airflow-java-sdk

A contributor guide for the Apache Airflow Java SDK, which lets Airflow tasks run Java, Kotlin, or other languages for the Java Virtual Machine. It covers both the JVM library and the Python process that starts it.

In plain words
What is it for?
Use it to add features, fix bugs, write tests, understand the Java SDK structure, or prepare changes for Airflow's Java SDK and coordinator.
Why use it?
It brings the SDK architecture, data exchange rules, build steps, tests, and contribution requirements into one place. This reduces guesswork when changing or debugging the Java integration.

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/apache/airflow/airflow-java-sdk
Any agent
npx skills add apache/airflow --skill airflow-java-sdk
Clone the repo
git clone --depth 1 https://github.com/apache/airflow

Made for: Claude Code, Codex.

Per session 119 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,495 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 $0.00119 $0.01495
Opus 5 $0.00060 $0.00747
Sonnet 5 $0.00024 $0.00299
Haiku 4.5 $0.00012 $0.00150

Measured yesterday against content hash 8905c19e0945, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

airflow-java-sdk 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 yesterday.

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.

.agents/skills/airflow-java-sdk/SKILL.md · 135 lines

How it starts

The opening of the file, as written. The whole thing — 135 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Airflow Java SDK contributor guide

The Java SDK lets Airflow tasks execute JVM code (Java, Kotlin, or any JVM language). You are helping a contributor work in one or both of these locations:

  • java-sdk/ — the JVM-side library (Kotlin source, published to Maven)
  • task-sdk/src/airflow/sdk/coordinators/java/ — the Python coordinator that launches the JVM subprocess

Read these two documents early in every session — they contain the authoritative reference material:

  • airflow-core/docs/authoring-and-scheduling/language-sdks/java.rst — user-facing guide: annotation vs. interface API, XCom type mapping, Gradle/Maven steps, coordinator config.
  • java-sdk/README.md — contributor guide: repository layout, detailed execution walkthrough, Gradle + Breeze test commands, coding conventions, common tasks, and PR checklist.

SDK package architecture

The JVM-side library is split into two packages with distinct visibility rules:

  • org.apache.airflow.sdk — public, user-facing API. Classes here (e.g. Client, Bundle, BundleBuilder, Server) are stable contracts that DAG authors and task implementers import directly. Changes to this package are breaking changes.
  • org.apache.airflow.sdk.execution — internal implementation detail. Everything in this package (CoordinatorComm, LogSender, Log, Client in execution/, generated schema models, etc.) is not intended to be imported by users. It may change between releases without notice.

When reviewing or writing code, enforce this boundary: user task code and BundleBuilder subclasses must only import from org.apache.airflow.sdk; any import of org.apache.airflow.sdk.execution.* in user-facing API surface is a red flag.


Bundle composition and coordinator discovery

A bundle is a directory of JAR files (typically build/bundle/) placed on the coordinator's jars_root. The coordinator scans the directory at task-dispatch time to find:

Read the full file on GitHub · 135 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. yesterday First seen · 135 lines · 119 tokens per session scan A 8905c19e0945

Subscribe to this mod's changes

airflow-java-sdk is a skill published in the GitHub repository apache/airflow (46,647 stars, last pushed yesterday), licensed Apache-2.0. It adds 119 tokens to every session and 1,495 once invoked, about $0.0006 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 2026-08-30.