Create nil cgroups reader for processor, improve error handling (#41198)

* create nil reader, improve error handling * add test, clean up * linter (cherry picked from commit 764ba96) # Conflicts: # filebeat/autodiscover/defaults_aix.go # libbeat/processors/add_docker_metadata/add_docker_metadata.go # libbeat/processors/add_process_metadata/add_process_metadata.go # libbeat/processors/add_process_metadata/add_process_metadata_test.go # libbeat/processors/add_process_metadata/gosigar_cid_provider.go
elastic · Oct 11, 2024 · 0b886fc · 0b886fc
1 parent 406aa55
commit 0b886fc
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Showing 5 changed files with 100 additions and 2 deletions.
diff --git a/filebeat/autodiscover/defaults_aix.go b/filebeat/autodiscover/defaults_aix.go
@@ -17,9 +17,27 @@
 
 //go:build aix
 
+<<<<<<< HEAD:filebeat/autodiscover/defaults_aix.go
 package autodiscover
+=======
+import (
+	"io/fs"
+
+	"github.com/elastic/elastic-agent-system-metrics/metric/system/cgroup"
+	"github.com/elastic/elastic-agent-system-metrics/metric/system/resolve"
+)
+>>>>>>> 764ba96d34 (Create nil cgroups reader for processor, improve error handling (#41198)):libbeat/processors/cgroups.go
 
 // InitializeModule initializes this module.
 func InitializeModule() {
 	// does nothing on aix
 }
+
+// NilCGReader does nothing
+type NilCGReader struct {
+}
+
+// ProcessCgroupPaths returns a blank pathLists and fs.ErrNotExist
+func (*NilCGReader) ProcessCgroupPaths(_ int) (cgroup.PathList, error) {
+	return cgroup.PathList{}, fs.ErrNotExist
+}
diff --git a/libbeat/processors/add_docker_metadata/add_docker_metadata.go b/libbeat/processors/add_docker_metadata/add_docker_metadata.go
@@ -110,6 +110,16 @@ func buildDockerMetadataProcessor(log *logp.Logger, cfg *conf.C, watcherConstruc
 		}
 	}
 
+<<<<<<< HEAD
+=======
+	reader, err := initCgroupPaths(resolve.NewTestResolver(config.HostFS), false)
+	if errors.Is(err, cgroup.ErrCgroupsMissing) {
+		reader = &processors.NilCGReader{}
+	} else if err != nil {
+		return nil, fmt.Errorf("error creating cgroup reader: %w", err)
+	}
+
+>>>>>>> 764ba96d34 (Create nil cgroups reader for processor, improve error handling (#41198))
 	return &addDockerMetadata{
 		log:             log,
 		watcher:         watcher,
@@ -277,11 +287,17 @@ func (d *addDockerMetadata) getProcessCgroups(pid int) (cgroup.PathList, error)
 		return cgroups, nil
 	}
 
+<<<<<<< HEAD
 	cgroups, err := processCgroupPaths(d.hostFS, pid)
+=======
+	cgroups, err := d.cgreader.ProcessCgroupPaths(pid)
+>>>>>>> 764ba96d34 (Create nil cgroups reader for processor, improve error handling (#41198))
 	if err != nil {
 		return cgroups, fmt.Errorf("failed to read cgroups for pid=%v: %w", pid, err)
 	}
-
+	if len(cgroups.Flatten()) == 0 {
+		return cgroup.PathList{}, fs.ErrNotExist
+	}
 	d.cgroups.Put(pid, cgroups)
 	return cgroups, nil
 }

diff --git a/libbeat/processors/add_process_metadata/add_process_metadata.go b/libbeat/processors/add_process_metadata/add_process_metadata.go
@@ -160,6 +160,16 @@ func newProcessMetadataProcessorWithProvider(config config, provider processMeta
 		}
 	}
 
+<<<<<<< HEAD
+=======
+	reader, err := initCgroupPaths(resolve.NewTestResolver(config.HostPath), false)
+	if errors.Is(err, cgroup.ErrCgroupsMissing) {
+		reader = &processors.NilCGReader{}
+	} else if err != nil {
+		return nil, fmt.Errorf("error creating cgroup reader: %w", err)
+	}
+
+>>>>>>> 764ba96d34 (Create nil cgroups reader for processor, improve error handling (#41198))
 	// don't use cgroup.ProcessCgroupPaths to save it from doing the work when container id disabled
 	if ok := containsValue(mappings, "container.id"); ok {
 		if withCache && config.CgroupCacheExpireTime != 0 {

diff --git a/libbeat/processors/add_process_metadata/add_process_metadata_test.go b/libbeat/processors/add_process_metadata/add_process_metadata_test.go
@@ -38,6 +38,55 @@ import (
 	"github.com/elastic/elastic-agent-system-metrics/metric/system/resolve"
 )
 
+<<<<<<< HEAD
+=======
+type testCGRsolver struct {
+	res func(pid int) (cgroup.PathList, error)
+}
+
+func (t testCGRsolver) ProcessCgroupPaths(pid int) (cgroup.PathList, error) {
+	return t.res(pid)
+}
+
+func newCGHandlerBuilder(handler testCGRsolver) processors.InitCgroupHandler {
+	return func(_ resolve.Resolver, _ bool) (processors.CGReader, error) {
+		return handler, nil
+	}
+}
+
+func TestNilProcessor(t *testing.T) {
+	initCgroupPaths = func(rootfsMountpoint resolve.Resolver, ignoreRootCgroups bool) (processors.CGReader, error) {
+		return &processors.NilCGReader{}, nil
+	}
+
+	proc, err := newProcessMetadataProcessorWithProvider(defaultConfig(), &procCache, false)
+	require.NoError(t, err)
+
+	// make sure a nil cgroup reader doesn't blow anything up
+	unwrapped, _ := proc.(*addProcessMetadata)
+	metadata, err := unwrapped.provider.GetProcessMetadata(os.Getpid())
+	require.NoError(t, err)
+	require.NotNil(t, metadata)
+
+}
+
+func TestDefaultProcessorStartup(t *testing.T) {
+	// set initCgroupPaths to system non-test defaults
+	initCgroupPaths = func(rootfsMountpoint resolve.Resolver, ignoreRootCgroups bool) (processors.CGReader, error) {
+		return cgroup.NewReader(rootfsMountpoint, ignoreRootCgroups)
+	}
+
+	proc, err := newProcessMetadataProcessorWithProvider(defaultConfig(), &procCache, false)
+	require.NoError(t, err)
+
+	// ensure the underlying provider has been initialized properly
+	unwrapped, _ := proc.(*addProcessMetadata)
+	metadata, err := unwrapped.provider.GetProcessMetadata(os.Getpid())
+	require.NoError(t, err)
+	require.NotNil(t, metadata.fields)
+}
+
+>>>>>>> 764ba96d34 (Create nil cgroups reader for processor, improve error handling (#41198))
 func TestAddProcessMetadata(t *testing.T) {
 	logp.TestingSetup(logp.WithSelectors(processorName))
 

diff --git a/libbeat/processors/add_process_metadata/gosigar_cid_provider.go b/libbeat/processors/add_process_metadata/gosigar_cid_provider.go
@@ -58,7 +58,7 @@ func (p gosigarCidProvider) GetCid(pid int) (result string, err error) {
 
 	cgroups, err := p.getProcessCgroups(pid)
 	if err != nil {
-		p.log.Debugf("failed to get cgroups for pid=%v: %v", pid, err)
+		return "", fmt.Errorf("failed to get cgroups for pid=%v: %w", pid, err)
 	}
 
 	cid = p.getContainerID(cgroups)
@@ -84,7 +84,12 @@ func newCidProvider(hostPath resolve.Resolver, cgroupPrefixes []string, cgroupRe
 // getProcessCgroups returns a mapping of cgroup subsystem name to path. It
 // returns an error if it failed to retrieve the cgroup info.
 func (p gosigarCidProvider) getProcessCgroups(pid int) (cgroup.PathList, error) {
+<<<<<<< HEAD
 	pathList, err := p.processCgroupPaths(p.hostPath, pid)
+=======
+	//return nil if we aren't supporting cgroups
+	pathList, err := p.processCgroupPaths.ProcessCgroupPaths(pid)
+>>>>>>> 764ba96d34 (Create nil cgroups reader for processor, improve error handling (#41198))
 	if err != nil {
 		var pathError *fs.PathError
 		if errors.As(err, &pathError) {