feat: [Geneva Exporter] Add configurable User-Agent Header #400

lalitb · 2025-07-30T23:01:21Z

Changes

The User-Agent HTTP header should ideally identify the application making the request, not just the library.
This PR adds configurable User-Agent header support to the Geneva Uploader, allowing applications to identify themselves in HTTP requests to Geneva services.

So the approach with the PR is:

Configuration	Resulting User-Agent
`None`	`RustGenevaClient/0.1`
`Some("MyApp/2.1.0")`	`MyApp/2.1.0 (RustGenevaClient/0.1)`

Also added support to provide the user-agent header in the Ingestion Service (along with Config Service)

Merge requirement checklist

CONTRIBUTING guidelines followed
Unit tests added/updated (if applicable)
Appropriate CHANGELOG.md files updated for non-trivial, user-facing changes
Changes in public API reviewed (if applicable)

opentelemetry-exporter-geneva/geneva-uploader/src/config_service/client.rs

utpilla · 2025-08-01T06:05:31Z

Changes

The User-Agent HTTP header should ideally identify the application making the request, not just the library.

If this is the only intention, then should we choose the User Agent ourselves instead of letting the user override it and potentially misuse or erroneously use it. We should be able to get hold of the executable name through std::env::args() or std::env::current_exe().

…ust-contrib into custom-user-agent

codecov · 2025-08-01T17:02:56Z

Codecov Report

❌ Patch coverage is 92.25352% with 11 lines in your changes missing coverage. Please review.
✅ Project coverage is 54.1%. Comparing base (8b9ef08) to head (aa6fb5e).

Files with missing lines	Patch %	Lines
...eneva/geneva-uploader/src/ingestion_service/mod.rs	0.0%	4 Missing ⚠️
...r-geneva/geneva-uploader/src/config_service/mod.rs	83.3%	3 Missing ⚠️
stress/src/geneva_exporter.rs	0.0%	3 Missing ⚠️
...try-exporter-geneva/geneva-uploader-ffi/src/lib.rs	66.6%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##            main    #400     +/-   ##
=======================================
+ Coverage   53.6%   54.1%   +0.4%     
=======================================
  Files         71      72      +1     
  Lines      11632   11763    +131     
=======================================
+ Hits        6244    6364    +120     
- Misses      5388    5399     +11

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lalitb · 2025-08-01T21:55:58Z

If this is the only intention, then should we choose the User Agent ourselves instead of letting the user override it and potentially misuse or erroneously use it. We should be able to get hold of the executable name through std::env::args() or std::env::current_exe().

Intention is to provide the applications to provide the customization for the User-Agent- according to the format they want (which could be say MyApp/1.0

utpilla · 2025-08-06T17:57:52Z

opentelemetry-exporter-geneva/geneva-uploader/src/common.rs

+        format!("{prefix} (GenevaUploader/0.1)")
+    };
+
+    HeaderValue::from_str(&user_agent).map_err(|e| {


It looks like this method does the ASCII characters validation check anyway so we could get avoid checking that ourselves.

utpilla · 2025-08-06T18:00:00Z

opentelemetry-exporter-geneva/geneva-uploader/src/common.rs

+    for (i, ch) in prefix.char_indices() {
+        match ch {
+            // Control characters that would break HTTP headers
+            '\r' | '\n' | '\0' => {


I think had initially suggested checking for control characters in a comment, but I realized they would anyway be outside of the ASCII range so we would never allow control characters as long as we only accept ASCII.

And the ASCII check is already done by HeaderValue::from_str() method, so we can probably get rid of this whole method.

It seems HeaderValue::from_str() allows non-ascii chars
https://play.rust-lang.org/?version=stable&mode=debug&edition=2024&gist=1e264800416082c69cbb17c474caab02

But I am good to remove the validation altogether, and let the reqwest crate handle it.

It seems HeaderValue::from_str() allows non-ascii chars https://play.rust-lang.org/?version=stable&mode=debug&edition=2024&gist=1e264800416082c69cbb17c474caab02

This led to some new learnings. The documentation for HeaderValue::from_str() method says that it doesn't allow non-ASCII characters so I would have expected the test cases you shared to fail. I then found this is in the documentation for HeaderValue struct:

In practice, HTTP header field values are usually valid ASCII. However, the HTTP spec allows for a header value to contain opaque bytes as well. In this case, the header field value is not able to be represented as a string.

To handle this, the HeaderValue is useable as a type and can be compared with strings and implements Debug. A to_str fn is provided that returns an Err if the header value contains non visible ascii characters.

This means that we need to check if HeaderValue::from_str(str).is_ok() && HeaderValue::from_str(str).unwrap().to_str().is_ok() to rule out the non-ASCII inputs.

Check this: https://play.rust-lang.org/?version=stable&mode=debug&edition=2024&gist=9802b30e262c93e92e71fd92fcb543dd

utpilla · 2025-08-06T18:02:14Z

opentelemetry-exporter-geneva/geneva-uploader/src/client.rs

    pub async fn new(cfg: GenevaClientConfig) -> Result<Self, String> {
-        // Build config client config
+        // Validate user agent prefix once and build headers once for both services
+        // This avoids duplicate validation and header building in config and ingestion services


This looks like a duplicate validation since build_geneva_headers method also calls validate_user_agent_prefix method.

Copilot

Pull Request Overview

This PR adds configurable user-agent prefix support to the Geneva client, allowing applications to identify themselves in HTTP requests. The user agent format becomes "{prefix} (RustGenevaClient/0.1)" when a prefix is provided, or defaults to "RustGenevaClient/0.1" when None.

Key changes:

Added user_agent_prefix field to GenevaClientConfig with validation and documentation
Introduced common.rs module with header building utilities and comprehensive validation
Refactored header construction to centralize logic and enable header reuse across config and ingestion services

Reviewed Changes

Copilot reviewed 13 out of 13 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
opentelemetry-exporter-geneva/geneva-uploader/src/common.rs	New module containing header building utilities with validation for user-agent strings
opentelemetry-exporter-geneva/geneva-uploader/src/client.rs	Added user_agent_prefix field to GenevaClientConfig with documentation and header building
opentelemetry-exporter-geneva/geneva-uploader/src/config_service/client.rs	Refactored to use static headers from config, removed build_static_headers method
opentelemetry-exporter-geneva/geneva-uploader/src/ingestion_service/uploader.rs	Added static_headers field to GenevaUploaderConfig and merged into client headers
opentelemetry-exporter-geneva/geneva-uploader/src/lib.rs	Added common module to public exports
stress/src/geneva_exporter.rs	Updated test configurations to include user_agent_prefix field
opentelemetry-exporter-geneva/opentelemetry-exporter-geneva/examples/*.rs	Updated example configurations to include user_agent_prefix field
opentelemetry-exporter-geneva/geneva-uploader-ffi/src/lib.rs	Added user_agent_prefix field with None default for FFI
opentelemetry-exporter-geneva/geneva-uploader/src/config_service/mod.rs	Updated tests to build and pass static_headers
opentelemetry-exporter-geneva/geneva-uploader/src/ingestion_service/mod.rs	Updated tests to build and pass static_headers

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Copilot · 2025-11-04T01:03:46Z

opentelemetry-exporter-geneva/geneva-uploader/src/client.rs

+    /// User agent prefix for the application. Will be formatted as "<prefix> (GenevaUploader/0.1)".
+    /// If None, defaults to "GenevaUploader/0.1".
+    ///
+    /// The prefix must contain only ASCII printable characters, be non-empty (after trimming),
+    /// and not exceed 200 characters in length.
+    ///
+    /// Examples:
+    /// - None: "GenevaUploader/0.1"
+    /// - Some("MyApp/2.1.0"): "MyApp/2.1.0 (GenevaUploader/0.1)"
+    /// - Some("ProductionService-1.0"): "ProductionService-1.0 (GenevaUploader/0.1)"


The documentation states the format will use 'GenevaUploader/0.1' but the actual implementation in build_user_agent_header uses 'RustGenevaClient/0.1'. This inconsistency between documented and actual behavior should be corrected to match the implementation.

Suggested change

/// User agent prefix for the application. Will be formatted as "<prefix> (GenevaUploader/0.1)".

/// If None, defaults to "GenevaUploader/0.1".

///

/// The prefix must contain only ASCII printable characters, be non-empty (after trimming),

/// and not exceed 200 characters in length.

///

/// Examples:

/// - None: "GenevaUploader/0.1"

/// - Some("MyApp/2.1.0"): "MyApp/2.1.0 (GenevaUploader/0.1)"

/// - Some("ProductionService-1.0"): "ProductionService-1.0 (GenevaUploader/0.1)"

/// User agent prefix for the application. Will be formatted as "<prefix> (RustGenevaClient/0.1)".

/// If None, defaults to "RustGenevaClient/0.1".

///

/// The prefix must contain only ASCII printable characters, be non-empty (after trimming),

/// and not exceed 200 characters in length.

///

/// Examples:

/// - None: "RustGenevaClient/0.1"

/// - Some("MyApp/2.1.0"): "MyApp/2.1.0 (RustGenevaClient/0.1)"

/// - Some("ProductionService-1.0"): "ProductionService-1.0 (RustGenevaClient/0.1)"

Copilot · 2025-11-04T01:03:46Z

opentelemetry-exporter-geneva/geneva-uploader/src/client.rs

+    /// User agent prefix for the application. Will be formatted as "<prefix> (GenevaUploader/0.1)".
+    /// If None, defaults to "GenevaUploader/0.1".
+    ///
+    /// The prefix must contain only ASCII printable characters, be non-empty (after trimming),
+    /// and not exceed 200 characters in length.
+    ///
+    /// Examples:
+    /// - None: "GenevaUploader/0.1"
+    /// - Some("MyApp/2.1.0"): "MyApp/2.1.0 (GenevaUploader/0.1)"
+    /// - Some("ProductionService-1.0"): "ProductionService-1.0 (GenevaUploader/0.1)"


The examples show 'GenevaUploader/0.1' but the actual format produced by the implementation is 'RustGenevaClient/0.1'. All examples should be updated to reflect the actual implementation.

Suggested change

/// User agent prefix for the application. Will be formatted as "<prefix> (GenevaUploader/0.1)".

/// If None, defaults to "GenevaUploader/0.1".

///

/// The prefix must contain only ASCII printable characters, be non-empty (after trimming),

/// and not exceed 200 characters in length.

///

/// Examples:

/// - None: "GenevaUploader/0.1"

/// - Some("MyApp/2.1.0"): "MyApp/2.1.0 (GenevaUploader/0.1)"

/// - Some("ProductionService-1.0"): "ProductionService-1.0 (GenevaUploader/0.1)"

/// User agent prefix for the application. Will be formatted as "<prefix> (RustGenevaClient/0.1)".

/// If None, defaults to "RustGenevaClient/0.1".

///

/// The prefix must contain only ASCII printable characters, be non-empty (after trimming),

/// and not exceed 200 characters in length.

///

/// Examples:

/// - None: "RustGenevaClient/0.1"

/// - Some("MyApp/2.1.0"): "MyApp/2.1.0 (RustGenevaClient/0.1)"

/// - Some("ProductionService-1.0"): "ProductionService-1.0 (RustGenevaClient/0.1)"

lalitb added 4 commits July 30, 2025 15:31

fix

d0792f3

fix

880d6e5

fix

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more changes

78be687

lalitb requested a review from a team as a code owner July 30, 2025 23:01

lalitb changed the title ~~feat: [Geneva Exporter] Add configurable User-Agent Header Support~~ feat: [Geneva Exporter] Add configurable User-Agent Header Jul 30, 2025

utpilla added the opentelemetry-exporter-geneva label Aug 1, 2025

utpilla reviewed Aug 1, 2025

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lalitb added 7 commits August 1, 2025 09:19

Merge branch 'main' into custom-user-agent

a0797f7

fix

99f10d7

Merge branch 'custom-user-agent' of github.com:lalitb/opentelemetry-r…

2806cf3

…ust-contrib into custom-user-agent

Merge branch 'main' into custom-user-agent

606caf6

fix

76da83c

Merge branch 'custom-user-agent' of github.com:lalitb/opentelemetry-r…

a381d16

…ust-contrib into custom-user-agent

fix

50d94cd

lalitb added 11 commits August 1, 2025 10:38

fix

7ecda1b

fix

7b2d972

fix

d912832

add missing common.rs

504845e

add user-agent support in ingestion_service

5881c06

fix warning

f57c640

fix

80e4528

more rearrange

d623496

fix

9cb1145

add todo

3c02e09

fix

683820c

lalitb added 3 commits August 1, 2025 14:46

reformat

1675d6c

build errors

c7121d1

fix

2ec20c4

Merge branch 'main' into custom-user-agent

6ab85ab

utpilla reviewed Aug 6, 2025

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lalitb added 5 commits August 6, 2025 11:03

Merge branch 'main' into custom-user-agent

6fb82cb

Merge branch 'main' into custom-user-agent

643e5ab

remove non-ascii validation

e2d84be

fix nit

f5d840d

nit doc

ca74e81

lalitb requested a review from utpilla November 3, 2025 23:54

more build fix

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lalitb requested a review from Copilot November 4, 2025 01:02

Copilot AI reviewed Nov 4, 2025

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lalitb added 2 commits November 3, 2025 18:07

doc fix

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fix

aa6fb5e

lalitb mentioned this pull request Nov 4, 2025

fix(geneva uploader): Replace unwrap/expect with graceful error handling #485

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