# Configure your cluster

:::info
This recording presents the essence of this page. It's recommended to read it in full for the motivation and all details.
:::

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---

Before you can create your cluster, you need to configure the identity and access management (IAM) for your cloud service provider (CSP) and choose machine types for the nodes.

## Creating the configuration file

You can generate a configuration file for your CSP by using the following CLI command:

<tabs groupId="csp">
<tabItem value="azure" label="Azure">

```bash
constellation config generate azure
```

</tabItem>
<tabItem value="gcp" label="GCP">

```bash
constellation config generate gcp
```

</tabItem>
<tabItem value="aws" label="AWS">

```bash
constellation config generate aws
```

</tabItem>
</tabs>

This creates the file `constellation-conf.yaml` in the current directory.

## Choosing a VM type

Constellation supports the following VM types:
<tabs groupId="csp">
<tabItem value="azure" label="Azure">

By default, Constellation uses `Standard_DC4as_v5` CVMs (4 vCPUs, 16 GB RAM) to create your cluster. Optionally, you can switch to a different VM type by modifying **instanceType** in the configuration file. For CVMs, any VM type with a minimum of 4 vCPUs from the [DCasv5 & DCadsv5](https://docs.microsoft.com/en-us/azure/virtual-machines/dcasv5-dcadsv5-series) or [ECasv5 & ECadsv5](https://docs.microsoft.com/en-us/azure/virtual-machines/ecasv5-ecadsv5-series) families is supported.

You can also run `constellation config instance-types` to get the list of all supported options.

</tabItem>
<tabItem value="gcp" label="GCP">

By default, Constellation uses `n2d-standard-4` VMs (4 vCPUs, 16 GB RAM) to create your cluster. Optionally, you can switch to a different VM type by modifying **instanceType** in the configuration file. Supported are all machines with a minimum of 4 vCPUs from the [C2D](https://cloud.google.com/compute/docs/compute-optimized-machines#c2d_machine_types) or [N2D](https://cloud.google.com/compute/docs/general-purpose-machines#n2d_machines) family. You can run  `constellation config instance-types` to get the list of all supported options.

</tabItem>
<tabItem value="aws" label="AWS">

By default, Constellation uses `m6a.xlarge` VMs (4 vCPUs, 16 GB RAM) to create your cluster.
Optionally, you can switch to a different VM type by modifying **instanceType** in the configuration file.
If you are using the default attestation variant `awsSEVSNP`, you can use the instance types described in [AWS's AMD SEV-SNP docs](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/snp-requirements.html).
Please mind the region restrictions mentioned in the [Getting started](../getting-started/first-steps.md#create-a-cluster) section.

If you are using the attestation variant `awsNitroTPM`, you can choose any of the [nitroTPM-enabled instance types](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/enable-nitrotpm-prerequisites.html).

The Constellation CLI can also print the supported instance types with: `constellation config instance-types`.

:::caution
Due to a bug in AWS's SNP implementation, SNP report generation currently fails in unforeseeable circumstances.
Therefore, even if you select attestation variant `awsSEVSNP`, Constellation still uses NitroTPM-based attestation.
Nonetheless, runtime encryption is enabled.
AWS is currently investigating the issue.
SNP-based attestation will be enabled as soon as a fix is verified.
:::

</tabItem>
</tabs>

Fill the desired VM type into the **instanceType** fields in the `constellation-conf.yml` file.

## Creating additional node groups

By default, Constellation creates the node groups `control_plane_default` and `worker_default` for control-plane nodes and workers, respectively.
If you require additional control-plane or worker groups with different instance types, zone placements, or disk sizes, you can add additional node groups to the `constellation-conf.yml` file.
Each node group can be scaled individually.


Consider the following example for AWS:

```yaml
nodeGroups:
  control_plane_default:
    role: control-plane
    instanceType: c6a.xlarge
    stateDiskSizeGB: 30
    stateDiskType: gp3
    zone: eu-west-1c
    initialCount: 3
  worker_default:
    role: worker
    instanceType: c6a.xlarge
    stateDiskSizeGB: 30
    stateDiskType: gp3
    zone: eu-west-1c
    initialCount: 2
  high_cpu:
    role: worker
    instanceType: c6a.24xlarge
    stateDiskSizeGB: 128
    stateDiskType: gp3
    zone: eu-west-1c
    initialCount: 1
```

This configuration creates an additional node group `high_cpu` with a larger instance type and disk.

You can use the field `zone` to specify what availability zone nodes of the group are placed in.
On Azure, this field is empty by default and nodes are automatically spread across availability zones.
Consult the documentation of your cloud provider for more information:

- [AWS](https://aws.amazon.com/about-aws/global-infrastructure/regions_az/)
- [Azure](https://azure.microsoft.com/en-us/explore/global-infrastructure/availability-zones)
- [GCP](https://cloud.google.com/compute/docs/regions-zones)

## Choosing a Kubernetes version

To learn which Kubernetes versions can be installed with your current CLI, you can run `constellation config kubernetes-versions`.
See also Constellation's [Kubernetes support policy](../architecture/versions.md#kubernetes-support-policy).

## Creating an IAM configuration

You can create an IAM configuration for your cluster automatically using the `constellation iam create` command.
If you already have a Constellation configuration file, you can add the `--update-config` flag to the command. This writes the needed IAM fields into your configuration. Furthermore, the flag updates the zone/region of the configuration if it hasn't been set yet.

<tabs groupId="csp">
<tabItem value="azure" label="Azure">

You must be authenticated with the [Azure CLI](https://learn.microsoft.com/en-us/cli/azure/install-azure-cli) in the shell session with a user that has the [required permissions for IAM creation](../getting-started/install.md#set-up-cloud-credentials).

```bash
constellation iam create azure --region=westus --resourceGroup=constellTest --servicePrincipal=spTest
```

This command creates IAM configuration on the Azure region `westus` creating a new resource group `constellTest` and a new service principal `spTest`.

Note that CVMs are currently only supported in a few regions, check [Azure's products available by region](https://azure.microsoft.com/en-us/global-infrastructure/services/?products=virtual-machines&regions=all). These are:

* `westus`
* `eastus`
* `northeurope`
* `westeurope`
* `southeastasia`

Paste the output into the corresponding fields of the `constellation-conf.yaml` file.

</tabItem>
<tabItem value="gcp" label="GCP">

You must be authenticated with the [GCP CLI](https://cloud.google.com/sdk/gcloud) in the shell session with a user that has the [required permissions for IAM creation](../getting-started/install.md#set-up-cloud-credentials).

```bash
constellation iam create gcp --projectID=yourproject-12345 --zone=europe-west2-a --serviceAccountID=constell-test
```

This command creates IAM configuration in the GCP project `yourproject-12345` on the GCP zone `europe-west2-a` creating a new service account `constell-test`.

Note that only regions offering CVMs of the `C2D` or `N2D` series are supported. You can find a [list of all regions in Google's documentation](https://cloud.google.com/compute/docs/regions-zones#available), which you can filter by machine type `N2D`.

Paste the output into the corresponding fields of the `constellation-conf.yaml` file.

</tabItem>
<tabItem value="aws" label="AWS">

You must be authenticated with the [AWS CLI](https://aws.amazon.com/en/cli/) in the shell session with a user that has the [required permissions for IAM creation](../getting-started/install.md#set-up-cloud-credentials).

```bash
constellation iam create aws --zone=us-east-2a --prefix=constellTest
```

This command creates IAM configuration for the AWS zone `us-east-2a` using the prefix `constellTest` for all named resources being created.

Constellation OS images are currently replicated to the following regions:

* `eu-central-1`
* `eu-west-1`
* `eu-west-3`
* `us-east-2`
* `ap-south-1`

If you require the OS image to be available in another region, [let us know](https://github.com/edgelesssys/constellation/issues/new?assignees=&labels=&template=feature_request.md&title=Support+new+AWS+image+region:+xx-xxxx-x).

You can find a list of all [regions in AWS's documentation](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/using-regions-availability-zones.html#concepts-available-regions).

Paste the output into the corresponding fields of the `constellation-conf.yaml` file.

</tabItem>
</tabs>

<details>
<summary>Alternatively, you can manually create the IAM configuration on your CSP.</summary>

The following describes the configuration fields and how you obtain the required information or create the required resources.

<tabs groupId="csp">
<tabItem value="azure" label="Azure">

* **subscription**: The UUID of your Azure subscription, e.g., `8b8bd01f-efd9-4113-9bd1-c82137c32da7`.

  You can view your subscription UUID via `az account show` and read the `id` field. For more information refer to [Azure's documentation](https://docs.microsoft.com/en-us/azure/azure-portal/get-subscription-tenant-id#find-your-azure-subscription).

* **tenant**: The UUID of your Azure tenant, e.g., `3400e5a2-8fe2-492a-886c-38cb66170f25`.

  You can view your tenant UUID via `az account show` and read the `tenant` field. For more information refer to [Azure's documentation](https://docs.microsoft.com/en-us/azure/azure-portal/get-subscription-tenant-id#find-your-azure-ad-tenant).

* **location**: The Azure datacenter location you want to deploy your cluster in, e.g., `westus`. CVMs are currently only supported in a few regions, check [Azure's products available by region](https://azure.microsoft.com/en-us/global-infrastructure/services/?products=virtual-machines&regions=all). These are:

  * `westus`
  * `eastus`
  * `northeurope`
  * `westeurope`
  * `southeastasia`

* **resourceGroup**: [Create a new resource group in Azure](https://learn.microsoft.com/azure/azure-resource-manager/management/manage-resource-groups-portal) for your Constellation cluster. Set this configuration     field to the name of the created resource group.

* **userAssignedIdentity**: [Create a new managed identity in Azure](https://learn.microsoft.com/azure/active-directory/managed-identities-azure-resources/how-manage-user-assigned-managed-identities). You should create the identity in a different resource group as all resources within the cluster resource group will be deleted on cluster termination.

  Add three role assignments to the identity: `Owner`, `Virtual Machine Contributor`, and `Application Insights Component Contributor`. The `scope` of all three should refer to the previously created cluster resource group.

  Set the configuration value to the full ID of the created identity, e.g., `/subscriptions/8b8bd01f-efd9-4113-9bd1-c82137c32da7/resourcegroups/constellation-identity/providers/Microsoft.ManagedIdentity/userAssignedIdentities/constellation-identity`. You can get it by opening the `JSON View` from the `Overview` section of the identity.

  The user-assigned identity is used by instances of the cluster to access other cloud resources.
  For more information about managed identities refer to [Azure's documentation](https://docs.microsoft.com/en-us/azure/active-directory/managed-identities-azure-resources/how-manage-user-assigned-managed-identities).

</tabItem>

<tabItem value="gcp" label="GCP">

* **project**: The ID of your GCP project, e.g., `constellation-129857`.

  You can find it on the [welcome screen of your GCP project](https://console.cloud.google.com/welcome). For more information refer to [Google's documentation](https://support.google.com/googleapi/answer/7014113).

* **region**: The GCP region you want to deploy your cluster in, e.g., `us-west1`.

  You can find a [list of all regions in Google's documentation](https://cloud.google.com/compute/docs/regions-zones#available).

* **zone**: The GCP zone you want to deploy your cluster in, e.g., `us-west1-a`.

  You can find a [list of all zones in Google's documentation](https://cloud.google.com/compute/docs/regions-zones#available).

* **serviceAccountKeyPath**: To configure this, you need to create a GCP [service account](https://cloud.google.com/iam/docs/service-accounts) with the following permissions:

  * `Compute Instance Admin (v1) (roles/compute.instanceAdmin.v1)`
  * `Compute Network Admin (roles/compute.networkAdmin)`
  * `Compute Security Admin (roles/compute.securityAdmin)`
  * `Compute Storage Admin (roles/compute.storageAdmin)`
  * `Service Account User (roles/iam.serviceAccountUser)`

  Afterward, create and download a new JSON key for this service account. Place the downloaded file in your Constellation workspace, and set the config parameter to the filename, e.g., `constellation-129857-15343dba46cb.json`.

</tabItem>

<tabItem value="aws" label="AWS">

* **region**: The name of your chosen AWS data center region, e.g., `us-east-2`.

  Constellation OS images are currently replicated to the following regions:
  * `eu-central-1`
  * `eu-west-1`
  * `eu-west-3`
  * `us-east-2`
  * `ap-south-1`

  If you require the OS image to be available in another region, [let us know](https://github.com/edgelesssys/constellation/issues/new?assignees=&labels=&template=feature_request.md&title=Support+new+AWS+image+region:+xx-xxxx-x).

  You can find a list of all [regions in AWS's documentation](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/using-regions-availability-zones.html#concepts-available-regions).

* **zone**: The name of your chosen AWS data center availability zone, e.g., `us-east-2a`.

  Learn more about [availability zones in AWS's documentation](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/using-regions-availability-zones.html#concepts-availability-zones).

* **iamProfileControlPlane**: The name of an IAM instance profile attached to all control-plane nodes.

  You can create the resource with [Terraform](https://www.terraform.io/). For that, use the [provided Terraform script](https://github.com/edgelesssys/constellation/tree/release/v2.2/hack/terraform/aws/iam) to generate the necessary profile. The profile name will be provided as Terraform output value: `control_plane_instance_profile`.

  Alternatively, you can create the AWS profile with a tool of your choice. Use the JSON policy in [main.tf](https://github.com/edgelesssys/constellation/tree/release/v2.2/hack/terraform/aws/iam/main.tf) in the resource `aws_iam_policy.control_plane_policy`.

* **iamProfileWorkerNodes**: The name of an IAM instance profile attached to all worker nodes.

  You can create the resource with [Terraform](https://www.terraform.io/). For that, use the [provided Terraform script](https://github.com/edgelesssys/constellation/tree/release/v2.2/hack/terraform/aws/iam) to generate the necessary profile. The profile name will be provided as Terraform output value: `worker_nodes_instance_profile`.

  Alternatively, you can create the AWS profile with a tool of your choice. Use the JSON policy in [main.tf](https://github.com/edgelesssys/constellation/tree/release/v2.2/hack/terraform/aws/iam/main.tf) in the resource `aws_iam_policy.worker_node_policy`.

</tabItem>

</tabs>
</details>

Now that you've configured your CSP, you can [create your cluster](./create.md).

## Deleting an IAM configuration

You can keep a created IAM configuration and reuse it for new clusters. Alternatively, you can also delete it if you don't want to use it anymore.

Delete the IAM configuration by executing the following command in the same directory where you executed `constellation iam create` (the directory that contains [`constellation-iam-terraform`](../reference/terraform.md) as a subdirectory):

```bash
constellation iam destroy
```

:::caution
For Azure, deleting the IAM configuration by executing `constellation iam destroy` will delete the whole resource group created by `constellation iam create`.
This also includes any additional resources in the resource group that weren't created by Constellation.
:::
