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      Peren documentation

      Compatibility and provider requirements

      Supported, bounded, and refused runtime and provider behavior before you migrate or deploy.

      Use this page before you migrate or deploy. It lists what Peren runs, what it limits, and what it refuses.

      Supported

      These work in this build:

      • JavaScript Workers in V8 isolates, with export default as the entry and fetch(request, env, ctx) where ctx is { waitUntil }.
      • Host-gated global fetch, outbound bindings, client mTLS certificates, and AWS SigV4 signing in the node process.
      • KV, native D1 and Turso, R2-style object storage, queues, cache via global caches, AI, vector indexes, service bindings, dispatch namespaces, workflows, rate limiting, analytics write points, Hyperdrive metadata, images gateways, loaders, and secrets-store strings.
      • Durable Object namespaces with stub fetch and cell-backed storage in the Peren host model.
      • Node compatibility modules that the runtime marks supported, including node:assert, node:buffer, node:events, node:path, node:url, and related Worker-safe helpers.
      • Prometheus metrics at /metrics, health at /healthz and /readyz, and peren logs / peren tail with --service.

      Bounded

      These work with stated limits:

      Surface Bound
      Isolate limits Defaults: 32 MiB request body, 128 MiB heap, 30000 ms wall clock, 10000 subrequests, 256 isolates. max_cpu_time_ms is config-only on the live HTTP path.
      Containers fetch proxies to the configured local port. exec, start, stop, destroy, writeFile, and readFile throw.
      KV compareAndSet Works on the native KV backend. Redis and bucket backends throw.
      Web Crypto HMAC, AES-GCM/CBC, PBKDF2/HKDF, Ed25519, and ECDSA P-256 are available. RSA and broader algorithm sets refuse.
      Node compatibility A deliberate subset. nodejs_compat and nodejs_compat_v2 produce a migration notice that you must verify each node: import. Modules such as node:fs, node:net, node:dns, and node:tls refuse in the isolate.
      Outbound fetch Allowed hosts come from configured bindings. Redirect targets are not checked again.
      Rate limiter Counters are process-local.
      WebSocketPair and hibernation Supported for the local Peren host model. Full Cloudflare edge hibernation parity outside that model is unsupported.

      Refused

      Peren refuses these instead of approximating them:

      • External D1 backends at query time. Native SQLite and Turso are the implemented database backends.
      • peren d1 restore. Native D1 has no time travel.
      • [otlp] and [logpush] during config validation.
      • Container sandbox control methods listed above.
      • Compatibility flags outside the migrate support table. Known partial flags are recorded as notices; unknown flags fail migration.
      • Inbound TLS termination with [mtls] paths. Peer listeners stay plain TCP. Keep the peer port off the public network.
      • Treating tenant revoke or scoped-credential authorize as a live request check. Revoke writes a registry. authorize is not on the Worker request path.

      Storage providers

      A fleet bucket used for ownership and recovery must preserve conditional-write and ranged-read behavior. Run peren conformance storage against the exact endpoint and credentials intended for production before serving fleet traffic from that store.