Golang Samber SlogSAFE

🧑🎨 A collection of Golang agentic skills that works

The instruction file, verbatim from the audited commit — this is the text the model reads, and the surface the audit's instruction layer examines. Quoted here so you can judge it without cloning anything.

---
name: golang-samber-slog
description: "Structured logging extensions for Golang using samber/slog-**** packages — multi-handler pipelines (slog-multi), log sampling (slog-sampling), attribute formatting (slog-formatter), HTTP middleware (slog-fiber, slog-gin, slog-chi, slog-echo), and backend routing (slog-datadog, slog-sentry, slog-loki, slog-syslog, slog-logstash, slog-graylog...). Apply when using or adopting slog, or when the codebase already imports any github.com/samber/slog-* package."
user-invocable: true
license: MIT
compatibility: Designed for Claude Code, Codex or similar harness, and for projects using Golang.
metadata:
  author: samber
  version: "1.1.2"
  openclaw:
    emoji: "🪵"
    homepage: https://github.com/samber/cc-skills-golang
    requires:
      bins:
        - go
    install: []
    skill-library-version:
      slog-multi: "1.8.0"
      slog-sampling: "1.6.0"
      slog-formatter: "1.3.0"
      slog-fiber: "1.22.1"
      slog-gin: "1.21.0"
      slog-chi: "1.19.0"
      slog-echo: "1.21.0"
      slog-http: "1.12.0"
      slog-betterstack: "1.4.4"
      slog-channel: "1.4.4"
      slog-datadog: "2.10.4"
      slog-sentry: "2.10.3"
      slog-loki: "3.7.2"
      slog-syslog: "2.5.4"
      slog-logstash: "2.6.4"
      slog-graylog: "2.7.5"
      slog-fluentd: "2.5.4"
      slog-kafka: "2.6.5"
      slog-logrus: "2.5.4"
      slog-zap: "2.6.4"
      slog-zerolog: "2.9.2"
      slog-slack: "2.7.5"
      slog-telegram: "2.4.4"
      slog-webhook: "2.8.4"
      slog-mattermost: "2.5.4"
      slog-microsoft-teams: "2.7.4"
      slog-nats: "0.4.5"
      slog-otel: "0.1.0"
      slog-parquet: "2.5.2"
      slog-quickwit: "0.3.4"
      slog-rollbar: "2.7.4"
      slog-mock: "0.1.0"
allowed-tools: Read Edit Write Glob Grep Bash(go:*) Bash(golangci-lint:*) Bash(git:*) Agent WebFetch mcp__context7__resolve-library-id mcp__context7__query-docs AskUserQuestion Bash(godig:*) Bash(gopls:*) LSP mcp__gopls__*
paths:
  - "**/*.go"
---

**Persona:** You are a Go logging architect. You design log pipelines where every record flows through the right handlers — sampling drops noise early, formatters strip PII before records leave the process, and routers send errors to Sentry while info goes to Loki.

# samber/slog-\*\*\*\* — Structured Logging Pipeline for Go

20+ composable `slog.Handler` packages for Go 1.21+. Three core pipeline libraries plus HTTP middlewares and backend sinks that all implement the standard `slog.Handler` interface.

**Official resources:**

- [github.com/samber/slog-multi](https://github.com/samber/slog-multi) — handler composition
- [github.com/samber/slog-sampling](https://github.com/samber/slog-sampling) — throughput control
- [github.com/samber/slog-formatter](https://github.com/samber/slog-formatter) — attribute transformation

This skill is not exhaustive — refer to library documentation and code examples for more information:

- For Go package docs, symbols, versions, importers, and known vulnerabilities, → See `samber/cc-skills-golang@golang-pkg-go-dev` skill (`godig`), preferred over Context7 for Go package facts.
- To navigate this library's usage in your own code (definitions, call sites, diagnostics), → See `samber/cc-skills-golang@golang-gopls` skill (`gopls`).
- Context7 remains a fallback for docs not indexed on pkg.go.dev.

## The Pipeline Model

Every samber/slog pipeline follows a canonical ordering. Records flow left to right — place sampling first to drop early and avoid wasting CPU on records that never reach a sink.

```
record → [Sampling] → [Pipe: trace/PII] → [Router] → [Sinks]
```

Order matters: sampling before formatting saves CPU. Formatting before routing ensures all sinks receive clean attributes. Reversing this wastes work on records that get dropped.

## Core Libraries

| Library | Purpose | Key constructors |
| --- | --- | --- |
| `slog-multi` | Handler composition | `Fanout`, `Router`, `FirstMatch`, `Failover`, `Pool`, `Pipe` |
| `slog-sampling` | Throughput control | `UniformSamplingOption`, `ThresholdSamplingOption`, `AbsoluteSamplingOption`, `CustomSamplingOption` |
| `slog-formatter` | Attribute transforms | `PIIFormatter`, `ErrorFormatter`, `FormatByType[T]`, `FormatByKey`, `FlattenFormatterMiddleware` |

## slog-multi — Handler Composition

Six composition patterns, each for a different routing need:

| Pattern | Behavior | Latency impact |
| --- | --- | --- |
| `Fanout(handlers...)` | Broadcast to all handlers sequentially | Sum of all handler latencies |
| `Router().Add(h, predicate).Handler()` | Route to ALL matching handlers | Sum of matching handlers |
| `Router().Add(...).FirstMatch().Handler()` | Route to FIRST match only | Single handler latency |
| `Failover()(handlers...)` | Try sequentially until one succeeds | Primary handler latency (happy path) |
| `Pool()(handlers...)` | Load-balance: sends each record to ONE handler | Single handler latency |
| `Pipe(middlewares...).Handler(sink)` | Middleware chain before sink | Middleware overhead + sink |

```go
// Route errors to Sentry, all logs to stdout
logger := slog.New(
    slogmulti.Router().
        Add(sentryHandler, slogmulti.LevelIs(slog.LevelError)).
        Add(slog.NewJSONHandler(os.Stdout, nil)).
        Handler(),
)
```

Built-in predicates: `LevelIs`, `LevelIsNot`, `MessageIs`, `MessageIsNot`, `MessageContains`, `MessageNotContains`, `AttrValueIs`, `AttrKindIs`.

For full code examples of every pattern, see [Pipeline Patterns](references/pipeline-patterns.md).

## slog-sampling — Throughput Control

| Strategy | Behavior | Best for |
| --- | --- | --- |
| Uniform | Drop fixed % of all records | Dev/staging noise reduction |
| Threshold | Log first N per interval, then sample at rate R | Production — preserves initial visibility |
| Absolute | Cap at N records per interval globally | Hard cost control |
| Custom | User function returns sample rate per record | Level-aware or time-aware rules |

Sampling MUST be the outermost handler in the pipeline — 

SAFEgrade B · trust 89/100 Nothing in the source contradicts what it says it does. Grade A is reserved for packages that have also passed the behavioural sandbox.

What the source does

Filesystem

none-observed

Network

none-observed

Shell

none-observed

Dependencies

pinned

Secrets in source

none-found

Findings (0)

No findings outside the package's declared scope.

Gates applied: no_behavioural_pass.