[sight] feat: bridge ilogtail SLS_LOG_PATH into agentsight config via /etc/anolisa/enable_token_collector switch

[chengshuyi]

Component

sight

Problem Statement

agentsight currently reads its SLS log upload path from runtime.sls_logtail_path in agentsight.json, but ilogtail is the canonical source of the cloud-distributed log path (SLS_LOG_PATH in /etc/anolisa/ilogtail.cfg). Operators need a switch that opts agentsight into ilogtail's path without manually editing the JSON config.

Proposed Solution

Add a background watcher thread that polls /etc/anolisa/enable_token_collector once per second:

• When the trigger file exists, parse SLS_LOG_PATH from /etc/anolisa/ilogtail.cfg (INI key=value, supports single/double quotes) and write it to runtime.sls_logtail_path of the agentsight config file.
• When the trigger file is removed, clear runtime.sls_logtail_path (write empty string).

The existing config-watcher detects the resulting IN_CLOSE_WRITE and activates the SLS LogtailExporter. This commit only adds the bridging layer — SLS activation logic is unchanged.

Implementation highlights:

• Enable serde_json preserve_order so JSON field order stays stable across rewrites.
• State machine caches last applied state to skip redundant disk writes.
• write_runtime_sls_path() is idempotent (no-op when value unchanged).
• Hardcoded production paths and 1s poll interval (no extra public API).

Alternatives Considered

• Embedding ilogtail.cfg parsing into the existing config-watcher: rejected — keeps watcher responsibilities mixed and forces tighter coupling to ilogtail's INI format.
• Inotify-only watch on the enable_file: rejected — file deletion + recreation cycles are simpler and more reliable to handle via 1s polling; deletions still propagate within 1 polling window.

Additional Context

• Tests:
  • 13 unit tests in src/unified.rs (read parsing + JSON rewriting + state-machine simulation).
  • scripts/int-test-token-collector.sh integration script: 9/9 PASS on a non-ECS host (phase 2 auto-skipped) and 10/10 PASS on a real ECS host with valid metadata where the disable→clear path is exercised end-to-end.
• Compatibility: Existing SLS uid validation guard at AgentSight::new() is unchanged; bridging cannot loosen the safety check.

[github-actions]

🔀 Issue Triage

This issue has been automatically assigned to @chengshuyi as the maintainer(s) of sight.

Maintainers, please review and triage this issue. Set a priority label and update the status as needed. Thanks! 🙏