jschoubben
870a541072
The file is shared — the operator's insecure-registries for the mesh's own store live there — and replacing it whole would break every pull from that store the moment the module is taken (the 098 class, caught in the pre-take diff this time). ADR 0102's verb is merge.
76 lines
5.7 KiB
JSON
76 lines
5.7 KiB
JSON
{
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"module": "dnsmasq",
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"version": "1",
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"provides": [
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"wildcard-resolution"
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],
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"requires": [
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"mesh-addressing"
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],
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"emits": [
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"module.dnsmasq.name.added",
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"module.dnsmasq.name.removed"
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],
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"own-secrets": {
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"broker": "/var/lib/mesh/dnsmasq/broker"
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},
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"claims": [
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{
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"name": "the-dns-port",
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"scope": "node"
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}
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],
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"listens": [
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{
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"port": 53,
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"protocol": "udp",
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"from": "mesh",
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"why": "every name for this machine and what it runs \u2014 the mesh's own answered here, the rest forwarded",
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"fixed": true
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}
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],
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"resources": [
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{
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"id": "mesh-state",
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"type": "directory",
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"path": "/var/lib/mesh/dnsmasq",
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"mode": "0700"
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},
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{
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"id": "package",
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"type": "package",
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"package": "dnsmasq"
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},
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{
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"id": "config",
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"type": "file",
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"path": "/etc/dnsmasq.conf",
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"mode": "0644",
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"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"
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},
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{
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"id": "runtime-dns",
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"type": "file",
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"path": "/etc/docker/daemon.json",
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"mode": "0644",
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"merge": "json",
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"into": "json",
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"content": "{\"dns\": [\"${machine:address}\"]}\n"
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},
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{
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"id": "service",
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"type": "service",
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"unit": "dnsmasq.service",
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"state": "running",
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"boot": "enabled",
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"restart-on": [
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"config",
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"dnsmasq.fact-node-zones"
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]
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}
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],
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"facts": {
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"node-zones": "/etc/mesh-resolver/nodes.conf"
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}
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}
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