debugging-dags

A structured guide for diagnosing failed Apache Airflow workflows, called DAGs. It helps trace a failure from the workflow or run to the task logs and underlying error.

In plain words
What is it for?
Use it to investigate broken or failed DAGs, inspect task logs, identify data or code problems, and recommend fixes and ways to prevent repeat failures.
Why use it?
It replaces guesswork with a sequence for finding recent failures, import errors, the real exception, and the likely category of the problem.

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/astronomer/agents/debugging-dags
Any agent
npx skills add astronomer/agents --skill debugging-dags
Clone the repo
git clone --depth 1 https://github.com/astronomer/agents

Made for: Claude Code, Codex.

Per session 111 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,802 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. 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 $0.00111 $0.01802
Opus 5 $0.00056 $0.00901
Sonnet 5 $0.00022 $0.00360
Haiku 4.5 $0.00011 $0.00180

Measured 2d ago against content hash 72e6f2caf8cf, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

debugging-dags scanned grade A with 1 finding 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 2d ago.

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.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

curl -s https://pypi.org/pypi/<pkg>/json | jq '.releases | to_entries | map({version: .key, uploaded: .value[0].upload_time}) | sort_by(.uploaded) | reverse | .[:5]'
skills/debugging-dags/SKILL.md · 129 lines

How it starts

The opening of the file, as written. The whole thing — 129 lines — stays where its author put it; the contents beside it link to each section on GitHub.

DAG Diagnosis

You are a data engineer debugging a failed Airflow DAG. Follow this systematic approach to identify the root cause and provide actionable remediation.

Running the CLI

These commands assume af is on PATH. Run via astro otto to get it automatically, or install standalone with uv tool install astro-airflow-mcp.


Step 1: Identify the Failure

If a specific DAG was mentioned:

  • Run af runs diagnose <dag_id> <dag_run_id> (if run_id is provided)
  • If no run_id specified, run af dags stats to find recent failures

If no DAG was specified:

  • Run af health to find recent failures across all DAGs
  • Check for import errors with af dags errors
  • Show DAGs with recent failures
  • Ask which DAG to investigate further

Step 2: Get the Error Details

Once you have identified a failed task:

  1. Get task logs using af tasks logs <dag_id> <dag_run_id> <task_id>
  2. Look for the actual exception - scroll past the Airflow boilerplate to find the real error
  3. Categorize the failure type:
    • Data issue: Missing data, schema change, null values, constraint violation
    • Code issue: Bug, syntax error, import failure, type error
    • Infrastructure issue: Connection timeout, resource exhaustion, permission denied
    • Dependency issue: Upstream failure, external API down, rate limiting

Step 3: Check Context

Gather additional context to understand WHY this happened:

  1. Recent changes: Was there a code deploy? Check git history if available
  2. Package version changes: Was a package upgraded — in the image, in a venv-style operator, or at the index? See Package version changes below.
  3. Data volume: Did data volume spike? Run a quick count on source tables
  4. Upstream health: Did upstream tasks succeed but produce unexpected data?
  5. Historical pattern: Is this a recurring failure? Check if same task failed before
  6. Timing: Did this fail at an unusual time? (resource contention, maintenance windows)

Read the full file on GitHub · 129 lines

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. 2d ago First seen · 129 lines · 111 tokens per session scan A 72e6f2caf8cf

Subscribe to this mod's changes

debugging-dags is a skill published in the GitHub repository astronomer/agents (432 stars, last pushed 15d ago), licensed Apache-2.0. It adds 111 tokens to every session and 1,802 once invoked, about $0.0006 per session on Opus 5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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