A route is a grant, and a provider is told where its consumer is

novox/hq 08-connectivity §3, built. The mirror of a database grant: there the
consumer supplies a name and receives credentials; here it supplies a target
and receives a name. Nothing new in the vocabulary — a route is a provision
like any other.

One field was missing and it is the one that matters for anything reaching
back: a contribution now carries where the mesh says that machine is. A reverse
proxy is told to send traffic to a consumer and has to open a connection, so
without it every provider implementing a provision would have to know how the
mesh names machines — a convention leaking into every module.

The proxy itself is an example, not part of the control plane: the contract is
the file, not this program. It replaces its table whole rather than merging,
because the file is the whole truth about who has a route and merging would
keep serving a name whose module was unassigned — the stale-route fault
08-connectivity lists as open, reintroduced one level down. A name it does not
serve is refused by saying which it does: a route withdrawn and a name that
never existed are different things.

Makefile

@@ -53,6 +53,15 @@ provisioner-image:
 	@echo
 	@docker image inspect $(PROVISIONER_IMAGE) --format 'built {{.RepoTags}}  {{.Size}} bytes'
 
+# The proxy that turns a route grant into traffic reaching a workload.
+PROXY_IMAGE ?= mesh-route-proxy:$(VERSION)
+PROXY_DEV_TAG ?= mesh-route-proxy:development
+
+proxy-image:
+	docker build -f examples/route-proxy/Dockerfile -t $(PROXY_IMAGE) -t $(PROXY_DEV_TAG) .
+	@echo
+	@docker image inspect $(PROXY_IMAGE) --format 'built {{.RepoTags}}  {{.Size}} bytes'
+
 # The whole gate. Raises a database, runs everything against it, and takes it down again --
 # including when the tests fail, which is why the teardown is not conditional.
 check: fmt vet postgres