Add logger for CLI telemetry

libs/telemetry/api.go

@@ -0,0 +1,20 @@
+package telemetry
+
+type RequestBody struct {
+	UploadTime int64    `json:"uploadTime"`
+	Items      []string `json:"items"`
+	ProtoLogs  []string `json:"protoLogs"`
+}
+
+type ResponseBody struct {
+	Errors          []LogError `json:"errors"`
+	NumProtoSuccess int64      `json:"numProtoSuccess"`
+}
+
+type LogError struct {
+	Message string `json:"message"`
+
+	// Confirm with Ankit that this signature is accurate. How can I intentionally
+	// trigger a error?
+	ErrorType string `json:"ErrorType"`
+}

libs/telemetry/frontend_log.go

@@ -0,0 +1,31 @@
+package telemetry
+
+// This corresponds to the FrontendLog lumberjack proto in universe.
+type FrontendLog struct {
+	// A unique identifier for the log event generated from the CLI.
+	FrontendLogEventID string `json:"frontend_log_event_id,omitempty"`
+
+	Entry FrontendLogEntry `json:"entry,omitempty"`
+}
+
+type FrontendLogEntry struct {
+	DatabricksCliLog DatabricksCliLog `json:"databricks_cli_log,omitempty"`
+}
+
+type DatabricksCliLog struct {
+	CliTestEvent CliTestEvent `json:"cli_test_event,omitempty"`
+}
+
+// dummy event for testing the telemetry pipeline
+type CliTestEvent struct {
+	Name DummyCliEnum `json:"name,omitempty"`
+}
+
+type DummyCliEnum string
+
+const (
+	DummyCliEnumUnspecified DummyCliEnum = "DUMMY_CLI_ENUM_UNSPECIFIED"
+	DummyCliEnumValue1      DummyCliEnum = "VALUE1"
+	DummyCliEnumValue2      DummyCliEnum = "VALUE2"
+	DummyCliEnumValue3      DummyCliEnum = "VALUE3"
+)

libs/telemetry/logger.go

@@ -0,0 +1,199 @@
+package telemetry
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"time"
+
+	"github.com/databricks/cli/cmd/root"
+	"github.com/databricks/cli/libs/log"
+	"github.com/databricks/databricks-sdk-go/client"
+)
+
+// Interface abstraction created to mock out the Databricks client for testing.
+type databricksClient interface {
+	Do(ctx context.Context, method, path string,
+		headers map[string]string, request, response any,
+		visitors ...func(*http.Request) error) error
+}
+
+type logger struct {
+	respChannel chan *ResponseBody
+
+	apiClient databricksClient
+
+	// TODO: Appropriately name this field.
+	w *io.PipeWriter
+
+	// TODO: wrap this in a mutex since it'll be concurrently accessed.
+	protoLogs []string
+}
+
+// TODO: Test that both sever and client side timeouts will spawn a new goroutine
+// TODO: Add comment here about the warm pool stuff.
+// TODO: Talk about why this request is made in a separate goroutine in the
+// background while the other requests are made in the main thread (since the
+// retry operations can be blocking).
+// TODO: The main thread also needs to appropriately communicate with this
+// thread.
+//
+//	TODO: Add an integration test for this functionality as well.
+
+// spawnTelemetryConnection will spawn a new TCP connection to the telemetry
+// endpoint and keep it alive until the main CLI thread is alive.
+//
+// Both the Databricks Go SDK client and Databricks control plane servers typically
+// timeout after 60 seconds. Thus if we see any error from the API client we'll
+// simply retry the request to establish a new TCP connection.
+//
+// The intent of this function is to reduce the RTT for the HTTP request to the telemetry
+// endpoint since underneath the hood the Go standard library http client will establish
+// the connection but will be blocked on reading the request body until we write
+// to the corresponding pipe writer for the request body pipe reader.
+//
+// Benchmarks suggest this reduces the RTT from ~700 ms to ~200 ms.
+func (l *logger) spawnTelemetryConnection(ctx context.Context, r *io.PipeReader) {
+	for {
+		select {
+		case <-ctx.Done():
+			return
+		default:
+			// Proceed
+		}
+
+		resp := &ResponseBody{}
+
+		// This API request will exchange TCP/TLS headers with the server but would
+		// be blocked on sending over the request body until we write to the
+		// corresponding writer for the request body reader.
+		err := l.apiClient.Do(ctx, http.MethodPost, "/telemetry-ext", nil, r, resp)
+
+		// The TCP connection can timeout while it waits for the CLI to send over
+		// the request body. It could be either due to the client which has a
+		// default timeout of 60 seconds or a server side timeout with a status code
+		// of 408.
+		//
+		// Thus as long as the main CLI thread is alive we'll simply keep trying again
+		// and establish a new TCL connection.
+		//
+		// TODO: Verify whether the server side timeout is 408 for the telemetry API
+		// TODO: Check where the telemetry API even has a server side timeout.
+		if err == nil {
+			l.respChannel <- resp
+			return
+		}
+	}
+
+}
+
+// TODO: Log warning or errors when any of these telemetry requests fail.
+// TODO: Figure out how to create or use an existing general purpose http mocking
+// library to unit test this functionality out.
+// TODO: Add the concurrency functionality to make the API call from a separate thread.
+// TODO: Add a cap for the maximum local timeout how long we'll wait for the telemetry
+// event to flush.
+// TODO: Do I need to customize exponential backoff for this? Since we don't want to
+// wait too long in between retries.
+// TODO: test that this client works for long running API calls.
+func NewLogger(ctx context.Context, apiClient databricksClient) (*logger, error) {
+	if apiClient == nil {
+		var err error
+		apiClient, err = client.New(root.WorkspaceClient(ctx).Config)
+		if err != nil {
+			return nil, fmt.Errorf("error creating telemetry client: %v", err)
+		}
+	}
+
+	r, w := io.Pipe()
+
+	l := &logger{
+		protoLogs:   []string{},
+		apiClient:   apiClient,
+		w:           w,
+		respChannel: make(chan *ResponseBody, 1),
+	}
+
+	go func() {
+		l.spawnTelemetryConnection(ctx, r)
+	}()
+
+	return l, nil
+}
+
+// TODO: Add unit test for this and verify that the quotes are retained.
+func (l *logger) TrackEvent(event FrontendLogEntry) {
+	protoLog, err := json.Marshal(event)
+	if err != nil {
+		return
+	}
+
+	l.protoLogs = append(l.protoLogs, string(protoLog))
+}
+
+// Maximum additional time to wait for the telemetry event to flush. We expect the flush
+// method to be called when the CLI command is about to exist, so this caps the maximum
+// additional time the user will experience because of us logging CLI telemetry.
+var MaxAdditionalWaitTime = 1 * time.Second
+
+// TODO: Talk about why we make only one API call at the end. It's because the
+// size limit on the payload is pretty high: ~1000 events.
+func (l *logger) Flush(ctx context.Context) {
+	// Set a maximum time to wait for the telemetry event to flush.
+	ctx, _ = context.WithTimeout(ctx, MaxAdditionalWaitTime)
+	var resp *ResponseBody
+
+	reqb := RequestBody{
+		UploadTime: time.Now().Unix(),
+		ProtoLogs:  l.protoLogs,
+	}
+
+	// Finally write to the pipe writer to unblock the API request.
+	b, err := json.Marshal(reqb)
+	if err != nil {
+		log.Debugf(ctx, "Error marshalling telemetry logs: %v", err)
+		return
+	}
+	_, err = l.w.Write(b)
+	if err != nil {
+		log.Debugf(ctx, "Error writing to telemetry pipe: %v", err)
+		return
+	}
+
+	select {
+	case <-ctx.Done():
+		log.Debugf(ctx, "Timed out before flushing telemetry events")
+		return
+	case resp = <-l.respChannel:
+		// The persistent TCP connection we create finally returned a response
+		// from the /telemetry-ext endpoint. We can now start processing the
+		// response in the main thread.
+	}
+
+	for {
+		select {
+		case <-ctx.Done():
+			log.Debugf(ctx, "Timed out before flushing telemetry events")
+			return
+		default:
+			// Proceed
+		}
+
+		// All logs were successfully sent. No need to retry.
+		if len(l.protoLogs) <= int(resp.NumProtoSuccess) && len(resp.Errors) == 0 {
+			return
+		}
+
+		// Some or all logs were not successfully sent. We'll retry and log everything
+		// again.
+		//
+		// Note: This will result in server side duplications but that's fine since
+		// we can always deduplicate in the data pipeline itself.
+		l.apiClient.Do(ctx, http.MethodPost, "/telemetry-ext", nil, RequestBody{
+			UploadTime: time.Now().Unix(),
+			ProtoLogs:  l.protoLogs,
+		}, resp)
+	}
+}