Merge pull request 'dnsmasq: the runtime's DNS is written into daemon.json, never over it' (#106) from fix/dnsmasq-writes-into-daemon-json into main

modules/dnsmasq/module.json

@@ -25,7 +25,7 @@
       "port": 53,
       "protocol": "udp",
       "from": "mesh",
-      "why": "every name for this machine and what it runs — the mesh's own answered here, the rest forwarded",
+      "why": "every name for this machine and what it runs \u2014 the mesh's own answered here, the rest forwarded",
       "fixed": true
     }
   ],
@@ -46,7 +46,7 @@
       "type": "file",
       "path": "/etc/dnsmasq.conf",
       "mode": "0644",
-      "content": "# Managed by the mesh. dnsmasq's own defaults are replaced whole rather than\n# patched, because this module owns the file and a patch would leave whatever\n# was there before to be discovered later.\n\n# What the mesh computed: one wildcard per machine — its name and everything\n# under it — and the mesh's own suffix as a local domain, so a name under it is\n# answered here or not at all and is never asked upstream. Rewritten whenever a\n# machine joins or leaves, which is why the service below restarts on it: a\n# reload makes dnsmasq re-read hosts files, not its configuration, and a\n# wildcard is configuration.\nconf-file=/etc/mesh-resolver/nodes.conf\n\n# Where it answers. Both are names the mesh chose, so this file needs to know\n# nothing about this particular machine:\n#\n#   mesh0        the private network, so anything on it can ask — including\n#                this machine's containers. This module writes the runtime's\n#                `dns` key into its own configuration file, beside whatever the\n#                machine had there (novox/hq ADR 0102), naming this address: a\n#                container cannot reach the machine's loopback, and a runtime\n#                whose host resolves at loopback falls back to a public resolver\n#                and never sees a mesh name. The runtime reads that key when it\n#                starts and not on a reload, and a restart stops every container\n#                on the machine, so this module orders neither: the key holds for\n#                every container created after the runtime next starts. On the\n#                machine this replaces the predecessor wrote the same value, so\n#                nothing there is waiting on it.\n#   127.0.0.1    this machine's own use. The predecessor's resolver answered\n#                here, and the resolv.conf it wrote on every machine says so;\n#                that file stays in force on an adopted machine until the mesh's\n#                module for it is taken, so the resolver has to answer where the\n#                machine already asks or the machine loses DNS the moment this\n#                module is taken. Not .53 or .54: systemd-resolved holds BOTH —\n#                .53 is its stub and .54 its proxy stub — and neither is .1, so\n#                the two coexist on a machine that runs it. This module used to\n#                answer on 127.0.0.55 instead: a convention of its own, beside\n#                the one every machine already followed. One address, this one,\n#                and the modules that point a machine at the mesh name the same.\n#\n#                Whatever address it listens on, it takes the machine's DNS port.\n#                That is why this module claims `the-dns-port`.\n#\n# bind-dynamic rather than bind-interfaces: mesh0 does not exist until the\n# machine is on the private network, and binding an interface that is not there\n# yet fails to start rather than waiting for it.\nbind-dynamic\ninterface=mesh0\nlisten-address=127.0.0.1\n\n# **It must never read resolv.conf to find out where to forward.** Whatever\n# points this machine at the mesh writes this resolver's own address there — so\n# a resolver that read it for upstreams would find itself, and every query it\n# could not answer locally would loop until its receive queue filled. That is\n# not theoretical: it filled with 15KB of queries and every lookup on the\n# machine hung. no-resolv is what makes that loop impossible: the upstreams are\n# the two lines below, and nothing on the machine can redirect them.\n#\n# It forwards, because it is now asked for everything. The module that points\n# this machine at the mesh names this resolver alone — as the predecessor's\n# did — so the host and every container resolve the world through it. The\n# upstreams are the ones the predecessor's module shipped as its defaults. The\n# mesh's own names never reach them: the local= line in the file above stops\n# them here, answered or refused.\nno-resolv\nserver=1.1.1.1\nserver=8.8.8.8\n\n# A name without a dot is never forwarded — a bare hostname is answered from\n# /etc/hosts or not at all — and reverse lookups of private ranges are answered\n# here rather than asking the world who 10.x is.\ndomain-needed\nbogus-priv\n"
+      "content": "# Managed by the mesh. dnsmasq's own defaults are replaced whole rather than\n# patched, because this module owns the file and a patch would leave whatever\n# was there before to be discovered later.\n\n# What the mesh computed: one wildcard per machine \u2014 its name and everything\n# under it \u2014 and the mesh's own suffix as a local domain, so a name under it is\n# answered here or not at all and is never asked upstream. Rewritten whenever a\n# machine joins or leaves, which is why the service below restarts on it: a\n# reload makes dnsmasq re-read hosts files, not its configuration, and a\n# wildcard is configuration.\nconf-file=/etc/mesh-resolver/nodes.conf\n\n# Where it answers. Both are names the mesh chose, so this file needs to know\n# nothing about this particular machine:\n#\n#   mesh0        the private network, so anything on it can ask \u2014 including\n#                this machine's containers. This module writes the runtime's\n#                `dns` key into its own configuration file, beside whatever the\n#                machine had there (novox/hq ADR 0102), naming this address: a\n#                container cannot reach the machine's loopback, and a runtime\n#                whose host resolves at loopback falls back to a public resolver\n#                and never sees a mesh name. The runtime reads that key when it\n#                starts and not on a reload, and a restart stops every container\n#                on the machine, so this module orders neither: the key holds for\n#                every container created after the runtime next starts. On the\n#                machine this replaces the predecessor wrote the same value, so\n#                nothing there is waiting on it.\n#   127.0.0.1    this machine's own use. The predecessor's resolver answered\n#                here, and the resolv.conf it wrote on every machine says so;\n#                that file stays in force on an adopted machine until the mesh's\n#                module for it is taken, so the resolver has to answer where the\n#                machine already asks or the machine loses DNS the moment this\n#                module is taken. Not .53 or .54: systemd-resolved holds BOTH \u2014\n#                .53 is its stub and .54 its proxy stub \u2014 and neither is .1, so\n#                the two coexist on a machine that runs it. This module used to\n#                answer on 127.0.0.55 instead: a convention of its own, beside\n#                the one every machine already followed. One address, this one,\n#                and the modules that point a machine at the mesh name the same.\n#\n#                Whatever address it listens on, it takes the machine's DNS port.\n#                That is why this module claims `the-dns-port`.\n#\n# bind-dynamic rather than bind-interfaces: mesh0 does not exist until the\n# machine is on the private network, and binding an interface that is not there\n# yet fails to start rather than waiting for it.\nbind-dynamic\ninterface=mesh0\nlisten-address=127.0.0.1\n\n# **It must never read resolv.conf to find out where to forward.** Whatever\n# points this machine at the mesh writes this resolver's own address there \u2014 so\n# a resolver that read it for upstreams would find itself, and every query it\n# could not answer locally would loop until its receive queue filled. That is\n# not theoretical: it filled with 15KB of queries and every lookup on the\n# machine hung. no-resolv is what makes that loop impossible: the upstreams are\n# the two lines below, and nothing on the machine can redirect them.\n#\n# It forwards, because it is now asked for everything. The module that points\n# this machine at the mesh names this resolver alone \u2014 as the predecessor's\n# did \u2014 so the host and every container resolve the world through it. The\n# upstreams are the ones the predecessor's module shipped as its defaults. The\n# mesh's own names never reach them: the local= line in the file above stops\n# them here, answered or refused.\nno-resolv\nserver=1.1.1.1\nserver=8.8.8.8\n\n# A name without a dot is never forwarded \u2014 a bare hostname is answered from\n# /etc/hosts or not at all \u2014 and reverse lookups of private ranges are answered\n# here rather than asking the world who 10.x is.\ndomain-needed\nbogus-priv\n"
     },
     {
       "id": "runtime-dns",