330 lines
14 KiB
Markdown
330 lines
14 KiB
Markdown
# NATS Server
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---
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[NATS](https://nats.io) is a simple, secure and performant communications system for digital systems, services and devices.
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NATS is part of the Cloud Native Computing Foundation ([CNCF](https://cncf.io)).
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NATS has over [30 client language implementations](https://nats.io/download/), and its server can run on-premise, in the cloud, at the edge, and even on a Raspberry Pi.
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NATS can secure and simplify design and operation of modern distributed systems.
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```shell
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helm repo add nats https://nats-io.github.io/k8s/helm/charts/
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helm upgrade --install nats nats/nats
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```
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## Upgrade Nodes
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- **Upgrading from 0.x**: The `values.yaml` schema changed significantly from 0.x to 1.x. Read [UPGRADING.md](UPGRADING.md) for instructions on upgrading a 0.x release to 1.x.
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## Values
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There are a handful of explicitly defined options which are documented with comments in the [values.yaml](values.yaml) file.
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Everything in the NATS Config or Kubernetes Resources can be overridden by `merge` and `patch`, which is supported for the following values:
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| key | type | enabled by default |
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|----------------------------------|-----------------------------------------------------------------------------------------------------------------------------|-----------------------------------------|
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| `config` | [NATS Config](https://docs.nats.io/running-a-nats-service/configuration) | yes |
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| `config.cluster` | [NATS Cluster](https://docs.nats.io/running-a-nats-service/configuration/clustering/cluster_config) | no |
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| `config.cluster.tls` | [NATS TLS](https://docs.nats.io/running-a-nats-service/configuration/securing_nats/tls) | no |
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| `config.jetstream` | [NATS JetStream](https://docs.nats.io/running-a-nats-service/configuration#jetstream) | no |
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| `config.jetstream.fileStore.pvc` | [k8s PVC](https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.24/#persistentvolumeclaim-v1-core) | yes, when `config.jetstream` is enabled |
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| `config.nats.tls` | [NATS TLS](https://docs.nats.io/running-a-nats-service/configuration/securing_nats/tls) | no |
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| `config.leafnodes` | [NATS LeafNodes](https://docs.nats.io/running-a-nats-service/configuration/leafnodes/leafnode_conf) | no |
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| `config.leafnodes.tls` | [NATS TLS](https://docs.nats.io/running-a-nats-service/configuration/securing_nats/tls) | no |
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| `config.websocket` | [NATS WebSocket](https://docs.nats.io/running-a-nats-service/configuration/websocket/websocket_conf) | no |
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| `config.websocket.tls` | [NATS TLS](https://docs.nats.io/running-a-nats-service/configuration/securing_nats/tls) | no |
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| `config.websocket.ingress` | [k8s Ingress](https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.24/#ingress-v1-networking-k8s-io) | no |
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| `config.mqtt` | [NATS MQTT](https://docs.nats.io/running-a-nats-service/configuration/mqtt/mqtt_config) | no |
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| `config.mqtt.tls` | [NATS TLS](https://docs.nats.io/running-a-nats-service/configuration/securing_nats/tls) | no |
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| `config.gateway` | [NATS Gateway](https://docs.nats.io/running-a-nats-service/configuration/gateways/gateway#gateway-configuration-block) | no |
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| `config.gateway.tls` | [NATS TLS](https://docs.nats.io/running-a-nats-service/configuration/securing_nats/tls) | no |
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| `config.resolver` | [NATS Resolver](https://docs.nats.io/running-a-nats-service/configuration/securing_nats/auth_intro/jwt/resolver) | no |
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| `config.resolver.pvc` | [k8s PVC](https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.24/#persistentvolumeclaim-v1-core) | yes, when `config.resolver` is enabled |
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| `container` | nats [k8s Container](https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.24/#container-v1-core) | yes |
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| `reloader` | config reloader [k8s Container](https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.24/#container-v1-core) | yes |
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| `promExporter` | prometheus exporter [k8s Container](https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.24/#container-v1-core) | no |
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| `promExporter.podMonitor` | [prometheus PodMonitor](https://prometheus-operator.dev/docs/operator/api/#monitoring.coreos.com/v1.PodMonitor) | no |
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| `service` | [k8s Service](https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.24/#service-v1-core) | yes |
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| `statefulSet` | [k8s StatefulSet](https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.24/#statefulset-v1-apps) | yes |
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| `podTemplate` | [k8s PodTemplate](https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.24/#pod-v1-core) | yes |
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| `headlessService` | [k8s Service](https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.24/#service-v1-core) | yes |
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| `configMap` | [k8s ConfigMap](https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.24/#configmap-v1-core) | yes |
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| `natsBox.contexts.default` | [NATS Context](https://docs.nats.io/using-nats/nats-tools/nats_cli#nats-contexts) | yes |
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| `natsBox.contexts.[name]` | [NATS Context](https://docs.nats.io/using-nats/nats-tools/nats_cli#nats-contexts) | no |
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| `natsBox.container` | nats-box [k8s Container](https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.24/#container-v1-core) | yes |
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| `natsBox.deployment` | [k8s Deployment](https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.24/#deployment-v1-apps) | yes |
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| `natsBox.podTemplate` | [k8s PodTemplate](https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.24/#pod-v1-core) | yes |
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| `natsBox.contextsSecret` | [k8s Secret](https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.24/#secret-v1-core) | yes |
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| `natsBox.contentsSecret` | [k8s Secret](https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.24/#secret-v1-core) | yes |
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### Merge
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Merging is performed using the Helm `merge` function. Example - add NATS accounts and container resources:
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```yaml
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config:
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merge:
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accounts:
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A:
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users:
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- {user: a, password: a}
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B:
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users:
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- {user: b, password: b}
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natsBox:
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contexts:
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a:
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merge: {user: a, password: a}
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b:
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merge: {user: b, password: b}
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defaultContextName: a
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```
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## Patch
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Patching is performed using [JSON Patch](https://jsonpatch.com/). Example - add additional route to end of route list:
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```yaml
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config:
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cluster:
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enabled: true
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patch:
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- op: add
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path: /routes/-
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value: nats://demo.nats.io:6222
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```
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## Common Configurations
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### JetStream Cluster on 3 separate hosts
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```yaml
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config:
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cluster:
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enabled: true
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replicas: 3
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jetstream:
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enabled: true
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fileStore:
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pvc:
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size: 10Gi
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podTemplate:
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topologySpreadConstraints:
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kubernetes.io/hostname:
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maxSkew: 1
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whenUnsatisfiable: DoNotSchedule
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```
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### NATS Container Resources
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```yaml
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container:
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env:
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# different from k8s units, suffix must be B, KiB, MiB, GiB, or TiB
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# should be ~90% of memory limit
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GOMEMLIMIT: 7GiB
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merge:
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# recommended limit is at least 2 CPU cores and 8Gi Memory for production JetStream clusters
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resources:
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requests:
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cpu: "2"
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memory: 8Gi
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limits:
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cpu: "2"
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memory: 8Gi
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```
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### Specify Image Version
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```yaml
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container:
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image:
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tag: x.y.z-alpine
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```
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### Operator Mode with NATS Resolver
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Run `nsc generate config --nats-resolver` and replace the `OPERATOR_JWT`, `SYS_ACCOUNT_ID`, and `SYS_ACCOUNT_JWT` with your values.
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Make sure that you do not include the trailing `,` in the `SYS_ACCOUNT_JWT`.
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```
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config:
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resolver:
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enabled: true
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merge:
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type: full
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interval: 2m
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timeout: 1.9s
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merge:
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operator: OPERATOR_JWT
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system_account: SYS_ACCOUNT_ID
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resolver_preload:
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SYS_ACCOUNT_ID: SYS_ACCOUNT_JWT
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```
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## Accessing NATS
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The chart contains 2 services by default, `service` and `headlessService`.
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### `service`
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The `service` is intended to be accessed by NATS Clients. It is a `ClusterIP` service by default, however it can easily be changed to a different service type.
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The `nats`, `websocket`, `leafnodes`, and `mqtt` ports will be exposed through this service by default if they are enabled.
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Example: change this service type to a `LoadBalancer`:
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```yaml
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service:
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merge:
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spec:
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type: LoadBalancer
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```
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### `headlessService`
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The `headlessService` is used for NATS Servers in the Stateful Set to discover one another. It is primarily intended to be used for Cluster Route connections.
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### TLS Considerations
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The TLS Certificate used for Client Connections should have a SAN covering DNS Name that clients access the `service` at.
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The TLS Certificate used for Cluster Route Connections should have a SAN covering the DNS Name that routes access each other on the `headlessService` at. This is `*.<headless-service-name>` by default.
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## Advanced Features
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### Templating Values
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Anything in `values.yaml` can be templated:
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- maps matching the following syntax will be templated and parsed as YAML:
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```yaml
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$tplYaml: |
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yaml template
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```
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- maps matching the follow syntax will be templated, parsed as YAML, and spread into the parent map/slice
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```yaml
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$tplYamlSpread: |
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yaml template
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```
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Example - change service name:
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```yaml
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service:
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name:
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$tplYaml: >-
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{{ include "nats.fullname" . }}-svc
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```
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### NATS Config Units and Variables
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NATS configuration extends JSON, and can represent Units and Variables. They must be wrapped in `<< >>` in order to template correctly. Example:
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```yaml
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config:
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merge:
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authorization:
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# variable
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token: << $TOKEN >>
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# units
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max_payload: << 2MB >>
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```
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templates to the `nats.conf`:
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```
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{
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"authorization": {
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"token": $TOKEN
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},
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"max_payload": 2MB,
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"port": 4222,
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...
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}
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```
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### NATS Config Includes
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Any NATS Config key ending in `$include` will be replaced with an include directive. Included files should be in paths relative to `/etc/nats-config`. Multiple `$include` keys are supported by using a prefix, and will be sorted alphabetically. Example:
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```yaml
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config:
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merge:
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00$include: auth.conf
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01$include: params.conf
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configMap:
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merge:
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data:
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auth.conf: |
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accounts: {
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A: {
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users: [
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{user: a, password: a}
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]
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},
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B: {
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users: [
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{user: b, password: b}
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]
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},
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}
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params.conf: |
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max_payload: 2MB
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```
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templates to the `nats.conf`:
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```
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include auth.conf;
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"port": 4222,
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...
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include params.conf;
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```
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### Extra Resources
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Enables adding additional arbitrary resources. Example - expose WebSocket via VirtualService in Istio:
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```yaml
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config:
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websocket:
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enabled: true
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extraResources:
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- apiVersion: networking.istio.io/v1beta1
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kind: VirtualService
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metadata:
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namespace:
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$tplYamlSpread: >
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{{ include "nats.metadataNamespace" $ }}
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name:
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$tplYaml: >
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{{ include "nats.fullname" $ | quote }}
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labels:
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$tplYaml: |
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{{ include "nats.labels" $ }}
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spec:
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hosts:
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- demo.nats.io
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gateways:
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- my-gateway
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http:
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- name: default
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match:
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- name: root
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uri:
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exact: /
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route:
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- destination:
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host:
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$tplYaml: >
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{{ .Values.service.name | quote }}
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port:
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number:
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$tplYaml: >
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{{ .Values.config.websocket.port }}
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```
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