Support Ambassador Host resources as sources

Ambassador can be configured with `Host` resources (based on the
`Host` CRD) for defining the external DNS host name.

This code adds a new source, `ambassador-host`, that looks for the
`ambassador/ambassador` Service and and uses the `hostname` from the
`Host` resource.

Signed-off-by: Alvaro Saurin <alvaro.saurin@gmail.com>
Signed-off-by: Flynn <flynn@datawire.io>

go.mod

@@ -8,7 +8,6 @@ require (
 	github.com/Azure/azure-sdk-for-go v45.1.0+incompatible
 	github.com/Azure/go-autorest/autorest v0.11.10
 	github.com/Azure/go-autorest/autorest/adal v0.9.5
-	github.com/Azure/go-autorest/autorest/azure/auth v0.5.3
 	github.com/Azure/go-autorest/autorest/to v0.4.0
 	github.com/akamai/AkamaiOPEN-edgegrid-golang v1.0.0
 	github.com/alecthomas/assert v0.0.0-20170929043011-405dbfeb8e38 // indirect
@@ -19,6 +18,7 @@ require (
 	github.com/aws/aws-sdk-go v1.31.4
 	github.com/cloudflare/cloudflare-go v0.10.1
 	github.com/cloudfoundry-community/go-cfclient v0.0.0-20190201205600-f136f9222381
+	github.com/datawire/ambassador v1.6.0
 	github.com/denverdino/aliyungo v0.0.0-20190125010748-a747050bb1ba
 	github.com/digitalocean/godo v1.36.0
 	github.com/dnsimple/dnsimple-go v0.60.0
@@ -46,24 +46,28 @@ require (
 	github.com/sanyu/dynectsoap v0.0.0-20181203081243-b83de5edc4e0
 	github.com/scaleway/scaleway-sdk-go v1.0.0-beta.6.0.20200623155123-84df6c4b5301
 	github.com/sirupsen/logrus v1.6.0
-	github.com/stretchr/testify v1.5.1
+	github.com/smartystreets/gunit v1.3.4 // indirect
+	github.com/stretchr/testify v1.6.1
 	github.com/terra-farm/udnssdk v1.3.5 // indirect
 	github.com/transip/gotransip v5.8.2+incompatible
 	github.com/ultradns/ultradns-sdk-go v0.0.0-20200616202852-e62052662f60
 	github.com/vinyldns/go-vinyldns v0.0.0-20200211145900-fe8a3d82e556
 	github.com/vultr/govultr v0.4.2
 	go.etcd.io/etcd v0.5.0-alpha.5.0.20200401174654-e694b7bb0875
 	go.uber.org/ratelimit v0.1.0
-	golang.org/x/net v0.0.0-20200324143707-d3edc9973b7e
+	golang.org/x/net v0.0.0-20200625001655-4c5254603344
 	golang.org/x/oauth2 v0.0.0-20200107190931-bf48bf16ab8d
+	golang.org/x/tools v0.0.0-20200708003708-134513de8882 // indirect
 	google.golang.org/api v0.15.0
 	gopkg.in/ns1/ns1-go.v2 v2.0.0-20190322154155-0dafb5275fd1
-	gopkg.in/yaml.v2 v2.2.8
+	gopkg.in/yaml.v2 v2.3.0
+	honnef.co/go/tools v0.0.1-2020.1.4 // indirect
 	istio.io/api v0.0.0-20200529165953-72dad51d4ffc
 	istio.io/client-go v0.0.0-20200529172309-31c16ea3f751
 	k8s.io/api v0.18.8
 	k8s.io/apimachinery v0.18.8
 	k8s.io/client-go v0.18.8
+	k8s.io/kubernetes v1.13.0
 )
 
 replace (