[receiver/ntp] Add a new NTP receiver (#35753)

#### Description
Introduce a new receiver, NTP receiver. This is the first PR as skeleton
for the receiver.

#### Link to tracking issue
Related to #34375 

#### Testing
N/A

#### Documentation
metadata.yaml, README.

.chloggen/ntp.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: new_component
+
+# The name of the component, or a single word describing the area of concern, (e.g. filelogreceiver)
+component: ntpreceiver
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Introduce new receiver reporting the offset between the local machine and a NTP server.
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [34375]
+
+# (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

@@ -264,6 +264,7 @@ receiver/mysqlreceiver/                                             @open-teleme
 receiver/namedpipereceiver/                                         @open-telemetry/collector-contrib-approvers @sinkingpoint @djaglowski
 receiver/nginxreceiver/                                             @open-telemetry/collector-contrib-approvers @djaglowski
 receiver/nsxtreceiver/                                              @open-telemetry/collector-contrib-approvers @dashpole @schmikei
+receiver/ntpreceiver/                                               @open-telemetry/collector-contrib-approvers @atoulme
 receiver/opencensusreceiver/                                        @open-telemetry/collector-contrib-approvers @open-telemetry/collector-approvers
 receiver/oracledbreceiver/                                          @open-telemetry/collector-contrib-approvers @dmitryax @crobert-1 @atoulme
 receiver/osqueryreceiver/                                           @open-telemetry/collector-contrib-approvers @codeboten @nslaughter @smithclay

.github/ISSUE_TEMPLATE/bug_report.yaml

@@ -259,6 +259,7 @@ body:
       - receiver/namedpipe
       - receiver/nginx
       - receiver/nsxt
+      - receiver/ntp
       - receiver/opencensus
       - receiver/oracledb
       - receiver/osquery

.github/ISSUE_TEMPLATE/feature_request.yaml

@@ -253,6 +253,7 @@ body:
       - receiver/namedpipe
       - receiver/nginx
       - receiver/nsxt
+      - receiver/ntp
       - receiver/opencensus
       - receiver/oracledb
       - receiver/osquery

.github/ISSUE_TEMPLATE/other.yaml

@@ -253,6 +253,7 @@ body:
       - receiver/namedpipe
       - receiver/nginx
       - receiver/nsxt
+      - receiver/ntp
       - receiver/opencensus
       - receiver/oracledb
       - receiver/osquery

.github/ISSUE_TEMPLATE/unmaintained.yaml

@@ -258,6 +258,7 @@ body:
       - receiver/namedpipe
       - receiver/nginx
       - receiver/nsxt
+      - receiver/ntp
       - receiver/opencensus
       - receiver/oracledb
       - receiver/osquery

receiver/ntpreceiver/Makefile

@@ -0,0 +1 @@
+include ../../Makefile.Common

receiver/ntpreceiver/README.md

@@ -0,0 +1,45 @@
+# NTP Receiver
+
+<!-- status autogenerated section -->
+| Status        |           |
+| ------------- |-----------|
+| Stability     | [development]: metrics   |
+| Distributions | [] |
+| Issues        | [![Open issues](https://img.shields.io/github/issues-search/open-telemetry/opentelemetry-collector-contrib?query=is%3Aissue%20is%3Aopen%20label%3Areceiver%2Fntp%20&label=open&color=orange&logo=opentelemetry)](https://github.com/open-telemetry/opentelemetry-collector-contrib/issues?q=is%3Aopen+is%3Aissue+label%3Areceiver%2Fntp) [![Closed issues](https://img.shields.io/github/issues-search/open-telemetry/opentelemetry-collector-contrib?query=is%3Aissue%20is%3Aclosed%20label%3Areceiver%2Fntp%20&label=closed&color=blue&logo=opentelemetry)](https://github.com/open-telemetry/opentelemetry-collector-contrib/issues?q=is%3Aclosed+is%3Aissue+label%3Areceiver%2Fntp) |
+| [Code Owners](https://github.com/open-telemetry/opentelemetry-collector-contrib/blob/main/CONTRIBUTING.md#becoming-a-code-owner)    | [@atoulme](https://www.github.com/atoulme) |
+
+[development]: https://github.com/open-telemetry/opentelemetry-collector#development
+<!-- end autogenerated section -->
+
+> :construction: This receiver is in development. Configuration fields and metric data model are subject to change.
+
+## Purpose
+
+This receiver periodically retrieves the clock offset from a NTP server.
+
+## Configuration
+
+- `endpoint`: (default = `pool.ntp.org:123`) Endpoint of the NTP server. Must be formatted as `{host}:{port}`. 
+
+- `collection_interval`: (default = `30m`): This receiver collects metrics on an interval. This value must be a string readable by Golang's [time.ParseDuration](https://pkg.go.dev/time#ParseDuration). Valid time units are `ns`, `us` (or `µs`), `ms`, `s`, `m`, `h`.
+
+- `initial_delay` (default = `1s`): defines how long this receiver waits before starting.
+
+- `metrics` (default: see DefaultMetricsSettings [here])(./internal/metadata/generated_metrics.go): Allows enabling and disabling specific metrics from being collected in this receiver.
+
+### Example Configuration
+
+```yaml
+receivers:
+  ntp:
+    endpoint: pool.ntp.org:123
+    collection_interval: 1h
+    initial_delay: 5m
+```
+
+The full list of settings exposed for this receiver are documented [here](./config.go) with detailed sample configurations [here](./internal/metadata/testdata/config.yaml).
+
+## Metrics
+
+Details about the metrics produced by this receiver can be found in [metadata.yaml](./metadata.yaml)
+

receiver/ntpreceiver/config.go

@@ -0,0 +1,17 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package ntpreceiver // import "github.com/open-telemetry/opentelemetry-collector-contrib/receiver/ntpreceiver"
+
+import (
+	"go.opentelemetry.io/collector/receiver/scraperhelper"
+
+	"github.com/open-telemetry/opentelemetry-collector-contrib/receiver/ntpreceiver/internal/metadata"
+)
+
+// Config is the configuration for the NSX receiver
+type Config struct {
+	scraperhelper.ControllerConfig `mapstructure:",squash"`
+	metadata.MetricsBuilderConfig  `mapstructure:",squash"`
+	Endpoint                       string `mapstructure:"endpoint"`
+}

receiver/ntpreceiver/doc.go

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

receiver/ntpreceiver/documentation.md

@@ -0,0 +1,27 @@
+[comment]: <> (Code generated by mdatagen. DO NOT EDIT.)
+
+# ntp
+
+## 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
+```
+
+### ntp.offset
+
+Time difference between local and NTP server clocks in seconds.
+
+| Unit | Metric Type | Value Type |
+| ---- | ----------- | ---------- |
+| s | Gauge | Int |
+
+## Resource Attributes
+
+| Name | Description | Values | Enabled |
+| ---- | ----------- | ------ | ------- |
+| ntp.host | NTP server used. Corresponds to configured `host`. | Any Str | true |

receiver/ntpreceiver/factory.go

@@ -0,0 +1,34 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package ntpreceiver // import "github.com/open-telemetry/opentelemetry-collector-contrib/receiver/ntpreceiver"
+
+import (
+	"context"
+
+	"go.opentelemetry.io/collector/component"
+	"go.opentelemetry.io/collector/consumer"
+	"go.opentelemetry.io/collector/receiver"
+	"go.opentelemetry.io/collector/receiver/scraperhelper"
+
+	"github.com/open-telemetry/opentelemetry-collector-contrib/receiver/ntpreceiver/internal/metadata"
+)
+
+func NewFactory() receiver.Factory {
+	return receiver.NewFactory(
+		metadata.Type,
+		createDefaultConfig,
+		receiver.WithMetrics(createMetricsReceiver, metadata.MetricsStability),
+	)
+}
+
+func createDefaultConfig() component.Config {
+	return &Config{
+		ControllerConfig:     scraperhelper.NewDefaultControllerConfig(),
+		MetricsBuilderConfig: metadata.DefaultMetricsBuilderConfig(),
+	}
+}
+
+func createMetricsReceiver(_ context.Context, _ receiver.Settings, _ component.Config, _ consumer.Metrics) (receiver.Metrics, error) {
+	return nil, nil
+}

receiver/ntpreceiver/go.mod

@@ -0,0 +1,55 @@
+module github.com/open-telemetry/opentelemetry-collector-contrib/receiver/ntpreceiver
+
+go 1.22.0
+
+require (
+	github.com/google/go-cmp v0.6.0
+	github.com/stretchr/testify v1.9.0
+	go.opentelemetry.io/collector/component v0.111.1-0.20241008154146-ea48c09c31ae
+	go.opentelemetry.io/collector/confmap v1.17.1-0.20241008154146-ea48c09c31ae
+	go.opentelemetry.io/collector/consumer v0.111.1-0.20241008154146-ea48c09c31ae
+	go.opentelemetry.io/collector/filter v0.111.1-0.20241008154146-ea48c09c31ae
+	go.opentelemetry.io/collector/pdata v1.17.1-0.20241008154146-ea48c09c31ae
+	go.opentelemetry.io/collector/receiver v0.111.1-0.20241008154146-ea48c09c31ae
+	go.uber.org/goleak v1.3.0
+	go.uber.org/zap v1.27.0
+)
+
+require (
+	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/go-logr/logr v1.4.2 // indirect
+	github.com/go-logr/stdr v1.2.2 // indirect
+	github.com/go-viper/mapstructure/v2 v2.1.0 // indirect
+	github.com/gogo/protobuf v1.3.2 // indirect
+	github.com/google/uuid v1.6.0 // indirect
+	github.com/json-iterator/go v1.1.12 // indirect
+	github.com/knadh/koanf/maps v0.1.1 // indirect
+	github.com/knadh/koanf/providers/confmap v0.1.0 // indirect
+	github.com/knadh/koanf/v2 v2.1.1 // indirect
+	github.com/mitchellh/copystructure v1.2.0 // indirect
+	github.com/mitchellh/reflectwalk v1.0.2 // indirect
+	github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd // indirect
+	github.com/modern-go/reflect2 v1.0.2 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
+	github.com/rogpeppe/go-internal v1.12.0 // indirect
+	go.opentelemetry.io/collector/config/configtelemetry v0.111.1-0.20241008154146-ea48c09c31ae // indirect
+	go.opentelemetry.io/collector/consumer/consumerprofiles v0.111.1-0.20241008154146-ea48c09c31ae // indirect
+	go.opentelemetry.io/collector/consumer/consumertest v0.111.1-0.20241008154146-ea48c09c31ae // indirect
+	go.opentelemetry.io/collector/internal/globalsignal v0.111.1-0.20241008154146-ea48c09c31ae // indirect
+	go.opentelemetry.io/collector/pdata/pprofile v0.111.1-0.20241008154146-ea48c09c31ae // indirect
+	go.opentelemetry.io/collector/pipeline v0.111.1-0.20241008154146-ea48c09c31ae // indirect
+	go.opentelemetry.io/collector/receiver/receiverprofiles v0.111.1-0.20241008154146-ea48c09c31ae // indirect
+	go.opentelemetry.io/otel v1.30.0 // indirect
+	go.opentelemetry.io/otel/metric v1.30.0 // indirect
+	go.opentelemetry.io/otel/sdk v1.30.0 // indirect
+	go.opentelemetry.io/otel/sdk/metric v1.30.0 // indirect
+	go.opentelemetry.io/otel/trace v1.30.0 // indirect
+	go.uber.org/multierr v1.11.0 // indirect
+	golang.org/x/net v0.30.0 // indirect
+	golang.org/x/sys v0.26.0 // indirect
+	golang.org/x/text v0.19.0 // indirect
+	google.golang.org/genproto/googleapis/rpc v0.0.0-20240822170219-fc7c04adadcd // indirect
+	google.golang.org/grpc v1.67.1 // indirect
+	google.golang.org/protobuf v1.35.1 // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
+)