the power and functionalities of databases.
Airtable service can be replaced by any other similar service that allows REST API to add records that can be viewed online.
Why Airtable?
- It provides an easy interface to view data in a spreadsheet-like experience.
- It has REST API to easily add data from Android app.
If you are not familiar with the amazing Android Timber library, I suggest you spend a few minutes reading the documentation. We will be building an AirtableLoggingTree that sends all the logs logged via Timber to the Airtable spreadsheet/database using their REST API.
Here are some pseudo task we need to accomplish this
- Save all the logs to a queue to process and send to REST API
- Format the logs and send a batched request (to avoid rate limit)
- Make the REST call based on API specification for creating a record.
First, let’s build a Kotlin data class to capture some log info that should be sent to Airtable.
data class LogMessage(
val priority: Int,
val tag: String?,
val message: String,
val throwable: Throwable?,
val logTime: Instant = Instant.now(),
val device: String = Build.MODEL,
)
Next, let’s create the AirtableLoggingTree that queues the logs and sends logs in batches using REST API via OkHttp client.
💁Inline comments have been added where applicable.
class AirtableLoggingTree(
// Create your token from https://airtable.com/create/tokens
private val authToken: String,
// Example: https://api.airtable.com/v0/appXXXXXXXXX/Table%20Name
private val endpointUrl: String,
) : Timber.Tree() {
private val client = OkHttpClient()
private val logQueue = ConcurrentLinkedQueue<LogMessage>()
private var flushJob: Job? = null
companion object {
/**
* The API is limited to 5 requests per second per base.
*/
private const val MAX_LOG_COUNT_PER_SECOND = 5
/**
* The API is limited to 10 records per request.
* - https://airtable.com/developers/web/api/create-records
*/
private const val MAX_RECORDS_PER_REQUEST = 10
}
init {
startFlushJob()
}
override fun log(priority: Int, tag: String?, message: String, t: Throwable?) {
// Adds the log to queue for batch processing
logQueue.add(LogMessage(priority, tag, message, t))
if (flushJob == null || flushJob?.isCancelled == true) {
// If there is enough log, it will start sending them
startFlushJob()
}
}
private fun startFlushJob() {
flushJob =
CoroutineScope(Dispatchers.IO).launch {
while (isActive) {
flushLogs()
// Wait long enough before sending next request
// https://airtable.com/developers/web/api/rate-limits
delay(1_100L)
}
}
}
private fun createLogMessage(logs: List<LogMessage>): String? {
if (logs.isEmpty()) {
return null
}
// Builds the JSON payload structure with multiple messages based on API spec
val records = JSONArray().apply { logs.forEach { put(it.toLogRecord()) } }
return JSONObject().apply {
put("records", records)
}.toString()
}
private fun getMaximumAllowedLogs(): List<LogMessage> {
val logs = mutableListOf<LogMessage>()
while (logQueue.isNotEmpty() && logs.size < MAX_RECORDS_PER_REQUEST) {
val log = logQueue.poll()
if (log != null) {
logs.add(log)
}
}
return logs
}
private suspend fun flushLogs() {
var sentLogCount = 0
// Collects all the queued logs and sends them in batches
// Based on rate-limit a total of 5x10 = 50 reconds can be sent per second
while (sentLogCount < MAX_LOG_COUNT_PER_SECOND) {
val jsonPayload = createLogMessage(getMaximumAllowedLogs())
if (jsonPayload != null) {
sendLogToApi(jsonPayload)
sentLogCount++
// This delay is added to ensure the order of log is maintained.
// However, there is no guarantee that the log will be sent in order.
delay(100L)
}
}
if (logQueue.isEmpty()) {
flushJob?.cancel()
}
}
// Finally, this is the OkHttp client that sends HTTP POST request to add those log records
private fun sendLogToApi(logPayloadJson: String) {
val mediaType = "application/json; charset=utf-8".toMediaTypeOrNull()
val body = logPayloadJson.toRequestBody(mediaType)
val request =
Request.Builder()
.url(endpointUrl)
.addHeader("Authorization", "Bearer $authToken")
.post(body)
.build()
client.newCall(request).enqueue(
object : okhttp3.Callback {
override fun onFailure(
call: okhttp3.Call,
e: IOException,
) {
Timber.e("Failed to send log to API: ${e.localizedMessage}")
}
override fun onResponse(
call: okhttp3.Call,
response: okhttp3.Response,
) {
response.use { // This ensures the response body is closed
if (!response.isSuccessful) {
Timber.e(
"Log is rejected: HTTP code: ${response.code}, " +
"message: ${response.message}, body: ${response.body?.string()}",
)
}
}
}
},
)
}
}
Everything is great except there is one piece of missing code that uses the API LogMessage.toLogRecord() in the AirtableLoggingTree. The snipped is shown below for clarity.
val records = JSONArray().apply { logs.forEach { put(it.toLogRecord()) } }
This function implementation will be very specific to how you have setup your Airtable spreadsheet.
For my case, I have two columns for the table in the Airtable base:
- "Device" — to store the device model. Single-line text.
- "Log" — to store the log message. Multiline text.
fun toLogRecord(): JSONObject {
val logMessage =
buildString {
append("Priority: ${priority}\n")
if (tag != null) append("Tag: $tag\n")
append("Message: $message\n")
if (throwable != null) append("Throwable: ${throwable.localizedMessage}")
append("App Version: ${BuildConfig.VERSION_NAME}\n")
append("Log Time: ${logTime}\n")
}
val fields =
JSONObject().apply {
put("Device", device)
put("Log", logMessage)
}
return JSONObject().apply {
put("fields", fields)
}
}
You could essentially have multiple columns for each of the properties.
✅ And that’s it. You have a working Timber tree that can send all logcat logs to the Airtable base (spreadsheet) that adheres to their API rate limit.
See it in action
You can take a look at the fully implemented tree in the following project
GitHub - hossain-khan/android-keep-alive: A simple app to keep alive specific apps
Here is a screenshot of how the log looks in the Airtable
Demo of remotly logged messages in the Airtable
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