opentelemetry_sdk/resource/
env.rs

1//! Environment variables resource detector
2//!
3//! Implementation of `ResourceDetector` to extract a `Resource` from environment
4//! variables.
5use crate::resource::{Resource, ResourceDetector};
6use opentelemetry::{Key, KeyValue, Value};
7use std::env;
8
9const OTEL_RESOURCE_ATTRIBUTES: &str = "OTEL_RESOURCE_ATTRIBUTES";
10const OTEL_SERVICE_NAME: &str = "OTEL_SERVICE_NAME";
11
12/// EnvResourceDetector extract resource from environment variable
13/// `OTEL_RESOURCE_ATTRIBUTES`. See [OpenTelemetry Resource
14/// Spec](https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/resource/sdk.md#specifying-resource-information-via-an-environment-variable)
15/// for details.
16#[derive(Debug)]
17pub struct EnvResourceDetector {
18    _private: (),
19}
20
21impl ResourceDetector for EnvResourceDetector {
22    fn detect(&self) -> Resource {
23        match env::var(OTEL_RESOURCE_ATTRIBUTES) {
24            Ok(s) if !s.is_empty() => construct_otel_resources(s),
25            Ok(_) | Err(_) => Resource::empty(), // return empty resource
26        }
27    }
28}
29
30impl EnvResourceDetector {
31    /// Create `EnvResourceDetector` instance.
32    pub fn new() -> Self {
33        EnvResourceDetector { _private: () }
34    }
35}
36
37impl Default for EnvResourceDetector {
38    fn default() -> Self {
39        EnvResourceDetector::new()
40    }
41}
42
43/// Extract key value pairs and construct a resource from resources string like
44/// key1=value1,key2=value2,...
45fn construct_otel_resources(s: String) -> Resource {
46    Resource::builder_empty()
47        .with_attributes(s.split_terminator(',').filter_map(|entry| {
48            let parts = match entry.split_once('=') {
49                Some(p) => p,
50                None => return None,
51            };
52            let key = parts.0.trim();
53            let value = parts.1.trim();
54
55            Some(KeyValue::new(key.to_owned(), value.to_owned()))
56        }))
57        .build()
58}
59
60/// There are attributes which MUST be provided by the SDK as specified in
61/// [the Resource SDK specification]. This detector detects those attributes and
62/// if the attribute cannot be detected, it uses the default value.
63///
64/// This detector will first try `OTEL_SERVICE_NAME` env. If it's not available,
65/// then it will check the `OTEL_RESOURCE_ATTRIBUTES` env and see if it contains
66/// `service.name` resource. If it's also not available, it will use `unknown_service`.
67///
68/// If users want to set an empty service name, they can provide
69/// a resource with empty value and `service.name` key.
70///
71/// [the Resource SDK specification]:https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/resource/sdk.md#sdk-provided-resource-attributes
72#[derive(Debug)]
73pub struct SdkProvidedResourceDetector;
74
75impl ResourceDetector for SdkProvidedResourceDetector {
76    fn detect(&self) -> Resource {
77        Resource::builder_empty()
78            .with_attributes([KeyValue::new(
79                super::SERVICE_NAME,
80                env::var(OTEL_SERVICE_NAME)
81                    .ok()
82                    .filter(|s| !s.is_empty())
83                    .map(Value::from)
84                    .or_else(|| {
85                        EnvResourceDetector::new()
86                            .detect()
87                            .get(&Key::new(super::SERVICE_NAME))
88                    })
89                    .unwrap_or_else(|| {
90                        // Fallback to unknown_service:<process.executable.name> per spec
91                        // https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/resource/sdk.md#sdk-provided-resource-attributes
92                        env::current_exe()
93                            .ok()
94                            .and_then(|path| {
95                                path.file_name()
96                                    .and_then(|name| name.to_str())
97                                    .map(|name| format!("unknown_service:{}", name))
98                            })
99                            .unwrap_or_else(|| "unknown_service".to_string())
100                            .into()
101                    }),
102            )])
103            .build()
104    }
105}
106
107#[cfg(test)]
108mod tests {
109    use crate::resource::env::{
110        SdkProvidedResourceDetector, OTEL_RESOURCE_ATTRIBUTES, OTEL_SERVICE_NAME,
111    };
112    use crate::resource::{EnvResourceDetector, Resource, ResourceDetector};
113    use opentelemetry::{Key, KeyValue, Value};
114
115    #[test]
116    fn test_read_from_env() {
117        temp_env::with_vars(
118            [
119                (
120                    "OTEL_RESOURCE_ATTRIBUTES",
121                    Some("key=value, k = v , a= x, a=z,base64=SGVsbG8sIFdvcmxkIQ=="),
122                ),
123                ("IRRELEVANT", Some("20200810")),
124            ],
125            || {
126                let detector = EnvResourceDetector::new();
127                let resource = detector.detect();
128                assert_eq!(
129                    resource,
130                    Resource::builder_empty()
131                        .with_attributes([
132                            KeyValue::new("key", "value"),
133                            KeyValue::new("k", "v"),
134                            KeyValue::new("a", "x"),
135                            KeyValue::new("a", "z"),
136                            KeyValue::new("base64", "SGVsbG8sIFdvcmxkIQ=="), // base64('Hello, World!')
137                        ])
138                        .build()
139                );
140            },
141        );
142
143        let detector = EnvResourceDetector::new();
144        let resource = detector.detect();
145        assert!(resource.is_empty());
146    }
147
148    #[test]
149    fn test_sdk_provided_resource_detector() {
150        // Ensure no env var set - should fallback to unknown_service:<executable_name>
151        // For cargo tests, the executable name is typically <crate_name>-<hash>
152        let no_env = SdkProvidedResourceDetector.detect();
153        let service_name = no_env
154            .get(&Key::from_static_str(crate::resource::SERVICE_NAME))
155            .map(|v| v.to_string())
156            .unwrap();
157
158        assert!(
159            service_name.starts_with("unknown_service:opentelemetry_sdk-"),
160            "Expected service name to start with 'unknown_service:opentelemetry_sdk-', got: {}",
161            service_name
162        );
163
164        temp_env::with_var(OTEL_SERVICE_NAME, Some("test service"), || {
165            let with_service = SdkProvidedResourceDetector.detect();
166            assert_eq!(
167                with_service.get(&Key::from_static_str(crate::resource::SERVICE_NAME)),
168                Some(Value::from("test service")),
169            )
170        });
171
172        temp_env::with_var(
173            OTEL_RESOURCE_ATTRIBUTES,
174            Some("service.name=test service1"),
175            || {
176                let with_service = SdkProvidedResourceDetector.detect();
177                assert_eq!(
178                    with_service.get(&Key::from_static_str(crate::resource::SERVICE_NAME)),
179                    Some(Value::from("test service1")),
180                )
181            },
182        );
183
184        // OTEL_SERVICE_NAME takes priority
185        temp_env::with_vars(
186            [
187                (OTEL_SERVICE_NAME, Some("test service")),
188                (OTEL_RESOURCE_ATTRIBUTES, Some("service.name=test service3")),
189            ],
190            || {
191                let with_service = SdkProvidedResourceDetector.detect();
192                assert_eq!(
193                    with_service.get(&Key::from_static_str(crate::resource::SERVICE_NAME)),
194                    Some(Value::from("test service"))
195                );
196            },
197        );
198    }
199}
opentelemetry_sdk/resource/env.rs

opentelemetry_sdk/resource/
env.rs
