Configure a catalog integration for Apache Iceberg™ REST catalogs¶

Create a REST API in Amazon API Gateway¶

To connect Snowflake to your Iceberg REST catalog, you need a REST API resource in Amazon API Gateway.

If you don’t already have a REST API resource in Amazon API Gateway for your Iceberg catalog, you can create a simple REST API by importing an Iceberg catalog OpenAPI definition file or manually adding endpoints.

1. In the AWS Management Console, search for and select API Gateway.

2. Select Create API.

3. Select Build under REST API. To create a private REST API, select Build under REST API Private.

4. Select one of the following options:

   • To create an API by manually adding endpoints, select New API.

   • To create an API using an OpenAPI definition file, select Import API, then upload the file or paste the definition in the code editor.

5. Enter an API name and optional Description.

   Note

   You don’t need to enter a VPC endpoint ID when you create a private REST API.

6. Select Create API.

For more information about creating and developing a REST API in API Gateway, see the Amazon API Gateway Developer Guide.

Create an IAM policy and attach it to a role¶

In this step, you create an AWS IAM role that Snowflake can use to connect to API Gateway. You attach a policy to the role that grants permission to call your API.

1. In the AWS Management Console, search for and select IAM.

2. From the left-hand navigation pane, select Policies.

3. Select Create policy and then select JSON for the Policy editor.

4. Replace the empty policy with a policy that has permission to invoke your API methods. For example, the following general policy allows the invoke action for all API Gateway resources in an AWS account.

   {
     "Version": "2012-10-17",
     "Statement": [
       {
           "Effect": "Allow",
           "Action": [
               "execute-api:Invoke"
           ],
           "Resource": "arn:aws:execute-api:*:<aws_account_id>:*"
       }
     ]
   }
   

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   Important

   As a best practice, use a policy that grants the minimum required privileges for your use case. For additional guidance and example policies, see Control access to an API with IAM permissions.

5. Select Next.

6. Enter a Policy name (for example, snowflake_access) and an optional Description.

7. Select Create policy.

8. From the left-hand navigation pane in the IAM dashboard, select Roles.

9. Select a role to attach the policy to. When you create a catalog integration, you specify this role. If you don’t have a role, create a new role.

10. On the role Summary page in the Permissions tab, select Add permissions » Attach policies.

11. Search for and check the box next to the policy that you created for API Gateway, then select Add permissions.

12. On the role Summary page, copy the role ARN. You specify this ARN when you create a catalog integration.

Attach an API Gateway resource policy (private APIs only)¶

If your REST API is private, you must attach an Amazon API Gateway resource policy to your API. The resource policy allows Snowflake to call your API from the Amazon Virtual Private Cloud (VPC) in which your Snowflake account is located.

1. In Snowflake, call the SYSTEM$GET_SNOWFLAKE_PLATFORM_INFO function to retrieve the ID for the VPC in which your Snowflake account is located. Copy the VPC ID from the function output.

   SELECT SYSTEM$GET_SNOWFLAKE_PLATFORM_INFO();
   

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   Output:

   {"snowflake-vpc-id":["vpc-c1c234a5"]}
   

2. Follow the instructions in Attaching API Gateway resource policies to attach a resource policy to your REST API.

   Paste and modify the following example policy.

   {
     "Version": "2012-10-17",
     "Statement": [
       {
         "Effect": "Deny",
         "Principal": "*",
         "Action": "execute-api:Invoke",
         "Resource": "<api_gateway_arn>",
         "Condition": {
           "StringNotEquals": {
             "aws:sourceVpc": "<snowflake_vpc_id>"
           }
         }
       },
       {
         "Effect": "Allow",
         "Principal": {
           "AWS": "arn:aws:sts::123456789XXX:assumed-role/<my_api_permissions_role_name>/snowflake"
         },
         "Action": "execute-api:Invoke",
         "Resource": "<api_gateway_arn>/*/*/*",
         "Condition": {
           "StringEquals": {
             "aws:sourceVpc": "<snowflake_vpc_id>"
           }
         }
       }
     ]
   }
   

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The first statement in the policy denies all requests that don’t originate from the Snowflake VPC. The second statement allows the invoke action (for all methods) from requests originating from the Snowflake VPC that use the assumed-role session principal.

To learn more about API Gateway resource policies, see:

• Controlling access to an API with API Gateway resource policies

• API Gateway resource policy examples

Select IAM-based authorization for your API¶

Select IAM-based authorization for each method that you want to provide access to in your REST API. With IAM-based authorization, Snowflake can use the IAM role that you configured to make calls to the API.

1. In the Amazon API Gateway console, select your REST API.

2. For each method:

   1. Under Resources, select a method from the list.

   2. Under Method request settings, select Edit.

   3. For Authorization, select AWS IAM.

   4. Select Save.

3. To apply the authorization changes, select Deploy API. For more information, see Deploying a REST API from the API Gateway console.

Retrieve the endpoint URL¶

Retrieve your REST API endpoint URL (or invoke URL). Your API must be deployed to a stage before you can retrieve the endpoint URL.

1. In the Amazon API Gateway console, select your REST API.

2. In the left-hand navigation pane, select Stages.

3. Under Stage details, copy the Invoke URL.

You specify the endpoint URL when you create a catalog integration.

Create a catalog integration for SigV4¶

After you have a REST API in Amazon API Gateway and have completed the initial steps to control access to your API using IAM permissions, you can create a catalog integration in Snowflake.

To view the command syntax and parameter descriptions, see CREATE CATALOG INTEGRATION (Apache Iceberg™ REST).

Public REST API

To create a catalog integration for a public REST API, specify ICEBERG_REST as the CATALOG_SOURCE and use SIGV4 authentication.

Include details such as your API endpoint URL and IAM role ARN.

CREATE OR REPLACE CATALOG INTEGRATION my_rest_catalog_integration
  CATALOG_SOURCE = ICEBERG_REST
  TABLE_FORMAT = ICEBERG
  CATALOG_NAMESPACE = 'my_namespace'
  REST_CONFIG = (
    CATALOG_URI = 'https://asdlkfjwoalk-execute-api.us-west-2-amazonaws.com/MyApiStage'
    CATALOG_API_TYPE = AWS_API_GATEWAY
  )
  REST_AUTHENTICATION = (
    TYPE = SIGV4
    SIGV4_IAM_ROLE = 'arn:aws:iam::123456789XXX:role/my_api_permissions_role'
  )
  ENABLED = TRUE;

Private REST API

To create a catalog integration for a private REST API, you must set the CATALOG_API_TYPE parameter to AWS_PRIVATE_API_GATEWAY.

CREATE OR REPLACE CATALOG INTEGRATION my_rest_catalog_integration
  CATALOG_SOURCE = ICEBERG_REST
  TABLE_FORMAT = ICEBERG
  CATALOG_NAMESPACE = 'my_namespace'
  REST_CONFIG = (
    CATALOG_URI = 'https://asdlkfjwoalk-execute-api.us-west-2-amazonaws.com/MyApiStage'
    CATALOG_API_TYPE = AWS_PRIVATE_API_GATEWAY
  )
  REST_AUTHENTICATION = (
    TYPE = SIGV4
    SIGV4_IAM_ROLE = 'arn:aws:iam::123456789XXX:role/my_api_permissions_role'
  )
  ENABLED = TRUE;

Configure the trust relationship in IAM¶

Next, you must retrieve information about the AWS IAM user and the external ID that were created for your Snowflake account when you created the catalog integration, and configure the trust relationship for your IAM role.

1. In Snowflake, call the DESCRIBE CATALOG INTEGRATION command:

   DESCRIBE CATALOG INTEGRATION my_rest_catalog_integration;
   

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   Record the following values:

   Value	Description
   API_AWS_IAM_USER_ARN	The AWS IAM user created for your Snowflake account, for example, arn:aws:iam::123456789001:user/abc1-b-self1234. Snowflake provisions a single IAM user for your entire Snowflake account.
   API_AWS_EXTERNAL_ID	The external ID that’s needed to establish a trust relationship.

2. In the AWS Management Console, search for and select IAM.

3. From the left-hand navigation pane, select Roles.

4. Select the IAM role that you created for your catalog integration.

5. Select the Trust relationships tab.

6. Select Edit trust policy.

7. Modify the policy document with the values that you recorded.

   {
     "Version": "2012-10-17",
     "Statement": [
       {
         "Sid": "",
         "Effect": "Allow",
         "Principal": {
           "AWS": "<api_aws_iam_user_arn>"
         },
         "Action": "sts:AssumeRole",
         "Condition": {
           "StringEquals": {
             "sts:ExternalId": "<api_aws_external_id>"
           }
         }
       }
     ]
   }
   

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8. Select Update policy to save your changes.

Step 1: Retrieve an access token¶

Use a curl command to retrieve an access token from your catalog. The following example requests an access token from Snowflake Open Catalog:

curl -X POST https://xx123xx.us-west-2.aws.snowflakecomputing.com/polaris/api/catalog/v1/oauth/tokens \
    -H 'Accepts: application/json' \
    -H 'Content-Type: application/x-www-form-urlencoded' \
    --data-urlencode 'grant_type=client_credentials' \
    --data-urlencode 'scope=PRINCIPAL_ROLE:ALL' \
    --data-urlencode 'client_id=<my_client_id>' \
    --data-urlencode 'client_secret=<my_client_secret>' | jq

Where:

• https://xx123xx.us-west-2.aws.snowflakecomputing.com/polaris/api/catalog/v1/oauth/tokens is the endpoint for retrieving an OAuth token (getToken).

• scope is the same as the value that you specify for OAUTH_ALLOWED_SCOPES parameter when you create a catalog integration. For multiple scopes, use a space as a separator.

• my_client_id is the same client ID that you specify for the OAUTH_CLIENT_ID parameter when you create a catalog integration.

• my_client_secret is the same client secret that you specify for the OAUTH_CLIENT_SECRET parameter when you create a catalog integration.

Example return value:

{
  "access_token": "xxxxxxxxxxxxxxxx",
  "token_type": "bearer",
  "issued_token_type": "urn:ietf:params:oauth:token-type:access_token",
  "expires_in": 3600
}

Step 2: Verify the access token permissions¶

Using the access token that you retrieved in the previous step, verify that you have permission to access your catalog server.

You can use a curl command to list the configuration settings for your catalog:

curl -X POST "https://xx123xx.us-west-2.aws.snowflakecomputing.com/polaris/api/catalog/v1/config?warehouse=<warehouse>" \
    -H 'Accepts: application/json' \
    -H 'Content-Type: application/x-www-form-urlencoded' \
    -H 'Authorization: Bearer ${ACCESS_TOKEN}' | jq

Where:

• ?warehouse=warehouse optionally specifies the warehouse name to request from your catalog (if supported). For Snowflake Open Catalog, the warehouse name is your catalog name.

• ACCESS_TOKEN is a variable that contains the access_token that you retrieved in the previous step.

Example return value:

{
  "defaults": {
    "default-base-location": "s3://my-bucket/polaris/"
  },
  "overrides": {
    "prefix": "my-catalog"
  }
}

Step 3: Load a table from the catalog¶

You can also make a GET request to load a table. Snowflake uses the loadTable operation to load table data from your REST catalog.

curl -X POST "https://xx123xx.us-west-2.aws.snowflakecomputing.com/polaris/api/catalog/v1/<prefix>/namespaces/<namespace>/tables/<table>" \
    -H 'Accepts: application/json' \
    -H 'Content-Type: application/x-www-form-urlencoded' \
    -H 'Authorization: Bearer ${ACCESS_TOKEN}' | jq

Where:

• prefix optionally specifies the prefix obtained from the previous getConfig response.

• namespace is the namespace of the table you want to retrieve. If the namespace is nested, use the %1F separator; for example, parentNamespace%1FchildNamespace.

• table is the table name.

Step 1: Verify the access token permissions¶

Use a curl command to verify that you have permission to access your catalog server:

curl -X POST "https://xx123xx.us-west-2.aws.snowflakecomputing.com/polaris/api/catalog/v1/config?warehouse=<warehouse>" \
    -H 'Accepts: application/json' \
    -H 'Content-Type: application/x-www-form-urlencoded' \
    -H 'Authorization: Bearer ${BEARER_TOKEN}' | jq

Where:

• https://xx123xx.us-west-2.aws.snowflakecomputing.com/polaris/api/catalog/v1/oauth/tokens is the endpoint for retrieving an OAuth token (getToken).

• ?warehouse=warehouse optionally specifies the warehouse name to request from your catalog (if supported).

• BEARER_TOKEN is a variable that contains the access_token that you retrieved in the previous step.

Example return value:

{
  "defaults": {
    "default-base-location": "s3://my-bucket/polaris"
  },
  "overrides": {
    "prefix": "my-catalog"
  }
}

Step 2: Load a table from the catalog¶

You can also make a GET request to load a table. Snowflake uses the loadTable operation to load table data from your REST catalog.

curl -X POST "https://xx123xx.us-west-2.aws.snowflakecomputing.com/polaris/api/catalog/v1/<prefix>/namespaces/<namespace>/tables/<table>" \
    -H 'Accepts: application/json' \
    -H 'Content-Type: application/x-www-form-urlencoded' \
    -H 'Authorization: Bearer ${BEARER_TOKEN}' | jq

Where:

• prefix optionally specifies the prefix obtained from the previous getConfig response.

• namespace is the namespace of the table you want to retrieve. If the namespace is nested, use the %1F separator; for example, parentNamespace%1FchildNamespace.

• table is the table name.

Step 1: Add your user to the IAM role trust relationship¶

When you create a REST catalog integration for SigV4, Snowflake provisions an AWS IAM user for your Snowflake account. You add that Snowflake IAM user to the trust relationship for an IAM role with permission to access your API Gateway resources.

To test your configuration, you can assume the role as a user in your AWS account after you add your AWS user to the role’s trust policy document. To retrieve your current IAM user ARN, use the sts get-caller-identity command for the AWS Command Line Interface (CLI) :

aws sts get-caller-identity

Example output:

{
  "UserId": "ABCDEFG1XXXXXXXXXXX",
  "Account": "123456789XXX",
  "Arn": "arn:aws:iam::123456789XXX:user/managed/my_user"
}

The updated trust policy document should include both the Snowflake user ARN and your user ARN as follows:

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Sid": "",
      "Effect": "Allow",
      "Principal": {
        "AWS": [
          "<snowflake_iam_user_arn>",
          "<my_iam_user_arn>"
        ]
      },
      "Action": "sts:AssumeRole",
      "Condition": {
        "StringEquals": {
          "sts:ExternalId": "my_external_id"
        }
      }
    }
  ]
}

For full instructions, see Update a role trust policy in the AWS IAM documentation.

Step 2: Assume your IAM role to get temporary credentials¶

To get temporary security credentials for AWS, use the sts assume-role command for the AWS CLI.

aws sts assume-role \
  --role-arn <my_role_arn> \
  --role-session-name <session_name>

Where:

• my_role_arn is the Amazon Resource Name (ARN) of the IAM role that you’ve configured for Snowflake.

• session_name is a string identifier of your choice for the assumed role session; for example, my_rest_session.

Example output:

{
  "Credentials": {
      "AccessKeyId": "XXXXXXXXXXXXXXXXXXXXX",
      "SecretAccessKey": "XXXXXXXXXXXXXXXXXXXXX",
      "SessionToken": "XXXXXXXXXXXXXXXXXXXXX",
      "Expiration": "2024-10-09T08:13:15+00:00"
  },
  "AssumedRoleUser": {
      "AssumedRoleId": "{AccessKeyId}:my_rest_catalog_session",
      "Arn": "arn:aws:sts::123456789XXX:assumed-role/my_catalog_role/my_rest_catalog_session"
  }
}

Step 3: Verify that your IAM role has the right permissions¶

Using the temporary credentials that you retrieved in the previous step, verify that your IAM role has permission to invoke your API Gateway APIs.

You can use a curl command to list the configuration settings for your catalog:

curl -v -X GET  "https://123xxxxxxx.execute-api.us-west-2.amazonaws.com/test_v2/v1/config?warehouse=<warehouse>" \
  --user "$AWS_ACCESS_KEY_ID":"$AWS_SECRET_ACCESS_KEY" \
  --aws-sigv4 "aws:amz:us-west-2:execute-api" \
  -H "x-amz-security-token: $AWS_SESSION_TOKEN"

Where:

• 123xxxxxxx.execute-api.us-west-2.amazonaws.com is your API Gateway hostname.

• test_v2 is the name of the stage that your API is deployed to.

• v1/config specifies the getConfig operation from the Iceberg catalog OpenAPI definition.

• ?warehouse=warehouse optionally specifies the warehouse name to request from your catalog (if supported).

• $AWS_ACCESS_KEY_ID is a variable that contains the AccessKeyId that you retrieved using the sts assume-role command.

• $AWS_SECRET_ACCESS_KEY is a variable that contains the SecretAccessKey that you retrieved using the sts assume-role command.

• $AWS_SESSION_TOKEN is a variable that contains the SessionToken that you retrieved using the sts assume-role command.

Example return value:

{
  "defaults": {},
  "overrides": {
    "prefix": "my-catalog"
  }
}

You can also make a GET request to load a table. Snowflake uses the loadTable operation to load table data from your REST catalog.

curl -v -X GET "https://123xxxxxxx.execute-api.us-west-2.amazonaws.com/test_v2/v1/<prefix>/namespaces/<namespace>/tables/<table>" \
    --user "$AWS_ACCESS_KEY_ID":"$AWS_SECRET_ACCESS_KEY" \
    --aws-sigv4 "aws:amz:us-west-2:execute-api" \
    -H "x-amz-security-token: $AWS_SESSION_TOKEN"

Where:

• prefix optionally specifies the prefix obtained from the previous getConfig response.

• namespace is the namespace of the table you want to retrieve. If the namespace is nested, use the %1F separator; for example, parentNamespace%1FchildNamespace.

• table is the table name.

Private API

For a private API, you can specify your VPC endpoint and private AWS API Gateway hostname in the same curl commands.

For example:

curl -v -X GET  "https://vpce-xxxxxxxxxxxxxxxxxxxxxxxxxx.execute-api.us-west-2.vpce.amazonaws.com/test_v2/v1/config?warehouse=<warehouse>" \
  --user "$AWS_ACCESS_KEY_ID":"$AWS_SECRET_ACCESS_KEY" \
  --aws-sigv4 "aws:amz:us-west-2:execute-api" \
  -H "x-amz-security-token: $AWS_SESSION_TOKEN"
  -H "Host: abc1defgh2.execute-api.us-west-2.amazonaws.com"

Where:

• https://vpce-xxxxxxxxxxxxxxxxxxxxxxxxxx.execute-api.us-west-2.vpce.amazonaws.com/... is the hostname of your VPC endpoint.

• abc1defgh2.execute-api.us-west-2.amazonaws.com is the hostname of your private API in AWS API Gateway.