Secrets Managers

How to set up storage for secrets

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Secrets managers provide a secure way of storing confidential information that is needed to run your ML pipelines. Most production pipelines will run on cloud infrastructure and therefore need credentials to authenticate with those services. Instead of storing these credentials in code or files, ZenML secrets managers can be used to store and retrieve these values in a secure manner.

When to use it

You should include a secrets manager in your ZenML stack if any other component of your stack requires confidential information (such as authentication credentials) or you want to access secret values inside your pipeline steps.

Secrets Manager Flavors

Out of the box, ZenML comes with a local secrets manager that stores secrets in local files. Additional cloud secrets managers are provided by integrations:

Secrets Manager	Flavor	Integration	Scoping Support	Notes
Local	local	built-in	No	Uses local files to store secrets
AWS	aws	aws	Yes	Uses AWS to store secrets
GCP	gcp_secrets_manager	gcp	Yes	Uses GCP to store secretes
Azure	azure_key_vault	azure	Yes	Uses Azure Key Vaults to store secrets
HashiCorp Vault	vault	vault	Yes	Uses HashiCorp Vault to store secrets
Custom Implementation	custom		No	Extend the secrets manager abstraction and provide your own implementation

If you would like to see the available flavors of secrets managers, you can use the command:

zenml secrets-manager flavor list

How to use it

In the CLI

A full guide on using the CLI interface to register, access, update and delete secrets is available here.

A ZenML secret is a grouping of key-value pairs which are defined by a schema. An AWS SecretSchema, for example, has key-value pairs for AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY as well as an optional AWS_SESSION_TOKEN. If you don't specify a schema when registering a secret, ZenML will use the ArbitrarySecretSchema, a schema where arbitrary keys are allowed.

Note that there are two ways you can register or update your secrets. If you wish to do so interactively, passing the secret name in as an argument (as in the following example) will initiate an interactive process:

zenml secrets-manager secret register SECRET_NAME -i

If you wish to specify key-value pairs using command line arguments, you can do so instead:

zenml secrets-manager secret register SECRET_NAME --key1=value1 --key2=value2

For secret values that are too big to pass as a command line argument, or have special characters, you can also use the special @ syntax to indicate to ZenML that the value needs to be read from a file:

zenml secrets-manager secret register SECRET_NAME --attr_from_literal=value \
   --attr_from_file=@path/to/file.txt ...

In a ZenML Step

You can access the secrets manager directly from within your steps through the StepContext. This allows you to use your secrets for querying APIs from within your step without hard-coding your access keys. Don't forget to make the appropriate decision regarding caching as it will be disabled by default when the StepContext is passed into the step.

from zenml.steps import step, StepContext


@step(enable_cache=True)
def secret_loader(
    context: StepContext,
) -> None:
    """Load the example secret from the secret manager."""
    # Load Secret from active secret manager. This will fail if no secret
    # manager is active or if that secret does not exist.
    retrieved_secret = context.stack.secrets_manager.get_secret(<SECRET_NAME>)

    # retrieved_secret.content will contain a dictionary with all Key-Value
    # pairs within your secret.
    return

This will only work if the environment that your ochestrator uses to execute steps has access to the secrets manager. For example a local secrets manager will not work in combination with a remote orchestrator.

Secret Schemas

The concept of secret schemas exists to support strongly typed secrets that validate which keys can be configured for a given secret and which values are allowed for those keys.

Secret schemas are available as builtin schemas, or loaded when an integration is installed. Custom schemas can also be defined by sub-classing the zenml.secret.BaseSecretSchema class. For example, the following is the builtin schema defined for the MySQL Metadata Store secrets:

from typing import ClassVar, Optional

from zenml.secret.base_secret import BaseSecretSchema

MYSQL_METADATA_STORE_SCHEMA_TYPE = "mysql"

class MYSQLSecretSchema(BaseSecretSchema):
    TYPE: ClassVar[str] = MYSQL_METADATA_STORE_SCHEMA_TYPE

    user: Optional[str]
    password: Optional[str]
    ssl_ca: Optional[str]
    ssl_cert: Optional[str]
    ssl_key: Optional[str]
    ssl_verify_server_cert: Optional[bool] = False

To register a secret regulated by a schema, the --schema argument must be passed to the zenml secrets-manager secret register command:

zenml secrets-manager secret register mysql_secret --schema=mysql --user=user --password=password
--ssl_ca=@./ca.pem --ssl_verify_server_cert=true

The keys and values passed to the CLI are validated using regular Pydantic rules:

• optional attributes don't need to be passed to the CLI and will be set to their default value if omitted

• required attributes must be passed to the CLI or an error will be raised

• all values must be a valid string representation of the data type indicated in the schema (i.e. that can be converted to the type indicated) or an error will be raised

Secret References

Secret references work with any secrets mananger and allow you to securely specify sensitive configurations for your stack components.

Check out the corresponding documentation page for more information.

Secret Scopes

Examples of situations in which Secrets Manager scoping can be useful:

• you want to control whether a secret configured in a Secrets Manager stack component is visible in another Secrets Manager stack component. This is useful when you want to share secrets without necessarily sharing stack components.

• you want to be able to configure two or more secrets with the same name but with different values in different Secrets Manager stack components.

• you want to emulate multiple virtual Secrets Manager instances on top of a single infrastructure secret management service

The scope determines how secrets are shared across different Secrets Manager instances that use the same backend domain (e.g. the same AWS region, GCP project or Azure Key Vault). To understand if and how that is important for you, we first need to define what these terms mean:

• a Secrets Manager instance is created by running zenml secrets-manager register. An instance is uniquely identified by its UUID (not by its name).

• a Secrets Manager backend domain can generally be thought of as the bucket where a Secrets Manager instance stores its secrets. Every Secrets Manager flavor uses a different implementation specific backend domain (e.g. an AWS region, a GCP project or an Azure Key Vault). This is usually reflected in the attributes that need to be configured for the Secrets Manager stack component.

All secrets in a backend domain share one global namespace, meaning that all Secrets Manager instances configured to use the same backend domain have to compete over the names of secrets that they store there. Secrets Manager scoping basically controls how the ZenML secret namespace is mapped to the underlying backend namespace.

The following diagram depicts the available secret scopes that you can configure for your Secrets Manager instance, if the flavor supports secret scoping. Note how the different secret namespaces are isolated from each other:

Secret Scoping

Secret Scope Configuration

All Secrets Managers have two configuration attributes that determine how and if a Secrets Manager instance shares secrets with other Secrets Manager instances connected to the same back-end domain:

• scope determines the secret scope and can be set to one of the following values:

  • none: no secret scoping is used when this scope value is configured. This essentially means that all secrets use the same global namespace that is shared not only with other ZenML Secrets Manager instances using a none scope, but also with other applications and users that configure secrets directly in the backend. This mode of operation is only used to preserve backwards compatibility with Secrets Manager instances that were already in use prior to the ZenML release 0.12.0 that introduced the concept of scoping. It is not recommended to use this scope with Secrets Manager instances that support scoping, as it will be deprecated and phased out in future ZenML versions.

  • global: secrets are shared across all Secrets Manager instances that connect to the same backend and have a global scope. You should use this scope if you want to share your secrets with everyone using ZenML in your team or organization and are not interested in micro-managing the access to these secrets.

  • component: secrets are not visible outside a Secrets Manager instance. This is the default for new instances of Secrets Manager flavors that support scoping. Use this scope if you don't intend to share your secrets with other projects or stacks. The component scope means that only stacks with a Secrets Manager with the exact UUID as your stack can access your secrets. The global or namespace scope are more suitable for sharing access to secrets.

  • namespace: secrets in a namespace scope are shared only by Secrets Manager instances that connect to the same backend and have the same namespace attribute value configured (see below). Use a namespace scope when you want to fine-tune the visibility of secrets across stacks and projects.

• namespace is a scope namespace value to use with the namespace scope