feat: add additional preset environment variables

[patrick-stephens]

Resolves #224 by adding preset environment variables based on the host or build metadata

• OS_TYPE = linux, windows or macos
• TELEMETRY_FORGE_AGENT_DISTRO = <the distro we're using, e.g. centos/7>
• TELEMETRY_FORGE_AGENT_PACKAGE_TYPE = CONTAINER or PACKAGE
• TELEMETRY_FORGE_AGENT_VERSION = <the agent version we're building>

In each case it will always check for an overridden variable in the environment first and then only set a default if not defined already.

Tests were added as well for the environment variables including the existing HOSTNAME one.
The macOS CI was not setting some variables either.

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Summary by cubic

Adds preset env vars for OS and agent metadata, shows them in --help, and makes distro/package type mandatory for enterprise builds. CI and packaging pass the required flags; unit and integration tests verify defaults and overrides, addressing #224.

• New Features

  • Auto-sets OS_TYPE to linux, windows, or macos.
  • Adds runtime presets AGENT_DISTRO, AGENT_PACKAGE_TYPE, AGENT_VERSION; derived from build metadata, respect overrides, fall back to "unknown".
  • Enforces TELEMETRY_FORGE_AGENT_DISTRO and TELEMETRY_FORGE_AGENT_PACKAGE_TYPE for enterprise builds; TELEMETRY_FORGE_AGENT_VERSION defaults to FLB_VERSION_STR.
  • Prints Distro, Package, and Version in --help.

• CI and Tests

  • Moves build metadata to source/cmake/enterprise.cmake.
  • Passes -DTELEMETRY_FORGE_* from packaging Dockerfiles, Dockerfile.ubi, macOS and unit-test workflows.
  • Updates build-and-test-container.sh to build a test image and run container integration tests.
  • Adds/updates unit tests for defaults/overrides and an integration test that validates env values via a dummy input and exit plugin.

^{Written for commit b218e0f. Summary will update on new commits.}

[github-actions]

Dependency Review

✅ No vulnerabilities or license issues or OpenSSF Scorecard issues found.

Scanned Files

None

[Copilot]

Pull request overview

This PR adds additional “preset” environment variables to the agent’s internal environment (flb_env) so configs can reliably reference OS and build/package metadata, while still honoring any values already provided by the process environment.

Changes:

• Add preset env vars: OS_TYPE, TELEMETRY_FORGE_AGENT_DISTRO, TELEMETRY_FORGE_AGENT_PACKAGE_TYPE, TELEMETRY_FORGE_AGENT_VERSION (defaults only applied when not already set).
• Add internal tests covering preset defaults and override behavior.
• Move build-metadata CMake defines into source/cmake/enterprise.cmake and update macOS package workflow to pass distro/package type.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 7 comments.

Show a summary per file

File	Description
source/src/flb_env.c	Adds new preset env vars for OS + Telemetry Forge agent build metadata.
source/tests/internal/env.c	Adds internal tests for preset defaults and override behavior.
source/CMakeLists.txt	Removes build-metadata defines from the top-level CMake file (moved elsewhere).
source/cmake/enterprise.cmake	Adds validation/definition of build metadata values for builds using enterprise cmake include.
.github/workflows/call-build-macos-packages.yaml	Passes distro/package type into macOS package builds.

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[coveralls]

Coverage Report for CI Build 28161193752

Warning

Build has drifted: This PR's base is out of sync with its target branch, so coverage data may include unrelated changes.
Quick fix: rebase this PR. Learn more →

Coverage increased (+0.01%) to 57.875%

Details

• Coverage increased (+0.01%) from the base build.
• Patch coverage: No coverable lines changed in this PR.
• 293 coverage regressions across 5 files.

Uncovered Changes

No uncovered changes found.

Coverage Regressions

293 previously-covered lines in 5 files lost coverage.

File	Lines Losing Coverage	Coverage
src/fluent-bit.c	190	24.2%
tests/internal/env.c	61	68.06%
src/flb_env.c	35	75.38%
plugins/in_telemetryforge/telemetryforge.c	6	0.0%
plugins/in_http/http_conn.c	1	64.48%

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Coverage Stats

Relevant Lines:	161483
Covered Lines:	94565
Line Coverage:	58.56%
Relevant Branches:	35615
Covered Branches:	19505
Branch Coverage:	54.77%
Branches in Coverage %:	Yes
Coverage Strength:	5773.9 hits per line

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