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Parameter Store

When working with ParameterStoreBaseSettings, you can work with parameters living in the same account and region, or with multiple accounts / regions.

Simplest way

The simplest way you can work with ParameterStoreBaseSettings is to leaving it all to boto3 and create your fields with the same name as your parameters:

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from pydantic_settings_aws import ParameterStoreBaseSettings


class ParameterStoreSettings(ParameterStoreBaseSettings):
    # no AWSSettingsConfigDict

    mongodb_host: str
    mongodb_db_name: str

In this case, pydantic-settings-aws will leave to boto3 to try to identify how he can connect to AWS, and then will look for the parameters with name mongodb_host and mongodb_db_name.

Structured exceptions

pydantic-settings-aws wraps errors into its own exception hierarchy so you can catch them precisely:

  • ParameterNotFoundError — the parameter does not exist in Parameter Store
  • AWSClientError — a boto3 session or client could not be created
  • AWSSettingsConfigError — the settings configuration is invalid or missing required fields

All of these inherit from PydanticSettingsAWSError, so you can catch them at any level. Unrecognised boto3 / botocore errors are re-raised as-is.

Specifying the name of the parameter

For almost all cases, your parameter's name will be different from your field name.

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from typing import Annotated
from pydantic_settings_aws import AWSSettingsConfigDict, ParameterStoreBaseSettings, SSM


class DynamoDBSettings(ParameterStoreBaseSettings):
    model_config = AWSSettingsConfigDict(
        ssm_client=my_ssm_client
    )

    db_name: Annotated[str, SSM(name="/databases/dynamodb/payments/dbname")]

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from typing import Annotated
from pydantic_settings_aws import AWSSettingsConfigDict, ParameterStoreBaseSettings


class DynamoDBSettings(ParameterStoreBaseSettings):
    model_config = AWSSettingsConfigDict(
        ssm_client=my_ssm_client
    )

    db_name: Annotated[str, "/databases/dynamodb/payments/dbname"]

Multiple accounts and regions

If you need to work with multiple accounts or regions, you can use Annotated and specify a per-field client:

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from typing import Annotated
from pydantic_settings_aws import ParameterStoreBaseSettings, SSM


class MongoDBSettings(ParameterStoreBaseSettings):

    prod_host: Annotated[str, SSM(name="/prod/databases/mongodb/host", client=prod_client)]
    release_host: Annotated[str, SSM(name="/release/databases/mongodb/host", client=release_client)]
    development_host: Annotated[str, SSM(name="/development/databases/mongodb/host", client=development_client)]

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from typing import Annotated
from pydantic_settings_aws import ParameterStoreBaseSettings


class MongoDBSettings(ParameterStoreBaseSettings):

    prod_host: Annotated[str, {"ssm": "/prod/databases/mongodb/host", "ssm_client": prod_client}]
    release_host: Annotated[str, {"ssm": "/release/databases/mongodb/host", "ssm_client": release_client}]
    development_host: Annotated[str, {"ssm": "/development/databases/mongodb/host", "ssm_client": development_client}]