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Author SHA1 Message Date
jschoubben 69a002fce3 Issue 172: the ssh client block matches one spelling of a machine's name
Reported by the operator: ssh by the bare name logs in, by the mesh name
is refused. The predecessor's generator writes the bare name only; the
mesh's ssh-client roster already matches both and is not yet shipped.
2026-09-30 15:25:30 +02:00
jschoubben 16a1a52cd8 Merge pull request 'Issue 171: a module that names its own resolver knows no mesh name' (#220) from issue/171-a-modules-own-resolver-knows-no-mesh-name into main 2026-09-30 13:20:30 +00:00
jschoubben af170e3a67 Issue 171: a module that names its own resolver knows no mesh name
Found and fixed the afternoon ADR 0148 landed: mailu-admin lost its
database behind Mailu's own resolver. Two catalogue PRs; an insight on
0148 that a container's dns is a decision, not a preference.
2026-09-30 15:20:26 +02:00
jschoubben 6c2d5f5913 Merge pull request 'Group 2 is resolved: containers resolve, nothing is copied, a route's name says where it arrives' (#219) from issue/110-resolved into main 2026-09-30 13:07:14 +00:00
3 changed files with 143 additions and 0 deletions
@@ -150,6 +150,16 @@ closed by this record, only answered by it.
resolvable inside the mesh — holds unchanged and by the same means the machine already uses. resolvable inside the mesh — holds unchanged and by the same means the machine already uses.
- **Issue 110 stops being a container-DNS inconvenience and becomes a prerequisite** for the mesh not - **Issue 110 stops being a container-DNS inconvenience and becomes a prerequisite** for the mesh not
restarting itself whenever it learns a name. restarting itself whenever it learns a name.
- **A container that names a resolver of its own has opted out of the machine's**, and the copy this
record removes was the only reason such a container could reach anything by a mesh name.
> **Progressive insight — 2026-09-30, the afternoon this landed. Found the hard way.** The mail
> system's admin, behind Mailu's own resolver, lost its database the moment the copy went
> ([issue 171](../04-ISSUES/171-a-modules-own-resolver-knows-no-mesh-name/00-report.md)). A `dns` on
> a container is a decision about whether mesh names exist inside it, not a preference; the module
> was corrected, and whether the controller should refuse the contradiction is that issue's open
> question.
- **A container started by hand gets the mesh's names too**, where before only declared containers did. - **A container started by hand gets the mesh's names too**, where before only declared containers did.
Design 08 drew that boundary deliberately, on the grounds that reaching into every container is what Design 08 drew that boundary deliberately, on the grounds that reaching into every container is what
a nameserver would be for. This record accepts that consequence rather than working around it: a a nameserver would be for. This record accepts that consequence rather than working around it: a
@@ -0,0 +1,78 @@
---
status: resolved
opened: 2026-09-30
located-in:
- mesh-catalog modules/mailu (eight containers name Mailu's own resolver, and one of them binds a mesh name)
- mesh-catalog modules/dnsmasq (dropped the DNSSEC bit its upstreams set)
fixed-by: mesh-catalog PR 178 (mailu-admin uses the machine's resolver) and PR 179 (the machine's resolver passes the DNSSEC bit down) — 2026-09-30, the same afternoon
amended-design:
---
# 171 — A module that names its own resolver knows no mesh name
## What was observed
The afternoon [ADR 0148](../../02-DECISIONS/0148-the-meshs-names-are-resolved-not-copied-into-containers.md)
landed — no container is given the mesh's names any more; it asks the machine's resolver — the mail
system's admin container began logging, 523 times in three minutes:
```
psycopg2.OperationalError: could not translate host name "novox.internal" to address: Name does not resolve
```
Mail was accepted on every port and the web front answered; the admin and the spam filter beside it
were unhealthy, and anything that needed the database — a mailbox change through the API, the spam
filter's domain list — failed. Found by the operator asking whether mail was back, forty minutes in.
Mailu ships its own resolver, an unbound in a container, and every other Mailu container is told to
use it — the module carries `dns: [192.168.203.254]` on eight containers. That resolver recurses from the
root and knows nothing under `.internal`. Until that afternoon the admin container had the database's
name anyway, because the mesh wrote every name into every container at creation; the copy was the only
reason a container behind its own resolver could reach anything by a mesh name, and nobody knew it was
load-bearing.
**Removing the override was not enough.** Given the machine's resolver instead, the admin refused to
start: `Your DNS resolver at 127.0.0.11 isn't doing DNSSEC validation`. Mailu checks, at start, that
its resolver returns the Authenticated Data bit for a signed name. The mesh's resolver forwards to two
upstreams that validate and set the bit, and dropped it on the way down — dnsmasq does unless told
otherwise. Mailu's own unbound has no hook to forward a zone elsewhere, so it could not be taught the
mesh's names either.
## Why it matters beyond this instance
**A container with a resolver of its own has opted out of the machine's, and nothing says so.** 0148
made the machine's resolver load-bearing for every container; a `dns` on a container is a quiet
exception to that, and the exception used to be papered over by the copy the record removed. The
manifest field reads like a preference and is a decision about whether mesh names exist inside the
container.
**A resolver that forwards to validating upstreams and hides the fact is less useful than it could
be**, and the first program to check found out.
**The mesh reported nothing.** Every container ran; the failing one accepted connections; the report
was about bytes. It is [issue 145](../145-a-machine-reads-healthy-while-its-modules-cannot-reach-each-other/00-report.md)
again, and the check that would have caught it is the same unbuilt one.
## What was done
- The one Mailu container that binds a mesh name — the admin, through the database it is granted —
no longer names Mailu's resolver and uses the machine's, like every container without a `dns` of
its own (mesh-catalog PR 178). The other seven keep unbound: the spam filter needs a validating
resolver for its blocklist lookups, and none of them asks for a mesh name.
- The machine's resolver passes the DNSSEC bit down from its upstreams, `proxy-dnssec` (PR 179). It
does not validate itself; the trust is the upstream's and the path to it, as a forwarding resolver's
always was, and the configuration says so.
## What checks it
The admin container's own start-up check, which is what failed, and the mesh's status once it reads
healthy. A container-level check that a mesh name resolves from inside every declared container is
the one 110 and 145 both ask for and is not built.
## Open questions
- Should a container's `dns` be refused, or made to say what it gives up? A module that names its
own resolver and binds a mesh name is a contradiction the controller can see at composition — the
grant hands it a name its resolver will not answer.
- Should the machine's resolver validate rather than proxy? It would cost a trust anchor on every
machine and make the resolver slower to start; proxying was enough for the one program that asked.
@@ -0,0 +1,55 @@
---
status: located
opened: 2026-09-30
located-in:
- the predecessor's terminal module (still generating the operator's ssh client blocks on every workstation)
- mesh-controller internal/catalogue (the ssh-client roster, tested and not yet a catalogue module)
fixed-by:
amended-design:
---
# 172 — The ssh client block for a machine matches one spelling of its name, and the other gets the wrong user
## What was observed
On a workstation, 2026-09-30, reported by the operator. `ssh home-server` logs in; `ssh
home-server.internal` is refused with `Permission denied (publickey)`. The operator expected the
opposite, if either: the full mesh name is the one the resolver serves.
The name is not the fault. Both spellings resolve to the machine's private address — the mesh's roster
region in the hosts file carries `<node>.internal <node>` on one line, and the resolver answers
anything under the node's name. What differs is the login: the generated client configuration has a
`Host home-server` block naming the account to log in as, and `home-server.internal` matches no block,
so ssh falls back to the operator's local username, which has no account on that machine. Spelled
`account@home-server.internal` it works.
The file is the predecessor's. `~/.ssh/config.d/mesh` says in its own header that it is generated by
the predecessor's terminal module, which only ever wrote the bare name. The mesh's own ssh-client
roster — every other machine's Host block, written as a marked region of the operator's `~/.ssh/config`
with the account the mesh knows for that machine (to-be 29) — already matches both spellings, and a
controller test holds `Host marge marge.internal`. It is composed and tested in the controller and is
not a module in the catalogue, so no machine receives it; every workstation still runs the
predecessor's generator.
## Why it matters beyond this instance
**A name the mesh serves and a name a person can use are not the same set**, and the difference is
silent. The resolver, the hosts file and the certificate authority all treat `<node>.internal` as the
machine's name; the one file that decides who you log in as does not know it. A person who learns the
mesh's name from `status` or from a certificate and types it is refused with an error that says
nothing about a missing Host block.
**It is the migration story for the operator's own tooling, arriving as a symptom.** The mesh has the
right file and does not ship it. Until the ssh-client roster is a module and is assigned to the
workstations, the predecessor's generator keeps writing a file the mesh has already superseded, and
every such file is one the mesh cannot correct.
## Open questions
- Should the ssh-client roster become a catalogue module now, assigned to every workstation, and take
the predecessor's `config.d/mesh` out of the operator's `Include`? Its content is settled; what is
not is the takeover of a file in a person's home that another generator still writes.
- Should the block match a third spelling — the machine's public name, where it has one — or is that
a different key and a different account?
- What checks it? A controller test holds the two spellings; nothing checks that the file a workstation
actually has is the mesh's rather than the predecessor's.