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ADR 0084: M1 keeps every microVM isolated from every other; an additive contract change carrying a project or isolation group on NetAttach and guest DNS on NodeNetwork lands in a standalone PR at the start of M2, before any multi-VM app feature

  • Status: Accepted
  • Date: 2026-11-02
  • Ledger id: D-0084
  • Tags: engine, networking, contracts
  • Supersedes: none
  • Superseded by: none
  • Related: none

Context

The maintainer accepted the recommendation on 2026-11-02. The frozen Engine trait has no carrier for a VM’s project or its DNS servers; full isolation is the safe side of engine-trait.md 3.3.

Decision

M1 keeps every microVM isolated from every other; an additive contract change carrying a project or isolation group on NetAttach and guest DNS on NodeNetwork lands in a standalone PR at the start of M2, before any multi-VM app feature.

Until then the CH engine isolates all VMs (bridge port isolation plus an nftables forward drop) and takes guest DNS from its own node configuration. Same-project VM-to-VM traffic is impossible in M1; this is documented, not a bug.

Some wording was changed for the public repository.

Consequences

  • This decision is binding for all contributors and agents. Changing it requires a new ADR approved by the maintainer (see ADR 0036).

Generated from decision D-0084 in the project decision ledger. Do not edit by hand; changes go through a new decision.