extend readme

Signed-off-by: Maskym Vavilov <[email protected]>

Author: maksymvavilov

docs/coredns/README.md

@@ -28,31 +28,6 @@ Configure CoreDNS
 (cd ../.. && make install-coredns-multi)
 ```
 
-Set up the provider and dns records and handle via dns operator
-
-```
-k get services -A 
-# get the external IPs from the c1 and c2 services
-
-kubectl create secret generic core-dns --namespace=kuadrant-coredns-1 --type=kuadrant.io/coredns --from-literal=NAMESERVERS="10.89.0.18:53,10.89.0.16:53" --from-literal=ZONES="k.example.com"
-kubectl create secret generic core-dns --namespace=kuadrant-coredns-2 --type=kuadrant.io/coredns --from-literal=NAMESERVERS="10.89.0.18:53,10.89.0.16:53" --from-literal=ZONES="k.example.com"
-
-kubectl apply -f coredns/examples/dnsrecord-c1.yaml
-kubectl apply -f coredns/examples/dnsrecord-c2.yaml
-
-make run
-
-dig @10.89.0.18 k.example.com
-dig @10.89.0.16 k.example.com
-
-
-Clean up
-
-kubectl delete -f coredns/examples/dnsrecord-c1.yaml
-kubectl delete -f coredns/examples/dnsrecord-c2.yaml
-
-```
-
 
 View Corefile configmap data
 ```shell
@@ -91,18 +66,55 @@ kubectl create secret generic core-dns --namespace=kuadrant-coredns-1 --type=kua
 kubectl create secret generic core-dns --namespace=kuadrant-coredns-2 --type=kuadrant.io/coredns --from-literal=NAMESERVERS="$KNS" --from-literal=ZONES="k.example.com"
 ```
 
+Run dns-operator instance
+```shell
+make run
+```
+
 Apply example dnsrecords:
 ```shell
 (cd ../.. && kubectl apply -f coredns/examples/dnsrecord-c1.yaml)
 (cd ../.. && kubectl apply -f coredns/examples/dnsrecord-c2.yaml)
 ```
+Dig nameservers
+```shell
+NS1=`kubectl get service -n kuadrant-coredns-1 -l app.kubernetes.io/name=coredns,app.kubernetes.io/component!=metrics -o yaml | yq '.items[0].status.loadBalancer.ingress[0].ip'`
+NS2=`kubectl get service -n kuadrant-coredns-2 -l app.kubernetes.io/name=coredns,app.kubernetes.io/component!=metrics -o yaml | yq '.items[0].status.loadBalancer.ingress[0].ip'`
+
+echo $NS1
+echo $NS2
+
+dig @${NS1} k.example.com
+dig @${NS2} k.example.com
+```
+
 
 Delete example dnsrecords:
 ```shell
 (cd ../.. && kubectl delete -f coredns/examples/dnsrecord-c1.yaml)
 (cd ../.. && kubectl delete -f coredns/examples/dnsrecord-c2.yaml)
 ```
 
+### GEO corner
+The geo functionality is provided by the `geoip` plugin from CoreDNS. It relies on the geo database. 
+In this demo we are using the mock database that is generated using `coredns/examples/db-generator.go`. 
+The mock database contains sets of "local" subnets that are typical for kind deployments on mac and linux that are pointing at IE and US locales:
+
+| Subnet           | Continent          | Country            |
+|------------------|--------------------|--------------------|
+| 127.0.100.0/24 	 | Europe / EU        | Ireland / IE       |
+| 27.0.200.0/24  	 | North America / NA | United States / US |
+| 10.89.100.0/24 	 | Europe / EU        | Ireland / IE       |
+| 10.89.200.0/24 	 | North America / NA | United States / US |
+
+You can use `-b` option with dig to use any available to host machine IP addresses as a "source". E.G `dig @[nameserver] [hostname] -p [exposed-port] -b 127.0.100.1` will be associated with IE locale and `-b 127.0.200.1` with US
+
+> **_NOTE:_** the demo DB contains only localhost addresses. I.E. will work only with CoreDNS instance running with `make coredns-run` (not in kind cluster) unless you specify desired subnet in dig with `+subnet=[subnet]`
+
+To add more subnets, it is the best to generate a new DB file. Add your desired CIDR range to the constants and at the end of the file associate it with the desired record (IE or US). 
+
+For a deployment using a real-world database you could refer to the [maxmind](https://dev.maxmind.com/geoip/) for their free db. Once obtained it must be mounted and referenced in the Corefile instead of the demo-db.
+
 ### Misc Commands
 
 Get all CoreDNS Deployments:
@@ -117,7 +129,7 @@ kubectl get service -A -l app.kubernetes.io/name=coredns,app.kubernetes.io/compo
 
 Get all CoreDNS service external IPs for multi deployment:
 ```shell
-kubectl get service -A -l app.kubernetes.io/name=coredns,app.kubernetes.io/component!=metrics,app.kubernetes.io/part-of=coredns-multi -o json | jq -r .items[].status.loadBalancer.ingress[].ip
+kubectl get service -A -l app.kubernetes.io/name=coredns,app.kubernetes.io/component!=metrics,app.kubernetes.io/part-of=coredns-multi -o json | jq -r '.items[].status.loadBalancer.ingress[].ip'
 ```
 
 Get Name servers string: