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flow-wallet-api

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Service for custodial wallets on Flow blockchain. This repository is currently not maintained.

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# Flow Wallet API

**NOTE: This repository is currently not maintained.**

The Flow Wallet API is a REST HTTP service that allows a developer to integrate wallet functionality into a larger Flow application infrastructure.
This service can be used by an application that needs to manage Flow user accounts and the assets inside them.

## Features

- Create new Flow accounts
- Securely store account private keys
- Send a transaction from an account
- Transfer fungible tokens (e.g. FLOW, FUSD)
- Detect fungible token deposits
- _Transfer NFTs (e.g. FLOW, FUSD) (coming soon)_
- _Detect NFT deposits (coming soon)_

View full list of functionality in the [API documentation](https://flow-hydraulics.github.io/flow-wallet-api/).

## Background

Some application developers may wish to manage Flow accounts in a fully-custodial fashion,
but without taking on the complexity of building an account management system.

An application may need to support custody of fungible tokens (FLOW, FUSD), non-fungible tokens, or both.

For security and/or legal reasons,
some developers need to use a custody service running on-premises as part of their existing infrastructure,
rather than a hosted 3rd-party solution.

### Example use cases

- **FLOW/FUSD Hot Wallet** — an application that allows users to convert fiat currency to FLOW or FUSD. A single admin account would be used as a hot wallet for outgoing payments, and additional deposit accounts would be created to accept incoming payments.
- **Exchange** — a cryptocurrency exchange that is listing FLOW and/or FUSD. Similar to the case above, one or more admin accounts may be used as a hot wallet for outgoing payments, and additional deposit accounts would be created to accept incoming payments.
- **Web Wallet** — a user-facing wallet application that is compatible with Flow dapps. Each user account would be created and managed by the wallet service.

## API Specification

View the [Wallet API documentation and OpenAPI (Swagger) specification](https://flow-hydraulics.github.io/flow-wallet-api/).

## Installation

The Wallet API is provided as a Docker image:

```sh
docker pull ghcr.io/flow-hydraulics/flow-wallet-api:latest
```

### Basic example usage

**NOTE:** This setup is only for demonstrative purposes, please do not run this on production

This setup requires [Docker](https://docs.docker.com/engine/install/), [Docker Compose](https://docs.docker.com/compose/install/) and the [Flow CLI](https://docs.onflow.org/flow-cli/install/).

Create a configuration file:

```sh
cp .env.example .env # and edit
```

Start the Wallet API, Flow Emulator, Postgres and Redis:

```sh
docker-compose up -d
```

You can now access the API at http://localhost:3000/v1.

Once you're finished, run this to stop the containers:

```sh
docker-compose down
```

## Configuration

The application is configured using _environment variables_. Make sure to prefix variables with `"FLOW_WALLET_"`

If you have an existing `.env` file (or you were using `-envfile`) you can run a command with the variables loaded:

# Replace <command> with the command you want to run
    env $(grep -e '^#' .env | xargs) <command>

# For example
    env $(grep -e '^#' .env | xargs) go run main.go

### Maintenance mode

You can put the service in maintenance mode via the [System API](https://flow-hydraulics.github.io/flow-wallet-api/#tag/System) by sending the following JSON body as a `POST` request to `/system/settings` (example in [api-test-scripts/system.http](api-test-scripts/system.http)):

```json
{
  "maintenanceMode": true
}
```

In maintenance mode, all on-chain transactions and event processing are halted. Disabling maintenance mode is done via the same API endpoint (`"maintenanceMode": false`).

### Updates on async requests (webhook)

If you have the possibility to setup a webhook endpoint, you can set `FLOW_WALLET_JOB_STATUS_WEBHOOK` to receive updates on async requests (requests which return a job). The wallet will send a `POST` request to this URL containing the job whenever the status of the job is updated.

**NOTE:** The wallet expects a response with status code **200** and will retry if unsuccessful.

### Configuring the server request timeout

When making `sync` requests it's sometimes required to adjust the server's request timeout. Try increasing `FLOW_WALLET_SERVER_REQUEST_TIMEOUT` if you're experiencing issues with `sync` requests, `FLOW_WALLET_SERVER_REQUEST_TIMEOUT=180s` for example.

**NOTE:** Using `sync` requests in production is not recommended, use asynchronous requests & optionally configure a webhook to receive job updates instead.

### Enabled fungible tokens

A comma separated list of _fungible tokens_ and their corresponding addresses and paths enabled for this instance. Make sure to name each token exactly as it is in the corresponding Cadence code (FlowToken, FUSD, etc). Include at least FlowToken as functionality without it is undetermined. Format is comma separated list of:

```
TokenName:ContractAddress:ReceiverPublicPath:BalancePublicPath:VaultStoragePath
```

Example (mainnet):
```
FiatToken:0xb19436aae4d94622:FiatToken.VaultReceiverPubPath:FiatToken.VaultBalancePubPath:FiatToken.VaultStoragePath
```

**DEPRECATION NOTICE:** You can optionally config each token with 3 parameters: a 3rd parameter "lowercamelcase" name for each token. For FlowToken this would be "flowToken" and for FUSD "fusd". This is used to construct the vault name, receiver name and balance name in generic transaction templates. Consult the contract code for each token to derive the proper name (search for `.*Vault`, `.*Receiver`, `.*Balance`).**THIS IS NOW DEPRECATED** It's best to grab paths from the token contract and set them explicitly here instead of generating them based on lowercase token name. The old format still works to maintain backward compatibility.

Examples:

FLOW_WALLET_ENABLED_TOKENS=FlowToken:0x0ae53cb6e3f42a79:flowToken,FUSD:0xf8d6e0586b0a20c7:fusd

**NOTE:** Non-fungible tokens _cannot_ be enabled using environment variables. Use the API endpoints for that.

### Database

| Config variable | Environment variable        | Description                                                                                      | Default     | Examples                  |
| --------------- | :-------------------------- | ------------------------------------------------------------------------------------------------ | ----------- | ------------------------- |
| `DatabaseType`  | `FLOW_WALLET_DATABASE_TYPE` | Type of database driver                                                                          | `sqlite`    | `sqlite`, `psql`, `mysql` |
| `DatabaseDSN`   | `FLOW_WALLET_DATABASE_DSN`  | Data source name ([DSN](https://en.wikipedia.org/wiki/Data_source_name)) for database connection | `wallet.db` | See below                 |

Examples of Database DSN

mysql://john:pass@localhost:3306/my_db

postgresql://postgres:postgres@localhost:5432/postgres

user:pass@tcp(127.0.0.1:3306)/dbname?charset=utf8mb4&parseTime=True&loc=Local

host=localhost user=gorm password=gorm dbname=gorm port=9920 sslmode=disable TimeZone=Asia/Shanghai

For more: https://gorm.io/docs/connecting_to_the_database.html

To learn more about database schema versioning and migrations, read [MIGRATIONS.md](MIGRATIONS.MD).

### Google KMS setup

**Note**: In order to use Google KMS for remote key management you'll need a Google Cloud Platform account.

Pre-requisites:

1. Create a new Project if you don't have one already. You'll need the Project ID later.
2. Enable Cloud Key Management Service (KMS) API for the project, Security -> [Cryptographic Keys](https://console.cloud.google.com/security/kms).
3. Create a new Key Ring for your wallet (or use an existing Key Ring), Security -> Cryptographic Keys -> [Create Key Ring](https://console.cloud.google.com/security/kms/keyring/create), you'll need the Location ID (or _Location_) and Key Ring ID (or _Name_) later.

Using a Service Account to access the KMS API (see [official docs](https://cloud.google.com/docs/authentication/getting-started) for more);

1. Create a new Service Account, IAM & Admin -> Service Accounts -> [Create Service Account](https://console.cloud.google.com/iam-admin/serviceaccounts/create)
2. Use the roles `Cloud KMS Admin` & `Cloud KMS Signer/Verifier` or grant the required permissions through a custom role (NOTE: deletion not supported yet):
   - `cloudkms.cryptoKeyVersions.useToSign`
   - `cloudkms.cryptoKeyVersions.viewPublicKey`
   - `cloudkms.cryptoKeys.create`
3. After creating the Service Account, select Manage Keys from the Actions menu in the Service Account listing.
4. Create a new key, Add Key -> Create New key, and select JSON as the key type.
5. Save the JSON file.

Configure the Google KMS client library by setting the environment variable `GOOGLE_APPLICATION_CREDENTIALS`:

```
export GOOGLE_APPLICATION_CREDENTIALS="/home/example/path/to/service-account-file.json"
```

Configure Google KMS as the key storage for `flow-wallet-api` and set the necessary environment variables:

| Config variable  | Environment variable                 | Description      | Default | Examples                    |
| ---------------- | ------------------------------------ | ---------------- | ------- | --------------------------- |
| `DefaultKeyType` | `FLOW_WALLET_DEFAULT_KEY_TYPE`       | Default key type | `local` | `local`, `google_kms`       |
| `ProjectID`      | `FLOW_WALLET_GOOGLE_KMS_PROJECT_ID`  | GCP Project ID   | -       | `flow-wallet-example`       |
| `LocationID`     | `FLOW_WALLET_GOOGLE_KMS_LOCATION_ID` | GCP Location ID  | -       | `europe-north1`, `us-west1` |
| `KeyRingID`      | `FLOW_WALLET_GOOGLE_KMS_KEYRING_ID`  | GCP Key Ring ID  | -       | `example-wallet-keyring`    |

### Google KMS for admin account

If you want to use a key stored in Google KMS for the admin account, just pass the resource identifier as the private key (`FLOW_WALLET_ADMIN_PRIVATE_KEY`) and set `FLOW_WALLET_ADMIN_KEY_TYPE` to `google_kms`.

**Creating an account on testnet via the faucet:**

1. When generating the key, choose "Asymmetric sign" as the purpose and "Elliptic Curve P-256 - SHA256 Digest" as the key type and algorithm (other combinations may work but these have been confirmed to work)
2. Download the public key from Google KMS in PEM format (should have a `.pub` ending)
3. Run it through `flow keys decode pem --from-file <filename>`
4. Copy the "Public Key" part
5. Go to https://testnet-faucet-v2.onflow.org
6. Paste the copied public key in the form
7. **IMPORTANT**: Choose **SHA2_256** as the hash algorithm (_SHA3_256_ won't work with the key setup above)
8. Copy the new address and use it as the `FLOW_WALLET_ADMIN_ADDRESS`
9. Set `FLOW_WALLET_ADMIN_PRIVATE_KEY` to the resource id of the key
10. Set `FLOW_WALLET_ADMIN_KEY_TYPE` to `google_kms`

Example environment:

FLOW_WALLET_ADMIN_ADDRESS=0x1234567890123456
    FLOW_WALLET_ADMIN_PRIVATE_KEY=projects/<project_id>/locations/<location_id>/keyRings/<keyring_id>/cryptoKeys/<key_name>/cryptoKeyVersions/<version_number> # Make sure this ends with the version number
    FLOW_WALLET_ADMIN_KEY_TYPE=google_kms

NOTE: This will mess up the docker-compose setup (emulator won't start) as it uses `FLOW_WALLET_ADMIN_PRIVATE_KEY` as `FLOW_SERVICEPRIVATEKEY`. It will cause an encoding error on the emulator.

### Google KMS key for database encryption

Before configuring a Google KMS key for database encryption please refer to the official guide for setting up a symmetric encryption key;

https://cloud.google.com/kms/docs/encrypt-decrypt#before_you_begin

If you want to use an Google KMS symmetric encryption key for encrypting the stored account keys, please refer to the following configuration settings;

| Config variable     | Environment variable              | Description                      | Default | Examples value for Google KMS                                                             |
| ------------------- | --------------------------------- | -------------------------------- | ------- | ----------------------------------------------------------------------------------------- |
| `EncryptionKeyType` | `FLOW_WALLET_ENCRYPTION_KEY_TYPE` | Encryption key type              | `local` | `google_kms`                                                                              |
| `EncryptionKey`     | `FLOW_WALLET_ENCRYPTION_KEY`      | KMS encryption key resource name | -       | `projects/my-project/locations/us-west1/keyRings/my-keyring/cryptoKeys/my-encryption-key` |

### AWS KMS setup

**Note**: In order to use AWS KMS for remote key management you'll need an AWS account.
**Note**: Custom key stores are not supported.

#### Pre-requisites:

1. AWS credentials for an account that has access to KMS

| Environment variable    | Description                                            | Default | Examples                    |
| ----------------------- | ------------------------------------------------------ | ------- | --------------------------- |
| `AWS_PROFILE`           | AWS profile name, when using a shared credentials file | -       | `my-aws-profile-name`       |
| `AWS_REGION`            | AWS KMS Region                                         | -       | `eu-central-1`, `us-west-1` |
| `AWS_ACCESS_KEY_ID`     | AWS access key ID                                      | -       | `AKIAXXX123FOOBAR1234`      |
| `AWS_SECRET_ACCESS_KEY` | AWS secret access key                                  | -       | `FooBaRBaZ12345...`         |

Configure AWS KMS as the key storage for `flow-wallet-api` and set the necessary environment variables, with the default key type as `aws_kms`:

| Config variable | Environment variable           | Description      | Default | Value for AWS KMS |
| --------------- | ------------------------------ | ---------------- | ------- | ----------------- |
| DefaultKeyType  | `FLOW_WALLET_DEFAULT_KEY_TYPE` | Default key type | `local` | `aws_kms`         |

### AWS KMS for admin account

If you want to use a key stored in AWS KMS for the admin account, please refer to the following configuration settings;

| Config variable   | Environment variable            | Description           | Default | Example value for AWS KMS                                                       |
| ----------------- | ------------------------------- | --------------------- | ------- | ------------------------------------------------------------------------------- |
| `AdminKeyType`    | `FLOW_WALLET_ADMIN_KEY_TYPE`    | Admin key type        | `local` | `aws_kms`                                                                       |
| `AdminPrivateKey` | `FLOW_WALLET_ADMIN_PRIVATE_KEY` | Admin private key ARN | -       | `arn:aws:kms:eu-central-1:012345678910:key/00000000-aaaa-bbbb-cccc-12345678910` |

When testing make sure to add the key to the admin account. You can convert the AWS public key (e.g. `aws.pem`) you downloaded/copied from AWS with flow-cli;

```
flow keys decode pem --from-file=aws.pem --sig-algo "ECDSA_secp256k1"
```

### AWS KMS for encrypting stored keys

If you want to use an AWS KMS symmetric encryption key for encrypting the stored account keys, please refer to the following configuration settings;

| Config variable     | Environment variable              | Description            | Default | Examples value for AWS KMS                                                      |
| ------------------- | --------------------------------- | ---------------------- | ------- | ------------------------------------------------------------------------------- |
| `EncryptionKeyType` | `FLOW_WALLET_ENCRYPTION_KEY_TYPE` | Encryption key type    | `local` | `aws_kms`                                                                       |
| `EncryptionKey`     | `FLOW_WALLET_ENCRYPTION_KEY`      | KMS encryption key ARN | -       | `arn:aws:kms:eu-central-1:012345678910:key/00000000-aaaa-bbbb-cccc-12345678910` |

### Idempotency middleware

Idempotency middleware ensures that `POST` requests are idempotent. When the middleware is enabled an `Idempotency-Key` HTTP header is required for `POST` requests. The header value should be a unique identifier for the request (UUID or similar is recommended). Trying to send a request with a duplicate idempotency key will result in a `409 Conflict` HTTP response.

To configure the middleware set the following configuration settings;

| Config variable                     | Environment variable                               | Description                                      | Default | Examples                                             |
| ----------------------------------- | -------------------------------------------------- | ------------------------------------------------ | ------- | ---------------------------------------------------- |
| `DisableIdempotencyMiddleware`      | `FLOW_WALLET_DISABLE_IDEMPOTENCY_MIDDLEWARE`       | Disable the idempotency middleware entirely      | `false` | `true`, `false`                                      |
| `IdempotencyMiddlewareDatabaseType` | `FLOW_WALLET_IDEMPOTENCY_MIDDLEWARE_DATABASE_TYPE` | Database type for idempotency key middleware     | `local` | `local`, `shared`, `redis`                           |
| `IdempotencyMiddlewareRedisURL`     | `FLOW_WALLET_IDEMPOTENCY_MIDDLEWARE_REDIS_URL`     | Redis URL for idempotency key middleware storage | -       | `redis://walletapi:wallet-api-redis@localhost:6379/` |

NOTE:

- The `local` option for `IdempotencyMiddlewareDatabaseType` does not support multiple instances.
- The provided `docker-compose.yml` provides a basic Redis instance for local development purposes, with basic configuration files in the [`redis-config`](redis-config) directory.
- There is currently no automatic cleanup of old idempotency keys when using the `shared` (sql) database. Redis is recommended for production use.

### Log level

The default log level of the service is `info`. You can change the log level by setting the environment variable `FLOW_WALLET_LOG_LEVEL`.

Valid log leves are (case-insensitive):

panic
    fatal
    error
    warn, warning
    info
    debug
    trace

### Multiple keys for custodial accounts

To enable multiple keys for custodial accounts you'll need to set `FLOW_WALLET_DEFAULT_ACCOUNT_KEY_COUNT` to the number of keys each account should have. When a new account is created the auto-generated account key is cloned so that the total number of keys matches the configured value.

NOTE: Changing `FLOW_WALLET_DEFAULT_ACCOUNT_KEY_COUNT` does not affect _existing_ accounts.

### All possible configuration variables

Refer to [configs/configs.go](configs/configs.go) for details and documentation.

## Credit

The Flow Wallet API is developed and maintained by [Equilibrium](https://equilibrium.co/),
with support from the Flow core contributors.

## Testing

You can run a fully dockerized test suite if you have _Docker_ and _Docker Compose_ installed.

# Run the test suite
    make run-test-suite

# If you don't want to leave background services running (database, redis, flow-emulator)
    make stop-test-suite

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