Prepare release v0.40.1 (#6569)

* ignore errors when the logging node empties the log buffer (#6558)

(cherry picked from commit b691a44)

* Fix wiring of custom component nodes (#6563)

* fix wiring of custom component nodes by checking import before local declares

* update changelog

* add comment in loader to explain why the imports should be checked before the local declare

(cherry picked from commit 0dde507)

* flow/logging: check for nil values when writing logs (#6561)

There may be situations where the flow mode logger receivers a nil
value, potentially due to misconfiguration or a component which exports
its values only after being ran.

Fixes #6557.

(cherry picked from commit bcc9b0a)

* changelog: cut 0.40.1 (#6568)

(cherry picked from commit 9154af3)

---------

Co-authored-by: William Dumont <william.dumont@grafana.com>

CHANGELOG.md

@@ -9,6 +9,17 @@ internal API changes are not present.
 
 
 
+v0.40.1 (2024-02-27)
+--------------------
+
+### Bugfixes
+
+- Fix an issues where the logging config block would trigger an error when trying to send logs to components that were not running. (@wildum)
+
+- Fix an issue where a custom component might be wired to a local declare instead of an import declare when they have the same label. (@wildum)
+
+- Fix an issue where flow mode panics if the `logging` config block is given a `null` Loki receiver to write log entries to. (@rfratto)
+
 v0.40.0 (2024-02-27)
 --------------------
 

docs/sources/_index.md

@@ -9,7 +9,7 @@ title: Grafana Agent
 description: Grafana Agent is a flexible, performant, vendor-neutral, telemetry collector
 weight: 350
 cascade:
-  AGENT_RELEASE: v0.40.0
+  AGENT_RELEASE: v0.40.1
   OTEL_VERSION: v0.87.0
 ---
 

pkg/flow/internal/controller/loader.go

@@ -589,15 +589,17 @@ func (l *Loader) wireGraphEdges(g *dag.Graph) diag.Diagnostics {
 
 // wireCustomComponentNode wires a custom component to the import/declare nodes that it depends on.
 func (l *Loader) wireCustomComponentNode(g *dag.Graph, cc *CustomComponentNode) {
-	if declare, ok := l.declareNodes[cc.customComponentName]; ok {
+	// It's important to check first if the importNamespace matches an import node because there might be a
+	// local node that has the same label as an imported declare.
+	if importNode, ok := l.importConfigNodes[cc.importNamespace]; ok {
+		// add an edge between the custom component and the corresponding import node.
+		g.AddEdge(dag.Edge{From: cc, To: importNode})
+	} else if declare, ok := l.declareNodes[cc.customComponentName]; ok {
 		refs := l.findCustomComponentReferences(declare.Block())
 		for ref := range refs {
 			// add edges between the custom component and declare/import nodes.
 			g.AddEdge(dag.Edge{From: cc, To: ref})
 		}
-	} else if importNode, ok := l.importConfigNodes[cc.importNamespace]; ok {
-		// add an edge between the custom component and the corresponding import node.
-		g.AddEdge(dag.Edge{From: cc, To: importNode})
 	}
 }
 

pkg/flow/logging/logger.go

@@ -126,9 +126,9 @@ func (l *Logger) Update(o Options) error {
 
 	// Print out the buffered logs since we determined the log format already
 	for _, bufferedLogChunk := range l.buffer {
-		if err := slogadapter.GoKit(l.handler).Log(bufferedLogChunk...); err != nil {
-			return err
-		}
+		// the buffered logs are currently only sent to the standard output
+		// because the components with the receivers are not running yet
+		slogadapter.GoKit(l.handler).Log(bufferedLogChunk...)
 	}
 	l.buffer = nil
 
@@ -164,6 +164,15 @@ type lokiWriter struct {
 
 func (fw *lokiWriter) Write(p []byte) (int, error) {
 	for _, receiver := range fw.f {
+		// We may have been given a nil value in rare circumstances due to
+		// misconfiguration or a component which generates exports after
+		// construction.
+		//
+		// Ignore nil values so we don't panic.
+		if receiver == nil {
+			continue
+		}
+
 		select {
 		case receiver.Chan() <- loki.Entry{
 			Labels: model.LabelSet{"component": "agent"},

pkg/flow/logging/logger_test.go

@@ -11,6 +11,7 @@ import (
 
 	"github.com/go-kit/log"
 	gokitlevel "github.com/go-kit/log/level"
+	"github.com/grafana/agent/component/common/loki"
 	"github.com/grafana/agent/pkg/flow/logging"
 	flowlevel "github.com/grafana/agent/pkg/flow/logging/level"
 	"github.com/stretchr/testify/require"
@@ -165,6 +166,25 @@ func TestLevels(t *testing.T) {
 	}
 }
 
+// Test_lokiWriter_nil ensures that writing to a lokiWriter doesn't panic when
+// given a nil receiver.
+func Test_lokiWriter_nil(t *testing.T) {
+	logger, err := logging.New(io.Discard, debugLevel())
+	require.NoError(t, err)
+
+	err = logger.Update(logging.Options{
+		Level:  logging.LevelDebug,
+		Format: logging.FormatLogfmt,
+
+		WriteTo: []loki.LogsReceiver{nil},
+	})
+	require.NoError(t, err)
+
+	require.NotPanics(t, func() {
+		_ = logger.Log("msg", "test message")
+	})
+}
+
 func BenchmarkLogging_NoLevel_Prints(b *testing.B) {
 	logger, err := logging.New(io.Discard, infoLevel())
 	require.NoError(b, err)

pkg/flow/testdata/import_file/import_file_16.txtar

@@ -0,0 +1,36 @@
+Imported declare and local declare have the same label.
+
+-- main.river --
+testcomponents.count "inc" {
+	frequency = "10ms"
+	max = 10
+}
+
+import.file "certmanager" {
+	filename = "module.river"
+}
+
+certmanager.config "this" { 
+	input = testcomponents.count.inc.count
+}
+
+declare "config" {
+}
+
+testcomponents.summation "sum" {
+	input = certmanager.config.this.output
+}
+
+-- module.river --
+declare "config" {
+	argument "input" {}
+
+	testcomponents.passthrough "pt" {
+		input = argument.input.value
+		lag = "1ms"
+	}
+
+	export "output" {
+		value = testcomponents.passthrough.pt.output
+	}
+}

pkg/operator/defaults.go

@@ -2,7 +2,7 @@ package operator
 
 // Supported versions of the Grafana Agent.
 var (
-	DefaultAgentVersion   = "v0.40.0"
+	DefaultAgentVersion   = "v0.40.1"
 	DefaultAgentBaseImage = "grafana/agent"
 	DefaultAgentImage     = DefaultAgentBaseImage + ":" + DefaultAgentVersion
 )

tools/gen-versioned-files/agent-version.txt

@@ -1 +1 @@
-v0.40.0
+v0.40.1