windmill-labs/windmill: technical due diligence, read from its repository

The median source file here is 65 lines. 213 files exceed 1,000 lines, the largest being 14,679. Size is not a defect on its own — some problems genuinely live in one place — but these are where merge conflicts, review fatigue and single-owner knowledge concentrate, and they are the first thing that slows an inheriting engineer down.

The suite is configured to retry failing tests (frontend/playwright.config.ts). A retry turns a flaky test green without saying why it failed, so a green build means the tests passed eventually. Ask how many retries a typical run needs, and which tests need them.

The code is pinned to Node.js 20 (end of life 2026-04-30). None of these receives security fixes any more; the first stopped on 2026-04-30. Moving off an unsupported runtime is rarely a one-line change, so a buyer should ask whether the upgrade is planned and what it touches.

.env, frontend/.env are tracked in git. Environment files are where credentials usually live, and committing one usually means nobody decided how secrets reach the running application. Whatever is in it is in the history for good. Check 05.1 says whether it holds anything credential-shaped.

25 third-party CI actions are referenced by a tag or branch rather than a commit, so they run whatever that tag points to on the day; 8 steps pipe a download straight into a shell. Tags have been moved to malicious commits in real supply-chain attacks, and a piped script is whatever the server returns that minute. Pinning to a commit is the fix, and it is small.

2 places in product code build SQL by formatting or joining strings rather than passing parameters. In each, what the code shows going in is a table or column name, a constant, or something the line does not show, not a request's value. Ask whether any value reaches these strings, rather than a parameter.

5 places run a command through a shell (`shell=True`, `os.system`, `exec` with a template) rather than passing arguments. Where any part comes from outside, it is command injection. Ask where each one's input comes from.

4 places read data with a deserialiser that executes what it reads (`yaml.load` without a safe loader, pickle). That is safe on data the system wrote itself and remote code execution on anything else. Ask where each one's input comes from.

66 places set HTML from a value that is neither a literal nor passed through a sanitiser. Where the value can come from a user, that is stored cross-site scripting, and it is the first thing a buyer's security review looks for in a frontend.

The newest was published on 2026-09-10. A project that publishes advisories is telling its users about its fixes, and the count and pace say how much security work it carries. Whether 3 of them are fixed in the code you ship could not be told from this history: its version is only known to be at least 1.820.0. Answer lives in: the release you run, set against each fixed version.

Nothing in the service initialises an error reporter (Sentry, Rollbar, Bugsnag, Honeybadger or an APM agent). An exception in production reaches a person only if someone is reading the logs, which usually means a customer reports it first.

1 images in the deployment configuration are named without a version or as `latest`. A redeploy can change the software without a commit, a rollback has nothing to roll back to, and nobody can say from the repository what is running.