# DNS service tags in Kubernetes

**URL:** <https://discuss.hashicorp.com/t/dns-service-tags-in-kubernetes/58891>\
**Category:** Consul\
**Created:** [October 6, 2023, 4:41pm UTC](https://discuss.hashicorp.com/t/dns-service-tags-in-kubernetes/58891 "2023-10-06T16:41:15Z")\
**Posts on this page:** 4\
**Page:** 1

<div class="post-metadata">

**Author:** ![kouzant](https://sea2.discourse-cdn.com/hashicorp/user_avatar/discuss.hashicorp.com/kouzant/32/5123_2.png) [@kouzant](https://discuss.hashicorp.com/u/kouzant)\
**Post date:** [October 6, 2023, 4:41pm UTC](https://discuss.hashicorp.com/t/dns-service-tags-in-kubernetes/58891/1 "2023-10-06T16:41:16Z")

</div>

Hi all,

We are running Consul on baremetal and we are primarily using the DNS interface. So we define service files for each service and then we address them with their Consul domain name such as `mysql.service.consul` For some instances of that service, in that case MySQL, we specify some tags so we can differentiate them ie `big.mysql.service.consul` or `small.mysql.service.consul`

We are trying to replicate this setup in Kubernetes but I haven’t figured out a way for the tags to work in DNS. The resolution of `mysql.service.consul` works fine but despite setting [service-tags](https://developer.hashicorp.com/consul/docs/k8s/service-sync#service-tags) it fails to resolve `big.mysql.service.consul`

Is this even supported in Kubernetes or am I configuring something wrong?

Cheers!

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<div class="post-metadata">

**Author:** ![Ranjandas](https://avatars.discourse-cdn.com/v4/letter/r/90ced4/32.png) [@Ranjandas](https://discuss.hashicorp.com/u/Ranjandas)\
**Post date:** [October 6, 2023, 11:35pm UTC](https://discuss.hashicorp.com/t/dns-service-tags-in-kubernetes/58891/2 "2023-10-06T23:35:08Z")

</div>

Hi @kouzant,

I hope you are using the syncCatalog feature, as the documentation you linked is to be used with sync catalog functionality.

By default when the services are synced from Kubernetes to Consul, the service name will be of type `<service-name>-<k8s-namespace>`. Where `<service-name>` is the `name` field under service `metadata`.

ref:

- [Service Sync for Consul on Kubernetes | Consul | HashiCorp Developer](https://developer.hashicorp.com/consul/docs/k8s/service-sync#service-name)
- [Helm Chart Reference | Consul | HashiCorp Developer](https://developer.hashicorp.com/consul/docs/k8s/helm#v-synccatalog-addk8snamespacesuffix)

With the above information, if your service name (`service.metadata.name`) is `mysql`, the service will be registered as `mysql-<k8s-namespace>`. So including the tag, you will have to use `big.mysql-<k8s-namespace>.service-consul`.

Instead of disabling this feature globally, you can override the service name using the [service-name annotation.](https://developer.hashicorp.com/consul/docs/k8s/service-sync#service-name)

```auto
eg.:

---
apiVersion: v1
kind: Service
metadata:
  name: mysql
  namespace: default
  labels:
    app: mysql
  annotations:
    'consul.hashicorp.com/service-tags': 'big'
    'consul.hashicorp.com/service-name': 'mysql'

```

I hope this helps.

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<div class="post-metadata">

**Author:** ![kouzant](https://sea2.discourse-cdn.com/hashicorp/user_avatar/discuss.hashicorp.com/kouzant/32/5123_2.png) [@kouzant](https://discuss.hashicorp.com/u/kouzant)\
**Post date:** [October 9, 2023, 8:29am UTC](https://discuss.hashicorp.com/t/dns-service-tags-in-kubernetes/58891/4 "2023-10-09T08:29:26Z")

</div>

Hi @Ranjandas  
I’ve followed the tutorial deploying consul and the example hashicups application. I haven’t changed the default helm values so service sync should be enabled by default.

I have slightly changed one of hashicups services, adding the service tags so now the service definition looks like the following

```auto
kubectl describe svc nginx 
Name: nginx
Namespace: default
Labels: app=nginx
Annotations: consul.hashicorp.com/service-tags: web
Selector: app=nginx
Type: ClusterIP
IP Family Policy: SingleStack
IP Families: IPv4
IP: 10.43.37.223
IPs: 10.43.37.223
Port: <unset> 80/TCP
TargetPort: 80/TCP
Endpoints: 10.42.2.50:80
Session Affinity: None
Events: <none>

```

I have also changed CoreDNS configuration and in fact from another pod I have resolve `nginx.service.consul` (k8s namespace does not seem to be working, maybe an enterprise feature?)

```auto
dig nginx.service.consul

; <<>> DiG 9.18.12-0ubuntu0.22.04.3-Ubuntu <<>> nginx.service.consul
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 28937
;; flags: qr aa rd; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1
;; WARNING: recursion requested but not available

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1232
; COOKIE: dda320202d60972c (echoed)
;; QUESTION SECTION:
;nginx.service.consul. IN	A

;; ANSWER SECTION:
nginx.service.consul.	5	IN	A	10.42.2.50

;; Query time: 4 msec
;; SERVER: 10.43.0.10#53(10.43.0.10) (UDP)
;; WHEN: Mon Oct 09 08:27:37 UTC 2023
;; MSG SIZE rcvd: 97

```

Nevertheless when I add my tag, I cannot resolve the domain name.

```auto
dig web.nginx.service.consul

; <<>> DiG 9.18.12-0ubuntu0.22.04.3-Ubuntu <<>> web.nginx.service.consul
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 34007
;; flags: qr aa rd; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 1
;; WARNING: recursion requested but not available

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1232
; COOKIE: 1c65bf7749bb848e (echoed)
;; QUESTION SECTION:
;web.nginx.service.consul.	IN	A

;; AUTHORITY SECTION:
consul. 5	IN	SOA	ns.consul. hostmaster.consul. 1696840112 3600 600 86400 0

;; Query time: 0 msec
;; SERVER: 10.43.0.10#53(10.43.0.10) (UDP)
;; WHEN: Mon Oct 09 08:28:32 UTC 2023
;; MSG SIZE rcvd: 133

```

Am I doing something wrong or my assumption of tags is invalid?

---

<div class="post-metadata">

**Author:** ![Ranjandas](https://avatars.discourse-cdn.com/v4/letter/r/90ced4/32.png) [@Ranjandas](https://discuss.hashicorp.com/u/Ranjandas)\
**Post date:** [October 9, 2023, 12:20pm UTC](https://discuss.hashicorp.com/t/dns-service-tags-in-kubernetes/58891/5 "2023-10-09T12:20:21Z")

</div>

Hi @kouzant,

Could you please link to the documentation that you referred to? In addition, sharing the Helm overrides (values.yaml) will be helpful (`helm get values <release name>`).

Please note that the default installation of Consul on K8S does not enable syncCatalog. If you have sync Catalog enabled, you should try querying for `web.nginx-<namespace>.service.consul`.

Here is a demo of how it works.

[https://asciinema.org/a/rlbkxfb1IPuw4LlTaPQjEMRiJ](https://asciinema.org/a/rlbkxfb1IPuw4LlTaPQjEMRiJ)