Configuration

This guide will help you to know the most important configuration options for SPV Wallet.

Order of resolving configuration

The configuration is resolved in the following priority

1. Environment variables - the environment variables are prefixed with SPVWALLET_ and are in uppercase. They have the highest priority when resolving the configuration.

2. Configuration file - the configuration file is resolved next. The default configuration file is config.yaml in the root of the project. You can also specify custom configuration file path using C flag in the command line.

3. If you don't specify the configuration file and environment variables, the default configuration will be used - it's resolved in defaults.go file in the config package. Default configuration from defaults.go is the same as the configuration from config.example.yaml.

Configuration File

We store the configuration in a file called config.example.yaml in the root of the project. You can copy this file to config.yaml and modify it to your needs.

The most important configuration options are:

auth:
  # xpub used for admin api authentication
  admin_key: xpub661MyMwAqRbcFgfmdkPgE2m5UjHXu9dj124DbaGLSjaqVESTWfCD4VuNmEbVPkbYLCkykwVZvmA8Pbf8884TQr1FgdG2nPoHR8aB36YdDQh
  # ...
  # other auth options
cache:
  # cache engine - freecache/redis
  engine: freecache
  # ...
  # other cache options
db:
  datastore:
  # enable datastore debug mode
  debug: false
  # datastore engine - sqlite/postgresql/mysql/mongodb (experimental)
  engine: sqlite
  # in this section you can define details about your database
  # ...
nodes:
  # deployment id used annotating api calls in XDeployment-ID header - this value will be randomly generated if not set
  _deployment_id: spv-wallet-deployment-id
  callback:
    callback_host: https://xyz.com
    # token to authenticate callback calls - default callback token will be generated from the Admin Key
    _callback_token: 44a82509
  # protocol - arc/mapi (arc is default)
  protocol: arc
  # list of apis used for getting and broadcasting transactions
  apis:
    # gorillapool can be used as well
    # - arc_url: https://arc.gorillapool.io
    # - token: ""
    - arc_url: https://api.taal.com/arc
      token: mainnet_06770f425eb00298839a24a49cbdc02c
  # use fee quotes for transaction fee calculation
  use_fee_quotes: true
  # used as the fee value if 'use_fee_quotes' is set to false
  fee_unit:
    satoshis: 1
    bytes: 1000
  # other nodes options
paymail:
  beef:
    block_headers_service_auth_token: mQZQ6WmxURxWz5ch
    # url to Block Headers Service, used for merkle root verification
    block_headers_service_url: http://localhost:8080/api/v1/chain/merkleroot/verify
    use_beef: false
  domains:
    - localhost
  enabled: true
# Prometheus metrics configuration
metrics:
  enabled: false

Going throught highlighted options:

• The auth section contains the admin_key which is used for admin api authentication. This key is used to authenticate the admin api calls.

• The cache section contains the engine option which can be set to freecache or redis. The freecache is the default option.

• The db section contains the datastore section which contains the engine option which can be set to sqlite, postgresql, mysql or mongodb (experimental). The sqlite is the default option. You can also define details about your database in this section.

• The nodes section contains the protocol option which can be set to arc or mapi (arc is default). The apis section contains the list of apis used for getting and broadcasting transactions. The use_fee_quotes option is used for transaction fee calculation. The fee_unit option is used as the fee value if use_fee_quotes is set to false.

• In the nodes section, the callback section contains the callback_host option which is used to define the callback host. The _callback_token option is used to authenticate callback calls. The _deployment_id option is used to define the deployment id used annotating api calls in XDeployment-ID header. This value will be randomly generated if not set.

Callback is an Arc feature that allows the wallet to receive notifications about broadcasted transactions. It is useful because it limits the need for polling the node for transaction status.

• The paymail section contains the enabled option which is used to enable or disable paymail. The domains option is used to define the list of domains.

• The beef section contains the use_beef option which is used to enable or disable beef. The block_headers_service_url option is used to define the url to Block Headers Service, used for merkle root verification. The block_headers_service_auth_token option is used to authenticate the Block Headers Service calls.

You can read more about the SPV and BEEF in the SPV and BEEF section.

Environment Variables

You can also set the configuration options using environment variables. The environment variables are prefixed with SPVWALLET_ and are in uppercase. For example, the auth.admin_key can be set using the SPVWALLET_AUTH_ADMIN_KEY environment variable.