Implement Environment Variable Context Propagation carriers in api/in… by Bhagirath00 · Pull Request #8074 · open-telemetry/opentelemetry-java

Bhagirath00 · 2026-02-12T12:55:48Z

This PR implements environmental variable context propagation by adding EnvironmentGetter and EnvironmentSetter carriers to the api/incubator module. This allows the Java SDK to extract and inject trace data through standard environment variables.

Changes

Added EnvironmentGetter to handle context extraction from environment variables.
Added EnvironmentSetter to handle context injection for child processes.
Implemented logic to ensure environment variable keys are handled in the standard uppercase format.
Added comprehensive unit tests to verify case-insensitive lookups and correct value extraction.

Terminal Screenshots

All new unit tests passed successfully.

Code has been formatted and passed style checks.

…cubator

linux-foundation-easycla · 2026-02-12T12:55:56Z

The committers listed above are authorized under a signed CLA.

✅ login: Bhagirath00 / name: Bhagirath (4cfffac, 521c041, b1c2d19, b8d7f67, c9cdbe4, df9a72b)

codecov · 2026-02-12T13:03:05Z

Codecov Report

❌ Patch coverage is 96.87500% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 90.33%. Comparing base (fff95e0) to head (b8d7f67).
⚠️ Report is 25 commits behind head on main.

Files with missing lines	Patch %	Lines
...y/api/incubator/propagation/EnvironmentGetter.java	93.33%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #8074      +/-   ##
============================================
+ Coverage     90.20%   90.33%   +0.13%     
- Complexity     7592     7629      +37     
============================================
  Files           841      841              
  Lines         22911    22920       +9     
  Branches       2288     2286       -2     
============================================
+ Hits          20666    20704      +38     
+ Misses         1529     1506      -23     
+ Partials        716      710       -6

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api/incubator/src/main/java/io/opentelemetry/api/incubator/propagation/EnvironmentGetter.java

jack-berg · 2026-02-13T16:51:39Z

api/incubator/src/main/java/io/opentelemetry/api/incubator/propagation/EnvironmentSetter.java

+      return;
+    }
+    // Spec recommends using uppercase for environment variable names.
+    carrier.put(key.toUpperCase(Locale.ROOT), value);


What about format restrictions? https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/context/env-carriers.md#format-restrictions

Marking as unresolved because I don't see anything related to the restriction of characters to those that are valid in HTTP header fields, or explanation for how we should be thinking about the platform specific size limitations. Size limitations could be an optional config parameter, for example. Not sure.

Okay, I've added value validation for HTTP header field characters per RFC 9110 — the setter skips and the getter ignores values with invalid characters. For size limits, I've documented the platform-specific limits in the Javadoc for now since the caller controls how many entries go into the map. Let me know if you'd prefer something more like a configurable limit instead.

This seems fine for now.

api/incubator/src/main/java/io/opentelemetry/api/incubator/propagation/EnvironmentGetter.java

jack-berg · 2026-02-13T16:59:38Z

api/incubator/src/main/java/io/opentelemetry/api/incubator/propagation/EnvironmentSetter.java

+ * TRACESTATE}, {@code BAGGAGE}). This setter translates keys to uppercase before inserting them
+ * into the carrier.
+ */
+public enum EnvironmentSetter implements TextMapSetter<Map<String, String>> {


So where would this type of thing be used in practice? Since its just setting into a map, the only thing about it specific to env vars is the formatting of the keys.

The caller would have to be managing sub processes and need to manipulate their environment. Something like:

Map<String, String> env = new HashMap<>(); contextPropagators.getTextMapPropagator().inject(context, env, EnvironmentSetter.getInstance()); ProcessBuilder processBuilder = new ProcessBuilder(); processBuilder.environment().putAll(env);

Is this what you had in mind? Have any users asked for this or this just to be spec complete?

Exactly. I just wanted a simple way to make sure the keys get formatted correctly for environment variables (uppercase/underscores) without having to do it manually every time we use something like a ProcessBuilder.

Makes sense to me. Marking as unresolved just so it be a more visible explanation for why we have this, when we don't have any other built-in getter / setter implementations. (Its occasionally useful to come back to PRs and find the key comments.)

I've added a ProcessBuilder usage example and a clearer explanation directly in the Javadoc now, so future readers can see the purpose without digging through PR comments.

Apply spotless auto-formatting to align with project code style

Bhagirath00 · 2026-02-15T12:02:57Z

Well i think Build are failing!!!

…ailures

Bhagirath00 · 2026-02-16T17:34:59Z

@jack-berg Plz review!

jack-berg · 2026-02-17T14:48:55Z

Please respond: #8074 (comment)

Bhagirath00 · 2026-02-17T15:40:32Z

@jack-berg Sorry for inconvenience!

Bhagirath00 · 2026-02-18T12:38:02Z

@jack-berg Updated the PR based on your feedback!!

jack-berg

Just a couple of remaining nits. @adrielp any chance you could take a look and confirm this matches your expectations based on the spec?

api/incubator/src/main/java/io/opentelemetry/api/incubator/propagation/EnvironmentGetter.java

Bhagirath00 · 2026-02-21T06:59:14Z

Plz update this Pr

adrielp · 2026-02-21T14:40:07Z

api/incubator/src/main/java/io/opentelemetry/api/incubator/propagation/EnvironmentGetter.java

+    // Spec recommends using uppercase and underscores for environment variable
+    // names for maximum
+    // cross-platform compatibility.
+    String sanitizedKey = key.replace('.', '_').replace('-', '_').toUpperCase(Locale.ROOT);


Since EnvironmentGetter reads from the environment, keeping a copy, shouldn't this be toLowerCase instead of toUpperCase? Upper case I don't think will end up matching header values since the spec for w3c for example is traceparent not TRACEPARENT. environment variables in the environment should be uppercase, _ separated, but to auto be mapped to the w3c spec the normalized to lower.

Hopefully this makes sense, and hopefully I'm reading this right. I haven't touched Java in a long time.

adrielp · 2026-02-21T14:43:57Z

Just a couple of remaining nits. @adrielp any chance you could take a look and confirm this matches your expectations based on the spec?

Thanks all for the work on this. I checked it out. Everything looks pretty good, I had one key question though about lower/upper case within the carrier.

jack-berg · 2026-02-21T21:31:31Z

Just a couple of remaining nits. @adrielp any chance you could take a look and confirm this matches your expectations based on the spec?

Thanks all for the work on this. I checked it out. Everything looks pretty good, I had one key question though about lower/upper case within the carrier.

@adrielp now that you mention it, it's not possible for lossless round tripping as a result of both the case and the fact that both . and - are converted to _. Did this come up when landing the spec work?

adrielp · 2026-02-23T14:31:32Z

@adrielp now that you mention it, it's not possible for lossless round tripping as a result of both the case and the fact that both . and - are converted to _. Did this come up when landing the spec work?

Can you elaborate more on that statement?

Implement Environment Variable Context Propagation carriers in api/in…

df9a72b

…cubator

Bhagirath00 requested a review from a team as a code owner February 12, 2026 12:55

jack-berg reviewed Feb 13, 2026

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Bhagirath00 added 2 commits February 15, 2026 16:46

fix: Align environment carriers with spec requirements

4cfffac

chore: Fix spotless formatting violations

b1c2d19

Apply spotless auto-formatting to align with project code style

fix: refactor environment carriers to standard singleton and fix CI f…

c9cdbe4

…ailures

Bhagirath00 mentioned this pull request Feb 17, 2026

Fix/declarative config no exceptions #8079

Open

[incubator] Add format restriction handling for EnvironmentGetter/Setter

521c041

jack-berg reviewed Feb 18, 2026

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api/incubator/src/main/java/io/opentelemetry/api/incubator/propagation/EnvironmentGetter.java Outdated Show resolved Hide resolved

api/incubator/src/main/java/io/opentelemetry/api/incubator/propagation/EnvironmentGetter.java Outdated Show resolved Hide resolved

Remove duplicate isValidHttpHeaderValue and fix log message quoting

b8d7f67

jack-berg approved these changes Feb 19, 2026

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adrielp reviewed Feb 21, 2026

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Bhagirath00 commented Feb 12, 2026

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