Development#

Working on the connectors themselves, rather than using them in a job. This page covers the toolchain and the build.


Testing	The three test kinds and how to run each
Gated E2E audit	The September 2026 audit inventory, shared repairs and validation boundaries
Checks	The repository-specific checkers CI runs, and the skills that answer their failures
Contributing	The issue-first process, pull-request expectations, licensing, and design records

Toolchain#

JDK 17 or 21. The build targets bytecode 17; Java 11 is not supported — see Supported versions.
Maven, through the included wrapper ./mvnw.
just as the command entrypoint and mise to install the tools the recipes need — mise install in the repository root installs everything mise.toml pins. In a shell without mise activated, mise x -- just <recipe> behaves the same.
Python 3.11 or newer, for the repository’s checker scripts that wrap the build. mise installs its pinned 3.12.
Docker, for the emulator-backed integration tests that run inside the ordinary build.

The justfile is the command index, and CI calls the same recipes, so what runs locally is what runs there. just --list prints every recipe with a one-line description; this section names only the handful most changes need, so it stays true when recipes are added.

Building#

The full build — formatting and license checks, unit tests, integration tests, packaging:

just verify

It needs Docker but no Google Cloud credentials. The recipe is a strict header check followed by ./mvnw verify, and CI’s build lanes run the same recipe — though CI also runs the checker suite alongside it, so a green local build is necessary rather than sufficient. Two narrower forms serve day-to-day work:

just verify-module flink-connector-gcp-bigquery   # one module and what it is built on
just verify-flink 1.20.4                          # the full build against another Flink version

One source tree supports Flink 2.x and 1.20 together: the few API differences between the majors live in per-major source roots (src/main/java-flink1 / src/main/java-flink2) selected by the flink.compat Maven property, whose comment in the root pom.xml documents the mechanism. just verify-flink selects the seam along with the version, which is the flag most easily forgotten in a raw Maven call. Supported versions states the user-facing contract and how the weekly build verifies the range.

Run just format before committing — CI fails on unformatted code. Format under a JDK 17: the inherited build skips Spotless on Java 21 (google-java-format does not run there), so on a 21-only toolchain both just format and just verify pass with unformatted Java and the JDK 17 CI lane fails it.

Working in an IDE#

Import the root pom.xml as a Maven project on a JDK 17. Nothing else is required: the formatter is Spotless, applied by just format and enforced by the JDK 17 build, so an IDE formatter profile is a convenience rather than a correctness requirement; Checkstyle also runs in the build, and an IDE plugin can point at its configuration in tools/maven/checkstyle.xml to surface violations while editing.