jschoubben
e7f4a49e40
novox/hq 04-ISSUES/022: a consumer is a module on a machine, not a machine. The mesh now writes <node>.<module>.secret and the provisioners name the role and the access key after both. The fixtures here write what the mesh writes, so they move with it — that is the whole point of them, and a fixture that kept the old shape would agree with the bug rather than catch it. The object-store assertions are the ones that mattered most: one store holds every bucket behind one endpoint, so isolation is a policy rather than a property. One access key per machine meant every module on a node shared it, and the policy confining each consumer to its own bucket confined none of them.
2.3 KiB
Provisioners
The half that makes a credential real.
The mesh generates a password, seals it to the machine that must accept it, and never holds the value — so it cannot tell PostgreSQL, or MinIO, or a broker, to start accepting it. Something on that machine reads what arrived and makes it true. That something is a provisioner, and it belongs to the module that ships the software, not to the mesh.
What the mesh owns is the contract. A provider module declares:
{
"provides": [{"name": "database", "scope": "mesh"}],
"receives": {"database": "/var/lib/postgres/grants/mesh.json"},
"grants": {"database": "/var/lib/postgres/grants"}
}
and is then given, by the host, from an ordinary declaration:
mesh.json |
every consumer, what it asked for, and where its credential is |
<node>.<module>.secret |
one consumer's password, alone in the file, sealed in transit and written in plain by the host. Named after both, because a consumer is a module on a machine and a node routinely runs several (novox/hq 04-ISSUES/022) |
Two files rather than one because the mesh discarded the plaintext and cannot compose a document containing it. The consequence is a good one: the readable half stays readable, and the secret half changes only when the secret does.
A provisioner reconciles; it is not told what changed. It runs after every declaration and must reach the same state from wherever it starts. That means, in order:
- every consumer in the manifest has what it asked for, with the password it was given — set every time, not only on creation, or a rotation reports success and changes nothing
- everything this provisioner made that is no longer asked for is removed. A consumer that goes away otherwise leaves a working login behind for ever, and nothing says so
Step 2 is the half usually missing, and it is the same rule the host follows about removing what it declared and no longer declares.
The reference implementation lives in mesh-control/examples/postgres-provisioner, because that
is where the contract is defined and where the language is already set up to read it. The lab's
job is the other half: raising a real PostgreSQL and proving that what the mesh delivered becomes
a login that works, a rotation that takes effect, and a revocation that bites.
Set MESH_LAB_PROVISIONER to a built one to run those.