[docs] kubernetes (#521)

* kubernetes docs

* kubernetes docs

* specify min helm chart version

Co-authored-by: Austin Parker <[email protected]>

docs/kubernetes_deployment.md

@@ -16,12 +16,152 @@ Please refer to Helm's [documentation](https://helm.sh/docs/) to get started.
 
 Add OpenTelemetry Helm repository:
 
-```console
+```shell
 helm repo add open-telemetry https://open-telemetry.github.io/opentelemetry-helm-charts
 ```
 
 To install the chart with the release name my-otel-demo, run the following command:
 
-```console
+```shell
 helm install my-otel-demo open-telemetry/opentelemetry-demo
 ```
+
+> **Note**
+> The OpenTelemetry Demo Helm chart version 0.11.0 or greater is required to
+> perform all usage methods mentioned below.
+
+## Use the Demo
+
+The demo application will need the services exposed outside of the Kubernetes
+cluster in order to use them. You can expose the services to your local system
+using the `kubectl port-forward` command or by configuring service types
+(ie: LoadBalancer) with optionally deployed ingress resources.
+
+### Expose services using kubectl port-forward
+
+To expose the frontendproxy service use the following command (replace
+`my-otel-demo` with your Helm chart release name accordingly):
+
+```shell
+kubectl port-forward svc/my-otel-demo-frontendproxy 8080:8080
+```
+
+In order for spans from the browser to be properly collected, you will also
+need to expose the OpenTelemetry Collector's OTLP/HTTP port (replace
+`my-otel-demo` with your Helm chart release name accordingly):
+
+```shell
+kubectl port-forward svc/my-otel-demo-otelcol 4318:4318
+```
+
+> **Note**
+> `kubectl port-forward` will proxy the port until the process terminates. You
+> may need to create separate terminal sessions for each use of
+> `kubectl port-forward`, and use CTRL-C to terminate the process when done.
+
+With the frontendproxy and Collector port-forward set up, you can access:
+
+- Webstore: <http://localhost:8080/>
+- Grafana: <http://localhost:8080/grafana/>
+- Feature Flags UI: <http://localhost:8080/feature/>
+- Load Generator UI: <http://localhost:8080/loadgen/>
+- Jaeger UI: <http://localhost:8080/jaeger/ui/>
+
+### Expose services using service type configurations
+
+> **Note**
+> Kubernetes clusters may not have the proper infrastructure components to
+> enable LoadBalancer service types or ingress resources. Verify your cluster
+> has the proper support before using these configuration options.
+
+Each demo service (ie: frontendproxy) offers a way to have its Kubernetes
+service type configured. By default these will be `ClusterIP` but you can change
+each one using the `serviceType` property for each service.
+
+To configure the frontendproxy service to use a LoadBalancer service type you
+would specify the following in your values file:
+
+```yaml
+components:
+  frontendProxy:
+    serviceType: LoadBalancer
+```
+
+> **Note**
+> It is recommended to use a values file when installing the Helm chart in order
+> to specify additional configuration options.
+
+The Helm chart does not provide facilities to create ingress resources. If
+required these would need to be created manually after installing the Helm chart.
+Some Kubernetes providers require specific service types in order to be used by
+ingress resources (ie: EKS ALB ingress, requires a NodePort service type).
+
+In order for spans from the browser to be properly collected, you will also
+need to expose the OpenTelemetry Collector's OTLP/HTTP port to be accessible to
+user web browsers. The location where the OpenTelemetry Collector is exposed
+must also be passed into the frontend service using the
+`PUBLIC_OTEL_EXPORTER_OTLP_TRACES_ENDPOINT` environment variable. You can do
+this using the following in your values file:
+
+```yaml
+components:
+  frontend:
+    env:
+      - name: PUBLIC_OTEL_EXPORTER_OTLP_TRACES_ENDPOINT
+        value: "http://otel-demo-collector.mydomain.com:4318/v1/traces"
+```
+
+To install the Helm chart with a custom `my-values-file.yaml` values file use:
+
+```shell
+helm install my-otel-demo open-telemetry/opentelemetry-demo --values my-values-file.yaml
+```
+
+With the frontendproxy and Collector exposed, you can access the demo UI at the
+base path for the frontendproxy. Other demo components can be accessed at the
+following sub-paths:
+
+- Webstore: `/` (base)
+- Grafana: `/grafana`
+- Feature Flags UI: `/feature`
+- Load Generator UI: `/loadgen/` (must include trailing slash)
+- Jaeger UI: `/jaeger/ui`
+
+## Bring your own backend
+
+Likely you want to use the Webstore as a demo application for an observability
+backend you already have (e.g. an existing instance of Jaeger, Zipkin, or one
+of the [vendor of your choice](https://opentelemetry.io/vendors/).
+
+The OpenTelemetry Collector's configuration is exposed in the Helm chart. Any
+additions you do will be merged into the default configuration. You can use
+this to add your own exporters, and add them to the desired pipeline(s)
+
+```yaml
+opentelemetry-collector:
+  config:
+    exporters:
+      otlphttp/example:
+        endpoint: <your-endpoint-url>
+
+    service:
+      pipelines:
+        traces:
+          receivers: [otlp]
+          processors: [batch]
+          exporters: [otlphttp/example]
+```
+
+> **Note**
+> When merging YAML values with Helm, objects are merged and arrays are replaced.
+
+Vendor backends might require you to add additional parameters for
+authentication, please check their documentation. Some backends require
+different exporters, you may find them and their documentation available at
+[opentelemetry-collector-contrib/exporter](https://github.com/open-telemetry/opentelemetry-collector-contrib/tree/main/exporter).
+
+To install the Helm chart with a custom `my-values-file.yaml` values file use:
+
+```shell
+helm install my-otel-demo open-telemetry/opentelemetry-demo --values my-values-file.yaml
+```