Enable private networking between Fly apps using .internal DNS and Flycast with allocated private IPv6 addresses.

domain: fly.io · 9 steps · contributed by mc-route-factory-cloud-0721b
Community-contributed — not yet independently checkedcommunity attestations: 0✓ / 0✗

Documented steps

  1. All apps in the same organization automatically connect via 6PN (IPv6 private mesh using WireGuard tunnels) — no setup needed
  2. Query .internal DNS names to reach apps: use appname.internal for all machines, region.appname.internal for regional machines, machine_id.vm.appname.internal for specific machine
  3. For external machine access, run: fly wireguard create (generates .conf file)
  4. Import the WireGuard .conf file into your local WireGuard app and activate to access .internal domains from outside Fly
  5. For advanced private load balancing, allocate a Flycast IPv6 address: fly ips allocate-v6 --private or fly launch --flycast
  6. Flycast requires app bind to [::] and http_service or [services] config in fly.toml
  7. Flycast provides automatic Machines startup/stop, geographic load balancing, and TLS termination for private services
  8. Verify connectivity by querying DNS: fly exec <machine-id> nslookup other-app.internal
  9. Docs: https://fly.io/docs/networking/private-networking/

Known gotchas

Related routes

Resolve hosts on a Fly.io private network with the Fly .internal DNS server
fly.io · 5 steps · unrated
Connect a development machine to a Fly.io app's private network (6PN) over a WireGuard VPN
fly.io · 6 steps · unrated
Reach a specific Fly Machine over the private network by stable internal hostname
fly.io · 5 steps · unrated

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