SYSTEM Cited by 3 sources

flycast

flycast is Fly.io's private-network load-balancing entrypoint — an internal, 6PN-reachable hostname (<app>.flycast) that resolves to the pooled set of private endpoints for a Fly App. Documented in Flycast - private Fly.io services.

Role in FKS

Under FKS, flycast is exposed as one of the three equivalent access paths for a Kubernetes Service:

• Direct IPv6 on the WireGuard mesh.
• http://<service>.svc.<app>.flycast:8080 — flycast URL form.
• In-cluster CoreDNS: <service>.<namespace>.svc.cluster.local.

Per the example in the FKS beta post:

Using internal DNS: http://<service_name>.svc.<app_name>.flycast:8080. Or, in our example: http://kuard.svc.fks-default-7zyjm3ovpdxmd0ep.flycast:8080.

Flycast URLs land on the Fly Proxy, which then forwards to the current pod-set IPv6 endpoints.

Access-scoping role — making autostop meaningful

Flycast is the load-bearing primitive for the patterns/flycast-scoped-internal-inference-endpoint pattern: an inference service (Ollama, vLLM, TGI, …) hosted on a Fly App with no public Fly Proxy exposure but with a .flycast hostname is reachable only from other Machines on the same org's WireGuard mesh. This matters because the Fly Proxy autostart/autostop model treats any inbound request as activity — a public endpoint under routine internet background noise would never idle. Scoping to Flycast makes "idle" well-defined and patterns/proxy-autostop-for-gpu-cost-control actually save money.

Seen in

• sources/2024-03-07-flyio-fly-kubernetes-does-more-now — named access path for FKS Services; exemplifies how FKS integrates K8s Service semantics with Fly's native private-networking surface.
• sources/2024-05-09-flyio-picture-this-open-source-ai-for-image-description — Flycast as the access-scoping primitive for an Ollama GPU Machine: "restricting Ollama access to internal requests over Flycast from the PocketBase app." The PocketBase app-tier Machine talks to Ollama over Flycast; users never address the GPU Machine directly, so Fly Proxy's autostop idle detection isn't confused by public scan traffic.
• sources/2025-03-27-flyio-operationalizing-macaroons — Flycast named as the reachability substrate for tkdb's multi-region isolated deployment. "If you're in Singapore, you're probably going to get routed to the Australian tkdb. If Australia falls over, you'll get routed to the closest backup. The proxy that implements FlyCast is smart, as is the tkdb client library, which will do exponential backoff retry transparently." A canonical example of Flycast as the Anycast routing layer for an internal-only security service (patterns/isolated-token-service).