in_http: add support for fixed tag configuration parameter

[kalavt]

Add Fixed Tag Configuration Parameter to in_http Plugin

Description

This PR adds support for a tag configuration parameter in the in_http input plugin, allowing users to specify a fixed tag for all incoming records. This addresses scenarios where users want consistent tagging without relying on URL paths or dynamic extraction from record content.

Problem Statement

Currently, the in_http plugin determines tags using the following logic:

1. Extract from record content if tag_key is configured
2. Use URL path from the HTTP request
3. Fall back to default plugin instance name (e.g., http.0)

This creates issues when:

• Users want a consistent fixed tag for all records
• The default http.0 tag doesn't match their routing configuration
• Dynamic URL-based tagging is not desired
• To consistent with other plugins to eliminate misunderstandings

Solution

Added a new tag configuration parameter that allows users to specify a fixed tag. The updated tag selection priority is now:

1. tag_key - Extract from record content (highest priority)
2. URL path - From HTTP request path
3. tag parameter - User-configured fixed tag (new)
4. Default plugin tag - Plugin instance name (e.g., http.0)

Changes

Source Code

• plugins/in_http/http.h: Added flb_sds_t tag field to struct flb_http
• plugins/in_http/http.c: Added tag parameter to config_map
• plugins/in_http/http_prot.c: Updated process_pack_record() to use ctx->tag as fallback
• plugins/in_http/http_config.c: Added cleanup for ctx->tag in http_config_destroy()

Tests

• tests/runtime/in_http.c: Added flb_test_http_fixed_tag() test case

Usage Example

[INPUT]
    Name http
    Port 9880
    Tag http_logs    # Fixed tag for all incoming records

[OUTPUT]
    Name kafka
    Match http_logs  # Now correctly matches the configured tag

Testing

All unit tests pass successfully:

Test http...                                    [ OK ]
Test successful_response_code_200...            [ OK ]
Test successful_response_code_204...            [ OK ]
Test failure_response_code_400_bad_json...      [ OK ]
Test failure_response_code_400_bad_disk_write... [ OK ]
Test tag_key_with_map_input...                  [ OK ]
Test tag_key_with_array_input...                [ OK ]
Test fixed_tag...                               [ OK ] ⭐ (new test)
Test oauth2_requires_token...                   [ OK ]
Test oauth2_accepts_valid_token...              [ OK ]

SUCCESS: All unit tests have passed.

Backward Compatibility

✅ This change is fully backward compatible. Existing configurations will continue to work as before since the tag parameter is optional and defaults to NULL.

Checklist

• Code follows project coding style
• Commit message follows project convention (in_http: description)
• All existing unit tests pass
• New unit test added for the feature
• Code compiles without errors or new warnings
• Memory cleanup properly implemented
• Signed-off-by line included in commit

Summary by CodeRabbit

• New Features

  • HTTP input can be configured with a fixed tag to apply to all incoming requests.

• Bug Fixes

  • Fixed-tag configuration now reliably overrides URL/path-based tagging when present.

• Tests

  • Added automated test validating fixed-tag routing, request handling, and output generation.

[coderabbitai]

📝 Walkthrough

Walkthrough

Adds a configurable fixed_tag to the HTTP input plugin: new tag field on struct flb_http, a fixed_tag config map entry, cleanup in destroy, tag-resolution change to prefer the configured tag when no per-record tag exists, and an accompanying runtime test.

Changes

Cohort / File(s)	Summary
Plugin header & struct plugins/in_http/http.h	Added flb_sds_t tag member to struct flb_http (user-configured fixed_tag).
Plugin config map plugins/in_http/http.c	Added FLB_CONFIG_MAP_STR entry "fixed_tag" wired via offsetof(struct flb_http, tag) to set a fixed tag overriding URL path-based tags.
Lifecycle / cleanup plugins/in_http/http_config.c	Free ctx->tag in http_config_destroy using flb_sds_destroy() when non-NULL.
Tag resolution / protocol plugins/in_http/http_prot.c	In process_pack_record, when no per-record tag is present, use ctx->tag if configured; minor comment wording tweak.
Tests tests/runtime/in_http.c	Added flb_test_http_fixed_tag() and registered it in TEST_LIST; test posts JSON to / and verifies output routed by the fixed tag.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~25 minutes

Suggested reviewers

• edsiper
• cosmo0920

Poem

🐰 I found a tag beneath the log,
I fixed it firm and gave a jog,
Requests hop in from near and far,
I stamp them neat — a steady star,
Tiny paws on data’s log.

🚥 Pre-merge checks | ✅ 2 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 25.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title 'in_http: add support for fixed tag configuration parameter' clearly and specifically describes the main change—adding a fixed tag configuration parameter to the in_http input plugin.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing touches

• 📝 Generate docstrings

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment

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[chatgpt-codex-connector]

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[coderabbitai]

Actionable comments posted: 1

🤖 Fix all issues with AI agents

In `@tests/runtime/in_http.c`:
- Around line 987-996: flb_http_add_header is called before confirming the HTTP
client pointer c was successfully created; reorder the checks so you first
verify c != NULL (the result of flb_http_client) and handle the error (TEST_MSG
and early exit) before calling flb_http_add_header, keeping the same variable
names (c) and functions (flb_http_client, flb_http_add_header) to locate and
update the logic.

[coderabbitai]

Actionable comments posted: 1

🤖 Fix all issues with AI agents

In `@tests/runtime/in_http.c`:
- Around line 944-1022: The test flb_test_http_fixed_tag sets a config with the
wrong key ("tag") so the plugin's "fixed_tag" option is never applied; update
the flb_input_set call in flb_test_http_fixed_tag to use the correct config key
name "fixed_tag" (i.e., replace the "tag" argument passed to flb_input_set with
"fixed_tag") so the fixed tag configuration is actually applied when the test
runs.