globus-action-provider-tools 0.10.0

Action Life-cycle

The Life-cycle of an Action defines the set of states that the Action may be in, and how it can transition among the states. The states are defined as follows:

• ACTIVE: The Action is executing and is making progress toward completion

• INACTIVE: The Action is paused in its execution and is not making progress toward completion. Out-of-band (i.e. not via the Action Provider Interface) measures may be required to allow the Action to proceed.
• SUCCEEDED: The Action reached a completion state which was considered “normal” or not due to failure or other unrecoverable error.
• FAILED: The Action is in a completion state which is “not normal” such as due to an error condition which is not considered recoverable in any manner.
• RELEASED: The Action Provider has removed the record of the existence of the Action. Further attempts to interact with the Action will be errors as if the Action had never existed. All resources associated with the Action may have been deleted or removed. This is not a true state in the sense that the state can be observed, but ultimately all Actions will be released and unavailable for further operations. Any subsequent references to the Action, e.g. via the API methods described below, will behave as if the Action never existed.

Upon initial creation of an Action (see operations below), the Action may be in any of the first four states. If it is in an ACTIVE or INACTIVE state, the Action is considered “asynchronous” and further queries to get the state of the Action may return updated information. If the Action is in a the SUCCEEDED or FAILED states, the Action is synchronous, all information about the Action is returned on the creation operation and no changes to the state are possible.

An asynchronous Action may change state between ACTIVE and INACTIVE during its life time, and may update further details about its progress while in either of these states. When a completed state of SUCCEEDED or FAILED is reached, the Action state cannot be updated further. The Action Provider is, however, required to maintain this final state for some period of time so that the client of the Action may retrieve the completion state. Upon completion, the client may request that the Action be “released” or the Action Provider may do so on its own after the required time-out occurs. To save server resources, it is preferred that the client release the Action when it has reliably retrieved and processed the final state.

Action Provider Interface and Document Types

The primary purpose of the Action Provider Interface is to securely support and report Actions progressing through the life-cycle described above. The document types supporting this are the initial Action invocation Action Request document, and the Action Status document which contains the life-cycle status described above along with additional detailed status information specific to the type of Action being executed.

Starting an Action: The Action Request Document and the POST /run Method

Starting an Action is performed by making a REST POST request to the path /run containing an Action Request document. The request document contains the following fields:

• request_id: A client-generated Identifier for this request. A user may re-invoke the /run method with the same request_id any number of times, but the Action must only be initiated once. In this way, the user may re-issue the request in case it cannot be determined if a request was successfully initiated for example due to network failure.
• body: An Action Provider-specific object which provides the input for the Action to be performed. The body must conform to the input specification for the Action Provider being invoked, and thus the client must understand the requirements of the Action Provider when providing the value of the body. Thus, the Action Provider must provide documentation on the format for the body property.
• manage_by and monitor_by: Each of these is a list of principal values in URN format, and they allow the user invoking the Action to delegate some capability over the Action to other principals. manage_by defines the principals who are allowed to attempt to change the execution of the Action (see operations /cancel and /release below) while it is running. monitor_by defines principals which are allowed to see the state of the Action before its state has been destroyed in a release operation. In both cases, the Globus Auth identity associated with the /run operation is implicitly part of both the manage_by and monitor_by sets. That is, the invoking user need not include their own identity into these lists.

Any request to the /run method which contains an Action Request which adheres to the input schema will return an Action Status document as described in the next section.

Monitoring and Completing an Action: The Action Status Document and Management Methods

All information about an Action is contained in the Action Status document which is returned on almost all operations related to an Action (the exception is the log operation which is optional and is described briefly below). Notable fields of the Action Status document include:

• action_id: The unique identifier for this particular action. The action_id may be any string, and it should be treated as an opaque value (that is, having no semantic or implied meaning) by the client. The client will first learn of an Action’s action_id in the Action Status returned by the /run method.
• status and display_status: These provide the description of the state of the Action. status is the specific life-cycle value as described above. display_status is an optional field the Action Provider may supply which gives a short text description of the status using language which is specific to the Action.
• details: The Action Provider-specific state, particularly the completion state, of the Action are returned in the details field. In the completion states, the details can be considered the “result” or the “return value” of the Action. It is the successful return value for a SUCCEEDED status, and it is the error result for the FAILED status. The exact content in details is always specific to the Action Provider, so must be documented by the Action Provider to describe its interpretation to clients.
• monitor_by and manage_by: Same as in the Action Request.
• start_time and completion_time: Represent the time the Action was first received by the /run operation and the time the Action Provider determined that the Action reached a completed state (SUCCEEDED or FAILED) respectively. Action Providers are not required to continuously monitor the progress of Actions, so the completion_time noted may be different than the executed Action’s actual completion time. These values may be the same in the case of a synchronous operation, but completion_time must never be before start_time.
• release_after: As stated above, Action state is automatically removed from the Action Provider after some time interval once it reaches a completion state. The release_after is a time duration, in seconds, which states how long after completion the Action will automatically be released. A typical value would be 30-days, but Action Providers may define their own policy which is to be exposed in the Action Status.

In addition to the /run method described above, the Action Status is the “universal” return value from operations on an Action. We describe the operations on Actions next. Each uses the action_id as part of the URL path much like other RESTful resources do with their ids, and none of them require any input body.

• GET /<action_id>/status: This is a read-only operation for retrieving the most recent state of the Action. It is commonly used to poll an Action’s state while awaiting it entering a completion state. Use of this API call requires that the user authenticate with a principal value which is in the monitor_by list established when the Action was started.
• POST /<action_id>/cancel: Cancellation provides an advisory or hint to the Action Provider that the user does not want the Action to continue execution. The Action Provider is not required to ensure immediate completion or that the cancel operation truly causes the Action to terminate in any manner other than it would have without the cancel request. Thus, the Action Status returned from the cancel operation may contain a non-completion state. If the Action is already in a completed state, the Action Provider may treat the request much as a /status request to simply return the current status. Use of this API call requires that the user authenticates with a principal value which is in the manage_by list established when the Action was started.
• POST /<action_id>/release: As described in the section on life-cycle, the very last step of the life-cycle is for the Action state to be removed from the Action Provider. A user can specify that it has retrieved the final state or is no longer interested in the state using the /release operation which returns the final state. If the Action is not already in a completion state, /release will return an error as this operation does not attempt to stop execution (that is what /cancel does). The Action Status document returned from /release will be the last record of the Action present at the Action Provider. After the call to /release the action_id is no longer valid, and use in any other calls will return an error, most likely an HTTP status 404 indicating the Action was not found.

Detailed Execution History: logging

Some Actions, particularly those that are long running, may have associated with them a list or log of activities or sub-events which occurred during the Action’s life. This detailed log is typically larger, more complex, or more fine-grain than the snapshot of the status returned by the /status method. Not all Action Providers or Actions are suitable for logging, so support is considered optional and will be advertised by the Action Provider in its description (see below). The request to retrieve the log takes the form GET /<action_id>/log?<filters,pagination>. The filters and pagination query parameters are used to limit (e.g. based on start time) which log records to retrieve and the pagination parameter is used to scroll through a long set of log records across multiple requests. Each record in the log contains the following properties:

• time: A timestamp representing the time this log record occurred.
• code: A short Action Provider-specific description of the type of the log record.
• description: A textual description of the purpose, cause, or information on the log record.
• details (optional): An object providing additional and structured Action Provider-specific representation of the log record.

Action Provider Introspection (GET /)

The Automate platform is intended to help users both find and make use of the variety of Action Providers which may be available on the network. The primary means of accomplishing this assistance is by making Action Providers, the services which implement the Action Provider Interface, self-describing via an Introspection interface. Accessing the introspection method is performed simply via a GET /. That is, the HTTP GET method on the Base URL. The returned JSON document contains the following fields:

• api_version: A version string defining the version of the Action Provider Interface supported by the Action Provider. The version described in this document and currently the only version available will have value "1.0".
• title, subtitle, description, keywords: Each of these provide human-readable text which helps a user discover the purpose of the Action Provider.
• visible_to and runnable_by: Access to the action provider is limited by and published through these properties. Each contains a list of principal values in URN format. visible_to controls who can retrieve the information via introspection (this operation) and may contain the string "public" indicating that all users, even those who present no credentials, may access the information. The runnable_by property enumerates who can use the /run method to start an Action at this provider. It allows the string "all_authenticated_users" indicating that any user who presents valid credentials via a Bearer token may start an Action at the provider.
• synchronous and log_supported: These are boolean values which simply describe capabilities and modes for the Action Provider. If synchronous is true, a user calling /run can assume that the returned status will always be in a completed (SUCCEEDED or FAILED) state and there will never be a need to poll using the /status method (use of /release is still permitted and encouraged to remove the status from the Action Provider). As indicated in the discussion of the /log method, support for it is optional, and the log_supported flag provides an indication to users whether they can make use of /log for fine grained monitoring of an Action.
• input_schema: The input_schema value provides a complete schema description for the body property of the Action Request understood by this Action Provider. The schema is provided in JSON Schema format.

Caching

To avoid excessively taxing Globus Auth, the AuthState will, by default, cache identities and group memberships for 30 seconds.

The cache is initialized when you first instantiate your TokenChecker(). You should only need to create one TokenChecker instance for your application, and then you can re-use it to check each new token. In the event that you do need more than one TokenChecker, be aware that all TokenChecker instances in an app share the same underlying cache.

It is possible to customize a TokenChecker by supplying a custom configuration which gets passed on to the dogpile cache backend. Each new instance of a TokenChecker with a custom configuration will drop the cache and recreate it with the desired settings. Since all TokenCheckers share the same underlying cache, subsequent attempts to configure the cache will overwrite the previous cache’s settings and therefore only the last applied configuration will persist.

from globus_action_provider_tools.authentication import TokenChecker

# Create TokenChecker with default settings
my_token_checker = TokenChecker(
    client_id=CLIENT_ID,
    client_secret=CLIENT_SECRET,
    expected_scopes=EXPECTED_SCOPES,
)

# Creating a TokenChecker with a custom config will drop the previous cache and
# create it with the new settings. Both TokenCheckers will use this new cache
new_token_checker = TokenChecker(
        client_id=config["client_id"],
        client_secret=config["client_secret"],
        expected_scopes=config["expected_scopes"],
        cache_config={
            "backend": "dogpile.cache.pylibmc",
            "timeout": "60",
            "url": ["127.0.0.1"],
        },
    )