Add OTEL_GO_AUTO_SHOW_VERIFIER_LOG env var

CHANGELOG.md

@@ -12,6 +12,8 @@ OpenTelemetry Go Automatic Instrumentation adheres to [Semantic Versioning](http
 
 - Add [gin-gonic/gin](https://github.com/gin-gonic/gin) instrumentation. ([#100](https://github.com/open-telemetry/opentelemetry-go-instrumentation/pull/100))
 - Add ARM64 support. ([#82](https://github.com/open-telemetry/opentelemetry-go-instrumentation/pull/82))
+- Add `OTEL_GO_AUTO_SHOW_VERIFIER_LOG` environment variable to control whether
+  the verifier log is shown. ([#128](https://github.com/open-telemetry/opentelemetry-go-instrumentation/pull/128))
 
 ### Changed
 

pkg/instrumentors/bpf/github.com/gin-gonic/gin/probe.go

@@ -18,6 +18,7 @@ import (
 	"bytes"
 	"encoding/binary"
 	"errors"
+
 	"os"
 
 	"go.opentelemetry.io/auto/pkg/instrumentors/bpffs"
@@ -30,6 +31,7 @@ import (
 	"go.opentelemetry.io/auto/pkg/inject"
 	"go.opentelemetry.io/auto/pkg/instrumentors/context"
 	"go.opentelemetry.io/auto/pkg/instrumentors/events"
+	"go.opentelemetry.io/auto/pkg/instrumentors/utils"
 	"go.opentelemetry.io/auto/pkg/log"
 	"go.opentelemetry.io/otel/attribute"
 	semconv "go.opentelemetry.io/otel/semconv/v1.7.0"
@@ -102,7 +104,7 @@ func (h *Instrumentor) Load(ctx *context.InstrumentorContext) error {
 	}
 
 	h.bpfObjects = &bpfObjects{}
-	err = spec.LoadAndAssign(h.bpfObjects, &ebpf.CollectionOptions{
+	err = utils.LoadEBPFObjects(spec, h.bpfObjects, &ebpf.CollectionOptions{
 		Maps: ebpf.MapOptions{
 			PinPath: bpffs.BPFFsPath,
 		},

pkg/instrumentors/bpf/github.com/gorilla/mux/probe.go

@@ -30,6 +30,7 @@ import (
 	"go.opentelemetry.io/auto/pkg/inject"
 	"go.opentelemetry.io/auto/pkg/instrumentors/context"
 	"go.opentelemetry.io/auto/pkg/instrumentors/events"
+	"go.opentelemetry.io/auto/pkg/instrumentors/utils"
 	"go.opentelemetry.io/auto/pkg/log"
 	"go.opentelemetry.io/otel/attribute"
 	semconv "go.opentelemetry.io/otel/semconv/v1.7.0"
@@ -102,7 +103,7 @@ func (g *Instrumentor) Load(ctx *context.InstrumentorContext) error {
 	}
 
 	g.bpfObjects = &bpfObjects{}
-	err = spec.LoadAndAssign(g.bpfObjects, &ebpf.CollectionOptions{
+	err = utils.LoadEBPFObjects(spec, g.bpfObjects, &ebpf.CollectionOptions{
 		Maps: ebpf.MapOptions{
 			PinPath: bpffs.BPFFsPath,
 		},

pkg/instrumentors/bpf/google/golang/org/grpc/probe.go

@@ -32,6 +32,7 @@ import (
 	"go.opentelemetry.io/auto/pkg/inject"
 	"go.opentelemetry.io/auto/pkg/instrumentors/context"
 	"go.opentelemetry.io/auto/pkg/instrumentors/events"
+	"go.opentelemetry.io/auto/pkg/instrumentors/utils"
 	"go.opentelemetry.io/auto/pkg/log"
 	"go.opentelemetry.io/otel/attribute"
 	semconv "go.opentelemetry.io/otel/semconv/v1.4.0"
@@ -95,11 +96,12 @@ func (g *Instrumentor) Load(ctx *context.InstrumentorContext) error {
 	}
 
 	g.bpfObjects = &bpfObjects{}
-	err = spec.LoadAndAssign(g.bpfObjects, &ebpf.CollectionOptions{
+	err = utils.LoadEBPFObjects(spec, g.bpfObjects, &ebpf.CollectionOptions{
 		Maps: ebpf.MapOptions{
 			PinPath: bpffs.BPFFsPath,
 		},
 	})
+
 	if err != nil {
 		return err
 	}

pkg/instrumentors/bpf/google/golang/org/grpc/server/probe.go

@@ -30,6 +30,7 @@ import (
 	"go.opentelemetry.io/auto/pkg/inject"
 	"go.opentelemetry.io/auto/pkg/instrumentors/context"
 	"go.opentelemetry.io/auto/pkg/instrumentors/events"
+	"go.opentelemetry.io/auto/pkg/instrumentors/utils"
 	"go.opentelemetry.io/auto/pkg/log"
 	"go.opentelemetry.io/otel/attribute"
 	semconv "go.opentelemetry.io/otel/semconv/v1.7.0"
@@ -113,7 +114,7 @@ func (g *Instrumentor) Load(ctx *context.InstrumentorContext) error {
 	}
 
 	g.bpfObjects = &bpfObjects{}
-	err = spec.LoadAndAssign(g.bpfObjects, &ebpf.CollectionOptions{
+	err = utils.LoadEBPFObjects(spec, g.bpfObjects, &ebpf.CollectionOptions{
 		Maps: ebpf.MapOptions{
 			PinPath: bpffs.BPFFsPath,
 		},

pkg/instrumentors/bpf/net/http/server/probe.go

@@ -30,6 +30,7 @@ import (
 	"go.opentelemetry.io/auto/pkg/inject"
 	"go.opentelemetry.io/auto/pkg/instrumentors/context"
 	"go.opentelemetry.io/auto/pkg/instrumentors/events"
+	"go.opentelemetry.io/auto/pkg/instrumentors/utils"
 	"go.opentelemetry.io/auto/pkg/log"
 	"go.opentelemetry.io/otel/attribute"
 	semconv "go.opentelemetry.io/otel/semconv/v1.7.0"
@@ -101,7 +102,7 @@ func (h *Instrumentor) Load(ctx *context.InstrumentorContext) error {
 	}
 
 	h.bpfObjects = &bpfObjects{}
-	err = spec.LoadAndAssign(h.bpfObjects, &ebpf.CollectionOptions{
+	err = utils.LoadEBPFObjects(spec, h.bpfObjects, &ebpf.CollectionOptions{
 		Maps: ebpf.MapOptions{
 			PinPath: bpffs.BPFFsPath,
 		},

pkg/instrumentors/utils/ebpf.go

@@ -0,0 +1,62 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package utils
+
+import (
+	"errors"
+	"fmt"
+	"os"
+	"strconv"
+
+	"github.com/cilium/ebpf"
+)
+
+const (
+	showVerifierLogEnvVar = "OTEL_GO_AUTO_SHOW_VERIFIER_LOG"
+)
+
+// LoadEBPFObjects loads eBPF objects from the given spec into the given interface.
+// If the environment variable OTEL_GO_AUTO_SHOW_VERIFIER_LOG is set to true, the verifier log will be printed.
+func LoadEBPFObjects(spec *ebpf.CollectionSpec, to interface{}, opts *ebpf.CollectionOptions) error {
+	// Getting full verifier log is expensive, so we only do it if the user explicitly asks for it.
+	showVerifierLogs := shouldShowVerifierLogs()
+	if showVerifierLogs {
+		opts.Programs.LogSize = ebpf.DefaultVerifierLogSize * 100
+		opts.Programs.LogLevel = ebpf.LogLevelInstruction | ebpf.LogLevelBranch | ebpf.LogLevelStats
+	}
+
+	err := spec.LoadAndAssign(to, opts)
+	if err != nil && showVerifierLogs {
+		var ve *ebpf.VerifierError
+		if errors.As(err, &ve) {
+			fmt.Printf("Verifier log: %+v\n", ve)
+		}
+	}
+
+	return err
+}
+
+// shouldShowVerifierLogs returns if the user has configured verifier logs to be emitted.
+func shouldShowVerifierLogs() bool {
+	val, exists := os.LookupEnv(showVerifierLogEnvVar)
+	if exists {
+		boolVal, err := strconv.ParseBool(val)
+		if err == nil {
+			return boolVal
+		}
+	}
+
+	return false
+}