A fully asynchronous DNS resolver for Akka.
Add a dependency to your build.sbt:
libraryDependencies += "ru.smslv.akka" %% "akka-dns" % "2.4.2"Configure akka-dns in application.conf. If you can rely on /etc/resolv.conf being available (which should be the case for most flavors of Unix):
akka.io.dns {
resolver = async-dns
async-dns.resolv-conf = on
}
Alternatively you can also configure the nameservers explicitly:
akka.io.dns {
resolver = async-dns
async-dns {
nameservers = ["8.8.8.8", "8.8.4.4"]
}
}
Note that you can declare both resolv-conf and nameservers in which case the latter will be used in the case where /etc/resolv.conf cannot be found/parsed.
There are some other tunables, too, here are their defaults:
akka.io.dns {
async-dns {
min-positive-ttl = 0s
max-positive-ttl = 1d
negative-ttl = 10s
resolve-ipv4 = true
resolve-ipv6 = true
resolve-srv = false
# How often to sweep out expired cache entries.
# Note that this interval has nothing to do with TTLs
cache-cleanup-interval = 120s
}
}
To actually resolve addresses using akka-dns:
// send dns request
IO(Dns) ! Dns.Resolve("a-single.test.smslv.ru")
// wait for Dns.Resolved
def receive = {
case Dns.Resolved(name, ipv4, ipv6) =>
...
}
// just to try it out synchronously
val answer = Await.result(IO(Dns) ? Dns.Resolve("a-single.test.smslv.ru"), duration).asInstanceOf[Dns.Resolved]You can also resolve SRV records if you enable a config option:
akka.io.dns.async-dns.resolve-srv = true
The only difference with ordinary usage is that you send a regular Dns.Resovle request with a domain name
that starts with _ and wait for a SrvResolved message instead of a Dns.Resolved one, like this:
// send dns request
IO(Dns) ! Dns.Resolve("_http._tcp.smslv.ru")
// wait for SrvResolved
def receive = {
case SrvResolved(name, records: immutable.Seq[SRVRecord]) =>
...
}
// just to try it out synchronously
val answer = Await.result(IO(Dns) ? Dns.Resolve("_http._tcp.smslv.ru"), duration).asInstanceOf[SrvResolved]