mesh-catalog/modules/systemd-resolved/module.json

{
  "module": "systemd-resolved",
  "version": "1",
  "upgrade": {
    "policy": "record",
    "why": "the machine's names: a build that breaks this resolver stops every name resolving on a machine a person works on, the bus's included, and then neither the gate's rollback nor a push reaches it (hq ADR 0236, ADR 0247)"
  },
  "provides": [
    {
      "name": "split-dns",
      "reach": "machine",
      "credential": {
        "form": "none"
      }
    }
  ],
  "requires": [
    "wildcard-resolution"
  ],
  "capabilities": [
    "service-manager"
  ],
  "claims": [
    {
      "name": "node-resolver",
      "scope": "node",
      "serves": [
        "routes",
        "route",
        "unroute"
      ]
    }
  ],
  "listens": [
    {
      "name": "dns-udp",
      "port": 53,
      "protocol": "udp",
      "from": "machine",
      "fixed": true,
      "why": "this machine's own resolver (ADR 0247), on loopback and on its private address for its own containers; never another machine's, so a VPN's domains routed here are asked by nothing beyond this machine"
    },
    {
      "name": "dns-tcp",
      "port": 53,
      "protocol": "tcp",
      "from": "machine",
      "fixed": true,
      "why": "the same names over tcp, which a resolver answers on for an answer too large for a datagram"
    }
  ],
  "facts": {
    "kept": {
      "path": "/etc/node-resolver/resolv.conf",
      "template": "# Managed by the mesh, and written by the module holding this machine's own resolver\n# (module systemd-resolved, novox/hq ADR 0247). On every other machine the module holding\n# the uplink writes this file, listing the mesh's resolvers (ADR 0223); here something\n# requires names routed by domain - a VPN client's domains to its own servers - so the file\n# names this machine's own resolver alone, which sends those domains over the VPN's link and\n# every other name to the mesh's resolvers. One server listed, so one answer per name.\n#\n# Its address on the private network, not loopback: a container copies this file, and\n# this address is one it can reach. Another program writing this file is put back by the\n# module's guard, which keeps what it wrote for whoever handles it on this machine.\n# Replaced on every push; edit nothing here.\n{{$own := \"\"}}{{range .Machines}}{{if eq .Name $.Node}}{{$own = .Address}}{{end}}{{end}}nameserver {{if $own}}{{$own}}{{else}}127.0.0.53{{end}}\noptions timeout:1 attempts:2 edns0\n"
    },
    "resolved": {
      "path": "/etc/systemd/resolved.conf.d/50-mesh.conf",
      "template": "# Managed by the mesh (module systemd-resolved, novox/hq ADR 0247). Replaced on every\n# push; a drop-in of the operator's that sorts after this one overrides it, and is theirs.\n#\n# The mesh's resolvers, every one of them (ADR 0223): they answer every name no link's own\n# domains route elsewhere. ~. makes them the default route for names, and a link's servers\n# answer only the domains routed to them (the module's verb `route`).\n[Resolve]\nDNS={{range index .Holders \"mesh-dns-resolver\"}}{{.Address}} {{end}}\nDomains=~.\n# No compiled-in public fallback: a public resolver beside the mesh's is what ADR 0223\n# removed, because one of them said \"no such name\" for a mesh name and was believed.\nFallbackDNS=\n# The stub on loopback for this machine, and on its private address for its containers,\n# which cannot reach loopback. The packet filter admits this machine's own guests and\n# nobody else: another machine never asks this resolver (ADR 0247).\nDNSStubListener=yes\n{{$own := \"\"}}{{range .Machines}}{{if eq .Name $.Node}}{{$own = .Address}}{{end}}{{end}}DNSStubListenerExtra={{$own}}\n# No cache: nothing on this machine keeps a copy of a mesh name or of a \"no such name\",\n# as before this resolver - each question is asked again (ADR 0223's objection to a\n# local forwarder was a copy disagreeing with the truth).\nCache=no\n# What this machine's own programs read from /etc/hosts they read themselves; containers\n# asking here get what the mesh's resolvers say, as before.\nReadEtcHosts=no\n# Names are the mesh's resolvers' and a routed link's to answer, never the local network's\n# guesses; validation stays the upstreams' (the mesh's resolvers pass the bit through).\nLLMNR=no\nMulticastDNS=no\nDNSSEC=no\nDNSOverTLS=no\n"
    },
    "resolvers": {
      "path": "/etc/resolv.conf",
      "template": "# Managed by the mesh, and written by the module holding this machine's own resolver\n# (module systemd-resolved, novox/hq ADR 0247). On every other machine the module holding\n# the uplink writes this file, listing the mesh's resolvers (ADR 0223); here something\n# requires names routed by domain - a VPN client's domains to its own servers - so the file\n# names this machine's own resolver alone, which sends those domains over the VPN's link and\n# every other name to the mesh's resolvers. One server listed, so one answer per name.\n#\n# Its address on the private network, not loopback: a container copies this file, and\n# this address is one it can reach. Another program writing this file is put back by the\n# module's guard, which keeps what it wrote for whoever handles it on this machine.\n# Replaced on every push; edit nothing here.\n{{$own := \"\"}}{{range .Machines}}{{if eq .Name $.Node}}{{$own = .Address}}{{end}}{{end}}nameserver {{if $own}}{{$own}}{{else}}127.0.0.53{{end}}\noptions timeout:1 attempts:2 edns0\n"
    },
    "suffix": {
      "path": "/etc/node-resolver/suffix",
      "template": "{{.Suffix}}\n"
    }
  },
  "resources": [
    {
      "id": "service",
      "type": "service",
      "unit": "systemd-resolved.service",
      "state": "running",
      "boot": "enabled",
      "restart-on": [
        "systemd-resolved.fact-resolved"
      ],
      "health": {
        "kind": "unit"
      }
    },
    {
      "id": "guard",
      "type": "process",
      "name": "systemd-resolved-guard",
      "artifact": "tools",
      "run": [
        "./resolver-tools",
        "guard"
      ],
      "health": {
        "kind": "unit"
      }
    }
  ],
  "build": {
    "artifacts": [
      {
        "name": "tools",
        "kind": "bundle",
        "language": "go",
        "system": "arch",
        "from": "cmd/resolver-tools",
        "binary": "resolver-tools",
        "loads": [
          "resolver-tools"
        ]
      }
    ]
  }
}