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nats-io / k8s

NATS on Kubernetes with Helm Charts
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Can not enable JetStream + Cluster when using Helm-Chart #846

Closed derMarcel98 closed 6 months ago

derMarcel98 commented 9 months ago

What version were you using?

Helm-Chart: 1.1.5 Nats-Server: v2.10.5

What environment was the server running in?

On a k8s cluster using the docker images provided from the helm-chart.

Is this defect reproducible?

Yes, use the helm-chart version 1.1.5 and activate cluster with 3 instances, JetStream and tls.

Given the capability you are leveraging, describe your expectation?

I expect the variable server_name to use its described default when the nats.conf is being generated so its unique for each server. Currently is being left empty.

Given the expectation, what is the defect you are observing?

When you apply the chart the server crashes with only a single error message: "nats-server requires server_name to be set". I expect the server_name to be the default value explained in the documentation (i dont set it explicitly) but when I check the generated nats.conf server_name value is blank.

caleblloyd commented 9 months ago

What is your values.yaml with any sensitive information removed?

derMarcel98 commented 9 months ago

values-without-sensitive-information.txt

derMarcel98 commented 9 months ago

Sadly cant upload a yml and when i paste it as code he always formats it into headlines etc..

caleblloyd commented 9 months ago

If you put 3 back ticks before and after it, it will show up as a code block

derMarcel98 commented 9 months ago

My bad, used single back ticks. Thanks!

################################################################################
# Global options
################################################################################
global:
  image:
    # global image pull policy to use for all container images in the chart
    # can be overridden by individual image pullPolicy
    pullPolicy:
    # global list of secret names to use as image pull secrets for all pod specs in the chart
    # secrets must exist in the same namespace
    # https://kubernetes.io/docs/tasks/configure-pod-container/pull-image-private-registry/
    pullSecretNames: []
    # global registry to use for all container images in the chart
    # can be overridden by individual image registry
    registry:

  # global labels will be applied to all resources deployed by the chart
  labels: {my-label}

################################################################################
# Common options
################################################################################
# override name of the chart
nameOverride:
# override full name of the chart+release
fullnameOverride:
# override the namespace that resources are installed into
namespaceOverride:

# reference a common CA Certificate or Bundle in all nats config `tls` blocks and nats-box contexts
# note: `tls.verify` still must be set in the appropriate nats config `tls` blocks to require mTLS
tlsCA:
  enabled: true
  # set configMapName in order to mount an existing configMap to dir
  configMapName:
  # set secretName in order to mount an existing secretName to dir
  secretName: nats-certs
  # directory to mount the configMap or secret to
  dir: /etc/nats-ca-cert
  # key in the configMap or secret that contains the CA Certificate or Bundle
  key: ca.crt

################################################################################
# NATS Stateful Set and associated resources
################################################################################

############################################################
# NATS config
############################################################
config:
  cluster:
    enabled: true
    port: 6222
    # must be 2 or higher when jetstream is enabled
    replicas: 3
    listen: 0.0.0.0:6222
    name: my-cluster-name
    # apply to generated route URLs that connect to other pods in the StatefulSet
    routeURLs:
      # if both user and password are set, they will be added to route URLs
      # and the cluster authorization block
      user:
      password:
      # set to true to use FQDN in route URLs
      useFQDN: false
      k8sClusterDomain: cluster.local

    tls:
      enabled: true
      # set secretName in order to mount an existing secret to dir
      secretName: nats-certs
      dir: /etc/nats-certs/cluster
      cert: tls.crt
      key: tls.key
      # merge or patch the tls config
      # https://docs.nats.io/running-a-nats-service/configuration/securing_nats/tls
      merge: {}
      patch: []

    # merge or patch the cluster config
    # https://docs.nats.io/running-a-nats-service/configuration/clustering/cluster_config
    merge: {
      routes: [
        nats://my-service.svc.cluster.local:6222,
        nats://my-service.svc.cluster.local:6222,
        nats://my-service.svc.cluster.local:6222
      ]
    }
    patch: []

  jetstream:
    enabled: true

    fileStore:
      enabled: true
      dir: /data

      ############################################################
      # stateful set -> volume claim templates -> jetstream pvc
      ############################################################
      pvc:
        enabled: true
        size: 2Gi
        storageClassName:

        # merge or patch the jetstream pvc
        # https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.24/#persistentvolumeclaim-v1-core
        merge: {}
        patch: []
        # defaults to "{{ include "nats.fullname" $ }}-js"
        #name:

      # defaults to the PVC size
      maxSize:

    memoryStore:
      enabled: false
      # ensure that container has a sufficient memory limit greater than maxSize
      maxSize: 1Gi

    # merge or patch the jetstream config
    # https://docs.nats.io/running-a-nats-service/configuration#jetstream
    merge: {}
    patch: []

  nats:
    port: 4222
    tls:
      enabled: true
      # set secretName in order to mount an existing secret to dir
      secretName: nats-certs
      dir: /etc/nats-certs/nats
      cert: tls.crt
      key: tls.key
      # merge or patch the tls config
      # https://docs.nats.io/running-a-nats-service/configuration/securing_nats/tls
      merge: {}
      patch: []

  leafnodes:
    enabled: false
    port: 7422
    tls:
      enabled: false
      # set secretName in order to mount an existing secret to dir
      secretName:
      dir: /etc/nats-certs/leafnodes
      cert: tls.crt
      key: tls.key
      # merge or patch the tls config
      # https://docs.nats.io/running-a-nats-service/configuration/securing_nats/tls
      merge: {}
      patch: []

    # merge or patch the leafnodes config
    # https://docs.nats.io/running-a-nats-service/configuration/leafnodes/leafnode_conf
    merge: {}
    patch: []

  websocket:
    enabled: false
    port: 8080
    tls:
      enabled: false
      # set secretName in order to mount an existing secret to dir
      secretName:
      dir: /etc/nats-certs/websocket
      cert: tls.crt
      key: tls.key
      # merge or patch the tls config
      # https://docs.nats.io/running-a-nats-service/configuration/securing_nats/tls
      merge: {}
      patch: []

    ############################################################
    # ingress
    ############################################################
    # service must be enabled also
    ingress:
      enabled: false
      # must contain at least 1 host otherwise ingress will not be created
      hosts: []
      path: /
      pathType: Exact
      # sets to the ingress class name
      className:
      # set to an existing secret name to enable TLS on the ingress; applies to all hosts
      tlsSecretName:

      # merge or patch the ingress
      # https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.24/#ingress-v1-networking-k8s-io
      merge: {}
      patch: []
      # defaults to "{{ include "nats.fullname" $ }}-ws"
      name:

    # merge or patch the websocket config
    # https://docs.nats.io/running-a-nats-service/configuration/websocket/websocket_conf
    merge: {}
    patch: []

  mqtt:
    enabled: false
    port: 1883
    tls:
      enabled: false
      # set secretName in order to mount an existing secret to dir
      secretName:
      dir: /etc/nats-certs/mqtt
      cert: tls.crt
      key: tls.key
      # merge or patch the tls config
      # https://docs.nats.io/running-a-nats-service/configuration/securing_nats/tls
      merge: {}
      patch: []

    # merge or patch the mqtt config
    # https://docs.nats.io/running-a-nats-service/configuration/mqtt/mqtt_config
    merge: {}
    patch: []

  gateway:
    enabled: false
    port: 7222
    tls:
      enabled: false
      # set secretName in order to mount an existing secret to dir
      secretName:
      dir: /etc/nats-certs/gateway
      cert: tls.crt
      key: tls.key
      # merge or patch the tls config
      # https://docs.nats.io/running-a-nats-service/configuration/securing_nats/tls
      merge: {}
      patch: []

    # merge or patch the gateway config
    # https://docs.nats.io/running-a-nats-service/configuration/gateways/gateway#gateway-configuration-block
    merge: {}
    patch: []

  monitor:
    enabled: true
    port: 8222
    tls:
      # config.nats.tls must be enabled also
      # when enabled, monitoring port will use HTTPS with the options from config.nats.tls
      enabled: false

  profiling:
    enabled: false
    port: 65432

  resolver:
    enabled: false
    dir: /data/resolver

    ############################################################
    # stateful set -> volume claim templates -> resolver pvc
    ############################################################
    pvc:
      enabled: true
      size: 1Gi
      storageClassName:

      # merge or patch the pvc
      # https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.24/#persistentvolumeclaim-v1-core
      merge: {}
      patch: []
      # defaults to "{{ include "nats.fullname" $ }}-resolver"
      #name:

    # merge or patch the resolver
    # https://docs.nats.io/running-a-nats-service/configuration/securing_nats/auth_intro/jwt/resolver
    merge: {}
    patch: []

  # adds a prefix to the server name, which defaults to the pod name
  # helpful for ensuring server name is unique in a super cluster
  serverNamePrefix: ""

  # merge or patch the nats config
  # https://docs.nats.io/running-a-nats-service/configuration
  # following special rules apply
  #  1. strings that start with << and end with >> will be unquoted
  #     use this for variables and numbers with units
  #  2. keys ending in $include will be switched to include directives
  #     keys are sorted alphabetically, use prefix before $includes to control includes ordering
  #     paths should be relative to /etc/nats-config/nats.conf
  # example:
  #
  #   merge:
  #     $include: ./my-config.conf
  #     zzz$include: ./my-config-last.conf
  #     server_name: nats
  #     authorization:
  #       token: << $TOKEN >>
  #     jetstream:
  #       max_memory_store: << 1GB >>
  #
  # will yield the config:
  # {
  #   include ./my-config.conf;
  #   "authorization": {
  #     "token": $TOKEN
  #   },
  #   "jetstream": {
  #     "max_memory_store": 1GB
  #   },
  #   "server_name": "nats",
  #   include ./my-config-last.conf;
  # }
  merge: {
    max_payload: 8388608,
    debug: true,
  }
  patch: []

############################################################
# stateful set -> pod template -> nats container
############################################################
container:
  image:
    repository: nats
    tag: 2.10.5-alpine
    pullPolicy:
    registry: public.ecr.aws/docker/library

  # container port options
  # must be enabled in the config section also
  # https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.24/#containerport-v1-core
  ports:
    nats: {}
    leafnodes: {}
    websocket: {}
    mqtt: {}
    cluster: {}
    gateway: {}
    monitor: {}
    profiling: {}

  # map with key as env var name, value can be string or map
  # example:
  #
  #   env:
  #     GOMEMLIMIT: 7GiB
  #     TOKEN:
  #       valueFrom:
  #         secretKeyRef:
  #           name: nats-auth
  #           key: token
  env: {}

  # merge or patch the container
  # https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.24/#container-v1-core
  merge: {}
  patch: []

############################################################
# stateful set -> pod template -> reloader container
############################################################
reloader:
  enabled: true
  image:
    repository: natsio/nats-server-config-reloader
    tag: latest
    pullPolicy:
    registry: private-mirrored-registry

  # env var map, see nats.env for an example
  env: {}

  # all nats container volume mounts with the following prefixes
  # will be mounted into the reloader container
  natsVolumeMountPrefixes:
    - /etc/

  # merge or patch the container
  # https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.24/#container-v1-core
  merge: {}
  patch: []

############################################################
# stateful set -> pod template -> prom-exporter container
############################################################
# config.monitor must be enabled
promExporter:
  enabled: true
  image:
    repository: natsio/prometheus-nats-exporter
    tag: latest
    pullPolicy:
    registry: private-mirrored-registry

  port: 7777
  # env var map, see nats.env for an example
  env: {}

  # merge or patch the container
  # https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.24/#container-v1-core
  merge: {}
  patch: []

  ############################################################
  # prometheus pod monitor
  ############################################################
  podMonitor:
    enabled: true

    # merge or patch the pod monitor
    # https://prometheus-operator.dev/docs/operator/api/#monitoring.coreos.com/v1.PodMonitor
    merge: {}
    patch: []
    # defaults to "{{ include "nats.fullname" $ }}"
    name:

############################################################
# service
############################################################
service:
  enabled: true

  # service port options
  # additional boolean field enable to control whether port is exposed in the service
  # must be enabled in the config section also
  # https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.24/#serviceport-v1-core
  ports:
    nats:
      enabled: true
    leafnodes:
      enabled: true
    websocket:
      enabled: true
    mqtt:
      enabled: true
    cluster:
      enabled: true
    gateway:
      enabled: false
    monitor:
      enabled: true
    profiling:
      enabled: false

  # merge or patch the service
  # https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.24/#service-v1-core
  merge: {}
  patch: []
  # defaults to "{{ include "nats.fullname" $ }}"
  #name: test

############################################################
# other nats extension points
############################################################

# stateful set
statefulSet:
  # merge or patch the stateful set
  # https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.24/#statefulset-v1-apps
  merge: {}
  patch: []
  # defaults to "{{ include "nats.fullname" $ }}"
  #name:

# stateful set -> pod template
podTemplate:
  # adds a hash of the ConfigMap as a pod annotation
  # this will cause the StatefulSet to roll when the ConfigMap is updated
  configChecksumAnnotation: true

  # map of topologyKey: topologySpreadConstraint
  # labelSelector will be added to match StatefulSet pods
  #
  # topologySpreadConstraints:
  #   kubernetes.io/hostname:
  #     maxSkew: 1
  #
  topologySpreadConstraints: {}

  # merge or patch the pod template
  # https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.24/#pod-v1-core
  merge: {}
  patch: []

# headless service
headlessService:
  # merge or patch the headless service
  # https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.24/#service-v1-core
  merge: {}
  patch: []
  # defaults to "{{ include "nats.fullname" $ }}-headless"
  name:

# config map
configMap:
  # merge or patch the config map
  # https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.24/#configmap-v1-core
  merge: {}
  patch: []
  # defaults to "{{ include "nats.fullname" $ }}-config"
  name:

# pod disruption budget
podDisruptionBudget:
  enabled: true
  # merge or patch the pod disruption budget
  # https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.24/#poddisruptionbudget-v1-policy
  merge: {}
  patch: []
  # defaults to "{{ include "nats.fullname" $ }}"
  name:

# service account
serviceAccount:
  enabled: false
  # merge or patch the service account
  # https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.24/#serviceaccount-v1-core
  merge: {}
  patch: []
  # defaults to "{{ include "nats.fullname" $ }}"
  name:

############################################################
# natsBox
#
# NATS Box Deployment and associated resources
############################################################
natsBox:
  enabled: false

  ############################################################
  # NATS contexts
  ############################################################
  contexts:
    default:
      creds:
        # set contents in order to create a secret with the creds file contents
        contents:
        # set secretName in order to mount an existing secret to dir
        secretName:
        # defaults to /etc/nats-creds/<context-name>
        dir:
        key: nats.creds
      nkey:
        # set contents in order to create a secret with the nkey file contents
        contents:
        # set secretName in order to mount an existing secret to dir
        secretName:
        # defaults to /etc/nats-nkeys/<context-name>
        dir:
        key: nats.nk
      # used to connect with client certificates
      tls:
        # set secretName in order to mount an existing secret to dir
        secretName:
        # defaults to /etc/nats-certs/<context-name>
        dir:
        cert: tls.crt
        key: tls.key

      # merge or patch the context
      # https://docs.nats.io/using-nats/nats-tools/nats_cli#nats-contexts
      merge: {}
      patch: []

  # name of context to select by default
  defaultContextName: default

  ############################################################
  # deployment -> pod template -> nats-box container
  ############################################################
  container:
    image:
      repository: natsio/nats-box
      tag: 0.14.1
      pullPolicy:
      registry:

    # env var map, see nats.env for an example
    env: {}

    # merge or patch the container
    # https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.24/#container-v1-core
    merge: {}
    patch: []

  ############################################################
  # other nats-box extension points
  ############################################################

  # deployment
  deployment:
    # merge or patch the deployment
    # https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.24/#deployment-v1-apps
    merge: {}
    patch: []
    # defaults to "{{ include "nats.fullname" $ }}-box"
    name:

  # deployment -> pod template
  podTemplate:
    # merge or patch the pod template
    # https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.24/#pod-v1-core
    merge: {}
    patch: []

  # contexts secret
  contextsSecret:
    # merge or patch the context secret
    # https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.24/#secret-v1-core
    merge: {}
    patch: []
    # defaults to "{{ include "nats.fullname" $ }}-box-contexts"
    name:

  # contents secret
  contentsSecret:
    # merge or patch the contents secret
    # https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.24/#secret-v1-core
    merge: {}
    patch: []
    # defaults to "{{ include "nats.fullname" $ }}-box-contents"
    name:

  # service account
  serviceAccount:
    enabled: false
    # merge or patch the service account
    # https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.24/#serviceaccount-v1-core
    merge: {}
    patch: []
    # defaults to "{{ include "nats.fullname" $ }}-box"
    name:

################################################################################
# Extra user-defined resources
################################################################################
#
# add arbitrary user-generated resources
# example:
#
# config:
#   websocket:
#     enabled: true
# extraResources:
# - apiVersion: networking.istio.io/v1beta1
#   kind: VirtualService
#   metadata:
#     name:
#       $tplYaml: >
#         {{ include "nats.fullname" $ | quote }}
#     labels:
#       $tplYaml: |
#         {{ include "nats.labels" $ }}
#   spec:
#     hosts:
#     - demo.nats.io
#     gateways:
#     - my-gateway
#     http:
#     - name: default
#       match:
#       - name: root
#         uri:
#           exact: /
#       route:
#       - destination:
#           host:
#             $tplYaml: >
#               {{ .Values.service.name | quote }}
#           port:
#             number:
#               $tplYaml: >
#                 {{ .Values.config.websocket.port }}
#
extraResources: []
caleblloyd commented 9 months ago

Try getting rid of config.cluster.merge.routes - that is set automatically for you by the chart

caleblloyd commented 9 months ago

Also -as a note - it is helpful if you don't include the default values in your values.yaml and only put the values that you are overriding. This has a couple beneficial side effects:

  1. It is much easier to see what changes you are making from the default chart values
  2. If a default value changes in a future release, you won't be overriding it back to the old default
derMarcel98 commented 9 months ago

Alright, will do so and post the version here. Thank you

derMarcel98 commented 9 months ago

Also -as a note - it is helpful if you don't include the default values in your values.yaml and only put the values that you are overriding. This has a couple beneficial side effects:

  1. It is much easier to see what changes you are making from the default chart values
  2. If a default value changes in a future release, you won't be overriding it back to the old default
################################################################################
# Global options
################################################################################
global:
  labels: {my-label}

# reference a common CA Certificate or Bundle in all nats config `tls` blocks and nats-box contexts
# note: `tls.verify` still must be set in the appropriate nats config `tls` blocks to require mTLS
tlsCA:
  enabled: true
  # set secretName in order to mount an existing secretName to dir
  secretName: nats-certs
  # directory to mount the configMap or secret to
  dir: /etc/nats-ca-cert
  # key in the configMap or secret that contains the CA Certificate or Bundle
  key: ca.crt

################################################################################
# NATS Stateful Set and associated resources
################################################################################

############################################################
# NATS config
############################################################
config:
  cluster:
    enabled: true
    port: 6222
    # must be 2 or higher when jetstream is enabled
    replicas: 3
    listen: 0.0.0.0:6222
    name: my-cluster

    tls:
      enabled: true
      # set secretName in order to mount an existing secret to dir
      secretName: nats-certs

    # merge or patch the cluster config
    # https://docs.nats.io/running-a-nats-service/configuration/clustering/cluster_config
    merge: {
      routes: [
        nats://my-service.svc.cluster.local:6222,
        nats://my-service.svc.cluster.local:6222,
        nats://my-service.svc.cluster.local:6222
      ]
    }

  jetstream:
    enabled: true

    fileStore:
      enabled: true
      dir: /data

      ############################################################
      # stateful set -> volume claim templates -> jetstream pvc
      ############################################################
      pvc:
        enabled: true
        size: 2Gi
        storageClassName:

        # merge or patch the jetstream pvc
        # https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.24/#persistentvolumeclaim-v1-core
        merge: {}
        patch: []
        # defaults to "{{ include "nats.fullname" $ }}-js"
        #name:

      # defaults to the PVC size
      maxSize:

    memoryStore:
      enabled: false
      # ensure that container has a sufficient memory limit greater than maxSize
      maxSize: 1Gi

    # merge or patch the jetstream config
    # https://docs.nats.io/running-a-nats-service/configuration#jetstream
    merge: {}
    patch: []

  nats:
    port: 4222
    tls:
      enabled: true
      # set secretName in order to mount an existing secret to dir
      secretName: nats-certs

  merge: {
    max_payload: 8388608,
    debug: true,
  }

############################################################
# stateful set -> pod template -> nats container
############################################################
container:
  image:
    repository: nats
    tag: 2.10.5-alpine
    pullPolicy:
    registry: public.ecr.aws/docker/library

############################################################
# stateful set -> pod template -> reloader container
############################################################
reloader:
  enabled: true
  image:
    repository: natsio/nats-server-config-reloader
    tag: latest
    pullPolicy:
    registry: private-registry

############################################################
# stateful set -> pod template -> prom-exporter container
############################################################
# config.monitor must be enabled
promExporter:
  enabled: true
  image:
    repository: natsio/prometheus-nats-exporter
    tag: latest
    pullPolicy:
    registry: private-registry

  ############################################################
  # prometheus pod monitor
  ############################################################
  podMonitor:
    enabled: true

############################################################
# service
############################################################
service:
  enabled: true

  # service port options
  # additional boolean field enable to control whether port is exposed in the service
  # must be enabled in the config section also
  # https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.24/#serviceport-v1-core
  ports:
    nats:
      enabled: true
    leafnodes:
      enabled: true
    websocket:
      enabled: true
    mqtt:
      enabled: true
    cluster:
      enabled: true
    gateway:
      enabled: false
    monitor:
      enabled: true
    profiling:
      enabled: false

############################################################
# natsBox
#
# NATS Box Deployment and associated resources
############################################################
natsBox:
  enabled: false

extraResources: []
oytunyuksel commented 8 months ago

i also faced same problem i think.

values.yaml:

fullnameOverride: nats
namespaceOverride: event
config:
  cluster:
    enabled: true
    port: 6222
    replicas: 3
  jetstream:
    enabled: true
    fileStore:
      enabled: true
      pvc:
        enabled: true
        storageClassName: resizable
        size: 10Gi
  nats:
    port: 4222
  mqtt:
    enabled: true
    port: 1883
  reloader:
    enabled: true
david-mtrade commented 7 months ago

UPDATE:

It seems you need to set the cluster name to a different name, as well as each of the servers. So in your values.yaml you can just set the following, and that will cause the cluster to be named in a unique manner, as well as each of the servers in the cluster.

statefulSet:
  name: your-unique-cluster-name

This way you don't need to set prefixes

OLD ANSWER:

Hello! In order to get a distinct server name for each cluster configure a distinct value for config.serverNamePrefix in each of your values.yaml that is used for each deployment. This value will be prefixed to your pod name, so it ends up registering server names like :your-prefix_nats-0

config:
  serverNamePrefix: 'your-prefix_'

For additional context. In order to follow the trail, these are the hints I used to solve the problem

  1. Check the generated nats.conf with kubectl get configmap -n nats nats-config -o=yaml and look at the following bit:

    {
...
"server_name": $SERVER_NAME,
...
}

  2. Find how is that SERVER_NAME env variable is generated. https://github.com/nats-io/k8s/blob/b572dc26f2c30dddf090c012886c0998a9183d8f/helm/charts/nats/files/stateful-set/nats-container.yaml#L22-L23

And there it is, it is concatenating .Values.config.serverNamePrefix with the pod name

Happy NATSing!