jschoubben
3d81bf41c6
Read against hal/modules/dnsmasq-app (hal dnsmasq-app conversion, hq 08-connectivity).
On the machines it runs, the predecessor's dnsmasq answers every name: the mesh's own
itself, the rest forwarded to 1.1.1.1 and 8.8.8.8, its module's defaults; resolv.conf
names it alone at 127.0.0.1, and the container runtime's dns is the machine's tunnel
address, so the host and every container resolve the world through it. The nox module
forwarded nothing, listened on 127.0.0.55 — a convention of its own beside the one every
machine already followed — and read a machines file that the module's `facts` already
asks the mesh for, so taking it would have left an adopted machine with a resolv.conf
pointing at an address nothing answered on, and no upstream for anything else.
Now the resolver keeps `no-resolv` (the documented loop — finding its own address in
resolv.conf and becoming its own upstream — stays impossible) and forwards to the same
two explicit upstreams; listens on mesh0 and 127.0.0.1, which systemd-resolved does not
hold; requires `mesh-addressing`, since its data is the mesh's addresses; and writes the
runtime's `dns` into daemon.json beside whatever the machine had (ADR 0102), at this
machine's own address — `${machine:address}`, new in the controller. The runtime is not
restarted for it: it reads the key at start, not on reload, and a restart stops every
container; on the machine this replaces the value is already there.
resolv-conf names the resolver alone, as the predecessor's file did; its placeholder second
line was a fallback nothing ever reached. resolved-split-dns follows the address. The
mesh's suffix as a local domain comes with the machines file, so a mesh name the resolver
does not know is refused here rather than asked upstream. mDNS is not carried: no module
does it and the design says mesh names are not multicast names.
20 lines
1.4 KiB
JSON
20 lines
1.4 KiB
JSON
{
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"module": "resolved-split-dns",
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"version": "1",
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"slug": "splitdns",
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"requires": ["wildcard-resolution"],
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"claims": [{"name": "the-resolver-configuration", "scope": "node"}],
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"resources": [
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{"id": "drop-in", "type": "directory", "path": "/etc/systemd/resolved.conf.d", "mode": "0755"},
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{"id": "route", "type": "file",
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"path": "/etc/systemd/resolved.conf.d/mesh.conf", "mode": "0644",
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"content": "# Managed by the mesh.\n#\n# **Only the mesh's names.** The tilde makes this a routing domain rather than a\n# search domain: queries under it go to the resolver below, and everything else\n# keeps going wherever this machine already sent it. A resolver that took over\n# all of DNS would be this module claiming the machine's whole network, which\n# is not what it says it claims. The mesh's resolver can forward the rest too;\n# this module is for a machine that wants systemd-resolved to stay in charge of\n# that, and only lends it the mesh's suffix.\n#\n# 127.0.0.1 is where the mesh's resolver answers on every machine — a fixed\n# address, so this file needs to know nothing about this particular machine.\n# systemd-resolved holds .53 and .54 itself, which is why the resolver is on\n# neither, and why the two coexist here.\n[Resolve]\nDNS=127.0.0.1\nDomains=~internal\n"},
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{"id": "resolved", "type": "service", "unit": "systemd-resolved.service",
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"state": "running", "boot": "enabled", "restart-on": ["route"]}
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]
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}
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