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AWS Multi-Cluster Storage Configuration

AWS/S3 Federation

Kubecost uses a shared storage bucket to store metrics from clusters (aka durable storage) in order to provide a single-pane-of-glass for viewing cost across many clusters. Multi-cluster is an enterprise feature of Kubecost.
There are multiple methods to provide Kubecost access to an S3 bucket. This guide has two examples:
  1. 1.
    Using a Kubernetes secret
  2. 2.
    Attaching an AWS Identity and Access Management (IAM) role to the service account used by Prometheus
Both methods require an S3 bucket. Our example bucket is named kc-thanos-store.
This is a simple S3 bucket with all public access blocked. No other bucket configuration changes should be required.
Once created, add an IAM policy to access this bucket (steps).

Method 1: Kubernetes Secret Method

To use the Kubernetes secret method for allowing access, create a yaml file named object-store.yaml with contents similar to the following example. See region to endpoint mappings here: https://docs.aws.amazon.com/general/latest/gr/rande.html#s3_region
type: S3
config:
bucket: "kc-thanos-store"
endpoint: "s3.amazonaws.com"
region: "us-east-1"
access_key: "<your-access-key>"
secret_key: "<your-secret-key>"
insecure: false
signature_version2: false
put_user_metadata:
"X-Amz-Acl": "bucket-owner-full-control"
http_config:
idle_conn_timeout: 90s
response_header_timeout: 2m
insecure_skip_verify: false
trace:
enable: true
part_size: 134217728
Note: Because this is a YAML, it requires this specific indention.

Method 2: Attach IAM role to Service Account Method

Instead of using a secret key in a file, many will want to use this method.
Attach the policy to the Thanos pods service accounts. Your object-store.yaml should follow the format below when using this option, which does not contain the secret_key and access_key fields.
type: S3
config:
bucket: "kc-thanos-store"
endpoint: "s3.amazonaws.com"
region: "us-east-1"
insecure: false
signature_version2: false
put_user_metadata:
"X-Amz-Acl": "bucket-owner-full-control"
http_config:
idle_conn_timeout: 90s
response_header_timeout: 2m
insecure_skip_verify: false
trace:
enable: true
part_size: 134217728
Then, follow the guide at https://docs.aws.amazon.com/eks/latest/userguide/enable-iam-roles-for-service-accounts.html to enable attaching IAM roles to pods.
You can define the IAM role to associate with a service account in your cluster by creating a service account in the same namespace as kubecost and adding an annotation to it of the form eks.amazonaws.com/role-arn: arn:aws:iam::<AWS_ACCOUNT_ID>:role/<IAM_ROLE_NAME> as described here: https://docs.aws.amazon.com/eks/latest/userguide/specify-service-account-role.html
Once that annotation has been created, configure the following:
.Values.prometheus.serviceAccounts.server.create: false
.Values.prometheus.serviceAccounts.server.name: serviceAccount # to the name of your created service account
.Values.thanos.compact.serviceAccount: serviceAccount
.Values.thanos.store.serviceAccount: serviceAccount

Thanos Encryption With S3 and KMS

You can encrypt the S3 bucket where Kubecost data is stored in AWS via S3 and KMS. However, because Thanos can store potentially millions of objects, it is suggested that you use bucket-level encryption instead of object-level encryption. More details available here:

Troubleshooting

Visit the Multi-Cluster / Long Term Storage article for troubleshooting help.