Namerd is a service for managing Linkerd (and finagle) name delegation (i.e. routing).

Application
  |
Request
  |
  V
Linkerd ----logical name-----> Namerd <--> Service Discovery
        <---concrete address--        <--> Dtab Storage
  |
Request
  |
  V
Destination

Namerd is a service that resolves logical names to concrete addresses. By having Linkerd use Namerd for name delegation, we reduce the load on service discovery backends and can use Namerd as a central place to control routing across a fleet of linkers.

Namerd supports pluggable modules for dtab storage, naming and service discovery, and servable interfaces. For example, Namerd can be configured to use ZooKeeper for storage, ZooKeeper Serversets for service discovery, and a long-poll thrift interface.

Namerd can be run locally with the commands

./sbt namerd-examples/basic:run

or

./sbt 'namerd-main/run path/to/config.yml'

Namerd provides an http interface to create, update and retrieve Dtabs, as defined in HttpControlService.

For a command-line tool which wraps this interface, try namerctl

Primary interface endpoints:

$ export NAMERD_URL=http://localhost:4180

Get all dtab namespaces:

$ curl $NAMERD_URL/api/1/dtabs

Get a dtab for the default namespace:

$ curl $NAMERD_URL/api/1/dtabs/default

Create or update a dtab namespace:

$ curl -v -X PUT -d"/foo => /bar" -H "Content-Type: application/dtab" $NAMERD_URL/api/1/dtabs/baz

Evaluate a path against a known dtab namespace:

$ curl -v $NAMERD_URL/api/1/delegate/baz?path=/foo

Evaluate a path against an arbitrary dtab:

$ curl -v "$NAMERD_URL/api/1/delegate?dtab=/foo=>/bar&path=/foo"

Resolve a logic or concrete name against a known dtab namespace:

$ curl -v $NAMERD_URL/api/1/resolve/baz?path=/foo