Plugins

Add what your app needs

A plugin adds hooks, middleware, endpoints or tags to every page. tern add puts one in your app’s main.go, and gets its module when it isn’t Tern’s own.

go tool tern add compress health

Tern’s own

compress

Gzips pages, data and JSON for clients that accept it, flushing streamed responses as they go.

go tool tern add compress

Docs github.com/Unfield/Tern/plugins/compress

cors

Lets other origins call the app's endpoints, with preflight requests answered.

go tool tern add cors

Docs github.com/Unfield/Tern/plugins/cors

health

Liveness and readiness endpoints, /healthz and /readyz, for load balancers and orchestrators.

go tool tern add health

Docs github.com/Unfield/Tern/plugins/health

images

Resizes remote images for <Image src="https://…">, with a disk cache.

go tool tern add images

Docs github.com/Unfield/Tern/plugins/images

metrics

Prometheus metrics at /metrics: requests by route and status, their durations, and the Go runtime.

go tool tern add metrics

Docs github.com/Unfield/Tern/plugins/metrics

ratelimit

Limits how often each client changes things, such as form actions and API writes, with 429 and Retry-After past the limit.

go tool tern add ratelimit

Docs github.com/Unfield/Tern/plugins/ratelimit

requestlog

Logs every request with slog: method, path, status, time and the request's ID.

go tool tern add requestlog

Docs github.com/Unfield/Tern/plugins/requestlog

secure

Security headers on every response: no framing by other sites, trimmed referrers, powerful browser features off, and HSTS when asked.

go tool tern add secure

Docs github.com/Unfield/Tern/plugins/secure

sessions

Per-user data in an encrypted, signed cookie.

go tool tern add sessions

Reads SESSION_SECRET

Docs github.com/Unfield/Tern/plugins/sessions

signals

Tells people from bots and recognizes devices, from TLS and HTTP fingerprints and a client check.

go tool tern add signals

Docs github.com/Unfield/Tern/plugins/signals

oauth

It needs each provider's client ID and secret: see the docs for the options.

Docs github.com/Unfield/Tern/plugins/oauth

oidc

Makes the app an OAuth 2.1 and OpenID Connect provider, with consent, for other apps and assistants.

It needs an issuer URL, a store and its clients: see the docs for the options.

Docs github.com/Unfield/Tern/plugins/oidc

From the community

None listed yet. Yours could be the first: see below.

List yours

Any Go package with a function that returns a kit.Plugin works with tern add, listed or not:

go tool tern add github.com/you/tern-thing

It looks for a function that makes the plugin without arguments, such as New(opts ...Option). To list it here, and let people add it by name, add an entry to plugins/registry.json in a pull request:

{
  "name": "stripe-webhooks",
  "description": "Verifies Stripe's webhooks and calls a Go function for each event.",
  "import": "github.com/you/tern-stripe",
  "module": "github.com/you/tern-stripe",
  "add": "stripe.New(os.Getenv(\"STRIPE_WEBHOOK_SECRET\"))",
  "imports": ["os"],
  "env": ["STRIPE_WEBHOOK_SECRET"],
  "docs": "https://github.com/you/tern-stripe#readme",
  "author": "Your name",
  "url": "https://github.com/you/tern-stripe"
}

add is the Go expression tern add puts in kit.WithPlugins; leave it out, and write notes, for a plugin that needs setting up first. A test checks that every entry compiles.