linkerd/linkerd2: technical due diligence, read from its repository

The median source file here is 141 lines. 7 files exceed 1,410 lines, the largest being 3,216. 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 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.

5 files were marked deprecated over two years ago and still are, the oldest since Oct 2018. A deprecation is a promise to remove. Ask what still depends on these, and whether removing them is scheduled.

2 HTTP calls use a client with no timeout (Python `requests` without `timeout=`, or Go's default client). When a dependency slows down, each one holds a worker until the connection gives up, and enough of them take the service down with the dependency.

15 workload manifests set no CPU or memory limits. One pod that leaks memory or spins can starve everything else on its node, and the scheduler cannot plan capacity for what it cannot see.

43 of 1,800 locked dependencies match 89 published advisories in OSV, 43 of them rated high or critical. A lockfile says which version is installed, not whether the flawed code is reachable from this product, so each needs a look. Most are fixed by an upgrade, and the advisory names the version. This lockfile pins development tools alongside what ships and does not say which is which, so some of these may never reach a user.

The newest was published on 2026-09-28. 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 7 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 18.9.1. 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.