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(|| "unknown_service".into()),
90            )])
91            .build()
92    }
93}
94
95#[cfg(test)]
96mod tests {
97    use crate::resource::env::{
98        SdkProvidedResourceDetector, OTEL_RESOURCE_ATTRIBUTES, OTEL_SERVICE_NAME,
99    };
100    use crate::resource::{EnvResourceDetector, Resource, ResourceDetector};
101    use opentelemetry::{Key, KeyValue, Value};
102
103    #[test]
104    fn test_read_from_env() {
105        temp_env::with_vars(
106            [
107                (
108                    "OTEL_RESOURCE_ATTRIBUTES",
109                    Some("key=value, k = v , a= x, a=z,base64=SGVsbG8sIFdvcmxkIQ=="),
110                ),
111                ("IRRELEVANT", Some("20200810")),
112            ],
113            || {
114                let detector = EnvResourceDetector::new();
115                let resource = detector.detect();
116                assert_eq!(
117                    resource,
118                    Resource::builder_empty()
119                        .with_attributes([
120                            KeyValue::new("key", "value"),
121                            KeyValue::new("k", "v"),
122                            KeyValue::new("a", "x"),
123                            KeyValue::new("a", "z"),
124                            KeyValue::new("base64", "SGVsbG8sIFdvcmxkIQ=="), // base64('Hello, World!')
125                        ])
126                        .build()
127                );
128            },
129        );
130
131        let detector = EnvResourceDetector::new();
132        let resource = detector.detect();
133        assert!(resource.is_empty());
134    }
135
136    #[test]
137    fn test_sdk_provided_resource_detector() {
138        // Ensure no env var set
139        let no_env = SdkProvidedResourceDetector.detect();
140        assert_eq!(
141            no_env.get(&Key::from_static_str(crate::resource::SERVICE_NAME)),
142            Some(Value::from("unknown_service")),
143        );
144
145        temp_env::with_var(OTEL_SERVICE_NAME, Some("test service"), || {
146            let with_service = SdkProvidedResourceDetector.detect();
147            assert_eq!(
148                with_service.get(&Key::from_static_str(crate::resource::SERVICE_NAME)),
149                Some(Value::from("test service")),
150            )
151        });
152
153        temp_env::with_var(
154            OTEL_RESOURCE_ATTRIBUTES,
155            Some("service.name=test service1"),
156            || {
157                let with_service = SdkProvidedResourceDetector.detect();
158                assert_eq!(
159                    with_service.get(&Key::from_static_str(crate::resource::SERVICE_NAME)),
160                    Some(Value::from("test service1")),
161                )
162            },
163        );
164
165        // OTEL_SERVICE_NAME takes priority
166        temp_env::with_vars(
167            [
168                (OTEL_SERVICE_NAME, Some("test service")),
169                (OTEL_RESOURCE_ATTRIBUTES, Some("service.name=test service3")),
170            ],
171            || {
172                let with_service = SdkProvidedResourceDetector.detect();
173                assert_eq!(
174                    with_service.get(&Key::from_static_str(crate::resource::SERVICE_NAME)),
175                    Some(Value::from("test service"))
176                );
177            },
178        );
179    }
180}
opentelemetry_sdk/resource/env.rs

opentelemetry_sdk/resource/
env.rs
