Kubernetes DNS operator based on coredns and developed with python3 using kubernetes and kopf libraries.
Currently it only supports coredns files (a configmap) as the backing storage using jinja2 templates to render config files. It could be easily adapted to use other backends due to the flexibility of coredns, being straightforward to connect with public cloud DNS services.
Extend kubernetes api with new CRDs to allow you:
- Manage DNS instances (create/delete):
$ cat qa/server-sample.yaml
---
apiVersion: davidp1404.github.com/v1
kind: dnsServer
metadata:
name: sample.org
namespace: default
spec:
zones:
- sample.org
- 0.0.10.in-addr.arpa
replicas: 2
$ kubectl create -f qa/server-sample.yaml
dnsserver.davidp1404.github.com/sample.org created
$ kubectl get cm,deployment,svc -l app.kubernetes.io/managed-by="dns-operator"
NAME DATA AGE
configmap/dns-operator-sample-org 3 137m
NAME READY UP-TO-DATE AVAILABLE AGE
deployment.apps/dns-operator-sample-org 2/2 2 2 137m
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
service/dns-operator-tcp-sample-org LoadBalancer 10.96.118.22 172.18.255.201 53:30366/TCP 137m
service/dns-operator-udp-sample-org LoadBalancer 10.96.72.49 172.18.255.201 53:30833/UDP 137m
$ k get dnss
NAME PROVIDER ZONES REPLICAS AGE
sample.org corednsFiles ["sample.org","0.0.10.in-addr.arpa"] 2 141m
- Manage DNS records (create/delete/update):
$ cat qa/record{1,3}.yaml
---
apiVersion: davidp1404.github.com/v1
kind: dnsRecord
metadata:
name: record1
namespace: default
spec:
dnsServerRef: sample.org
recordType: A
zone: sample.org
recordKey: "record1"
recordValue: ["10.0.0.2"]
---
apiVersion: davidp1404.github.com/v1
kind: dnsRecord
metadata:
name: record3
namespace: default
spec:
dnsServerRef: sample.org
recordType: PTR
zone: 0.0.10.in-addr.arpa
recordKey: "3"
recordValue: ["record3.sample.org."]
$ cat qa/record{1,3}.yaml | kubectl create -f -
dnsrecord.davidp1404.github.com/record1 created
dnsrecord.davidp1404.github.com/record3 created
$ k get dnsr
NAME ZONE KEY TYPE VALUE TTL AGE
record1 sample.org record1 A ["10.0.0.2"] 5 19s
record3 0.0.10.in-addr.arpa 3 PTR ["record3.sample.org."] 5 19s
$ git clone --depth 1 https://github.com/davidp1404/dns-operator.git
$ cd dns-operator
# Tune the docker-image defintion in the Makefile to reflect your scenario
$ cd dns-operator
# Modify yaml/dns-operator-deployment.yaml file with the image url/tag chosen
# Ensure your kubeconfig/context grants you the privileges needed to create crds, clusterroles, clusterrolebindings, serviceaccounts, configmaps, deployments
$ make docker-image
$ make install-crd
$ make install-operator
# Ensure your kubeconfig/context grants you the privileges needed to create crds, clusterroles, clusterrolebindings, serviceaccounts, configmaps, deployments
$ cat <<EOF > values.yaml
operator:
image:
# You should provide your own as no public image is available
repository: "davidp1404/dns-operator"
pullPolicy: "IfNotPresent"
tag: "latest"
EOF
$ helm install dns-operator \
https://github.com/davidp1404/dns-operator/blob/main/helm/dns-operator-0.1.0.tgz?raw=true \
-f values.yaml
$ make install-qasamples
$ kubectl -n default get dnss,dnsr
NAME PROVIDER ZONES REPLICAS AGE
dnsserver.davidp1404.github.com/sample.org corednsFiles ["sample.org","0.0.10.in-addr.arpa","1.0.0.0.0.0.0.0.0.0.f.7.2.0.0.2.ip6.arpa"] 2 10s
NAME ZONE KEY TYPE VALUE TTL AGE
dnsrecord.davidp1404.github.com/record1 sample.org record1 A ["10.0.0.1"] 5 10s
dnsrecord.davidp1404.github.com/record2 sample.org record2 A ["10.0.0.1","10.0.0.3"] 5 10s
dnsrecord.davidp1404.github.com/record3 0.0.10.in-addr.arpa 3 PTR ["record3.sample.org."] 5 10s
dnsrecord.davidp1404.github.com/record4 0.0.10.in-addr.arpa 4 PTR ["record4.sample.org."] 5 10s
dnsrecord.davidp1404.github.com/record5 0.0.10.in-addr.arpa 5 PTR ["record5.sample.org."] 5 10s
dnsrecord.davidp1404.github.com/record6 sample.org record6 CNAME ["record1.sample.org."] 5 10s
dnsrecord.davidp1404.github.com/record7 sample.org record7 AAAA ["2002:7f00:0:1::1"] 5 10s
dnsrecord.davidp1404.github.com/record8 1.0.0.0.0.0.0.0.0.0.f.7.2.0.0.2.ip6.arpa 1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0 PTR ["record8.sample.org."] 5 10s
// Install jq if not present with "apt install jq"
$ svcip=$(kubectl -n default get svc -l app=dns-operator-sample-org -o json | jq -r .items[0].status.loadBalancer.ingress[0].ip)
$ dig +short record1.sample.org @$svcip
10.0.0.1
$ dig +short -x 10.0.0.3 @$svcip
record3.sample.org.
$ dig +short record7.sample.org AAAA @$svcip
2002:7f00:0:1::1
$ dig +short -x 2002:7f00:0:1::1 @$svcip
record8.sample.org.
By defatul the services were tuned for metal-lb, but you can adapt them to your specific use case editing the configmap with the jinja2 templates.
$ kubectl -n dns-operator get cm dns-operator-templates -o json | jq -r '.data."service-tcp.j2"'
apiVersion: v1
kind: Service
metadata:
name: dns-operator-tcp-{{name}}
namespace: {{namespace}}
labels:
app: dns-operator-{{name}}
app.kubernetes.io/managed-by: "dns-operator"
annotations:
metallb.universe.tf/allow-shared-ip: dns-operator-{{name}}
spec:
selector:
app: dns-operator-{{name}}
type: {{lbtype}}
sessionAffinity: None
ports:
- name: dnstcp
protocol: TCP
port: 53
targetPort: 1053
$ kubectl -n dns-operator get cm dns-operator-templates -o json | jq -r '.data."service-udp.j2"'
apiVersion: v1
kind: Service
metadata:
name: dns-operator-udp-{{name}}
namespace: {{namespace}}
labels:
app: dns-operator-{{name}}
app.kubernetes.io/managed-by: "dns-operator"
annotations:
metallb.universe.tf/allow-shared-ip: dns-operator-{{name}}
spec:
selector:
app: dns-operator-{{name}}
type: {{lbtype}}
sessionAffinity: None
ports:
- name: dnstcp
protocol: UDP
port: 53
targetPort: 1053
$ make uninstall-qasamples # In all cases clean custom resources before removing the operator
$ make uninstall-crd # If you installed with kustomize option
$ make uninstall-operator # If you installed with kustomize option
$ helm uninstall dns-operator # If you installed with helm
Maturity: early beta
Limitations:
- You can't change a DNS instance, only create or delete
- Develop an admission controller to disable updated verbs in dsnServers crds
- Makefile to create docker images and install
- Operator with multiple replicas
- Package with kustomize
- Enable ipv6
- Enable managing of optional forward directives (currently only resolve for authoritative zones)
- Reload all present records after recreating a dns instance
- Improving QA tests (pytest)
- Package with helm
- Refactor with python modules to encapsulate multiple backend providers.
- Add support to manage cloud dns services (route53/AWS, Azure DNS, Google Cloud DNS)
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