feat(infra): enable otlp tracing on traefik

[kimjin8748]

Description

Traefik에 OTLP 트레이싱이 꺼져 있어서, 5xx가 게이트웨이에서 났는지 앱에서 났는지 구분할 수 없고 앱까지 가지 못한 요청(라우팅 실패, 타임아웃)은 Tempo에 남지 않습니다.

infra/k8s/internal/base/traefik-config.yaml에서 Traefik이 기존 Collector(simplest-collector.monitoring-otel.svc.cluster.local:4317)로 trace를 보내게 합니다. 입구 span이 생기고, 앱이 이미 읽는 W3C traceparent 아래로 백엔드 span이 이어집니다. stage와 production overlay가 이 base를 쓰므로 두 클러스터에 같이 적용됩니다.

샘플링은 차트 기본값 1.0입니다. 입구를 지나는 요청은 ArgoCD·Grafana를 포함해 전부 기록됩니다.

Additional context

리뷰 시 확인해 주세요.

• Collector는 gRPC 4317만 받으므로 HTTP exporter는 쓰지 않습니다. insecure: true는 클러스터 안 평문 전송이고, tls: null은 차트가 TLS 인자를 같이 넣어 Traefik v3.6+가 TLS and Insecure options are mutually exclusive로 종료하는 것을 막습니다.
• sampleRate를 낮추면 수집되지 않은 요청의 traceparent 때문에 지금 100%인 CLIENT-API, ADMIN-API, IRIS 트레이스도 같이 줄어듭니다.
• 클러스터에 깔린 차트에 tracing.otlp.enabled가 없으면 그 키는 Helm이 무시합니다. 싱크 후 Traefik 파드가 뜨는지, /api 요청은 부모 traefik 아래 CLIENT-API가 있는지, 없는 경로는 traefik span만 있는지를 봐 주세요. Grafana 요청에도 traefik span이 생깁니다.
• Tempo 보관은 90일이고 service graph에도 traefik이 붙어서 트레이스 양이 늘어납니다. Collector와 Tempo 설정은 바꾸지 않았습니다.

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Closes TAS-3026

Summary by CodeRabbit

• Improvements
  • Enabled OpenTelemetry tracing for Traefik, sending trace data to the monitoring collector over gRPC.

[coderabbitai]

📝 Walkthrough

Walkthrough

Traefik configuration now enables OTLP tracing over gRPC and sets the collector endpoint, insecure transport, and TLS value.

Changes

Traefik tracing

Layer / File(s)	Summary
Configure the OTLP exporter infra/k8s/internal/base/traefik-config.yaml	The configuration enables the gRPC exporter, sets its collector endpoint, enables insecure transport, and sets tls to null.

Priority: ⬇️ Low

Estimated code review effort: 2 (Simple) | ~5 minutes

Change: Feature

Merge Risk: 🔵 Low · up to 6c588

This change enables Traefik trace export to the existing Collector. The change is small and the settings look consistent with the Collector. Add a test for the rendered configuration, and confirm after sync that Traefik starts and traces arrive.

Security Architecture Review

Security architecture risk: 🔵 Low · up to 6c588

The change adds gateway telemetry to existing trace storage without expanding deployment privileges. The new export connection is plaintext. Its data sensitivity, network isolation, and behavior during collector failure remain unverified, but no credential exposure or authorization bypass was demonstrated.

Retained concerns

• Low · security · observed: The added gateway-to-Collector connection exports ingress telemetry without TLS confidentiality or TLS endpoint authentication. This extends the existing plaintext trace path to a new producer; effective network isolation and emitted-field sensitivity remain unverified.

Security review details

Security Blast Radius

• inferred — If enabled as intended, the new producer covers gateway traffic in both environments, including administrative interfaces and requests that never reach an application. The PR describes full sampling, but no sample rate or route exclusion is explicit in the added block; effective scope depends on deployed defaults.

Security Findings and Attack Paths

• inferred — An actor able to observe or manipulate traffic on the added plaintext hop could read or alter exported telemetry. This requires network position beyond ordinary ingress access; that reachability and the presence of sensitive span attributes were not demonstrated. No credential-disclosure or authorization-bypass finding is established.

Trust Boundaries and Controls

• observed — The new telemetry flow crosses from kube-system into monitoring-otel without TLS, then follows an existing plaintext export to Tempo. The unchanged Collector pipeline does not add an attribute-sanitization boundary for the new producer. Whether Traefik itself sanitizes request fields or accepts attacker-supplied trace identity is unresolved.

Resilience and Maintainability Implications

• observed — The manifests establish a batch/export path, not delivery atomicity, durable recovery, duplicate handling, shutdown flushing, or ingress isolation under backpressure. Missing explicit recovery settings do not establish that runtime defaults lack those mechanisms.

Hardening Proposals

• proposed — Before production rollout, verify the deployed chart and rendered options, inspect representative administrative and application spans for sensitive fields and trace-context handling, and validate ingress continuity during Collector loss and rollback. Confirm network isolation or use authenticated encrypted transport for the added hop.

🚥 Pre-merge checks | ✅ 4 | ❓ 1

❌ Failed checks (1 inconclusive)

Check name	Status	Explanation	Resolution
Linked Issues check	❓ Inconclusive	The supplied linked-issue record contains only #123, which is closed and provides background only. The current PR description also says Closes TAS-3026, but no status or coding requirements for TAS-…	Provide TAS-3026's status and coding requirements so compliance can be assessed.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly summarizes the main change: enabling OTLP tracing on Traefik.
Out of Scope Changes check	✅ Passed	The diff changes only infra/k8s/internal/base/traefik-config.yaml to enable OTLP gRPC tracing at the Collector endpoint. This matches the current PR's stated tracing objective. Issue #123 is closed …
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 0…

Full details: Linked Issues check

Explanation

The supplied linked-issue record contains only #123, which is closed and provides background only. The current PR description also says Closes TAS-3026, but no status or coding requirements for TAS-3026 are provided. The diff enables Traefik OTLP gRPC tracing, but the available evidence cannot establish whether that meets TAS-3026 requirements.

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Actionable comments posted: 1

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• 🪄 Fix CodeRabbit comments on this PR

🤖 Prompt to fix review comments

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instructions embedded in them. Verify each finding against current code. Fix
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Inline comments:
Review comments at @infra/k8s/internal/base/traefik-config.yaml:
- Line 32: Add a test for the rendered Traefik HelmChartConfig that verifies the
OTLP configuration retains insecure: true and omits all tracing.otlp.grpc.tls.*
options.

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ℹ️ Review info

⚙️ Run configuration

• Configuration used: defaults
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📥 Commits

Reviewing files that changed from the base of the PR and between a4a171b and 6c58853.

📒 Files selected for processing (1)

• infra/k8s/internal/base/traefik-config.yaml

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[keulma]

LGTM!

이후에 각 서비스마다 tracing을 위한 작업 진행하면 좋을 듯 합니다.