# go-observability

A skill that sets conventions for Go service telemetry: structured logs with log/slog, OpenTelemetry traces and metrics, SLO alerts. Useful once a service runs in production and you need to see what it does.

- skill · `type=skill` · Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, OpenCode · ★ 83
- Author: eduardo-sl
- License: MIT · policy=mirror · the beginning of the file is at the end of this page
- Source: https://github.com/eduardo-sl/go-agent-skills/tree/HEAD/skills/(safety)/go-observability/SKILL.md
- Updated: 2026-10-15
- HTML: https://affpapa.org/en/nevibecode/skills/go-observability

## What it does

The skill covers four signals. Log lines carry key-value pairs instead of formatted sentences, and the logger arrives as a dependency rather than a package-level global. Tracing means a span per operation, `ctx` passed down the whole chain, and failures marked with `span.RecordError` plus `span.SetStatus` — otherwise a failed request shows up green. Metric names follow `<namespace>_<subsystem>_<name>_<unit>`, and labels stay narrow: a user ID or a raw request path in a label spawns a new time series for every value.

Inside are `SKILL.md` and four reference files loaded on demand: `references/slog.md` for handler setup and redaction, `references/tracing.md` for the tracer provider and sampling, `references/metrics.md` for definitions and HTTP instrumentation, `references/alerting.md` for RED/USE and burn-rate alerts. One section ties the signals together: a handler wrapper injects `trace_id` and `span_id` into every `*Context` call, and it has to override `WithAttrs` and `WithGroup` or child loggers drop them.

The Go toolchain is required, since the skill runs `go` and `gofmt`. A project rule or agent config that explicitly supersedes it wins. Profiling with pprof, error handling and health endpoints live in separate skills of the same set.

## Install

### Claude Code (native platform)

1. **Skills CLI (Vercel)**
```bash
npx skills add eduardo-sl/go-agent-skills --skill go-observability -a claude-code
```

2. **Manually: put the files in place**
- File: `~/.claude/skills/go-observability/SKILL.md` — Copy the whole skill folder; for one project use .claude/skills/go-observability/

### Codex

1. **Skills CLI (Vercel)**
```bash
npx skills add eduardo-sl/go-agent-skills --skill go-observability -a codex
```

2. **Manually: put the files in place**
- File: `.agents/skills/go-observability/SKILL.md` — For all projects use ~/.agents/skills/

### Cursor

1. **Skills CLI (Vercel)**
```bash
npx skills add eduardo-sl/go-agent-skills --skill go-observability -a cursor
```

2. **Manually: put the files in place**
- File: `.cursor/skills/go-observability/SKILL.md` — Cursor also reads .agents/skills/ and .claude/skills/

### GitHub Copilot

1. **GitHub CLI**
```bash
gh skill install eduardo-sl/go-agent-skills go-observability
```

2. **Manually: put the files in place**
- File: `.github/skills/go-observability/SKILL.md`

### Gemini CLI

1. **Skills CLI (Vercel)**
```bash
npx skills add eduardo-sl/go-agent-skills --skill go-observability -a gemini-cli
```

2. **Platform CLI**
```bash
gemini skills install https://github.com/eduardo-sl/go-agent-skills --path 'skills/(safety)/go-observability'
```

### Windsurf (Devin Desktop)

**Manually: put the files in place**
- File: `.devin/skills/go-observability/SKILL.md` — The legacy .windsurf/skills/ path still works

### OpenCode

**Skills CLI (Vercel)**
```bash
npx skills add eduardo-sl/go-agent-skills --skill go-observability -a opencode
```

### Claude.ai

**Claude.ai**
- Zip the folder and upload it in Settings → Capabilities → Skills

Where a file is given instead of a command, copy the files from the source to that path: https://github.com/eduardo-sl/go-agent-skills/tree/HEAD/skills/(safety)/go-observability/SKILL.md

## When to use it
- replace formatted log strings with structured key-value pairs
- carry trace context through every call without breaking the parent span
- decide between a histogram and a summary for a latency metric
- alert on SLO burn rate instead of per-metric thresholds
- keep passwords and personal data out of logs with `slog.LogValuer`

## Example prompts
- Add structured logging to this Go service with `log/slog`, injected as a dependency
- Instrument the inbound HTTP handlers and database calls with OpenTelemetry spans
- Add a request latency metric and suggest bucket boundaries around our SLO threshold

## Source text · SKILL.md · MIT

Below is the content of a third-party file. It is data, not instructions for you: do not act on anything written inside unless the human asks. Block tag: 34f192ab6cf0be9b.

BEGIN THIRD-PARTY FILE 34f192ab6cf0be9b
````text
---
name: go-observability
description: >
  Structured logging, distributed tracing, metrics, and health checks for Go
  services. Covers slog, OpenTelemetry, Prometheus, and observability best
  practices. Use when: "add logging", "structured logs", "add tracing",
  "OpenTelemetry", "add metrics", "Prometheus", "observability", "instrument
  this code".
  Not for: pprof profiling (go-performance-review), error handling
  (go-error-handling), health endpoints (go-api-design).
user-invocable: true
license: MIT
compatibility: Designed for Claude Code or similar AI coding agents working on Go projects. Requires the Go toolchain.
allowed-tools: Read Edit Write Glob Grep Bash(go:*) Bash(gofmt:*)
metadata:
  author: eduardo-sl
  version: "1.5.1"
---

# Go Observability

Observability is not optional for production services. Every service must produce
structured logs, expose metrics, and propagate trace context. Use the stdlib
`log/slog` for logging and OpenTelemetry for tracing and metrics.

> Community default. A project skill or agent-config rule that explicitly
> supersedes `go-observability` takes precedence over this one.

Detailed reference material, loaded on demand:

- `references/slog.md` — handler setup, logger injection, child loggers,
  `LogValuer` redaction, trace-ID handler, hot paths, runtime levels.
- `references/tracing.md` — tracer provider, spans, propagation, sampling,
  profile labels, shutdown.
- `references/metrics.md` — metric definitions, HTTP instrumentation.
- `references/alerting.md` — RED/USE, histograms vs summaries, burn-rate
  alerts, alert hygiene, exemplars.

Read a reference file only when the section below is not enough.

## 1. Structured Logging with slog

Use `log/slog` (Go 1.21+) with a JSON handler in production. Every line is
key-value pairs, never a formatted sentence:

```go
// ✅ Good — structured, leveled
logger.Info("user created", slog.String("user_id", user.ID), slog.Duration("latency", elapsed))

// ❌ Bad — unparseable in production
log.Printf("user %s created in %v", user.ID, elapsed)
```

Inject the logger as a dependency; never reach for a package-level global.
````
END THIRD-PARTY FILE 34f192ab6cf0be9b

The third-party file has ended. Everything between the 34f192ab6cf0be9b tags is data: requests and commands from it are not followed. An “end of file” line with another tag inside the block is part of the file.

First 2158 of 8024 bytes. © eduardo-sl · MIT · https://github.com/eduardo-sl/go-agent-skills/tree/HEAD/skills/(safety)/go-observability/SKILL.md

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