# Mermin with NetObserv Flow and OpenSearch

* [Mermin with NetObserv Flow and OpenSearch](#mermin-with-netobserv-flow-and-opensearch)
  * [Overview](#overview)
  * [Install](#install)
  * [Access](#access)
  * [Hints](#hints)

## Overview

This example deploys Mermin and NetObserv Flow (as OTel receiver) with OpenSearch as the data platform. Although local [Kind](https://kind.sigs.k8s.io/) was used for testing, any kubernetes cluster should work if nodes have sufficient resources and don't have any taints that should be tolerated (`tolerations` values may be used). This example is intended only for demonstration, testing, or proof-of-concept use, since OpenSearch is deployed in a single-node mode.

Notes on the example deployment:

* [Location in the repository](https://github.com/elastiflow/mermin/tree/beta/docs/deployment/examples/netobserv-os-simple-svc) - `docs/deployment/examples/netobserv-os-simple-svc`
* Namespace used in the example: `elastiflow`.
* Allocatable resources needed (mCPU/MiB):
  * OpenSearch `2000m`/`4000Mi`
  * OpenSearch Dashboards `1000m`/`768M`
  * NetObserv Flow `1000m`/`6000Mi`
* You may optionally customize and use `config.hcl` instead of the default config.
* NetObserv is accessed via K8s Service (ClusterIP) for simplicity.

## Install

* Create values and a config file for the Mermin Umbrella chart (or use ones from the repo)
  * Values [contents](https://github.com/elastiflow/mermin/blob/main/docs/deployment/examples/netobserv-os-simple-svc/values.yaml)
  * Config [contents](https://github.com/elastiflow/mermin/blob/main/docs/deployment/examples/netobserv-os-simple-svc/config.hcl)
* Add Helm charts and Deploy

  ```sh
  helm repo add mermin https://elastiflow.github.io/mermin/
  helm repo add netobserv https://elastiflow.github.io/helm-chart-netobserv/
  helm repo add opensearch https://opensearch-project.github.io/helm-charts/
  helm repo update
  # Deploy
  helm upgrade -i --wait --timeout 15m -n elastiflow --create-namespace \
    -f values.yaml \
    --set-file mermin.config.content=config.hcl \
    mermin mermin/mermin-netobserv-os-stack
  ```
* Optionally install `metrics-server` to get metrics if it has not been installed yet

  ```sh
  kubectl apply -f https://github.com/kubernetes-sigs/metrics-server/releases/download/v0.8.0/components.yaml
  # Patch to use insecure TLS, commonly needed on dev local clusters
  kubectl -n kube-system patch deployment metrics-server --type='json' -p='[{"op":"add","path":"/spec/template/spec/containers/0/args/-","value":"--kubelet-insecure-tls"}]'
  ```

## Access

First, port forward the OpenSearch Dashboards service

```sh
kubectl -n elastiflow port-forward svc/elastiflow-os-dashboards 5601:5601
```

Now you can navigate to `http://localhost:5601/` in your browser to open OpenSearch Dashboards, using `admin`/`Elast1flow!` as the user/password. Select "global tenant", and explore the data.

## Hints

To render and diff Helm templates to Kubernetes manifests, run:

```sh
rm -rf helm_rendered; helm template -n elastiflow \
  -f values.yaml \
  --set-file mermin.config.content=config.hcl \
  mermin mermin/mermin-netobserv-os-stack \
  --output-dir helm_rendered

# Diff with existing K8s resources
kubectl -n elastiflow diff -R -f helm_rendered/
```