[receiver/hostmetrics] Add skeleton for new hostmetrics scraper: nfsscraper (open-telemetry#40050)

nfsscraper will provide metrics for the OS NFS client and server.

#### Link to tracking issue
[https://github.com/open-telemetry/opentelemetry-collector-contrib/issues/39978](https://github.com/open-telemetry/opentelemetry-collector-contrib/issues/39978)

nfsscraper is not initialized from hostmetricsreceiver in this skeleton
PR. I did need to include a single metric in metadata.yaml so mdatagen
would create the required files for tests to pass.

---------

Co-authored-by: Braydon Kains <[email protected]>

Author: 2 people

.chloggen/add-nfsscraper-skeleton.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: hostmetricsreceiver
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Skeleton nfsscraper -- adds Linux nfs and nfsd metrics from /proc
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [39978]
+
+# (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: [user, api]

.github/CODEOWNERS

@@ -255,6 +255,7 @@ receiver/hostmetricsreceiver/internal/scraper/filesystemscraper/ @open-telemetry
 receiver/hostmetricsreceiver/internal/scraper/loadscraper/       @open-telemetry/collector-contrib-approvers @dmitryax @braydonk
 receiver/hostmetricsreceiver/internal/scraper/memoryscraper/     @open-telemetry/collector-contrib-approvers @dmitryax @braydonk
 receiver/hostmetricsreceiver/internal/scraper/networkscraper/    @open-telemetry/collector-contrib-approvers @dmitryax @braydonk
+receiver/hostmetricsreceiver/internal/scraper/nfsscraper/        @open-telemetry/collector-contrib-approvers @dmitryax @braydonk
 receiver/hostmetricsreceiver/internal/scraper/pagingscraper/     @open-telemetry/collector-contrib-approvers @dmitryax @braydonk
 receiver/hostmetricsreceiver/internal/scraper/processesscraper/  @open-telemetry/collector-contrib-approvers @dmitryax @braydonk
 receiver/hostmetricsreceiver/internal/scraper/processscraper/    @open-telemetry/collector-contrib-approvers @dmitryax @braydonk

.github/ISSUE_TEMPLATE/bug_report.yaml

@@ -260,6 +260,7 @@ body:
       - receiver/hostmetrics/internal/scraper/loadscraper
       - receiver/hostmetrics/internal/scraper/memoryscraper
       - receiver/hostmetrics/internal/scraper/networkscraper
+      - receiver/hostmetrics/internal/scraper/nfsscraper
       - receiver/hostmetrics/internal/scraper/pagingscraper
       - receiver/hostmetrics/internal/scraper/processesscraper
       - receiver/hostmetrics/internal/scraper/processscraper

.github/ISSUE_TEMPLATE/feature_request.yaml

@@ -254,6 +254,7 @@ body:
       - receiver/hostmetrics/internal/scraper/loadscraper
       - receiver/hostmetrics/internal/scraper/memoryscraper
       - receiver/hostmetrics/internal/scraper/networkscraper
+      - receiver/hostmetrics/internal/scraper/nfsscraper
       - receiver/hostmetrics/internal/scraper/pagingscraper
       - receiver/hostmetrics/internal/scraper/processesscraper
       - receiver/hostmetrics/internal/scraper/processscraper

.github/ISSUE_TEMPLATE/other.yaml

@@ -254,6 +254,7 @@ body:
       - receiver/hostmetrics/internal/scraper/loadscraper
       - receiver/hostmetrics/internal/scraper/memoryscraper
       - receiver/hostmetrics/internal/scraper/networkscraper
+      - receiver/hostmetrics/internal/scraper/nfsscraper
       - receiver/hostmetrics/internal/scraper/pagingscraper
       - receiver/hostmetrics/internal/scraper/processesscraper
       - receiver/hostmetrics/internal/scraper/processscraper

.github/ISSUE_TEMPLATE/unmaintained.yaml

@@ -259,6 +259,7 @@ body:
       - receiver/hostmetrics/internal/scraper/loadscraper
       - receiver/hostmetrics/internal/scraper/memoryscraper
       - receiver/hostmetrics/internal/scraper/networkscraper
+      - receiver/hostmetrics/internal/scraper/nfsscraper
       - receiver/hostmetrics/internal/scraper/pagingscraper
       - receiver/hostmetrics/internal/scraper/processesscraper
       - receiver/hostmetrics/internal/scraper/processscraper

.github/component_labels.txt

@@ -235,6 +235,7 @@ receiver/hostmetricsreceiver/internal/scraper/filesystemscraper receiver/hostmet
 receiver/hostmetricsreceiver/internal/scraper/loadscraper receiver/hostmetrics/internal/scraper/loadscraper
 receiver/hostmetricsreceiver/internal/scraper/memoryscraper receiver/hostmetrics/internal/scraper/memory
 receiver/hostmetricsreceiver/internal/scraper/networkscraper receiver/hostmetrics/internal/scraper/network
+receiver/hostmetricsreceiver/internal/scraper/nfsscraper receiver/hostmetrics/internal/scraper/nfsscraper
 receiver/hostmetricsreceiver/internal/scraper/pagingscraper receiver/hostmetrics/internal/scraper/paging
 receiver/hostmetricsreceiver/internal/scraper/processesscraper receiver/hostmetrics/internal/scraper/processes
 receiver/hostmetricsreceiver/internal/scraper/processscraper receiver/hostmetrics/internal/scraper/process

receiver/hostmetricsreceiver/internal/scraper/nfsscraper/config.go

@@ -0,0 +1,14 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package nfsscraper // import "github.com/open-telemetry/opentelemetry-collector-contrib/receiver/hostmetricsreceiver/internal/scraper/nfsscraper"
+
+import (
+	"github.com/open-telemetry/opentelemetry-collector-contrib/receiver/hostmetricsreceiver/internal/scraper/nfsscraper/internal/metadata"
+)
+
+// Config relating to NFS Metric Scraper.
+type Config struct {
+	// MetricsBuilderConfig allows to customize scraped metrics/attributes representation.
+	metadata.MetricsBuilderConfig `mapstructure:",squash"`
+}

receiver/hostmetricsreceiver/internal/scraper/nfsscraper/doc.go

@@ -0,0 +1,6 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+//go:generate mdatagen metadata.yaml
+
+package nfsscraper // import "github.com/open-telemetry/opentelemetry-collector-contrib/receiver/hostmetricsreceiver/internal/scraper/nfsscraper"

receiver/hostmetricsreceiver/internal/scraper/nfsscraper/documentation.md

@@ -0,0 +1,21 @@
+[comment]: <> (Code generated by mdatagen. DO NOT EDIT.)
+
+# nfs
+
+## Default Metrics
+
+The following metrics are emitted by default. Each of them can be disabled by applying the following configuration:
+
+```yaml
+metrics:
+  <metric_name>:
+    enabled: false
+```
+
+### system.nfs.net.count
+
+Reports the count of kernel NFS client network requests handled
+
+| Unit | Metric Type | Value Type |
+| ---- | ----------- | ---------- |
+| {request} | Gauge | Int |

receiver/hostmetricsreceiver/internal/scraper/nfsscraper/factory.go

@@ -0,0 +1,50 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package nfsscraper // import "github.com/open-telemetry/opentelemetry-collector-contrib/receiver/hostmetricsreceiver/internal/scraper/nfsscraper"
+
+import (
+	"context"
+	"errors"
+	"runtime"
+
+	"go.opentelemetry.io/collector/component"
+	"go.opentelemetry.io/collector/scraper"
+
+	"github.com/open-telemetry/opentelemetry-collector-contrib/receiver/hostmetricsreceiver/internal/scraper/nfsscraper/internal/metadata"
+)
+
+var (
+	supportedOS      = runtime.GOOS == "linux"
+	errUnsupportedOS = errors.New("the nfs scraper is only available on Linux")
+)
+
+// NewFactory for NFS scraper.
+func NewFactory() scraper.Factory {
+	return scraper.NewFactory(metadata.Type, createDefaultConfig, scraper.WithMetrics(createMetricsScraper, metadata.MetricsStability))
+}
+
+// createDefaultConfig creates the default configuration for the Scraper.
+func createDefaultConfig() component.Config {
+	return &Config{
+		MetricsBuilderConfig: metadata.DefaultMetricsBuilderConfig(),
+	}
+}
+
+// createMetricsScraper creates a resource scraper based on provided config.
+func createMetricsScraper(
+	ctx context.Context,
+	settings scraper.Settings,
+	cfg component.Config,
+) (scraper.Metrics, error) {
+	if !supportedOS {
+		return nil, errUnsupportedOS
+	}
+
+	nfsScraper := newNfsScraper(ctx, settings, cfg.(*Config))
+
+	return scraper.NewMetrics(
+		nfsScraper.scrape,
+		scraper.WithStart(nfsScraper.start),
+	)
+}

receiver/hostmetricsreceiver/internal/scraper/nfsscraper/factory_test.go

@@ -0,0 +1,29 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package nfsscraper
+
+import (
+	"context"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"go.opentelemetry.io/collector/scraper/scrapertest"
+
+	"github.com/open-telemetry/opentelemetry-collector-contrib/receiver/hostmetricsreceiver/internal/scraper/nfsscraper/internal/metadata"
+)
+
+func TestNfsScraper(t *testing.T) {
+	factory := NewFactory()
+	cfg := &Config{}
+
+	scraper, err := factory.CreateMetrics(context.Background(), scrapertest.NewNopSettings(metadata.Type), cfg)
+
+	if supportedOS {
+		assert.NoError(t, err)
+		assert.NotNil(t, scraper)
+	} else {
+		assert.ErrorIs(t, err, errUnsupportedOS)
+		assert.Nil(t, scraper)
+	}
+}