Environments

Tamer supports per-env configuration via local, env, and the --env flag. --env defaults to local for most commands; deploy requires it explicitly. No command silently defaults to prod.

Env override structure

defineWorker({
  // base config (applies to all envs)
  vars: { ENVIRONMENT: "local" },
  tamerRoutes: [{ host: "app.example.com", customDomain: true }],

  local: {
    // local-only overrides
    vars: { ENVIRONMENT: "local" },
  },

  env: {
    dev: {
      // dev overrides
      vars: { ENVIRONMENT: "dev" },
      tamerRoutes: [{ host: "dev.app.example.com", customDomain: true }],
    },
    prod: {
      vars: { ENVIRONMENT: "prod" },
    },
  },
});

How merging works

The merge is a shallow overlay: env-specific values replace base values by key. For vars, individual keys are merged (not replaced wholesale):

// base
vars: { TENANT_ID: "abc", ENVIRONMENT: "local", API_URL: "http://localhost:3000" }

// env.dev override
vars: { ENVIRONMENT: "dev", API_URL: "https://dev.api.example.com" }

// merged result for --env dev
vars: { TENANT_ID: "abc", ENVIRONMENT: "dev", API_URL: "https://dev.api.example.com" }

Route expansion

tamerRoutes are expanded per env:

Env	Pattern	Example
prod / production	Bare apex	app.example.com
Any other env (incl. ephemeral pr-*)	{env}.{apex}	dev.app.example.com, pr-1234.app.example.com
local	No route	—

wfp.ephemeralEnvPattern does not affect routing. It controls dispatch-namespace sharing, the ephemeral env fallback to env.dev overrides, and tamer env gc eligibility.

The local env

local is special: no Cloudflare API calls, no state DB, in-memory resources only. Used for wrangler dev / vite dev against local resources.

Ephemeral envs

Any env matching wfp.ephemeralEnvPattern (e.g. ^pr-) gets its own resource namespace within a shared dispatch namespace. Useful for PR preview environments. Set the pattern under wfp at the stack root:

export default defineConfig({
  stack: "my-app",
  wfp: { ephemeralEnvPattern: "^pr-", namespaces: { /* … */ } },
  // …
});

${tamer:env} reference

Use ${tamer:env} in worker vars to interpolate the current env name. This eliminates per-env overrides for env-derived URLs:

vars: {
  VITE_API_CLIENT_URL: "https://${tamer:env}.api.example.com/v1",
}

• dev → https://dev.api.example.com/v1
• pr-1234 → https://pr-1234.api.example.com/v1
• prod → override with the bare apex URL

Combined with ephemeral fallback (below), PR preview envs resolve correctly without per-PR config.

Ephemeral env fallback

When an env matches wfp.ephemeralEnvPattern and has no explicit override block in env: { ... }, Tamer falls back to env.dev overrides. This means ephemeral PR envs automatically inherit dev's configuration (routes, observability, vars) with ${tamer:env} making values correct per env.