Add agent diagnostics action

internal/pkg/agent/application/actions/handlers/handler_action_diagnostics.go

@@ -0,0 +1,85 @@
+// Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+// or more contributor license agreements. Licensed under the Elastic License;
+// you may not use this file except in compliance with the Elastic License.
+
+package handlers
+
+import (
+	"bytes"
+	"context"
+	"fmt"
+
+	"github.com/elastic/elastic-agent/internal/pkg/agent/control/v2/client"
+	"github.com/elastic/elastic-agent/internal/pkg/diagnostics"
+	"github.com/elastic/elastic-agent/internal/pkg/fleetapi"
+	"github.com/elastic/elastic-agent/internal/pkg/fleetapi/acker"
+	"github.com/elastic/elastic-agent/pkg/core/logger"
+)
+
+// Uploader is the interface used to upload a diagnostics bundle to fleet-server.
+type Uploader interface {
+	UploadDiagnostics(context.Context, string, *bytes.Buffer) (string, error)
+}
+
+// Diagnostics is the handler to process Diagnostics actions.
+// When a Diagnostics action is received a full diagnostics bundle is taken and uploaded to fleet-server.
+type Diagnostics struct {
+	log      *logger.Logger
+	client   client.Client
+	uploader Uploader
+}
+
+// NewDiagnostics returns a new Diagnostics handler.
+func NewDiagnostics(log *logger.Logger, uploader Uploader) *Diagnostics {
+	return &Diagnostics{
+		log:      log,
+		client:   client.New(),
+		uploader: uploader,
+	}
+}
+
+// Handle processes the passed Diagnostics action.
+func (h *Diagnostics) Handle(ctx context.Context, a fleetapi.Action, ack acker.Acker) error {
+	h.log.Debugf("handlerDiagnostics: action '%+v' received", a)
+	action, ok := a.(*fleetapi.ActionDiagnostics)
+	if !ok {
+		return fmt.Errorf("invalid type, expected ActionDiagnostics and received %T", a)
+	}
+	defer ack.Ack(ctx, action) //nolint:errcheck // no path for a failed ack
+
+	// Gather agent diagnostics
+	aDiag, err := h.client.DiagnosticAgent(ctx)
+	if err != nil {
+		action.Err = err
+		return fmt.Errorf("unable to gather agent diagnostics: %w", err)
+	}
+	uDiag, err := h.client.DiagnosticUnits(ctx)
+	if err != nil {
+		action.Err = err
+		return fmt.Errorf("unable to gather unit diagnostics: %w", err)
+	}
+
+	var b bytes.Buffer
+	// create a buffer that any redaction error messages are written into as warnings.
+	// if the buffer is not empty after the bundle is assembled then the message is written to the log
+	// zapio.Writer would be a better way to pass a writer to ZipArchive, but logp embeds the zap.Logger so we are unable to access it here.
+	var wBuf bytes.Buffer
+	defer func() {
+		if str := wBuf.String(); str != "" {
+			h.log.Warn(str)
+		}
+	}()
+	err = diagnostics.ZipArchive(&wBuf, &b, aDiag, uDiag) // TODO Do we want to pass a buffer/a reader around? or write the file to a temp dir and read (to avoid memory usage)? file usage may need more thought for containerized deployments
+	if err != nil {
+		action.Err = err
+		return fmt.Errorf("error creating diagnostics bundle: %w", err)
+	}
+
+	uploadID, err := h.uploader.UploadDiagnostics(ctx, action.ActionID, &b)
+	action.Err = err
+	action.UploadID = uploadID
+	if err != nil {
+		return fmt.Errorf("unable to upload diagnostics: %w", err)
+	}
+	return nil
+}