feat(propagator-env-carrier): make EnvironmentGetter read the current process.env

experimental/CHANGELOG.md

@@ -19,6 +19,7 @@ For notes on migrating to 2.x / 0.200.x see [the upgrade guide](doc/upgrade-to-2
 * feat(configuration): bump config schema to v1.1.0; rename `without_scope_info` → `scope_info_enabled` and `without_target_info/development` → `target_info_enabled/development` on the Prometheus pull exporter (semantics inverted), rename `with_resource_constant_labels` → `resource_constant_labels`. Validate `file_format` per the configuration versioning spec: accept any minor version of major `1` (e.g. `1.0`, `1.1`), warn when the minor version is newer than supported, and reject other major versions. [#6781](https://github.com/open-telemetry/opentelemetry-js/pull/6781) @MikeGoldsmith
 * feat(sdk-node): wire up `id_generator` from declarative config [#6782](https://github.com/open-telemetry/opentelemetry-js/pull/6782) @MikeGoldsmith
 * feat(propagator-env-carrier): empty name normalization [#6827](https://github.com/open-telemetry/opentelemetry-js/pull/6827) @pellared
+* feat(propagator-env-carrier): make `EnvironmentGetter` read the current `process.env` [#6853](https://github.com/open-telemetry/opentelemetry-js/pull/6853) @pellared
 
 ### :bug: Bug Fixes
 

experimental/packages/opentelemetry-propagator-env-carrier/README.md

@@ -50,8 +50,8 @@ console.log(output);
 ```
 
 Use `EnvironmentGetter` during process startup to extract context that was
-provided through environment variables. It reads from its own snapshot, so pass
-`undefined` as the carrier when extracting.
+provided through environment variables. It reads from the current `process.env`,
+so pass `undefined` as the carrier when extracting.
 
 ```javascript
 const { ROOT_CONTEXT, trace } = require('@opentelemetry/api');
@@ -72,9 +72,9 @@ console.log(spanContext.traceId);
 // 0102030405060708090a0b0c0d0e0f10
 ```
 
-`EnvironmentGetter` snapshots `process.env` when it is constructed. Later
-changes to `process.env` are not reflected in that getter. Only environment
-variables whose names are already normalized are included in the snapshot.
+`EnvironmentGetter` reads `process.env` each time `get()` or `keys()` is called.
+Later changes to `process.env` are reflected in the same getter. Its `keys()`
+method returns only environment variables whose names are already normalized.
 
 ## Key Normalization
 
@@ -92,10 +92,10 @@ For example, `traceparent` becomes `TRACEPARENT`, `trace-state` becomes
 
 `EnvironmentSetter` always writes normalized key names to its environment map.
 `EnvironmentGetter` normalizes the requested propagator key and reads the
-corresponding normalized environment variable name from its snapshot. Its
-`keys()` method returns only environment variable names that are already
-normalized. For example, a propagator request for `x-b3-traceid` matches
-`X_B3_TRACEID` from `process.env`, but does not match `x-b3-traceid`.
+corresponding normalized environment variable name from the current
+`process.env`. Its `keys()` method returns only environment variable names that
+are already normalized. For example, a propagator request for `x-b3-traceid`
+matches `X_B3_TRACEID` from `process.env`, but does not match `x-b3-traceid`.
 
 Name collisions after normalization should be avoided. For example,
 `trace-state` and `TRACE_STATE` both normalize to `TRACE_STATE`. When injecting,

experimental/packages/opentelemetry-propagator-env-carrier/src/env-carrier.ts

@@ -94,35 +94,40 @@ function normalizeKey(key: string): string {
 }
 
 /**
- * TextMapGetter that reads propagation values from a process environment
- * snapshot.
+ * TextMapGetter that reads propagation values from the process environment.
  *
- * `EnvironmentGetter` snapshots `process.env` when it is constructed and
- * ignores the carrier passed to `get()` and `keys()`. Pass `undefined` as the
- * carrier when using this getter with a `TextMapPropagator`.
+ * `EnvironmentGetter` reads the current `process.env` and ignores the carrier
+ * passed to `get()` and `keys()`. Pass `undefined` as the carrier when using
+ * this getter with a `TextMapPropagator`.
  *
- * Only environment variables whose names are already normalized are stored in
- * the snapshot. The requested propagator key is normalized before lookup.
+ * `keys()` returns only environment variables whose names are already
+ * normalized. The requested propagator key is normalized before lookup.
  *
  * @see https://opentelemetry.io/docs/specs/otel/context/env-carriers/
  */
 export class EnvironmentGetter implements TextMapGetter<void> {
-  private readonly _carrier: Record<string, string> = {};
+  get(_carrier: void, key: string): string | undefined {
+    const normalizedKey = normalizeKey(key);
 
-  constructor() {
-    for (const [key, value] of Object.entries(process.env)) {
-      if (value !== undefined && isNormalizedKey(key)) {
-        this._carrier[key] = value;
+    for (const [envKey, value] of Object.entries(process.env)) {
+      if (value !== undefined && envKey === normalizedKey) {
+        return value;
       }
     }
-  }
 
-  get(_carrier: void, key: string): string | undefined {
-    return this._carrier[normalizeKey(key)];
+    return undefined;
   }
 
   keys(_carrier: void): string[] {
-    return Object.keys(this._carrier);
+    const keys: string[] = [];
+
+    for (const [key, value] of Object.entries(process.env)) {
+      if (value !== undefined && isNormalizedKey(key)) {
+        keys.push(key);
+      }
+    }
+
+    return keys;
   }
 }
 

experimental/packages/opentelemetry-propagator-env-carrier/test/env-carrier.test.ts

@@ -144,7 +144,7 @@ describe('EnvironmentGetter and EnvironmentSetter', () => {
       assert.strictEqual(getter.get(undefined, 'x-b3-traceid'), 'b3-value');
     });
 
-    it('should return only already normalized snapshot keys', () => {
+    it('should return only already normalized environment keys', () => {
       process.env.TRACEPARENT = 'traceparent-value';
       process.env.TRACE_STATE = 'tracestate-value';
       process.env['trace-state'] = 'ignored';
@@ -159,13 +159,13 @@ describe('EnvironmentGetter and EnvironmentSetter', () => {
       ]);
     });
 
-    it('should return empty keys for an empty environment snapshot', () => {
+    it('should return empty keys for an empty environment', () => {
       const getter = new EnvironmentGetter();
 
       assert.deepStrictEqual(getter.keys(undefined), []);
     });
 
-    it('should ignore empty environment names when snapshotting', () => {
+    it('should ignore empty environment names when listing keys', () => {
       const env = process.env;
       process.env = {
         '': 'ignored',
@@ -213,18 +213,28 @@ describe('EnvironmentGetter and EnvironmentSetter', () => {
       assert.strictEqual(getter.get(undefined, 'empty'), '');
     });
 
-    it('should snapshot process.env at construction time', () => {
+    it('should read current process.env values after construction', () => {
       process.env.TRACEPARENT = 'original';
+      process.env.TRACESTATE = 'initial';
       const getter = new EnvironmentGetter();
 
       process.env.TRACEPARENT = 'updated';
-      process.env.TRACESTATE = 'added-after-construction';
+      process.env.BAGGAGE = 'added-after-construction';
+      delete process.env.TRACESTATE;
 
-      assert.strictEqual(getter.get(undefined, 'traceparent'), 'original');
+      assert.strictEqual(getter.get(undefined, 'traceparent'), 'updated');
       assert.strictEqual(getter.get(undefined, 'tracestate'), undefined);
+      assert.strictEqual(
+        getter.get(undefined, 'baggage'),
+        'added-after-construction'
+      );
+      assert.deepStrictEqual(getter.keys(undefined).sort(), [
+        'BAGGAGE',
+        'TRACEPARENT',
+      ]);
     });
 
-    it('should read from the environment snapshot without a carrier', () => {
+    it('should read from process.env without a carrier', () => {
       process.env.TRACEPARENT = 'environment-value';
 
       const getter = new EnvironmentGetter();
@@ -258,7 +268,7 @@ describe('EnvironmentGetter and EnvironmentSetter', () => {
       });
     });
 
-    it('should extract W3C trace context from an environment snapshot', () => {
+    it('should extract W3C trace context from process.env', () => {
       process.env.TRACEPARENT = `00-${traceId}-${spanId}-01`;
       process.env.TRACESTATE = 'vendor1=value1,vendor2=value2';
 
@@ -308,7 +318,7 @@ describe('EnvironmentGetter and EnvironmentSetter', () => {
       assert.strictEqual(carrier.BAGGAGE, 'first=one,second=two');
     });
 
-    it('should extract W3C baggage from an environment snapshot', () => {
+    it('should extract W3C baggage from process.env', () => {
       process.env.BAGGAGE = 'first=one,second=two';
 
       const propagator = new W3CBaggagePropagator();