Show client hostnames in per-client benchmark output

[eco-minio]

In distributed runs, the per-client breakdown can't be tied to a particular machine. Each warp client makes up a random ID (pRandASCII), and the "Throughput by client" report prints them as Client 1, Client 2. analyze --full also replaced IDs with a, b, … when loading a file.

Changes:

• Each warp client's ID is now <hostname>-<4 random chars> (the random suffix keeps several clients on one host apart). It falls back to the old random ID if the hostname can't be read. This applies to both the live (default) and --full collectors.
• "Throughput by client" prints the client ID (quoted with %q, so control characters are escaped) instead of its position.
• When loading a CSV, analyze --full keeps the original ID instead of a one-letter name. It still stores one copy per client, so memory use doesn't grow.

Example (2 clients in separate containers, one endpoint):

Throughput by client:
Client "warp-client-1-egU5" throughput: 70.46 MiB/s, 1127.31 obj/s (8s)
Client "warp-client-2-Jdoc" throughput: 70.52 MiB/s, 1128.31 obj/s (8s)

Notes:

• The hostname is whatever os.Hostname() returns on the client. In containers or Kubernetes, that's the container or pod name.
• Files recorded before this change keep their random IDs.
• The data files written by warp client now include the hostname in their name (warp-put-<date>-<host>-<id>.csv.zst). Standalone runs are unchanged.

Testing:

• go test -race ./pkg/bench passes. go vet and gofmt are clean.
• Podman, with static linux/arm64 builds of warp (this branch) and MinIO in $D, each client in its own container with its own hostname:

podman network create wcid-net

podman run -d --name wcid-minio --hostname wcid-minio --network wcid-net \
  -v $D:/bin-test:ro -v "$MINIO_LICENSE":/license:ro -e MINIO_LICENSE=/license \
  -e MINIO_ROOT_USER=minioadmin -e MINIO_ROOT_PASSWORD=minioadmin \
  docker.io/library/alpine:3.20 /bin-test/minio server /data --address :9000

for i in 1 2; do
  podman run -d --name wcid-client-$i --hostname warp-client-$i --network wcid-net \
    -v $D:/bin-test:ro -w /tmp docker.io/library/alpine:3.20 /bin-test/warp client
done

# default mode, then --full; also ran with --host=wcid-minio:9000,<minio-ip>:9000 for 2 endpoints
podman run --rm --name wcid-server --hostname warp-server --network wcid-net \
  -v $D:/bin-test:ro -v $D:/out -w /out docker.io/library/alpine:3.20 \
  /bin-test/warp put --warp-client=wcid-client-1,wcid-client-2 --host=wcid-minio:9000 \
  --access-key=minioadmin --secret-key=minioadmin --obj.size=64KiB --concurrent=4 \
  --duration=8s --noclear [--full --benchdata=pm-full]

# analyze the server's single file
podman run --rm --network wcid-net -v $D:/bin-test:ro -v $D:/out -w /out \
  docker.io/library/alpine:3.20 /bin-test/warp analyze [--full] pm-full.csv.zst

Every case (default and --full, 1 and 2 endpoints, analyze and analyze --full) showed warp-client-1-* and warp-client-2-*.

🤖 Generated with Claude Code

Summary by CodeRabbit

• Bug Fixes
  • Benchmark and live aggregate reports use client IDs with the hostname and a short random suffix when available, or a random ID otherwise.
  • Per-client throughput reports display each client’s ID instead of a sequential number.
  • Analyze-only CSV processing preserves distinct original client IDs instead of replacing them with sequential labels.

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📝 Walkthrough

Walkthrough

Benchmark and aggregate clients now use hostname-based client IDs when available, with a random-ID fallback. Per-client reports display client IDs. Analyze-only CSV processing retains cloned copies of distinct source client IDs.

Changes

Client ID handling

Layer / File(s)	Summary
Generate and report client IDs cli/benchmark.go, pkg/aggregate/live.go	clientID() uses the hostname and a four-character random suffix when the hostname is available, or a six-character random ID otherwise. Benchmark and aggregate clients use this function. Per-client reports display client IDs.
Preserve analyze-only client IDs pkg/bench/ops.go	Analyze-only mode stores and returns cloned copies of source client IDs. Other modes continue to return IDs unchanged.

Priority: ⬇️ Low

Estimated code review effort: 2 (Simple) | ~10 minutes

Change: Feature

Merge Risk: ⚪ Minimal · up to cc565

Client IDs are shown in reports while unavailable hostnames retain a fallback, and analyzed files retain their source IDs. No actionable merge-blocking risk is established.

Security Architecture Review

Security architecture risk: 🔵 Low · up to cc565

Client IDs remain reporting labels, not authentication credentials. Quoted report output limits direct text injection, and the inspected lifecycle behavior is unchanged. However, hostnames now appear in saved artifacts and generated filenames; deployment constraints and filename handling leave a limited, unresolved exposure.

Retained concerns
No architecture-level concerns identified.

Security review details

Security Blast Radius

• inferred — The demonstrated exposure is to recipients of benchmark reports and artifacts, plus the executing client's filesystem permissions for default artifact creation. CSV authors can influence displayed client labels, but the inspected CSV-to-report path does not grant them authentication or filesystem authority.

Trust Boundaries and Controls

• observed — Report treats client IDs as string arguments to a fixed %q format and returns buffered text. It does not interpret them as format strings, execute them, or make authorization decisions from them.
• observed — A separate boundary remains unresolved: clientID incorporates os.Hostname without normalization, and runClientBenchmark inserts that value into default paths passed to os.Create. A fixed application, command, and timestamp prefix and a random suffix constrain the constructed name; explicit benchdata bypasses default naming. These facts establish the data flow, not an attacker-controlled path traversal.

Resilience and Maintainability Implications

• observed — The identity change does not alter benchmark stage ordering, cancellation, result publication, collector closure, or cleanup conditions. Preserved CSV IDs are interned within one parser invocation; repeated values remain stable without introducing shared cross-invocation mutable state.

Hardening Proposals

• proposed — Keep the displayed hostname-bearing ID separate from a filename-safe component, normalizing or rejecting path separators before constructing default artifact names. This would make path safety independent of deployment hostname policy; it is a hardening proposal, not a verified vulnerability.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 60.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 5 functions across 3 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the primary change: showing client hostnames in per-client benchmark output.

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_{A hostname leads the client’s way,
Four random marks complete its name.
If no host name comes into view,
Six random marks will see it through.
Source IDs stay cloned and clear,
Reports show each client here.}

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Actionable comments posted: 1

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Inline comments:
Review comments at @pkg/aggregate/live.go:
- Line 403: Update LiveAggregate.Report’s client ID output to escape control
characters before printing; use Go’s quoted-string formatting for the client
value in the throughput label.

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Configuration used: Organization UI

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Run ID: 09c7e62d-5410-439a-80c5-847c30f0cbe4

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• cli/benchmark.go
• pkg/aggregate/live.go
• pkg/bench/ops.go

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