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@jmdeal
jmdeal committed Apr 25, 2024
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121 changes: 77 additions & 44 deletions website/content/en/preview/concepts/nodeclasses.md
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Expand Up @@ -28,8 +28,8 @@ kind: EC2NodeClass
metadata:
name: default
spec:
# Required, resolves a default ami and userdata
amiFamily: AL2
# Required, configures the bootstrapping mode
amiFamily: AL2023

# Required, discovers subnets to attach to instances
# Each term in the array of subnetSelectorTerms is ORed together
Expand Down Expand Up @@ -66,7 +66,7 @@ spec:
# Must specify one of "role" or "instanceProfile" for Karpenter to launch nodes
instanceProfile: "KarpenterNodeInstanceProfile-${CLUSTER_NAME}"

# Optional, discovers amis to override the amiFamily's default amis
# Required, discovers amis.
# Each term in the array of amiSelectorTerms is ORed together
# Within a single term, all conditions are ANDed
amiSelectorTerms:
Expand All @@ -79,6 +79,11 @@ spec:
- name: my-ami
- id: ami-123

# Automatically select the latest EKS optimzed AMI for the given AMI family.
# Note: This term is mutually exclusive and may not be specified with other AMI selector terms
# - eksOptimized:
# family: AL2023

# Optional, use instance-store volumes for node ephemeral-storage
instanceStorePolicy: RAID0

Expand Down Expand Up @@ -164,7 +169,7 @@ Refer to the [NodePool docs]({{<ref "./nodepools" >}}) for settings applicable t

## spec.amiFamily

AMIFamily is a required field, dictating both the default bootstrapping logic for nodes provisioned through this `EC2NodeClass` but also selecting a group of recommended, latest AMIs by default. Currently, Karpenter supports `amiFamily` values `AL2`, `AL2023`, `Bottlerocket`, `Ubuntu`, `Windows2019`, `Windows2022` and `Custom`. GPUs are only supported by default with `AL2` and `Bottlerocket`. The `AL2` amiFamily does not support ARM64 GPU instance types unless you specify custom [`amiSelectorTerms`]({{<ref "#specamiselectorterms" >}}). Default bootstrapping logic is shown below for each of the supported families.
AMIFamily is a required field that dictates the bootstrapping logic for nodes provisioned through this `EC2NodeClass`. Currently, Karpenter supports `amiFamily` values `AL2`, `AL2023`, `Bottlerocket`, `Ubuntu`, `Windows2019`, `Windows2022` and `Custom`. Default generated UserData for each of the supported AMI families is shown below.

### AL2

Expand Down Expand Up @@ -264,10 +269,6 @@ exec > >(tee /var/log/user-data.log|logger -t user-data -s 2>/dev/console) 2>&1
</powershell>
```

{{% alert title="Note" color="primary" %}}
Karpenter will automatically query for the appropriate [EKS optimized AMI](https://docs.aws.amazon.com/eks/latest/userguide/eks-optimized-amis.html) via AWS Systems Manager (SSM). In the case of the `Custom` AMIFamily, no default AMIs are defined. As a result, `amiSelectorTerms` must be specified to inform Karpenter on which custom AMIs are to be used.
{{% /alert %}}

### Custom

The `Custom` AMIFamily ships without any default userData to allow you to configure custom bootstrapping for control planes or images that don't support the default methods from the other families.
Expand Down Expand Up @@ -429,13 +430,17 @@ spec:

## spec.amiSelectorTerms

AMI Selector Terms are used to configure custom AMIs for Karpenter to use, where the AMIs are discovered through ids, owners, name, and [tags](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/Using_Tags.html). **When you specify `amiSelectorTerms`, you fully override the default AMIs that are selected on by your EC2NodeClass [`amiFamily`]({{< ref "#specamifamily" >}}).**
AMI Selector Terms are used to select which AMIs Karpenter will use when launching nodes with this `EC2NodeClass`. You can opt-in to the latest EKS optimized AMIs through an `eksOptimzed` term or AMIs can be discovered through ids, ownders, name, and [tags](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/Using_Tags.html).

{{% alert title="Note" color="primary" %}}
[`amiFamily`]({{< ref "#specamifamily" >}}) determines the bootstrapping mode, while `amiSelectorTerms` specifies specific AMIs to be used. Therefore, you need to ensure consistency between [`amiFamily`]({{< ref "#specamifamily" >}}) and `amiSelectorTerms` to avoid conflicts during bootstrapping.
{{% /alert %}}

This selection logic is modeled as terms, where each term contains multiple conditions that must all be satisfied for the selector to match. Effectively, all requirements within a single term are ANDed together. It's possible that you may want to select on two different AMIs that have unrelated requirements. In this case, you can specify multiple terms which will be ORed together to form your selection logic. The example below shows how this selection logic is fulfilled.
This selection logic is modeled as terms, where each term contains multiple conditions that must all be satisfied for the selector to match.
Effectively, all requirements within a single term are ANDed together.
It's possible that you may want to select on two different AMIs that have unrelated requirements.
In this case, you can specify multiple terms which will be ORed together to form your selection logic.
The example below shows how this selection logic is fulfilled.

```yaml
amiSelectorTerms:
Expand All @@ -449,14 +454,36 @@ amiSelectorTerms:
- id: ami-123
```

This field is optional, and Karpenter will use the latest EKS-optimized AMIs for the AMIFamily if no amiSelectorTerms are specified. To select an AMI by name, use the `name` field in the selector term. To select an AMI by id, use the `id` field in the selector term. To ensure that AMIs are owned by the expected owner, use the `owner` field - you can use a combination of account aliases (e.g. `self` `amazon`, `your-aws-account-name`) and account IDs.
To select the latest EKS optimized AMIs, use the `eksOptimized` field in the selector term. To select an AMI by name, use the `name` field in the selector term. To select an AMI by id, use the `id` field in the selector term. To ensure that AMIs are owned by the expected owner, use the `owner` field - you can use a combination of account aliases (e.g. `self`, `amazon`, `your-aws-account-name`) and account IDs.

If owner is not set for `name`, it defaults to `self,amazon`, preventing Karpenter from inadvertently selecting an AMI that is owned by a different account. Tags don't require an owner as tags can only be discovered by the user who created them.

{{% alert title="Tip" color="secondary" %}}
AMIs may be specified by any AWS tag, including `Name`. Selecting by tag or by name using wildcards (`*`) is supported.
{{% /alert %}}

{{% alert title="Note" color="primary" %}}
The `eksOptimized` term is mutually exclusive. When an `eksOptimized` term is specified, other requirements may not be added to the term and no other terms may be specified. The following examples would be invalid:

```yaml
amiSelectorTerms:
- eksOptimzed:
family: AL2023
# Can not specify other fields with eksOptimzed
tags:
karpenter.sh/discover: "${CLUSTER_NAME}"
environment: test
```

```yaml
amiSelectorTerms:
- eksOptimzed:
family: AL2023
# Can not specify other terms with eksOptimzed
- id: ami-123
```
{{% /alert %}}

{{% alert title="Note" color="primary" %}}
If `amiSelectorTerms` match more than one AMI, Karpenter will automatically determine which AMI best fits the workloads on the launched worker node under the following constraints:

Expand All @@ -468,6 +495,13 @@ If `amiSelectorTerms` match more than one AMI, Karpenter will automatically dete

#### Examples

Select EKS optimzed AMIs by family:
```yaml
amiSelectorTerms:
- eksOptimized:
family: AL2023
```

Select all with a specified tag:
```yaml
amiSelectorTerms:
Expand Down Expand Up @@ -584,7 +618,7 @@ spec:

## spec.blockDeviceMappings

The `blockDeviceMappings` field in an `EC2NodeClass` can be used to control the [Elastic Block Storage (EBS) volumes](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/block-device-mapping-concepts.html#instance-block-device-mapping) that Karpenter attaches to provisioned nodes. Karpenter uses default block device mappings for the AMIFamily specified. For example, the `Bottlerocket` AMI Family defaults with two block device mappings, one for Bottlerocket's control volume and the other for container resources such as images and logs.
The `blockDeviceMappings` field in an `EC2NodeClass` can be used to control the [Elastic Block Storage (EBS) volumes](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/block-device-mapping-concepts.html#instance-block-device-mapping) that Karpenter attaches to provisioned nodes. Karpenter uses default block device mappings for the [AMIFamily]({{< ref "#specamifamily" >}}) specified. For example, the `Bottlerocket` AMI Family defaults with two block device mappings, one for Bottlerocket's control volume and the other for container resources such as images and logs.

```yaml
spec:
Expand All @@ -601,7 +635,7 @@ spec:
snapshotID: snap-0123456789
```

The following blockDeviceMapping defaults are used for each `AMIFamily` if no `blockDeviceMapping` overrides are specified in the `EC2NodeClass`
The following blockDeviceMapping defaults are used for each [AMIFamily]({{< ref "#specamifamily" >}}) if no `blockDeviceMapping` overrides are specified in the `EC2NodeClass`

### AL2
```yaml
Expand Down Expand Up @@ -684,7 +718,7 @@ spec:

This will set the allocatable ephemeral-storage of each node to the total size of the instance-store volume(s).

The disks must be formatted & mounted in a RAID0 and be the underlying filesystem for the Kubelet & Containerd. Instructions for each AMI family are listed below:
The disks must be formatted & mounted in a RAID0 and be the underlying filesystem for the Kubelet & Containerd. Instructions for each [AMIFamily]({{< ref "#specamifamily" >}}) are listed below:

#### AL2

Expand Down Expand Up @@ -1157,15 +1191,40 @@ status:

## status.amis

[`status.amis`]({{< ref "#statusamis" >}}) contains the resolved `id`, `name`, and `requirements` of either the default AMIs for the [`spec.amiFamily`]({{< ref "#specamifamily" >}}) or the AMIs selected by the [`spec.amiSelectorTerms`]({{< ref "#specamiselectorterms" >}}) if this field is specified.
[`status.amis`]({{< ref "#statusamis" >}}) contains the resolved `id`, `name`, and `requirements` of the AMIs selected by the [`spec.amiSelectorTerms`]({{< ref "#specamiselectorterms" >}}).

#### Examples
When discovering AMIs via id, owner, tags, and/or name, Karpenter will only discover a `kubernetes.io/arch` requirement.

```yaml
spec:
amiSelectorTerms:
- tags:
karpenter.sh/discovery: "${CLUSTER_NAME}"
status:
amis:
- id: ami-01234567890123456
name: custom-ami-amd64
requirements:
- key: kubernetes.io/arch
operator: In
values:
- amd64
- id: ami-01234567890123456
name: custom-ami-arm64
requirements:
- key: kubernetes.io/arch
operator: In
values:
- arm64
```

Default AMIs resolved from the AL2 AMIFamily:
However, specifying an `eksOptimized` term may allow Karpenter to discover more requirements.

```yaml
spec:
amiFamily: AL2
amiSelectorTerms:
- eksOptimized:
family: AL2
status:
amis:
- id: ami-03c3a3dcda64f5b75
Expand Down Expand Up @@ -1210,32 +1269,6 @@ status:
operator: DoesNotExist
```

AMIs resolved from [`spec.amiSelectorTerms`]({{< ref "#specamiselectorterms" >}}):

```yaml
spec:
amiFamily: AL2
amiSelectorTerms:
- tags:
karpenter.sh/discovery: "${CLUSTER_NAME}"
status:
amis:
- id: ami-01234567890123456
name: custom-ami-amd64
requirements:
- key: kubernetes.io/arch
operator: In
values:
- amd64
- id: ami-01234567890123456
name: custom-ami-arm64
requirements:
- key: kubernetes.io/arch
operator: In
values:
- arm64
```

## status.instanceProfile

[`status.instanceProfile`]({{< ref "#statusinstanceprofile" >}}) contains the resolved instance profile generated by Karpenter from the [`spec.role`]({{< ref "#specrole" >}})
Expand Down

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