[processor/resourcedetection] Add Dynatrace resource detector (open-telemetry#37766)

<!--Ex. Fixing a bug - Describe the bug and how this fixes the issue.
Ex. Adding a feature - Explain what this achieves.-->
#### Description

This PR adds the Dynatrace detector to the resource detection processor.
The Dynatrace detector loads resource information from the
`dt_host_metadata.properties` file which is located in
the `/var/lib/dynatrace/enrichment` (on *nix systems) or
`%ProgramData%\dynatrace\enrichment` (on Windows) directories.
If present in the file, the following attributes will be added:

- `dt.entity.host`
- `host.name`

The Dynatrace detector does not require any additional configuration,
other than being added to the list of detectors.

<!-- Issue number (e.g. open-telemetry#1234) or full URL to issue, if applicable. -->
#### Link to tracking issue
Fixes open-telemetry#37577

<!--Describe what testing was performed and which tests were added.-->
#### Testing
Added unit tests

<!--Describe the documentation added.-->
#### Documentation
Added a description of the detector to the readme

<!--Please delete paragraphs that you did not use before submitting.-->

---------

Signed-off-by: Florian Bacher <[email protected]>
Co-authored-by: Evan Bradley <[email protected]>

Author: 2 people

.chloggen/dynatrace-resource-detection-processor.yaml

@@ -0,0 +1,27 @@
+# Use this changelog template to create an entry for release notes.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: enhancement
+
+# The name of the component, or a single word describing the area of concern, (e.g. filelogreceiver)
+component: resourcedetectionprocessor
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: add the Dynatrace detector to the resource detection processor
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [37577]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext:
+
+# If your change doesn't affect end users or the exported elements of any package,
+# you should instead start your pull request title with [chore] or use the "Skip Changelog" label.
+# Optional: The change log or logs in which this entry should be included.
+# e.g. '[user]' or '[user, api]'
+# Include 'user' if the change is relevant to end users.
+# Include 'api' if there is a change to a library API.
+# Default: '[user]'
+change_logs: []

.github/CODEOWNERS

@@ -192,6 +192,7 @@ processor/probabilisticsamplerprocessor/                         @open-telemetry
 processor/redactionprocessor/                                    @open-telemetry/collector-contrib-approvers @dmitryax @mx-psi @TylerHelmuth
 processor/remotetapprocessor/                                    @open-telemetry/collector-contrib-approvers @atoulme @jaronoff97
 processor/resourcedetectionprocessor/                            @open-telemetry/collector-contrib-approvers @Aneurysm9 @dashpole
+processor/resourcedetectionprocessor/internal/dynatrace/         @open-telemetry/collector-contrib-approvers @bacherfl @evan-bradley
 processor/resourceprocessor/                                     @open-telemetry/collector-contrib-approvers @dmitryax
 processor/routingprocessor/                                      @open-telemetry/collector-contrib-approvers @jpkrohling
 processor/schemaprocessor/                                       @open-telemetry/collector-contrib-approvers @MovieStoreGuy @ankitpatel96

.github/ISSUE_TEMPLATE/bug_report.yaml

@@ -196,6 +196,7 @@ body:
       - processor/remotetap
       - processor/resource
       - processor/resourcedetection
+      - processor/resourcedetection/internal/dynatrace
       - processor/routing
       - processor/schema
       - processor/span

.github/ISSUE_TEMPLATE/feature_request.yaml

@@ -190,6 +190,7 @@ body:
       - processor/remotetap
       - processor/resource
       - processor/resourcedetection
+      - processor/resourcedetection/internal/dynatrace
       - processor/routing
       - processor/schema
       - processor/span

.github/ISSUE_TEMPLATE/other.yaml

@@ -190,6 +190,7 @@ body:
       - processor/remotetap
       - processor/resource
       - processor/resourcedetection
+      - processor/resourcedetection/internal/dynatrace
       - processor/routing
       - processor/schema
       - processor/span

.github/ISSUE_TEMPLATE/unmaintained.yaml

@@ -195,6 +195,7 @@ body:
       - processor/remotetap
       - processor/resource
       - processor/resourcedetection
+      - processor/resourcedetection/internal/dynatrace
       - processor/routing
       - processor/schema
       - processor/span

processor/resourcedetectionprocessor/README.md

@@ -582,10 +582,29 @@ processors:
 
 See: [TLS Configuration Settings](https://github.com/open-telemetry/opentelemetry-collector/blob/main/config/configtls/README.md) for the full set of available options.
 
+### Dynatrace
+
+Loads resource information from the `dt_host_metadata.properties` file which is located in
+the `/var/lib/dynatrace/enrichment` (on *nix systems) or `%ProgramData%\dynatrace\enrichment` (on Windows) directories.
+If present in the file, the following attributes will be added:
+
+- `dt.entity.host`
+- `host.name`
+
+The Dynatrace detector does not require any additional configuration, other than being added to the list of detectors.
+
+Example:
+
+```yaml
+processors:
+  resourcedetection/dynatrace:
+    detectors: [dynatrace]
+```
+
 ## Configuration
 
 ```yaml
-# a list of resource detectors to run, valid options are: "env", "system", "gcp", "ec2", "ecs", "elastic_beanstalk", "eks", "lambda", "azure", "heroku", "openshift"
+# a list of resource detectors to run, valid options are: "env", "system", "gcp", "ec2", "ecs", "elastic_beanstalk", "eks", "lambda", "azure", "heroku", "openshift", "dynatrace"
 detectors: [ <string> ]
 # determines if existing resource attributes should be overridden or preserved, defaults to true
 override: <bool>

processor/resourcedetectionprocessor/doc.go

@@ -17,6 +17,7 @@
 //go:generate mdatagen internal/system/metadata.yaml
 //go:generate mdatagen internal/k8snode/metadata.yaml
 //go:generate mdatagen internal/kubeadm/metadata.yaml
+//go:generate mdatagen internal/dynatrace/metadata.yaml
 
 // package resourcedetectionprocessor implements a processor
 // which can be used to detect resource information from the host,

processor/resourcedetectionprocessor/factory.go

@@ -28,6 +28,7 @@ import (
 	"github.com/open-telemetry/opentelemetry-collector-contrib/processor/resourcedetectionprocessor/internal/azure/aks"
 	"github.com/open-telemetry/opentelemetry-collector-contrib/processor/resourcedetectionprocessor/internal/consul"
 	"github.com/open-telemetry/opentelemetry-collector-contrib/processor/resourcedetectionprocessor/internal/docker"
+	"github.com/open-telemetry/opentelemetry-collector-contrib/processor/resourcedetectionprocessor/internal/dynatrace"
 	"github.com/open-telemetry/opentelemetry-collector-contrib/processor/resourcedetectionprocessor/internal/env"
 	"github.com/open-telemetry/opentelemetry-collector-contrib/processor/resourcedetectionprocessor/internal/gcp"
 	"github.com/open-telemetry/opentelemetry-collector-contrib/processor/resourcedetectionprocessor/internal/heroku"
@@ -68,6 +69,7 @@ func NewFactory() processor.Factory {
 		openshift.TypeStr:        openshift.NewDetector,
 		k8snode.TypeStr:          k8snode.NewDetector,
 		kubeadm.TypeStr:          kubeadm.NewDetector,
+		dynatrace.TypeStr:        dynatrace.NewDetector,
 	})
 
 	f := &factory{

processor/resourcedetectionprocessor/internal/dynatrace/documentation.md

@@ -0,0 +1,10 @@
+[comment]: <> (Code generated by mdatagen. DO NOT EDIT.)
+
+# dynatracedetector
+
+## Resource Attributes
+
+| Name | Description | Values | Enabled |
+| ---- | ----------- | ------ | ------- |
+| dt.entity.host | The Dynatrace host entity | Any Str | true |
+| host.name | The hostname | Any Str | true |

processor/resourcedetectionprocessor/internal/dynatrace/dynatrace.go

@@ -0,0 +1,102 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+// Package dynatrace provides a detector that loads resource information from
+// the dt_host_metadata.properties file which is located in
+// the /var/lib/dynatrace/enrichment (on *nix systems) and %ProgramData%\dynatrace\enrichment
+// (on Windows) directories.
+
+package dynatrace // import "github.com/open-telemetry/opentelemetry-collector-contrib/processor/resourcedetectionprocessor/internal/dynatrace"
+import (
+	"bufio"
+	"context"
+	"os"
+	"path/filepath"
+	"runtime"
+	"slices"
+	"strings"
+
+	"go.opentelemetry.io/collector/pdata/pcommon"
+	"go.opentelemetry.io/collector/processor"
+	"go.uber.org/zap"
+
+	"github.com/open-telemetry/opentelemetry-collector-contrib/processor/resourcedetectionprocessor/internal"
+)
+
+const TypeStr = "dynatrace"
+
+const dtHostMetadataProperties = "dt_host_metadata.properties"
+
+var dtHostProperties = []string{"dt.entity.host", "host.name"}
+
+type Detector struct {
+	enrichmentDirectory string
+	logger              *zap.Logger
+}
+
+func NewDetector(set processor.Settings, _ internal.DetectorConfig) (internal.Detector, error) {
+	enrichmentDir := "/var/lib/dynatrace/enrichment"
+	if runtime.GOOS == "windows" {
+		// Windows default is "%ProgramData%\dynatrace\enrichment"
+		// If the ProgramData environment variable is not set,
+		// it falls back to C:\ProgramData
+		programDataDir := os.Getenv("ProgramData")
+		if programDataDir == "" {
+			programDataDir = `C:\ProgramData`
+		}
+
+		enrichmentDir = filepath.Join(programDataDir, "dynatrace", "enrichment")
+	}
+
+	return &Detector{
+		enrichmentDirectory: enrichmentDir,
+		logger:              set.Logger,
+	}, nil
+}
+
+func (d Detector) Detect(_ context.Context) (pcommon.Resource, string, error) {
+	res := pcommon.NewResource()
+
+	if err := d.readPropertiesFile(res.Attributes()); err != nil {
+		return res, "", err
+	}
+	return res, "", nil
+}
+
+func (d Detector) readPropertiesFile(attributes pcommon.Map) error {
+	filePath := filepath.Join(d.enrichmentDirectory, dtHostMetadataProperties)
+
+	file, err := os.Open(filePath)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return nil
+		}
+		return err
+	}
+
+	defer func() {
+		_ = file.Close()
+	}()
+
+	scanner := bufio.NewScanner(file)
+
+	for scanner.Scan() {
+		line := scanner.Text()
+		// split by the first "=" character. If there is another "=" afterward, this will be part of the value
+		split := strings.SplitN(line, "=", 2)
+		if len(split) != 2 {
+			d.logger.Warn("Skipping line as it does not match the expected format of '<key>=<value>", zap.String("line", line))
+			continue
+		}
+		key, value := split[0], split[1]
+
+		if key != "" && value != "" {
+			if !slices.Contains(dtHostProperties, key) {
+				continue
+			}
+			attributes.PutStr(strings.TrimSpace(key), strings.TrimSpace(value))
+		}
+	}
+
+	return scanner.Err()
+}

processor/resourcedetectionprocessor/internal/dynatrace/dynatrace_test.go

@@ -0,0 +1,96 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package dynatrace
+
+import (
+	"context"
+	"os"
+	"path/filepath"
+	"runtime"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+	"go.opentelemetry.io/collector/component"
+	"go.opentelemetry.io/collector/processor"
+	"go.uber.org/zap"
+)
+
+const testPropertiesFile = `
+dt.entity.host=my-host-from-properties
+host.name=my-host-from-properties
+dt.entity.host_group=my-host-group-from-properties
+dt.foo=bar
+invalid-entry
+`
+
+func TestDetectorNewDetector(t *testing.T) {
+	d, err := NewDetector(processor.Settings{}, nil)
+
+	require.NoError(t, err)
+	require.NotNil(t, d)
+
+	if runtime.GOOS == "windows" {
+		t.Setenv("ProgramData", "C:\\ProgramData")
+		require.Equal(t, "C:\\ProgramData\\dynatrace\\enrichment", d.(*Detector).enrichmentDirectory)
+	} else {
+		require.Equal(t, "/var/lib/dynatrace/enrichment", d.(*Detector).enrichmentDirectory)
+	}
+}
+
+func TestDetector_DetectFromProperties(t *testing.T) {
+	d, err := NewDetector(processor.Settings{
+		TelemetrySettings: component.TelemetrySettings{
+			Logger: zap.NewNop(),
+		},
+	}, nil)
+
+	require.NoError(t, err)
+
+	tempDir := t.TempDir()
+
+	require.NoError(t, createTestFile(tempDir, dtHostMetadataProperties, testPropertiesFile))
+	d.(*Detector).enrichmentDirectory = tempDir
+
+	resource, _, err := d.Detect(context.Background())
+
+	require.NoError(t, err)
+	require.NotNil(t, resource)
+	require.Equal(t, 2, resource.Attributes().Len())
+
+	get, ok := resource.Attributes().Get("dt.entity.host")
+	require.True(t, ok)
+	require.Equal(t, "my-host-from-properties", get.Str())
+
+	get, ok = resource.Attributes().Get("host.name")
+	require.True(t, ok)
+	require.Equal(t, "my-host-from-properties", get.Str())
+
+	// verify that we do not take any additional properties
+	_, ok = resource.Attributes().Get("dt.entity.host_group")
+	require.False(t, ok)
+}
+
+func TestDetector_DetectNoFileAvailable(t *testing.T) {
+	d, err := NewDetector(processor.Settings{
+		TelemetrySettings: component.TelemetrySettings{
+			Logger: zap.NewNop(),
+		},
+	}, nil)
+
+	require.NoError(t, err)
+
+	tempDir := t.TempDir()
+
+	d.(*Detector).enrichmentDirectory = tempDir
+
+	resource, _, err := d.Detect(context.Background())
+
+	require.NoError(t, err)
+	require.NotNil(t, resource)
+	require.Equal(t, 0, resource.Attributes().Len())
+}
+
+func createTestFile(directory, name, content string) error {
+	return os.WriteFile(filepath.Join(directory, name), []byte(content), 0o600)
+}