This PR implements Nomad built-in support for running Consul Connect
terminating gateways. Such a gateway can be used by services running
inside the service mesh to access "legacy" services running outside
the service mesh while still making use of Consul's service identity
based networking and ACL policies.
https://www.consul.io/docs/connect/gateways/terminating-gateway
These gateways are declared as part of a task group level service
definition within the connect stanza.
service {
connect {
gateway {
proxy {
// envoy proxy configuration
}
terminating {
// terminating-gateway configuration entry
}
}
}
}
Currently Envoy is the only supported gateway implementation in
Consul. The gateay task can be customized by configuring the
connect.sidecar_task block.
When the gateway.terminating field is set, Nomad will write/update
the Configuration Entry into Consul on job submission. Because CEs
are global in scope and there may be more than one Nomad cluster
communicating with Consul, there is an assumption that any terminating
gateway defined in Nomad for a particular service will be the same
among Nomad clusters.
Gateways require Consul 1.8.0+, checked by a node constraint.
Closes#9445
The field names within the structs representing the Connect proxy
definition were not the same (nomad/structs/ vs api/), causing the
values to be lost in translation for the 'nomad job inspect' command.
Since the field names already shipped in v0.11.0 we cannot simply
fix the names. Instead, use the json struct tag on the structs/ structs
to remap the name to match the publicly expose api/ package on json
encoding.
This means existing jobs from v0.11.0 will continue to work, and
the JSON API for job submission will remain backwards compatible.
After spending hours re-learning this lesson more than once,
update the jobspec contribution guide with a reminder about
how to configure FieldDiff comparisons.
