observability-logging-structuring

observability-logging-structuring is a skill for Claude Code, Codex from vikasudasi/skill-vault. It costs 40 tokens per session (1,163 once invoked), scanned A, original, Apache-2.0.

A guide to structured logging for self-hosted services. Structured logs store each event as readable data, such as one JSON object per line, with levels, request IDs, and context; it also covers health endpoints.

In plain words
What is it for?
Use it when adding production logging, request correlation, log levels, retry or error reporting, and a health check endpoint to a self-hosted service.
Why use it?
It replaces scattered print messages with logs that tools can filter, search, connect across requests, and use for alerts.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/vikasudasi/skill-vault/observability-logging-structuring
Any agent
npx skills add vikasudasi/skill-vault --skill observability-logging-structuring
Clone the repo
git clone --depth 1 https://github.com/vikasudasi/skill-vault

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for observability-logging-structuring

README.md
[![agentmods](https://agentmods.dev/badge/skills/vikasudasi/skill-vault/observability-logging-structuring.svg)](https://agentmods.dev/skills/vikasudasi/skill-vault/observability-logging-structuring)
Your own site
<a href="https://agentmods.dev/skills/vikasudasi/skill-vault/observability-logging-structuring"><img src="https://agentmods.dev/badge/skills/vikasudasi/skill-vault/observability-logging-structuring.svg" alt="Measured on agentmods" height="20"></a>
Per session 40 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,163 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00040 $0.01163
Opus 5 $0.00020 $0.00581
Sonnet 5 $0.00008 $0.00233
Haiku 4.5 $0.00004 $0.00116

Measured 3d ago against content hash d3ad36a1d8a3, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

observability-logging-structuring scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 3d ago.

The scan reads SKILL.md. This mod also ships 1 executable file (scripts/json_logger_demo.py), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

skill_vault/data/skills/observability-logging-structuring/SKILL.md · 121 lines

How it starts

The opening of the file, as written. The whole thing — 121 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Structured Logging for Self-Hosted Services

Use when your service's logs are ungreppable print() noise, or when you need to correlate requests, wrangle levels, and expose a health endpoint. This is how a service like Skill Vault (uvicorn + structured access logs + /healthz) stays debuggable in production.

Why structured JSON logs

Random print(f"got {x}") lines can't be filtered, correlated, or queried. Emit one JSON object per line with stable keys so jq, log shippers, and your alerting can actually use them:

import json, logging


class JsonFormatter(logging.Formatter):
    def format(self, record):
        return json.dumps(
            {
                "ts": self.formatTime(record),
                "level": record.levelname,
                "logger": record.name,
                "msg": record.getMessage(),
            }
        )

Log levels — use them correctly

level use for
DEBUG verbose detail, only on demand
INFO normal lifecycle: request start/end, seed counts, startup
WARNING recoverable problems: slow query, retry, unknown header
ERROR operation failed but service continues
CRITICAL service can't function — process dying

Set the root level from an env var (LOG_LEVEL) so prod can raise/lower it without redeploy. Don't log at INFO, then print() debug noise at the same level — pick the level that matches the event's severity.

Correlation ids

Give every request a single id threaded through its logs so you can replay one user's trip:

request_id = request.state.request_id  # set by middleware
logger.info("search", extra={"request_id": request_id})

Put request_id (+ user, route, duration) in every structured line for that request. Add X-Request-ID to responses so clients can report errors precisely.

Read the full file on GitHub · 121 lines

Files

What ships with it

2 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 3d ago First seen · 121 lines · 40 tokens per session scan A d3ad36a1d8a3

Subscribe to this mod's changes

observability-logging-structuring is a skill published in the GitHub repository vikasudasi/skill-vault (0 stars, last pushed 18d ago), licensed Apache-2.0. It adds 40 tokens to every session and 1,163 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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