combine platform specific readers and tests

This allows us to run tests for the BSD, Darwin, and Linux readers
on all platforms.

sdk/resource/host_id.go

@@ -16,8 +16,10 @@ package resource // import "go.opentelemetry.io/otel/sdk/resource"
 
 import (
 	"context"
+	"errors"
 	"os"
 	"os/exec"
+	"strings"
 
 	semconv "go.opentelemetry.io/otel/semconv/v1.17.0"
 )
@@ -42,7 +44,6 @@ type hostIDReader interface {
 
 type fileReader func(string) (string, error)
 
-// nolint:unused // commandExecutor is used on darwin and BSD, but excluded on linux where the lint job runs
 type commandExecutor func(string, ...string) (string, error)
 
 func readFile(filename string) (string, error) {
@@ -54,7 +55,7 @@ func readFile(filename string) (string, error) {
 	return string(b), nil
 }
 
-// nolint:unused // execCommand is used on darwin and BSD, but excluded on linux where the lint job runs
+// nolint: unused  // This is used by the hostReaderBSD, gated by build tags.
 func execCommand(name string, arg ...string) (string, error) {
 	cmd := exec.Command(name, arg...)
 	b, err := cmd.Output()
@@ -65,6 +66,74 @@ func execCommand(name string, arg ...string) (string, error) {
 	return string(b), nil
 }
 
+// hostIDReaderBSD implements hostIDReader.
+type hostIDReaderBSD struct {
+	execCommand commandExecutor
+	readFile    fileReader
+}
+
+// read attempts to read the machine-id from /etc/hostid. If not found it will
+// execute `kenv -q smbios.system.uuid`. If neither location yields an id an
+// error will be returned.
+func (r *hostIDReaderBSD) read() (string, error) {
+	if result, err := r.readFile("/etc/hostid"); err == nil {
+		return strings.TrimSpace(result), nil
+	}
+
+	if result, err := r.execCommand("kenv", "-q", "smbios.system.uuid"); err == nil {
+		return strings.TrimSpace(result), nil
+	}
+
+	return "", errors.New("host id not found in: /etc/hostid or kenv")
+}
+
+// hostIDReaderDarwin implements hostIDReader.
+type hostIDReaderDarwin struct {
+	execCommand commandExecutor
+}
+
+// read executes `ioreg -rd1 -c "IOPlatformExpertDevice"` and parses host id
+// from the IOPlatformUUID line. If the command fails or the uuid cannot be
+// parsed an error will be returned.
+func (r *hostIDReaderDarwin) read() (string, error) {
+	result, err := r.execCommand("ioreg", "-rd1", "-c", "IOPlatformExpertDevice")
+	if err != nil {
+		return "", err
+	}
+
+	lines := strings.Split(result, "\n")
+	for _, line := range lines {
+		if strings.Contains(line, "IOPlatformUUID") {
+			parts := strings.Split(line, " = ")
+			if len(parts) == 2 {
+				return strings.Trim(parts[1], "\""), nil
+			}
+			break
+		}
+	}
+
+	return "", errors.New("could not parse IOPlatformUUID")
+}
+
+type hostIDReaderLinux struct {
+	readFile fileReader
+}
+
+// read attempts to read the machine-id from /etc/machine-id followed by
+// /var/lib/dbus/machine-id. If neither location yields an ID an error will
+// be returned.
+func (r *hostIDReaderLinux) read() (string, error) {
+	if result, err := r.readFile("/etc/machine-id"); err == nil {
+		return strings.TrimSpace(result), nil
+	}
+
+	if result, err := r.readFile("/var/lib/dbus/machine-id"); err == nil {
+		return strings.TrimSpace(result), nil
+	}
+
+	return "", errors.New("host id not found in: /etc/machine-id or /var/lib/dbus/machine-id")
+}
+
 type hostIDDetector struct{}
 
 // Detect returns a *Resource containing the platform specific host id.

sdk/resource/host_id_bsd.go

@@ -22,27 +22,6 @@ import (
 	"strings"
 )
 
-// hostIDReaderBSD implements hostIDReader
-type hostIDReaderBSD struct {
-	execCommand commandExecutor
-	readFile    fileReader
-}
-
-// read attempts to read the machine-id from /etc/hostid. If not found it will
-// execute `kenv -q smbios.system.uuid`. If neither location yields an id an
-// error will be returned.
-func (r *hostIDReaderBSD) read() (string, error) {
-	if result, err := r.readFile("/etc/hostid"); err == nil {
-		return strings.TrimSpace(result), nil
-	}
-
-	if result, err := r.execCommand("kenv", "-q", "smbios.system.uuid"); err == nil {
-		return strings.TrimSpace(result), nil
-	}
-
-	return "", errors.New("host id not found in: /etc/hostid or kenv")
-}
-
 var platformHostIDReader hostIDReader = &hostIDReaderBSD{
 	execCommand: execCommand,
 	readFile:    readFile,

sdk/resource/host_id_darwin.go

@@ -14,39 +14,6 @@
 
 package resource // import "go.opentelemetry.io/otel/sdk/resource"
 
-import (
-	"errors"
-	"strings"
-)
-
-// hostIDReaderDarwin implements hostIDReader
-type hostIDReaderDarwin struct {
-	execCommand commandExecutor
-}
-
-// read executes `ioreg -rd1 -c "IOPlatformExpertDevice"` and parses host id
-// from the IOPlatformUUID line. If the command fails or the uuid cannot be
-// parsed an error will be returned.
-func (r *hostIDReaderDarwin) read() (string, error) {
-	result, err := r.execCommand("ioreg", "-rd1", "-c", "IOPlatformExpertDevice")
-	if err != nil {
-		return "", err
-	}
-
-	lines := strings.Split(result, "\n")
-	for _, line := range lines {
-		if strings.Contains(line, "IOPlatformUUID") {
-			parts := strings.Split(line, " = ")
-			if len(parts) == 2 {
-				return strings.Trim(parts[1], "\""), nil
-			}
-			break
-		}
-	}
-
-	return "", errors.New("could not parse IOPlatformUUID")
-}
-
 var platformHostIDReader hostIDReader = &hostIDReaderDarwin{
 	execCommand: execCommand,
 }

sdk/resource/host_id_export_test.go

@@ -0,0 +1,37 @@
+// 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 resource_test
+
+import (
+	"errors"
+
+	"go.opentelemetry.io/otel/sdk/resource"
+)
+
+func mockHostIDProvider() {
+	resource.SetHostIDProvider(
+		func() (string, error) { return "f2c668b579780554f70f72a063dc0864", nil },
+	)
+}
+
+func mockHostIDProviderWithError() {
+	resource.SetHostIDProvider(
+		func() (string, error) { return "", errors.New("not found") },
+	)
+}
+
+func restoreHostIDProvider() {
+	resource.SetDefaultHostIDProvider()
+}

sdk/resource/host_id_linux.go

@@ -17,30 +17,6 @@
 
 package resource // import "go.opentelemetry.io/otel/sdk/resource"
 
-import (
-	"errors"
-	"strings"
-)
-
-type hostIDReaderLinux struct {
-	readFile fileReader
-}
-
-// read attempts to read the machine-id from /etc/machine-id followed by
-// /var/lib/dbus/machine-id. If neither location yields an ID an error will
-// be returned.
-func (r *hostIDReaderLinux) read() (string, error) {
-	if result, err := r.readFile("/etc/machine-id"); err == nil {
-		return strings.TrimSpace(result), nil
-	}
-
-	if result, err := r.readFile("/var/lib/dbus/machine-id"); err == nil {
-		return strings.TrimSpace(result), nil
-	}
-
-	return "", errors.New("host id not found in: /etc/machine-id or /var/lib/dbus/machine-id")
-}
-
 var platformHostIDReader hostIDReader = &hostIDReaderLinux{
 	readFile: readFile,
 }