trace: add OTEL initialization (#10526)

This is a bunch of OTEL initialization code. It's all in
`internal/` because there are re-usable parts here, but Compose
isn't the right spot. Once we've stabilized the interfaces a bit
and the need arises, we can move it to a separate module.

Currently, a single span is produced to wrap the root Compose
command.

Compose will respect the standard OTEL environment variables
as well as OTEL metadata from the Docker context. Both can be
used simultaneously. The latter is intended for local system
integration and is restricted to Unix sockets / named pipes.

None of this is enabled by default. It requires setting the
`COMPOSE_EXPERIMENTAL_OTEL=1` environment variable to
gate it during development.

Signed-off-by: Milas Bowman <[email protected]>

cmd/main.go

@@ -17,23 +17,33 @@
 package main
 
 import (
+	"context"
 	"os"
+	"time"
 
 	dockercli "github.com/docker/cli/cli"
 	"github.com/docker/cli/cli-plugins/manager"
 	"github.com/docker/cli/cli-plugins/plugin"
 	"github.com/docker/cli/cli/command"
+	"github.com/pkg/errors"
 	"github.com/spf13/cobra"
+	"go.opentelemetry.io/otel/attribute"
+	"go.opentelemetry.io/otel/codes"
+	"go.opentelemetry.io/otel/trace"
 
 	"github.com/docker/compose/v2/cmd/compatibility"
 	commands "github.com/docker/compose/v2/cmd/compose"
 	"github.com/docker/compose/v2/internal"
+	"github.com/docker/compose/v2/internal/tracing"
 	"github.com/docker/compose/v2/pkg/api"
 	"github.com/docker/compose/v2/pkg/compose"
 )
 
 func pluginMain() {
 	plugin.Run(func(dockerCli command.Cli) *cobra.Command {
+		var tracingShutdown tracing.ShutdownFunc
+		var cmdSpan trace.Span
+
 		serviceProxy := api.NewServiceProxy().WithService(compose.NewComposeService(dockerCli))
 		cmd := commands.RootCommand(dockerCli, serviceProxy)
 		originalPreRun := cmd.PersistentPreRunE
@@ -41,11 +51,52 @@ func pluginMain() {
 			if err := plugin.PersistentPreRunE(cmd, args); err != nil {
 				return err
 			}
+			// the call to plugin.PersistentPreRunE is what actually
+			// initializes the command.Cli instance, so this is the earliest
+			// that tracing can be practically initialized (in the future,
+			// this could ideally happen in coordination with docker/cli)
+			tracingShutdown, _ = tracing.InitTracing(dockerCli)
+
+			ctx := cmd.Context()
+			ctx, cmdSpan = tracing.Tracer.Start(
+				ctx, "cli/"+cmd.Name(),
+				trace.WithAttributes(
+					attribute.String("compose.version", internal.Version),
+					attribute.String("docker.context", dockerCli.CurrentContext()),
+				),
+			)
+			cmd.SetContext(ctx)
+
 			if originalPreRun != nil {
 				return originalPreRun(cmd, args)
 			}
 			return nil
 		}
+
+		// manually wrap RunE instead of using PersistentPostRunE because the
+		// latter only runs when RunE does _not_ return an error, but the
+		// tracing clean-up logic should always be invoked
+		originalPersistentPostRunE := cmd.PersistentPostRunE
+		cmd.PersistentPostRunE = func(cmd *cobra.Command, args []string) (err error) {
+			defer func() {
+				if cmdSpan != nil {
+					if err != nil && !errors.Is(err, context.Canceled) {
+						cmdSpan.SetStatus(codes.Error, "CLI command returned error")
+						cmdSpan.RecordError(err)
+					}
+					cmdSpan.End()
+				}
+				if tracingShutdown != nil {
+					ctx, cancel := context.WithTimeout(context.Background(), 2*time.Second)
+					defer cancel()
+					_ = tracingShutdown(ctx)
+				}
+			}()
+			if originalPersistentPostRunE != nil {
+				return originalPersistentPostRunE(cmd, args)
+			}
+			return nil
+		}
 		cmd.SetFlagErrorFunc(func(c *cobra.Command, err error) error {
 			return dockercli.StatusError{
 				StatusCode: compose.CommandSyntaxFailure.ExitCode,

go.mod

@@ -4,6 +4,7 @@ go 1.20
 
 require (
 	github.com/AlecAivazis/survey/v2 v2.3.6
+	github.com/Microsoft/go-winio v0.5.2
 	github.com/buger/goterm v1.0.4
 	github.com/compose-spec/compose-go v1.14.0
 	github.com/containerd/console v1.0.3
@@ -16,12 +17,15 @@ require (
 	github.com/docker/docker v24.0.2+incompatible
 	github.com/docker/go-connections v0.4.0
 	github.com/docker/go-units v0.5.0
+	github.com/fsnotify/fsevents v0.1.1
 	github.com/golang/mock v1.6.0
 	github.com/hashicorp/go-multierror v1.1.1
 	github.com/hashicorp/go-version v1.6.0
+	github.com/jonboulle/clockwork v0.4.0
 	github.com/mattn/go-shellwords v1.0.12
 	github.com/mitchellh/mapstructure v1.5.0
 	github.com/moby/buildkit v0.11.7-0.20230519102302-348e79dfed17
+	github.com/moby/patternmatcher v0.5.0
 	github.com/moby/term v0.5.0
 	github.com/morikuni/aec v1.0.0
 	github.com/opencontainers/go-digest v1.0.0
@@ -34,15 +38,19 @@ require (
 	github.com/theupdateframework/notary v0.7.0
 	github.com/tilt-dev/fsnotify v1.4.8-0.20220602155310-fff9c274a375
 	go.opentelemetry.io/otel v1.15.1
+	go.opentelemetry.io/otel/exporters/otlp/otlptrace v1.4.1
+	go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracegrpc v1.4.1
+	go.opentelemetry.io/otel/sdk v1.4.1
+	go.opentelemetry.io/otel/trace v1.15.1
 	go.uber.org/goleak v1.2.1
 	golang.org/x/sync v0.2.0
+	google.golang.org/grpc v1.53.0
 	gopkg.in/yaml.v2 v2.4.0
 	gotest.tools/v3 v3.4.0
 )
 
 require (
 	github.com/Azure/go-ansiterm v0.0.0-20210617225240-d185dfc1b5a1 // indirect
-	github.com/Microsoft/go-winio v0.5.2 // indirect
 	github.com/aws/aws-sdk-go-v2 v1.16.3 // indirect
 	github.com/aws/aws-sdk-go-v2/config v1.15.5 // indirect
 	github.com/aws/aws-sdk-go-v2/credentials v1.12.0 // indirect
@@ -70,7 +78,6 @@ require (
 	github.com/docker/go v1.5.1-1.0.20160303222718-d30aec9fd63c // indirect
 	github.com/docker/go-metrics v0.0.1 // indirect
 	github.com/felixge/httpsnoop v1.0.2 // indirect
-	github.com/fsnotify/fsevents v0.1.1
 	github.com/fsnotify/fsnotify v1.6.0 // indirect
 	github.com/fvbommel/sortorder v1.0.2 // indirect
 	github.com/go-logr/logr v1.2.4 // indirect
@@ -95,7 +102,6 @@ require (
 	github.com/imdario/mergo v0.3.15 // indirect
 	github.com/inconshreveable/mousetrap v1.1.0 // indirect
 	github.com/jinzhu/gorm v1.9.11 // indirect
-	github.com/jonboulle/clockwork v0.4.0
 	github.com/json-iterator/go v1.1.12 // indirect
 	github.com/kballard/go-shellquote v0.0.0-20180428030007-95032a82bc51 // indirect
 	github.com/klauspost/compress v1.16.5 // indirect
@@ -107,7 +113,6 @@ require (
 	github.com/mgutz/ansi v0.0.0-20170206155736-9520e82c474b // indirect
 	github.com/miekg/pkcs11 v1.1.1 // indirect
 	github.com/moby/locker v1.0.1 // indirect
-	github.com/moby/patternmatcher v0.5.0
 	github.com/moby/spdystream v0.2.0 // indirect
 	github.com/moby/sys/mountinfo v0.6.2 // indirect
 	github.com/moby/sys/sequential v0.5.0 // indirect
@@ -140,13 +145,9 @@ require (
 	go.opentelemetry.io/contrib/instrumentation/net/http/httptrace/otelhttptrace v0.29.0 // indirect
 	go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.29.0 // indirect
 	go.opentelemetry.io/otel/exporters/otlp/internal/retry v1.4.1 // indirect
-	go.opentelemetry.io/otel/exporters/otlp/otlptrace v1.4.1 // indirect
-	go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracegrpc v1.4.1 // indirect
 	go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp v1.4.1 // indirect
 	go.opentelemetry.io/otel/internal/metric v0.27.0 // indirect
 	go.opentelemetry.io/otel/metric v0.27.0 // indirect
-	go.opentelemetry.io/otel/sdk v1.4.1 // indirect
-	go.opentelemetry.io/otel/trace v1.15.1 // indirect
 	go.opentelemetry.io/proto/otlp v0.12.0 // indirect
 	golang.org/x/crypto v0.7.0 // indirect
 	golang.org/x/net v0.8.0 // indirect
@@ -157,7 +158,6 @@ require (
 	golang.org/x/time v0.1.0 // indirect
 	google.golang.org/appengine v1.6.7 // indirect
 	google.golang.org/genproto v0.0.0-20230320184635-7606e756e683 // indirect
-	google.golang.org/grpc v1.53.0 // indirect
 	google.golang.org/protobuf v1.29.1 // indirect
 	gopkg.in/inf.v0 v0.9.1 // indirect
 	gopkg.in/ini.v1 v1.67.0 // indirect

internal/tracing/conn_unix.go

@@ -0,0 +1,44 @@
+//go:build !windows
+
+/*
+   Copyright 2023 Docker Compose CLI 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 tracing
+
+import (
+	"context"
+	"fmt"
+	"net"
+	"strings"
+	"syscall"
+)
+
+const maxUnixSocketPathSize = len(syscall.RawSockaddrUnix{}.Path)
+
+func DialInMemory(ctx context.Context, addr string) (net.Conn, error) {
+	if !strings.HasPrefix(addr, "unix://") {
+		return nil, fmt.Errorf("not a Unix socket address: %s", addr)
+	}
+	addr = strings.TrimPrefix(addr, "unix://")
+
+	if len(addr) > maxUnixSocketPathSize {
+		//goland:noinspection GoErrorStringFormat
+		return nil, fmt.Errorf("Unix socket address is too long: %s", addr)
+	}
+
+	var d net.Dialer
+	return d.DialContext(ctx, "unix", addr)
+}

internal/tracing/conn_windows.go

@@ -0,0 +1,35 @@
+/*
+   Copyright 2023 Docker Compose CLI 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 tracing
+
+import (
+	"context"
+	"fmt"
+	"net"
+	"strings"
+
+	"github.com/Microsoft/go-winio"
+)
+
+func DialInMemory(ctx context.Context, addr string) (net.Conn, error) {
+	if !strings.HasPrefix(addr, "npipe://") {
+		return nil, fmt.Errorf("not a named pipe address: %s", addr)
+	}
+	addr = strings.TrimPrefix(addr, "npipe://")
+
+	return winio.DialPipeContext(ctx, addr)
+}

internal/tracing/docker_context.go

@@ -0,0 +1,122 @@
+/*
+   Copyright 2023 Docker Compose CLI 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 tracing
+
+import (
+	"context"
+	"fmt"
+	"os"
+	"time"
+
+	"github.com/docker/cli/cli/command"
+	"github.com/docker/cli/cli/context/store"
+	"go.opentelemetry.io/otel/exporters/otlp/otlptrace"
+	"go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracegrpc"
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/credentials/insecure"
+)
+
+const otelConfigFieldName = "otel"
+
+// traceClientFromDockerContext creates a gRPC OTLP client based on metadata
+// from the active Docker CLI context.
+func traceClientFromDockerContext(dockerCli command.Cli, otelEnv envMap) (otlptrace.Client, error) {
+	// attempt to extract an OTEL config from the Docker context to enable
+	// automatic integration with Docker Desktop;
+	cfg, err := ConfigFromDockerContext(dockerCli.ContextStore(), dockerCli.CurrentContext())
+	if err != nil {
+		return nil, fmt.Errorf("loading otel config from docker context metadata: %v", err)
+	}
+
+	if cfg.Endpoint == "" {
+		return nil, nil
+	}
+
+	// HACK: unfortunately _all_ public OTEL initialization functions
+	// 	implicitly read from the OS env, so temporarily unset them all and
+	// 	restore afterwards
+	defer func() {
+		for k, v := range otelEnv {
+			if err := os.Setenv(k, v); err != nil {
+				panic(fmt.Errorf("restoring env for %q: %v", k, err))
+			}
+		}
+	}()
+	for k := range otelEnv {
+		if err := os.Unsetenv(k); err != nil {
+			return nil, fmt.Errorf("stashing env for %q: %v", k, err)
+		}
+	}
+
+	dialCtx, cancel := context.WithTimeout(context.Background(), 1*time.Second)
+	defer cancel()
+	conn, err := grpc.DialContext(
+		dialCtx,
+		cfg.Endpoint,
+		grpc.WithContextDialer(DialInMemory),
+		grpc.WithTransportCredentials(insecure.NewCredentials()),
+		grpc.WithBlock(),
+	)
+	if err != nil {
+		return nil, fmt.Errorf("initializing otel connection from docker context metadata: %v", err)
+	}
+
+	client := otlptracegrpc.NewClient(otlptracegrpc.WithGRPCConn(conn))
+	return client, nil
+}
+
+// ConfigFromDockerContext inspects extra metadata included as part of the
+// specified Docker context to try and extract a valid OTLP client configuration.
+func ConfigFromDockerContext(st store.Store, name string) (OTLPConfig, error) {
+	meta, err := st.GetMetadata(name)
+	if err != nil {
+		return OTLPConfig{}, err
+	}
+
+	var otelCfg interface{}
+	switch m := meta.Metadata.(type) {
+	case command.DockerContext:
+		otelCfg = m.AdditionalFields[otelConfigFieldName]
+	case map[string]interface{}:
+		otelCfg = m[otelConfigFieldName]
+	}
+	otelMap, ok := otelCfg.(map[string]interface{})
+	if !ok {
+		return OTLPConfig{}, fmt.Errorf(
+			"unexpected type for field %q: %T (expected: %T)",
+			otelConfigFieldName,
+			otelCfg,
+			otelMap,
+		)
+	}
+
+	// keys from https://opentelemetry.io/docs/concepts/sdk-configuration/otlp-exporter-configuration/
+	cfg := OTLPConfig{
+		Endpoint: valueOrDefault[string](otelMap, "OTEL_EXPORTER_OTLP_ENDPOINT"),
+	}
+	return cfg, nil
+}
+
+// valueOrDefault returns the type-cast value at the specified key in the map
+// if present and the correct type; otherwise, it returns the default value for
+// T.
+func valueOrDefault[T any](m map[string]interface{}, key string) T {
+	if v, ok := m[key].(T); ok {
+		return v
+	}
+	return *new(T)
+}

cmd/compose/tracing.go → internal/tracing/errors.go

@@ -1,5 +1,5 @@
 /*
-   Copyright 2020 Docker Compose CLI authors
+   Copyright 2023 Docker Compose CLI authors
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
@@ -14,22 +14,16 @@
    limitations under the License.
 */
 
-package compose
+package tracing
 
 import (
-	"github.com/moby/buildkit/util/tracing/detect"
 	"go.opentelemetry.io/otel"
-
-	_ "github.com/moby/buildkit/util/tracing/detect/delegated" //nolint:blank-imports
-	_ "github.com/moby/buildkit/util/tracing/env"              //nolint:blank-imports
 )
 
-func init() {
-	detect.ServiceName = "compose"
-	// do not log tracing errors to stdio
-	otel.SetErrorHandler(skipErrors{})
-}
-
+// skipErrors is a no-op otel.ErrorHandler.
 type skipErrors struct{}
 
-func (skipErrors) Handle(err error) {}
+// Handle does nothing, ignoring any errors passed to it.
+func (skipErrors) Handle(_ error) {}
+
+var _ otel.ErrorHandler = skipErrors{}

internal/tracing/mux.go

@@ -0,0 +1,54 @@
+/*
+   Copyright 2023 Docker Compose CLI 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 tracing
+
+import (
+	"context"
+	"log"
+
+	"github.com/hashicorp/go-multierror"
+	sdktrace "go.opentelemetry.io/otel/sdk/trace"
+)
+
+type MuxExporter struct {
+	exporters []sdktrace.SpanExporter
+}
+
+func (m MuxExporter) ExportSpans(ctx context.Context, spans []sdktrace.ReadOnlySpan) error {
+	var eg multierror.Group
+	for i := range m.exporters {
+		exporter := m.exporters[i]
+		eg.Go(func() error {
+			return exporter.ExportSpans(ctx, spans)
+		})
+	}
+	if err := eg.Wait(); err != nil {
+		log.Fatal(err)
+	}
+	return nil
+}
+
+func (m MuxExporter) Shutdown(ctx context.Context) error {
+	var eg multierror.Group
+	for i := range m.exporters {
+		exporter := m.exporters[i]
+		eg.Go(func() error {
+			return exporter.Shutdown(ctx)
+		})
+	}
+	return eg.Wait()
+}

internal/tracing/tracing.go

@@ -0,0 +1,151 @@
+/*
+   Copyright 2020 Docker Compose CLI 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 tracing
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"os"
+	"strconv"
+	"strings"
+
+	"github.com/docker/cli/cli/command"
+	"github.com/moby/buildkit/util/tracing/detect"
+	_ "github.com/moby/buildkit/util/tracing/detect/delegated" //nolint:blank-imports
+	_ "github.com/moby/buildkit/util/tracing/env"              //nolint:blank-imports
+	"go.opentelemetry.io/otel"
+	"go.opentelemetry.io/otel/exporters/otlp/otlptrace"
+	"go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracegrpc"
+	"go.opentelemetry.io/otel/propagation"
+	"go.opentelemetry.io/otel/sdk/resource"
+	sdktrace "go.opentelemetry.io/otel/sdk/trace"
+	semconv "go.opentelemetry.io/otel/semconv/v1.18.0"
+)
+
+func init() {
+	detect.ServiceName = "compose"
+	// do not log tracing errors to stdio
+	otel.SetErrorHandler(skipErrors{})
+}
+
+var Tracer = otel.Tracer("compose")
+
+// OTLPConfig contains the necessary values to initialize an OTLP client
+// manually.
+//
+// This supports a minimal set of options based on what is necessary for
+// automatic OTEL configuration from Docker context metadata.
+type OTLPConfig struct {
+	Endpoint string
+}
+
+// ShutdownFunc flushes and stops an OTEL exporter.
+type ShutdownFunc func(ctx context.Context) error
+
+// envMap is a convenience type for OS environment variables.
+type envMap map[string]string
+
+func InitTracing(dockerCli command.Cli) (ShutdownFunc, error) {
+	// set global propagator to tracecontext (the default is no-op).
+	otel.SetTextMapPropagator(propagation.TraceContext{})
+
+	if v, _ := strconv.ParseBool(os.Getenv("COMPOSE_EXPERIMENTAL_OTEL")); !v {
+		return nil, nil
+	}
+
+	return InitProvider(dockerCli)
+}
+
+func InitProvider(dockerCli command.Cli) (ShutdownFunc, error) {
+	ctx := context.Background()
+
+	var errs []error
+	var exporters []sdktrace.SpanExporter
+
+	envClient, otelEnv := traceClientFromEnv()
+	if envClient != nil {
+		if envExporter, err := otlptrace.New(ctx, envClient); err != nil {
+			errs = append(errs, err)
+		} else if envExporter != nil {
+			exporters = append(exporters, envExporter)
+		}
+	}
+
+	if dcClient, err := traceClientFromDockerContext(dockerCli, otelEnv); err != nil {
+		errs = append(errs, err)
+	} else if dcClient != nil {
+		if dcExporter, err := otlptrace.New(ctx, dcClient); err != nil {
+			errs = append(errs, err)
+		} else if dcExporter != nil {
+			exporters = append(exporters, dcExporter)
+		}
+	}
+	if len(errs) != 0 {
+		return nil, errors.Join(errs...)
+	}
+
+	res, err := resource.New(
+		ctx,
+		resource.WithAttributes(
+			semconv.ServiceName("compose"),
+		),
+	)
+	if err != nil {
+		return nil, fmt.Errorf("failed to create resource: %v", err)
+	}
+
+	muxExporter := MuxExporter{exporters: exporters}
+	sp := sdktrace.NewSimpleSpanProcessor(muxExporter)
+	tracerProvider := sdktrace.NewTracerProvider(
+		sdktrace.WithSampler(sdktrace.AlwaysSample()),
+		sdktrace.WithResource(res),
+		sdktrace.WithSpanProcessor(sp),
+	)
+	otel.SetTracerProvider(tracerProvider)
+
+	// Shutdown will flush any remaining spans and shut down the exporter.
+	return tracerProvider.Shutdown, nil
+}
+
+// traceClientFromEnv creates a GRPC OTLP client based on OS environment
+// variables.
+//
+// https://opentelemetry.io/docs/concepts/sdk-configuration/otlp-exporter-configuration/
+func traceClientFromEnv() (otlptrace.Client, envMap) {
+	hasOtelEndpointInEnv := false
+	otelEnv := make(map[string]string)
+	for _, kv := range os.Environ() {
+		k, v, ok := strings.Cut(kv, "=")
+		if !ok {
+			continue
+		}
+		if strings.HasPrefix(k, "OTEL_") {
+			otelEnv[k] = v
+			if strings.HasSuffix(k, "ENDPOINT") {
+				hasOtelEndpointInEnv = true
+			}
+		}
+	}
+
+	if !hasOtelEndpointInEnv {
+		return nil, nil
+	}
+
+	client := otlptracegrpc.NewClient()
+	return client, otelEnv
+}

internal/tracing/tracing_test.go

@@ -0,0 +1,60 @@
+/*
+   Copyright 2023 Docker Compose CLI 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 tracing_test
+
+import (
+	"testing"
+
+	"github.com/docker/cli/cli/command"
+	"github.com/docker/cli/cli/context/store"
+	"github.com/stretchr/testify/require"
+
+	"github.com/docker/compose/v2/internal/tracing"
+)
+
+var testStoreCfg = store.NewConfig(
+	func() interface{} {
+		return &map[string]interface{}{}
+	},
+)
+
+func TestExtractOtelFromContext(t *testing.T) {
+	if testing.Short() {
+		t.Skip("Requires filesystem access")
+	}
+
+	dir := t.TempDir()
+
+	st := store.New(dir, testStoreCfg)
+	err := st.CreateOrUpdate(store.Metadata{
+		Name: "test",
+		Metadata: command.DockerContext{
+			Description: t.Name(),
+			AdditionalFields: map[string]interface{}{
+				"otel": map[string]interface{}{
+					"OTEL_EXPORTER_OTLP_ENDPOINT": "localhost:1234",
+				},
+			},
+		},
+		Endpoints: make(map[string]interface{}),
+	})
+	require.NoError(t, err)
+
+	cfg, err := tracing.ConfigFromDockerContext(st, "test")
+	require.NoError(t, err)
+	require.Equal(t, "localhost:1234", cfg.Endpoint)
+}

internal/variables.go

@@ -1,5 +1,5 @@
 /*
-   Copyright 2020 Docker Compose CLI authors
+   Copyright 2023 Docker Compose CLI authors
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.