--- topic: building it status: accepted date: 2026-09-17 deciders: jochen reconstructed: false extends: 0072-two-graphs-and-the-build-chain.md --- # 82. The registry is reached by name, and the overlay is its security ## Context Delivery ends at a node pulling an image, and for every node but the one that built it, that step has never worked. Three facts conspired, each recorded separately: - Artifact references are written under `127.0.0.1:5000` — a deliberate parking (the catalogue says so in the commit that reverted the mesh-reachable name: *"the runtime refused it: 'http: server gave HTTP response to HTTPS client' … the binding expression returns then"*), so a joined node is told to pull from its own loopback ([issue 048](../04-ISSUES/048-nothing-makes-a-machine-trust-the-mesh-registry/00-report.md)). - A container runtime treats any non-loopback registry as HTTPS, and the mesh's registry serves plain HTTP; nothing the mesh writes tells any runtime otherwise — the one place that file existed was the lab's, which is why this never failed in a bed (issue 048). - Nothing gives a node an account for the registry ([issue 042](../04-ISSUES/042-nothing-gives-a-node-an-account-for-a-registry/00-report.md)) — and nothing has ever said whether one is required. The tempting fix is TLS from the mesh's own authority. The machinery even exists — the mesh CA issues leaves for `.internal` names, and a `certificate:` manifest field delivers them. But the registry is reached **over the overlay**, and the overlay is WireGuard: every byte is already encrypted and already authenticated to a peer the mesh admitted. The mesh's own code has carried this position for weeks: *"the registry is reached over the mesh's own private network … a second layer inside it would be certificates to issue and rotate for no property the first does not have."* TLS inside the tunnel would also re-order genesis (a certificate needs the network, the registry precedes it) and put CA handling into three clients (the runtime, the archive fetcher, the builder) — cost with no new property. ## Decision **The overlay is the registry's transport security, and the mesh writes the trust it means.** 1. **References name the registry by its mesh name.** The builder publishes to `.internal:` (the binding's `at` and `port`) — the parked one-line change lands. Genesis still publishes to loopback on the first machine, before any overlay exists; references minted at genesis stay loopback and are valid where they matter — on that machine. A rebuild re-pins to the mesh name. 2. **Every node on the private network is told the mesh's registry speaks plain HTTP.** The controller injects, into every such node's declaration, a merged `/etc/docker/daemon.json` naming `.internal:` under `insecure-registries`, and a service resource that restarts the runtime when that file changes — the `/etc/hosts` pattern for the content, the nftables pattern for the reload. No module author is involved; being on the network is what grants the trust, because being on the network is what the trust *is*. 3. **No accounts (issue 042), recorded as the position it always was.** Reading and pushing require presence on the overlay and nothing else. The boundary is enforced, not assumed: the registry's `listens` is `from: mesh`, the firewall derives from it, and the overlay admits only peers holding mesh-issued keys. An operator's *external* registry credential is an ordinary operator-supplied secret (`secret accept`), owned by whichever module names that registry. Per-node accounts return as a decision, not a patch, if the boundary assumption ever changes — the shape would be the existing provision flow. ## How this is checked - The no-fake lab bed: a joined node pulls a mesh-built image by the registry's `.internal` name over the overlay — an address outside every range the lab's own runtime configuration trusts, so the mesh-written trust is what makes it work or nothing does. - The firewall half is generated from `listens` and visible in the node's ruleset (`from: mesh`). - The plaintext-inside-tunnel position holds exactly as long as the registry is unreachable off the overlay; the `listens` stanza and the derived ruleset are the check. ## Consequences A runtime restart when the trust first lands on a node — at joining, before workloads, where it is free. The registry's HTTP is exposed to whatever stands on the overlay, which is the stated boundary; a mesh that wants defence in depth inside its own tunnel reopens this record rather than bolting certificates on quietly. Issues 042 and 048 close on this record. ## References - [issue 042](../04-ISSUES/042-nothing-gives-a-node-an-account-for-a-registry/00-report.md), [issue 048](../04-ISSUES/048-nothing-makes-a-machine-trust-the-mesh-registry/00-report.md). - [ADR 0072](0072-two-graphs-and-the-build-chain.md) — the build chain this completes. - [ADR 0029](0029-a-network-is-a-shape-because-an-action-cannot-be-undone.md) — the overlay as a boundary.