Add InstallDescriptorSource abstraction

Author: pchila

.mockery.yaml

@@ -54,3 +54,4 @@ packages:
     interfaces:
       WatcherHelper:
       watcherGrappler:
+      installDescriptorSource:

internal/pkg/agent/application/application.go

@@ -7,10 +7,12 @@ package application
 import (
 	"context"
 	"fmt"
+	"path/filepath"
 	"time"
 
 	"go.elastic.co/apm/v2"
 
+	"github.com/elastic/elastic-agent/pkg/utils/install"
 	"github.com/elastic/go-ucfg"
 
 	"github.com/elastic/elastic-agent-libs/logp"
@@ -124,7 +126,7 @@ func New(
 
 	// monitoring is not supported in bootstrap mode https://github.com/elastic/elastic-agent/issues/1761
 	isMonitoringSupported := !disableMonitoring && cfg.Settings.V1MonitoringEnabled
-	upgrader, err := upgrade.NewUpgrader(log, cfg.Settings.DownloadConfig, cfg.Settings.Upgrade, agentInfo, new(upgrade.AgentWatcherHelper))
+	upgrader, err := upgrade.NewUpgrader(log, cfg.Settings.DownloadConfig, cfg.Settings.Upgrade, agentInfo, new(upgrade.AgentWatcherHelper), install.NewFileDescriptorSource(filepath.Join(paths.Top(), paths.MarkerFileName)))
 	if err != nil {
 		return nil, nil, nil, fmt.Errorf("failed to create upgrader: %w", err)
 	}

internal/pkg/agent/application/coordinator/coordinator_unit_test.go

@@ -26,6 +26,7 @@ import (
 
 	"github.com/elastic/elastic-agent-client/v7/pkg/proto"
 	"github.com/elastic/elastic-agent/internal/pkg/testutils"
+	"github.com/elastic/elastic-agent/pkg/utils/install"
 
 	"github.com/open-telemetry/opentelemetry-collector-contrib/pkg/status"
 	"go.opentelemetry.io/collector/component/componentstatus"
@@ -462,7 +463,8 @@ func TestCoordinatorReportsInvalidPolicy(t *testing.T) {
 		}
 	}()
 
-	upgradeMgr, err := upgrade.NewUpgrader(log, &artifact.Config{}, nil, &info.AgentInfo{}, new(upgrade.AgentWatcherHelper))
+	tmpDir := t.TempDir()
+	upgradeMgr, err := upgrade.NewUpgrader(log, &artifact.Config{}, nil, &info.AgentInfo{}, new(upgrade.AgentWatcherHelper), install.NewFileDescriptorSource(filepath.Join(tmpDir, paths.MarkerFileName)))
 	require.NoError(t, err, "errored when creating a new upgrader")
 
 	// Channels have buffer length 1, so we don't have to run on multiple