upgrade(installer): Report and store policies metadata

pkg/fleet/daemon/daemon.go

@@ -71,7 +71,7 @@ type daemonImpl struct {
 	env           *env.Env
 	installer     installer.Installer
 	rc            *remoteConfig
-	cdn           cdn.CDN
+	cdn           *cdn.CDN
 	catalog       catalog
 	requests      chan remoteAPIRequest
 	requestsWG    sync.WaitGroup
@@ -105,7 +105,7 @@ func NewDaemon(rcFetcher client.ConfigFetcher, config config.Reader) (Daemon, er
 	return newDaemon(rc, installer, env, cdn), nil
 }
 
-func newDaemon(rc *remoteConfig, installer installer.Installer, env *env.Env, cdn cdn.CDN) *daemonImpl {
+func newDaemon(rc *remoteConfig, installer installer.Installer, env *env.Env, cdn *cdn.CDN) *daemonImpl {
 	i := &daemonImpl{
 		env:           env,
 		rc:            rc,
@@ -556,15 +556,15 @@ func setRequestDone(ctx context.Context, err error) {
 	}
 }
 
-func (d *daemonImpl) resolveRemoteConfigVersion(ctx context.Context, pkg string) (string, error) {
+func (d *daemonImpl) resolveRemoteConfigVersion(ctx context.Context, pkg string) (*pbgo.PoliciesState, error) {
 	if !d.env.RemotePolicies {
-		return "", nil
+		return nil, nil
 	}
 	config, err := d.cdn.Get(ctx, pkg)
 	if err != nil {
-		return "", err
+		return nil, err
 	}
-	return config.Version(), nil
+	return config.State(), nil
 }
 
 func (d *daemonImpl) refreshState(ctx context.Context) {
@@ -597,13 +597,13 @@ func (d *daemonImpl) refreshState(ctx context.Context) {
 		}
 		cs, hasConfig := configState[pkg]
 		if hasConfig {
-			p.StableConfigVersion = cs.Stable
-			p.ExperimentConfigVersion = cs.Experiment
+			p.StableConfigState = cs.StablePoliciesState
+			p.ExperimentConfigState = cs.ExperimentPoliciesState
 		}
 
-		configVersion, err := d.resolveRemoteConfigVersion(ctx, pkg)
-		if err == nil {
-			p.RemoteConfigVersion = configVersion
+		configState, err := d.resolveRemoteConfigVersion(ctx, pkg)
+		if err == nil && configState != nil {
+			p.RemoteConfigState = configState
 		} else if err != cdn.ErrProductNotSupported {
 			log.Warnf("could not get remote config version: %v", err)
 		}

pkg/fleet/installer/installer.go

@@ -72,7 +72,7 @@ type installerImpl struct {
 	m sync.Mutex
 
 	env        *fleetEnv.Env
-	cdn        cdn.CDN
+	cdn        *cdn.CDN
 	db         *db.PackagesDB
 	downloader *oci.Downloader
 	packages   *repository.Repositories
@@ -308,8 +308,8 @@ func (i *installerImpl) InstallConfigExperiment(ctx context.Context, pkg string,
 	if err != nil {
 		return fmt.Errorf("could not get cdn config: %w", err)
 	}
-	if config.Version() != version {
-		return fmt.Errorf("version mismatch: expected %s, got %s", config.Version(), version)
+	if config.State().GetVersion() != version {
+		return fmt.Errorf("version mismatch: expected %s, got %s", config.State().GetVersion(), version)
 	}
 
 	tmpDir, err := i.packages.MkdirTemp()
@@ -619,7 +619,7 @@ func (i *installerImpl) configurePackage(ctx context.Context, pkg string) (err e
 		if err != nil {
 			return fmt.Errorf("could not write %s config: %w", pkg, err)
 		}
-		err = i.configs.Create(pkg, config.Version(), tmpDir)
+		err = i.configs.Create(pkg, config.State().GetVersion(), tmpDir)
 		if err != nil {
 			return fmt.Errorf("could not create %s repository: %w", pkg, err)
 		}

pkg/fleet/installer/repository/repository.go

@@ -7,6 +7,7 @@
 package repository
 
 import (
+	"encoding/json"
 	"errors"
 	"fmt"
 	"io/fs"
@@ -16,6 +17,7 @@ import (
 
 	"github.com/DataDog/gopsutil/process"
 
+	pbgo "github.com/DataDog/datadog-agent/pkg/proto/pbgo/core"
 	"github.com/DataDog/datadog-agent/pkg/util/log"
 )
 
@@ -62,6 +64,9 @@ type Repository struct {
 type State struct {
 	Stable     string
 	Experiment string
+
+	StablePoliciesState     *pbgo.PoliciesState
+	ExperimentPoliciesState *pbgo.PoliciesState
 }
 
 // HasStable returns true if the repository has a stable package.
@@ -98,12 +103,51 @@ func (r *Repository) GetState() (State, error) {
 	if experiment == stable {
 		experiment = ""
 	}
+
+	// Load the policies state
+	stablePoliciesState, err := r.loadPoliciesMetadata(stable)
+	if err != nil {
+		return State{}, fmt.Errorf("could not load stable policies state: %w", err)
+	}
+
+	experimentPoliciesState, err := r.loadPoliciesMetadata(experiment)
+	if err != nil {
+		return State{}, fmt.Errorf("could not load experiment policies state: %w", err)
+	}
+
 	return State{
 		Stable:     stable,
 		Experiment: experiment,
+
+		StablePoliciesState:     stablePoliciesState,
+		ExperimentPoliciesState: experimentPoliciesState,
 	}, nil
 }
 
+func (r *Repository) loadPoliciesMetadata(version string) (*pbgo.PoliciesState, error) {
+	if version == "" {
+		return nil, nil
+	}
+
+	statePath := filepath.Join(r.rootPath, version, "policy.metadata")
+	stateFile, err := os.ReadFile(statePath)
+	if err != nil {
+		if errors.Is(err, os.ErrNotExist) {
+			return nil, nil
+		}
+		return nil, fmt.Errorf("could not read policies state: %w", err)
+	}
+
+	state := &pbgo.PoliciesState{}
+	err = json.Unmarshal(stateFile, state)
+	if err != nil {
+		return nil, fmt.Errorf("could not unmarshal policies state: %w", err)
+	}
+	state.Version = version
+
+	return state, nil
+}
+
 // Create creates a fresh new repository at the given root path
 // and moves the given stable source path to the repository as the first stable.
 // If a repository already exists at the given path, it is fully removed.

pkg/fleet/internal/cdn/cdn.go

@@ -8,59 +8,170 @@ package cdn
 
 import (
 	"context"
+	"encoding/json"
 	"errors"
+	"fmt"
+	"os"
+	"path/filepath"
 	"runtime"
 
 	"github.com/DataDog/datadog-agent/pkg/fleet/env"
+	pbgo "github.com/DataDog/datadog-agent/pkg/proto/pbgo/core"
+	"gopkg.in/DataDog/dd-trace-go.v1/ddtrace/tracer"
 )
 
+const policyMetadataFilename = "policy.metadata"
+
 var (
 	// ErrProductNotSupported is returned when the product is not supported.
 	ErrProductNotSupported = errors.New("product not supported")
 )
 
 // Config represents a configuration.
 type Config interface {
-	Version() string
+	State() *pbgo.PoliciesState
 	Write(dir string) error
 }
 
+// fetcher provides access to the Remote Config CDN.
+type fetcher interface {
+	get(ctx context.Context) ([][]byte, error)
+	close() error
+}
+
 // CDN provides access to the Remote Config CDN.
-type CDN interface {
-	Get(ctx context.Context, pkg string) (Config, error)
-	Close() error
+type CDN struct {
+	fetcher        fetcher
+	hostTagsGetter hostTagsGetter
 }
 
 // New creates a new CDN and chooses the implementation depending
 // on the environment
-func New(env *env.Env, configDBPath string) (CDN, error) {
+func New(env *env.Env, configDBPath string) (*CDN, error) {
+	cdn := CDN{
+		hostTagsGetter: newHostTagsGetter(env),
+	}
+
 	if runtime.GOOS == "windows" {
 		// There's an assumption on windows that some directories are already there
 		// but they are in fact created by the regular CDN implementation. Until
 		// there is a fix on windows we keep the previous CDN behaviour for them
-		return newCDNHTTP(env, configDBPath)
+		fetcher, err := newHTTPFetcher(env, configDBPath)
+		if err != nil {
+			return nil, err
+		}
+		cdn.fetcher = fetcher
+		return &cdn, nil
 	}
 
 	if !env.RemotePolicies {
 		// Remote policies are not enabled -- we don't need the CDN
 		// and we don't want to create the directories that the CDN
 		// implementation would create. We return a no-op CDN to avoid
 		// nil pointer dereference.
-		return newCDNNoop()
+		fetcher, err := newNoopFetcher()
+		if err != nil {
+			return nil, err
+		}
+		cdn.fetcher = fetcher
+		return &cdn, nil
 	}
 
 	if env.CDNLocalDirPath != "" {
 		// Mock the CDN for local development or testing
-		return newCDNLocal(env)
+		fetcher, err := newLocalFetcher(env)
+		if err != nil {
+			return nil, err
+		}
+		cdn.fetcher = fetcher
+		return &cdn, nil
 	}
 
 	if !env.CDNEnabled {
 		// Remote policies are enabled but we don't want to use the CDN
 		// as it's still in development. We use standard remote config calls
 		// instead (dubbed "direct" CDN).
-		return newCDNRC(env, configDBPath)
+		fetcher, err := newRCFetcher(env, configDBPath)
+		if err != nil {
+			return nil, err
+		}
+		cdn.fetcher = fetcher
+		return &cdn, nil
 	}
 
 	// Regular CDN with the cloudfront distribution
-	return newCDNHTTP(env, configDBPath)
+	fetcher, err := newHTTPFetcher(env, configDBPath)
+	if err != nil {
+		return nil, err
+	}
+	cdn.fetcher = fetcher
+	return &cdn, nil
+}
+
+// Get fetches the configuration for the given package.
+func (c *CDN) Get(ctx context.Context, pkg string) (cfg Config, err error) {
+	span, _ := tracer.StartSpanFromContext(ctx, "cdn.Get")
+	defer func() {
+		spanErr := err
+		if spanErr == ErrProductNotSupported {
+			spanErr = nil
+		}
+		span.Finish(tracer.WithError(spanErr))
+	}()
+
+	switch pkg {
+	case "datadog-agent":
+		orderedLayers, err := c.fetcher.get(ctx)
+		if err != nil {
+			return nil, err
+		}
+		cfg, err = newAgentConfig(orderedLayers...)
+		if err != nil {
+			return nil, err
+		}
+	case "datadog-apm-inject":
+		orderedLayers, err := c.fetcher.get(ctx)
+		if err != nil {
+			return nil, err
+		}
+		cfg, err = newAPMConfig(c.hostTagsGetter.get(), orderedLayers...)
+		if err != nil {
+			return nil, err
+		}
+	default:
+		return nil, ErrProductNotSupported
+	}
+
+	return cfg, nil
+}
+
+// Close closes the CDN.
+func (c *CDN) Close() error {
+	return c.fetcher.close()
+}
+
+// writePolicyMetadata writes the policy metadata to the given directory
+// and makes it readable to dd-agent
+func writePolicyMetadata(config Config, dir string) error {
+	ddAgentUID, ddAgentGID, err := getAgentIDs()
+	if err != nil {
+		return fmt.Errorf("error getting dd-agent user and group IDs: %w", err)
+	}
+
+	state := config.State()
+	stateBytes, err := json.Marshal(state)
+	if err != nil {
+		return fmt.Errorf("could not marshal state: %w", err)
+	}
+	err = os.WriteFile(filepath.Join(dir, policyMetadataFilename), stateBytes, 0440)
+	if err != nil {
+		return fmt.Errorf("could not write %s: %w", policyMetadataFilename, err)
+	}
+	if runtime.GOOS != "windows" {
+		err = os.Chown(filepath.Join(dir, policyMetadataFilename), ddAgentUID, ddAgentGID)
+		if err != nil {
+			return fmt.Errorf("could not chown %s: %w", policyMetadataFilename, err)
+		}
+	}
+	return nil
 }