Encryption at rest

By default, Amazon Managed Service for Prometheus automatically provides you with encryption at rest and does this using AWS owned encryption keys.

Encryption of data at rest helps reduce the operational overhead and complexity that goes into protecting sensitive customer data, such as personally identifiable information. It allows you to build secure applications that meet strict encryption compliance and regulatory requirements.

You can alternatively choose to use a customer managed key when you create your workspace:

Choose whether to use customer managed keys or AWS owned keys carefully. Workspaces created with customer managed keys can't be converted to use AWS owned keys later (and vice versa).

For more information on AWS KMS, see What is AWS Key Management Service?

How Amazon Managed Service for Prometheus uses grants in AWS KMS

Amazon Managed Service for Prometheus requires three grants to use your customer managed key.

When you create an Amazon Managed Service for Prometheus workspace encrypted with a customer managed key, Amazon Managed Service for Prometheus creates the three grants on your behalf by sending CreateGrant requests to AWS KMS. Grants in AWS KMS are used to give Amazon Managed Service for Prometheus access to the KMS key in your account, even when not called directly on your behalf (for example, when storing metrics data that has been scraped from an Amazon EKS cluster.

Amazon Managed Service for Prometheus requires the grants to use your customer managed key for the following internal operations:

Amazon Managed Service for Prometheus creates three grants to the AWS KMS key that allow Amazon Managed Service for Prometheus to use the key on your behalf. You can remove access to the key by changing the key policy, by disabling the key, or by revoking the grant. You should understand the consequences of these actions before performing them. This can cause data loss in your workspace.

If you remove access to any of the grants in any way, Amazon Managed Service for Prometheus won't be able to access any of the data encrypted by the customer managed key, nor store new data sent to the workspace, which affects operations that are dependent on that data. New data sent to the workspace will not be accessible and may be permanently lost.

Step 1: Create a customer managed key

You can create a symmetric customer managed key by using the AWS Management Console, or the AWS KMS APIs. The key does not need to be in the same account as the Amazon Managed Service for Prometheus workspace, as long as you provide the correct access through policy, as described below.

To create a symmetric customer managed key

Follow the steps for Creating symmetric customer managed key in the AWS Key Management Service Developer Guide.

Key policy

Key policies control access to your customer managed key. Every customer managed key must have exactly one key policy, which contains statements that determine who can use the key and how they can use it. When you create your customer managed key, you can specify a key policy. For more information, see Managing access to customer managed keys in the AWS Key Management Service Developer Guide.

To use your customer managed key with your Amazon Managed Service for Prometheus workspaces, the following API operations must be permitted in the key policy:

The following are policy statement examples you can add for Amazon Managed Service for Prometheus:

  "Statement" : [ 
    {
      "Sid" : "Allow access to Amazon Managed Service for Prometheus principal within your account",
      "Effect" : "Allow",
      "Principal" : {
        "AWS" : "*"
      },
      "Action" : [ 
        "kms:DescribeKey", 
        "kms:CreateGrant",
        "kms:GenerateDataKey",
        "kms:Decrypt"
      ],
      "Resource" : "*",
      "Condition" : {
        "StringEquals" : {
          "kms:ViaService" : "aps.region.amazonaws.com",
          "kms:CallerAccount" : "111122223333"
        }
    },
    {
      "Sid": "Allow access for key administrators - not required for Amazon Managed Service for Prometheus",
      "Effect": "Allow",
      "Principal": {
        "AWS": "arn:aws:iam::111122223333:root"
       },
      "Action" : [ 
        "kms:*"
       ],
      "Resource": "arn:aws:kms:region:111122223333:key/key_ID"
    },
    <other statements needed for other non-Amazon Managed Service for Prometheus scenarios>
  ]

Step 2: Specifying a customer managed key for Amazon Managed Service for Prometheus

When you create a workspace, you can specify the customer managed key by entering a KMS Key ARN, which Amazon Managed Service for Prometheus uses to encrypt the data stored by the workspace.

Step 3: Accessing data from other services, such as Amazon Managed Grafana

This step is optional — it is only required if you need to access your Amazon Managed Service for Prometheus data from another service.

Your encrypted data is not accessible from other services, unless they also have access to use the AWS KMS key. For example, if you want to use Amazon Managed Grafana to create a dashboard or alert on your data, you must give Amazon Managed Grafana access to the key.

Your Amazon Managed Grafana workspace can now access the data in your Amazon Managed Service for Prometheus workspace. You can add other users or roles to the key users to enable other services to access your workspace.

Amazon Managed Service for Prometheus encryption context

An encryption context is an optional set of key-value pairs that contain additional contextual information about the data.

AWS KMS uses the encryption context as additional authenticated data to support authenticated encryption. When you include an encryption context in a request to encrypt data, AWS KMS binds the encryption context to the encrypted data. To decrypt data, you include the same encryption context in the request.

Amazon Managed Service for Prometheus encryption context

Amazon Managed Service for Prometheus uses the same encryption context in all AWS KMS cryptographic operations, where the key is aws:amp:arn and the value is the Amazon Resource Name (ARN) of the workspace.

"encryptionContext": {
    "aws:aps:arn": "arn:aws:aps:us-west-2:111122223333:workspace/ws-sample-1234-abcd-56ef-7890abcd12ef"
}

Using encryption context for monitoring

When you use a symmetric customer managed key to encrypt your workspace data, you can also use the encryption context in audit records and logs to identify how the customer managed key is being used. The encryption context also appears in logs generated by AWS CloudTrail or Amazon CloudWatch Logs.

Using encryption context to control access to your customer managed key

You can use the encryption context in key policies and IAM policies as conditions to control access to your symmetric customer managed key. You can also use encryption context constraints in a grant.

Amazon Managed Service for Prometheus uses an encryption context constraint in grants to control access to the customer managed key in your account or region. The grant constraint requires that the operations that the grant allows use the specified encryption context.

{
    "Sid": "Enable DescribeKey",
    "Effect": "Allow",
    "Principal": {
        "AWS": "arn:aws:iam::111122223333:role/ExampleReadOnlyRole"
     },
     "Action": "kms:DescribeKey",
     "Resource": "*"
},
{
     "Sid": "Enable CreateGrant",
     "Effect": "Allow",
     "Principal": {
         "AWS": "arn:aws:iam::111122223333:role/ExampleReadOnlyRole"
     },
     "Action": "kms:CreateGrant",
     "Resource": "*",
     "Condition": {
         "StringEquals": {
             "kms:EncryptionContext:aws:aps:arn": "arn:aws:aps:us-west-2:111122223333:workspace/ws-sample-1234-abcd-56ef-7890abcd12ef"
          }
     }
}

Monitoring your encryption keys for Amazon Managed Service for Prometheus

When you use an AWS KMS customer managed key with your Amazon Managed Service for Prometheus workspaces, you can use AWS CloudTrail or Amazon CloudWatch Logs to track requests that Amazon Managed Service for Prometheus sends to AWS KMS.

The following examples are AWS CloudTrail events for CreateGrant, GenerateDataKey, Decrypt, and DescribeKey to monitor KMS operations called by Amazon Managed Service for Prometheus to access data encrypted by your customer managed key:

Learn more

The following resources provide more information about data encryption at rest.