clarify installation section

archived/ha-cluster copy.md

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+date = "2017-03-20T22:25:17+11:00"
+title = "HA Cluster Setup"
+weight = 5
+type = "docs"
+[menu.main]
+    parent = "installation"
++++
+
+You can run three Dgraph Alpha servers and three Dgraph Zero servers in a highly available cluster setup. For a highly available setup, start the Dgraph Zero server  with `--replicas 3` flag, so that all data is replicated on three Alpha servers and forms one Alpha group. You can install a highly available cluster using:
+*  [dgraph-ha.yaml](https://github.com/dgraph-io/dgraph/blob/main/contrib/config/kubernetes/dgraph-ha/dgraph-ha.yaml) file
+*  Helm charts.
+
+### Install a highly available Dgraph cluster using YAML or Helm
+
+{{% tabs %}} {{< tab "YAML" >}}
+#### Before you begin:
+
+* Install [kubectl](https://kubernetes.io/docs/tasks/tools/install-kubectl/).
+* Ensure that you have a production-ready Kubernetes cluster with at least three worker nodes running in a cloud provider of your choice.
+* (Optional) To run Dgraph Alpha with TLS, see [TLS Configuration]({{< relref "tls-configuration.md" >}}).
+
+#### Installing a highly available Dgraph cluster
+
+1.  Verify that you are able to access the nodes in the Kubernetes cluster:
+
+    ```bash
+    kubectl get nodes
+    ```
+
+    An output similar to this appears:
+
+     ```bash
+       NAME                                          STATUS   ROLES    AGE   VERSION
+      <aws-ip-hostname>.<region>.compute.internal   Ready    <none>   1m   v1.15.11-eks-af3caf
+      <aws-ip-hostname>.<region>.compute.internal   Ready    <none>   1m   v1.15.11-eks-af3caf
+      <aws-ip-hostname>.<region>.compute.internal   Ready    <none>   1m   v1.15.11-eks-af3caf
+      ```
+    After your Kubernetes cluster is up, you can use [dgraph-ha.yaml](https://github.com/dgraph-io/dgraph/blob/main/contrib/config/kubernetes/dgraph-ha/dgraph-ha.yaml) to start the cluster. 
+
+1.  Start a StatefulSet that creates Pods with `Zero`, `Alpha`, and `Ratel UI`:
+
+     ```bash
+     kubectl create --filename https://raw.githubusercontent.com/dgraph-io/dgraph/main/contrib/config/kubernetes/dgraph-ha/dgraph-ha.yaml
+     ```
+    An output similar to this appears:
+
+      ```bash
+      service/dgraph-zero-public created
+      service/dgraph-alpha-public created
+      service/dgraph-ratel-public created
+      service/dgraph-zero created
+      service/dgraph-alpha created
+      statefulset.apps/dgraph-zero created
+      statefulset.apps/dgraph-alpha created
+      deployment.apps/dgraph-ratel created
+      ```
+1. Confirm that the Pods were created successfully.
+
+    ```bash
+    kubectl get pods
+    ```
+    An output similar to this appears:
+
+     ```bash
+      NAME                  READY   STATUS    RESTARTS   AGE
+     dgraph-alpha-0        1/1     Running   0          6m24s
+     dgraph-alpha-1        1/1     Running   0          5m42s
+     dgraph-alpha-2        1/1     Running   0          5m2s
+     dgraph-ratel-<pod-id> 1/1     Running   0          6m23s
+     dgraph-zero-0         1/1     Running   0          6m24s
+     dgraph-zero-1         1/1     Running   0          5m41s
+     dgraph-zero-2         1/1     Running   0          5m6s
+     ```
+    You can check the logs for the Pod using `kubectl logs --follow <POD_NAME>`.. 
+
+1. Port forward from your local machine to the Pod:
+
+    ```bash
+       kubectl port-forward service/dgraph-alpha-public 8080:8080
+       kubectl port-forward service/dgraph-ratel-public 8000:8000
+    ```
+1.  Go to `http://localhost:8000` to access Dgraph using the Ratel UI.
+
+{{% notice "note" %}} You can also access the service on its External IP address.{{% /notice %}}
+
+#### Deleting highly available Dgraph resources
+
+Delete all the resources using:
+
+```sh
+kubectl delete --filename https://raw.githubusercontent.com/dgraph-io/dgraph/main/contrib/config/kubernetes/dgraph-ha/dgraph-ha.yaml
+kubectl delete persistentvolumeclaims --selector app=dgraph-zero
+kubectl delete persistentvolumeclaims --selector app=dgraph-alpha
+```
+{{< /tab >}} 
+{{< tab "Helm" >}}
+
+#### Before you begin
+
+* Install [kubectl](https://kubernetes.io/docs/tasks/tools/install-kubectl/).
+* Ensure that you have a production-ready Kubernetes cluster with atleast three worker nodes running in a cloud provider of your choice.
+* Install [Helm](https://helm.sh/docs/intro/install/).
+* (Optional) To run Dgraph Alpha with TLS, see [TLS Configuration]({{< relref "tls-configuration.md" >}}).
+
+#### Installing a highly available Dgraph cluster using Helm
+
+1.  Verify that you are able to access the nodes in the Kubernetes cluster:
+
+    ```bash
+    kubectl get nodes
+    ```
+
+    An output similar to this appears:
+
+     ```bash
+       NAME                                          STATUS   ROLES    AGE   VERSION
+      <aws-ip-hostname>.<region>.compute.internal   Ready    <none>   1m   v1.15.11-eks-af3caf
+      <aws-ip-hostname>.<region>.compute.internal   Ready    <none>   1m   v1.15.11-eks-af3caf
+      <aws-ip-hostname>.<region>.compute.internal   Ready    <none>   1m   v1.15.11-eks-af3caf
+      ```
+     After your Kubernetes cluster is up and running, you can use of the [Dgraph Helm chart](https://github.com/dgraph-io/charts/) to install a highly available Dgraph cluster
+
+1.  Add the Dgraph helm repository::
+
+     ```bash
+     helm repo add dgraph https://charts.dgraph.io
+     ```
+1. Install the chart with `<RELEASE-NAME>`:
+
+    ```bash
+    helm install <RELEASE-NAME> dgraph/dgraph
+    ```
+
+    You can also specify the version using:
+    ```bash
+       helm install <RELEASE-NAME> dgraph/dgraph --set image.tag="{{< version >}}"
+    ```
+    When configuring the Dgraph image tag, be careful not to use `latest` or `main` in a production environment. These tags may have the Dgraph version change, causing a mixed-version Dgraph cluster that can lead to an outage and potential data loss.
+
+    An output similar to this appears:
+
+        ```bash
+        NAME: <RELEASE-NAME>
+        LAST DEPLOYED: Wed Feb  1 21:26:32 2023
+        NAMESPACE: default
+        STATUS: deployed
+        REVISION: 1
+        TEST SUITE: None
+        NOTES:
+        1. You have just deployed Dgraph, version 'v21.12.0'.
+
+           For further information:
+            * Documentation: https://dgraph.io/docs/
+            * Community and Issues: https://discuss.dgraph.io/   
+        2. Get the Dgraph Alpha HTTP/S endpoint by running these commands.
+           export ALPHA_POD_NAME=$(kubectl get pods --namespace default --selector "statefulset.kubernetes.io/pod-name=<RELEASE-NAME>-dgraph-alpha-0,release=<RELEASE-NAME>-dgraph" --output jsonpath="{.items[0].metadata.name}")
+           echo "Access Alpha HTTP/S using http://localhost:8080"
+           kubectl --namespace default port-forward $ALPHA_POD_NAME 8080:8080
+
+          NOTE: Change "http://" to "https://" if TLS was added to the Ingress, Load Balancer, or Dgraph Alpha service.
+        ```
+1. Get the name of the Pods in the cluster using `kubectl get pods`:
+    ```bash
+       NAME                          READY   STATUS    RESTARTS   AGE
+      <RELEASE-NAME>-dgraph-alpha-0   1/1     Running   0          4m48s
+      <RELEASE-NAME>-dgraph-alpha-1   1/1     Running   0          4m2s
+      <RELEASE-NAME>-dgraph-alpha-2   1/1     Running   0          3m31s
+      <RELEASE-NAME>-dgraph-zero-0    1/1     Running   0          4m48s
+      <RELEASE-NAME>-dgraph-zero-1    1/1     Running   0          4m10s
+      <RELEASE-NAME>-dgraph-zero-2    1/1     Running   0          3m50s
+
+1. Get the Dgraph Alpha HTTP/S endpoint by running these commands:
+    ```bash
+        export ALPHA_POD_NAME=$(kubectl get pods --namespace default --selector "statefulset.kubernetes.io/pod-name=<RELEASE-NAME>-dgraph-alpha-0,release=<RELEASE-NAME>-dgraph" --output jsonpath="{.items[0].metadata.name}")
+        echo "Access Alpha HTTP/S using http://localhost:8080"
+        kubectl --namespace default port-forward $ALPHA_POD_NAME 8080:8080
+    ```
+#### Deleting the resources from the cluster
+
+1. Delete the Helm deployment using:
+
+   ```sh
+     helm delete my-release
+   ```
+2. Delete associated Persistent Volume Claims:
+
+   ```sh
+   kubectl delete pvc --selector release=my-release
+   ```
+{{< /tab >}}    
+{{% /tabs %}}
+
+
+### Dgraph configuration files
+
+You can create a Dgraph [Config]({{< relref "cli/config" >}}) files for Alpha server and Zero server with Helm chart configuration values, `<MY-CONFIG-VALUES>`. For more information about the values, see the latest [configuration settings](https://github.com/dgraph-io/charts/blob/master/charts/dgraph/README.md#configuration).
+
+1. Open an editor of your choice and create a config file named `<MY-CONFIG-VALUES>.yaml`:
+
+```yaml
+# <MY-CONFIG-VALUES>.yaml
+alpha:
+  configFile:
+    config.yaml: |
+      alsologtostderr: true
+      badger:
+        compression_level: 3
+        tables: mmap
+        vlog: mmap
+      postings: /dgraph/data/p
+      wal: /dgraph/data/w
+zero:
+  configFile:
+    config.yaml: |
+      alsologtostderr: true
+      wal: /dgraph/data/zw
+```
+
+2. Change to the director in which you created `<MY-CONFIG-VALUES>`.yaml and then install with Alpha and Zero configuration using:
+
+```sh
+helm install <RELEASE-NAME> dgraph/dgraph --values <MY-CONFIG-VALUES>.yaml
+```
+
+### Exposing Alpha and Ratel Services
+
+By default Zero and Alpha services are exposed only within the Kubernetes cluster as
+Kubernetes service type `ClusterIP`.
+
+In order to expose the Alpha service and Ratel service publicly you can use Kubernetes service type `LoadBalancer` or an Ingress resource.
+
+{{% tabs %}} {{< tab "LoadBalancer" >}}
+
+##### Public Internet
+
+To use an external load balancer, set the service type to `LoadBalancer`. 
+
+{{% notice "note" %}}For security purposes we recommend limiting access to any public endpoints, such as using a white list.{{% /notice %}}
+
+1.  To expose Alpha service to the Internet use:
+
+```sh
+helm install <RELEASE-NAME> dgraph/dgraph --set alpha.service.type="LoadBalancer"
+```
+
+2.  To expose Alpha and Ratel services to the Internet use:
+
+```sh
+helm install <RELEASE-NAME> dgraph/dgraph --set alpha.service.type="LoadBalancer" --set ratel.service.type="LoadBalancer"
+```
+
+##### Private Internal Network
+
+An external load balancer can be configured to face internally to a private subnet rather the public Internet.  This way it can be accessed securely by clients on the same network, through a VPN, or from a jump server. In Kubernetes, this is often configured through service annotations by the provider.  Here's a small list of annotations from cloud providers:
+
+|Provider    | Documentation Reference   | Annotation |
+|------------|---------------------------|------------|
+|AWS         |[Amazon EKS: Load Balancing](https://docs.aws.amazon.com/eks/latest/userguide/load-balancing.html)|`service.beta.kubernetes.io/aws-load-balancer-internal: "true"`|
+|Azure       |[AKS: Internal Load Balancer](https://docs.microsoft.com/azure/aks/internal-lb)|`service.beta.kubernetes.io/azure-load-balancer-internal: "true"`|
+|Google Cloud|[GKE: Internal Load Balancing](https://cloud.google.com/kubernetes-engine/docs/how-to/internal-load-balancing)|`cloud.google.com/load-balancer-type: "Internal"`|
+
+
+As an example, using Amazon [EKS](https://aws.amazon.com/eks/) as the provider.
+
+1. Create a Helm chart configuration values file `<MY-CONFIG-VALUES>`.yaml file: 
+
+```yaml
+# <MY-CONFIG-VALUES>.yaml
+alpha:
+  service:
+    type: LoadBalancer
+    annotations:
+      service.beta.kubernetes.io/aws-load-balancer-internal: "true"
+ratel:
+  service:
+    type: LoadBalancer
+    annotations:
+      service.beta.kubernetes.io/aws-load-balancer-internal: "true"
+```
+
+1. To expose Alpha and Ratel services privately, use:
+
+```sh
+helm install <RELEASE-NAME> dgraph/dgraph --values <MY-CONFIG-VALUES>.yaml
+```
+{{% /tab %}}
+{{% tab "Ingress Resource" %}}
+
+You can expose Alpha and Ratel using an [ingress](https://kubernetes.io/docs/concepts/services-networking/ingress/) resource that can route traffic to service resources.  Before using this option you may need to install an [ingress controller](https://kubernetes.io/docs/concepts/services-networking/ingress-controllers/) first, as is the case with [AKS](https://docs.microsoft.com/azure/aks/) and [EKS](https://aws.amazon.com/eks/), while in the case of [GKE](https://cloud.google.com/kubernetes-engine), this comes bundled with a default ingress controller.  When routing traffic based on the `hostname`, you may want to integrate an addon like [ExternalDNS](https://github.com/kubernetes-sigs/external-dns) so that DNS records can be registered automatically when deploying Dgraph.
+
+As an example, you can configure a single ingress resource that uses [ingress-nginx](https://github.com/kubernetes/ingress-nginx) for Alpha and Ratel services.
+
+1.  Create a Helm chart configuration values file, `<MY-CONFIG-VALUES>`.yaml file:
+
+```yaml
+# <MY-CONFIG-VALUES>.yaml
+global:
+  ingress:
+    enabled: false
+    annotations:
+      kubernetes.io/ingress.class: nginx
+    ratel_hostname: "ratel.<my-domain-name>"
+    alpha_hostname: "alpha.<my-domain-name>"
+```
+
+2. To expose Alpha and Ratel services through an ingress:
+
+```sh
+helm install <RELEASE-NAME> dgraph/dgraph --values <MY-CONFIG-VALUES>.yaml
+```
+
+You can run `kubectl get ingress` to see the status and access these through their hostname, such as `http://alpha.<my-domain-name>` and `http://ratel.<my-domain-name>`
+
+
+{{% notice "tip" %}}Ingress controllers will likely have an option to configure access for private internal networks.  Consult documentation from the ingress controller provider for further information.{{% /notice %}}
+{{% /tab %}}{{% /tabs %}}
+
+### Upgrading the Helm chart
+
+You can update your cluster configuration by updating the configuration of the
+Helm chart. Dgraph is a stateful database that requires some attention on
+upgrading the configuration carefully in order to update your cluster to your
+desired configuration.
+
+In general, you can use [`helm upgrade`][helm-upgrade] to update the
+configuration values of the cluster. Depending on your change, you may need to
+upgrade the configuration in multiple steps.
+
+[helm-upgrade]: https://helm.sh/docs/helm/helm_upgrade/
+
+To upgrade to an HA cluster setup: 
+
+1. Ensure that the shard replication setting is more than one and `zero.shardReplicaCount`. For example, set the shard replica flag on the Zero node group to 3,`zero.shardReplicaCount=3`.
+2. Run the Helm upgrade command to restart the Zero node group:
+   ```sh
+   helm upgrade <RELEASE-NAME> dgraph/dgraph [options]
+   ```
+3. Set the Alpha replica count flag. For example: `alpha.replicaCount=3`.
+4. Run the Helm upgrade command again:
+   ```sh
+   helm upgrade <RELEASE-NAME> dgraph/dgraph [options]
+   ```
+
+