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Developer's Read Me for Hyperledger Aries Cloud Agent - Python

See the README for details about this repository and information about how the Aries Cloud Agent - Python fits into the Aries project and relates to Indy.

Table of Contents

Introduction

Aries Cloud Agent Python (ACA-Py) is a configurable, extensible, non-mobile Aries agent that implements an easy way for developers to build decentralized identity applications that use verifiable credentials.

The information on this page assumes you are developer with a background in decentralized identity, Indy, Aries and verifiable credentials. If you aren't familiar with those concepts and projects, please use our Getting Started Guide to learn more.

Installing

This package is available on PyPI and can be installed with the following command:

pip install aries-cloudagent

Developer Demos

To put ACA-Py through its paces at the command line, checkout our demos page.

Running

After installing the PyPi package, the executable aca-py should be available in your PATH.

Find out more about the available command line parameters by running:

aca-py --help

Currently you must specify at least one inbound and one outbound transport.

For example:

aca-py start    --inbound-transport http 0.0.0.0 8000 \
                --outbound-transport http

or

aca-py start    --inbound-transport http 0.0.0.0 8000 \
                --inbound-transport ws 0.0.0.0 8001 \
                --outbound-transport ws \
                --outbound-transport http

Currently, Aries Cloud Agent Python ships with both inbound and outbound transport drivers for http and websockets. More information on how to develop your own transports will be coming soon.

Most configuration parameters are provided to the the agent at startup. Refer to the section below for details on all available command-line arguments.

Command Line Arguments

argument format example effect required
--inbound-transport, -it --inbound-transport http 0.0.0.0 8000 Defines the inbound transport(s) to listen on. This parameter can be passed multiple times to create multiple interfaces. Supported internal transport types are http and ws. true
--outbound-transport, -ot --outbound-transport http Defines the outbound transport(s) to support for outgoing messages. This parameter can be passed multiple times to supoort multiple transport types. Supported internal transport types are http and ws. true
--log-config --log-config /path/to/log/config.ini Provides a custom python logging config file to use. By default, a default logging config is used. false
--log-file --log-file /path/to/logfile Overrides the output destination for the root logger as defined by the log config file. false
--log-level --log-level debug Specifies the python log level. false
--endpoint, -e --endpoint https://example.com/agent-endpoint Specifies the endpoint for which other agents should contact this agent. This endpoint could point to a different agent if routing is configured. The endpoint is used in the formation of a connection with another agent. false
--label, -l --label "My Agent" Specifies the label for this agent. This label is publicized to other agents as part of forming a connection. false
--seed --seed 00000000000000000000000000000000 Specifies the seed for the creation of a public did for use with a Hyperledger Indy ledger false
--storage-type --storage-type basic Specifies the type of storage provider to use for the internal storage engine. This storage interface is used to store internal state. Supported internal storage types are basic (memory) and indy. false
--wallet-key --wallet-key b548y2b1919s71081583 Specifies the master key value to use when opening the wallet. false
--wallet-name --wallet-name my_wallet Specifies the wallet name. This is useful if you have multiple wallets. false
--wallet-type --wallet-type basic Specifies the type of indy wallet provider to use. Supported internal storage types are basic (memory) and indy. false
--wallet-storage-type --wallet-storage-type postgres_storage Specifies the type of indy wallet backend to use. Supported internal storage types are basic (memory), indy, and postgres_storage. false
--wallet-storage-config --wallet-storage-config {"url":"localhost:5432"} Provides configuration data to the indy wallet storage driver. false
--wallet-storage-creds --wallet-storage-creds {"account":"postgres","password":"mysecretpassword", "admin_account":"postgres","admin_password":"mysecretpassword"} Provides credential data to the indy wallet storage driver. false
--pool-name --pool-name my_pool Specifies the name of the indy pool to be opened. This is useful if you have multiple pool configurations. false
--genesis-transactions --genesis-transactions {"reqSignature":{},"txn":{"data":{"d... <snip> Specifies the genesis transactions to use to connect to an Hyperledger Indy ledger. false
--genesis-url --genesis-url https://example.com/genesis Specifies the url from which to download the genesis transaction data. For example, the Sovrin Network genesis transactions. false
--admin --admin 0.0.0.0 5050 Specifies the host and port on which to run the administrative server. If not provided, no admin server is made available. false
--admin-insecure-mode --admin-insecure-mode Instructs the agent to run the admin web server in insecure mode. The admin server will be publicly available to anyone who has access to the interface. false
--admin-api-key --admin-api-key abc123 Instructs the agent to protect all admin endpoints with the provided API key. The API must be pass in the header X-API-Key: <api key>. false
--debug --debug Enables a remote debugging service that can be accessed using ptvsd. The framework will wait for the debugger to connect at start-up. false
--debug-connections --debug-connections Enables additional logging of connection information. false
--public-invites --public-invites Allows the creation and reception of invitations from the public DID. false
--auto-accept-invites --auto-accept-invites Instructs the agent to automatically accept invites. false
--auto-accept-requests --auto-accept-requests Instructs the agent to automatically connection requests. false
--auto-ping-connection --auto-ping-connection Instructs the agent to automatically send a trust ping to a connection after it is formed. false
--auto-respond-messages --auto-respond-messages Instructs the agent to automatically respond to basic messages. false
--auto-respond-credential-offer --auto-respond-credential-offer Instructs the agent to automatically respond to indy credential offers with a credential request. false
--auto-respond-presentation-request --auto-respond-presentation-request Instructs the agent to automatically respond to indy presentation requests with a constructed presentation if exactly one credential can be retrieved for every referent in the presentation request. false
--auto-verify-presentation --auto-verify-presentation Instructs the agent to automatically verify a presentation when it is received. false
--no-receive-invites --no-receive-invites Disables the receive invitations administration function. false
--help-link --help-link Defines the help URL for the administration interface. false
--invite --invite Generates and print a new connection invitation URL on start-up. false
--timing --timing Includes timing information in response messages. false
--protocol --protocol Instructs the agent to load an external protocol module. false
--webhook-url --webhook-url Instructs the agent to send webhooks containing internal state changes to a URL. This is useful for a controller to monitor changes and prompt new behaviour using the admin API. false

Provisioning a Wallet

It is possible to provision an Indy wallet before running an agent to avoid passing in the wallet seed on every invocation of aca-py start.

aca-py provision --wallet-type indy --seed $SEED

For additional options, execute aca-py provision --help.

Developing

Prerequisites

Docker must be installed to run software locally and to run the test suite.

Running Locally

To run the locally, we recommend using the provided Docker images to run the software.

./scripts/run_docker start <args>
./scripts/run_docker start --inbound-transport http 0.0.0.0 10000 --outbound-transport http --debug --log-level DEBUG

To enable the ptvsd Python debugger for Visual Studio/VSCode use the debug flag

Publish any ports you will be using from the docker container using the PORTS environment variable. For example:

PORTS="5000:5000 8000:8000 1000:1000" ./scripts/run_docker start --inbound-transport http 0.0.0.0 10000 --outbound-transport http --debug --log-level DEBUG

Refer to the previous section for instructions on how to run the software.

Running Tests

To run the test suite, use the following script:

./scripts/run_tests

To run the tests including Indy SDK and related dependencies, run the script:

./scripts/run_tests_indy

Development Workflow

We use Flake8 to enforce a coding style guide.

We use Black to automatically format code.

Please write tests for the work that you submit.

Tests should reside in a directory named tests alongside the code under test. Generally, there is one test file for each file module under test. Test files must have a name starting with test_ to be automatically picked up the test runner.

There are some good examples of various test scenarios for you to work from including mocking external imports and working with async code so take a look around!

The test suite also displays the current code coverage after each run so you can see how much of your work is covered by tests. Use your best judgement for how much coverage is sufficient.

Please also refer to the contributing guidelines and code of conduct.

Dynamic Injection of Services

The Agent employs a dynamic injection system whereby providers of base classes are registered with the RequestContext instance, currently within conductor.py. Message handlers and services request an instance of the selected implementation using await context.inject(BaseClass); for instance the wallet instance may be injected using wallet = await context.inject(BaseWallet). The inject method normally throws an exception if no implementation of the base class is provided, but can be called with required=False for optional dependencies (in which case a value of None may be returned).

Providers are registered with either context.injector.bind_instance(BaseClass, instance) for previously-constructed (singleton) object instances, or context.injector.bind_provider(BaseClass, provider) for dynamic providers. In some cases it may be desirable to write a custom provider which switches implementations based on configuration settings, such as the wallet provider.

The BaseProvider classes in the config.provider module include ClassProvider, which can perform dynamic module inclusion when given the combined module and class name as a string (for instance aries_cloudagent.wallet.indy.IndyWallet). ClassProvider accepts additional positional and keyword arguments to be passed into the class constructor. Any of these arguments may be an instance of ClassProvider.Inject(BaseClass), allowing dynamic injection of dependencies when the class instance is instantiated.