# Configuration

DATP is configured using a JSON file, which is accessed using Tooltwist's juice-client package. This npm package allows an environment to specify where to access the configuration.

during development, the config is usually stored in a JSON file on the file system.
if deployed on AWS the config is JSON stored in AWS Secrets Manager.

It's common to store your application configuration variables in this same config file.

If you have multiple node groups you will need one configuration definition for each node group. All nodes within the node group will use the same definition.

# Example

{
  "datp": {
    "description": "Master DATP node",
    "protocol": "http",
    "host": "localhost",
    "port": 4000,
    "midiSupported": false,
    "nodeGroup": "master",
    "webhook-credentials": {
      "publicKey": "-----BEGIN PUBLIC KEY-----\n....\n-----END PUBLIC KEY-----\n",
      "privateKey": "-----BEGIN PRIVATE KEY-----\n....\n-----END PRIVATE KEY-----\n"
    },
    "statePersistanceInterval": 15,
    "logDestination": "datadog",
    "deltaDestination": "none",
    "keepAliveTimeout": 65000,
    "headersTimeout": 66000
  },
  "datadog": {
    "apikey": ".....",
    "appkey": "....."
  },
  "db": {
    "host": "localhost",
    "writeHost": "localhost",
    "port": 3306,
    "user": "root",
    "password": "",
    "database": "datp_master"
  },
  "redis": {
    "host": "localhost",
    "port": 6379,
    "user": "harry",
    "password": "xyz"
  },

  // Application specific configuration
  "myApp": {
    "name": "value"
  }
}

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# datp.deltaDestination

db | dynamodb | none

This defines where DATP will write it's transaction journal entries ("deltas").

In most applications this can be set to none to reduce processing overhead. It is only required where micro-level tracking of the transaction state is required. For example, you might turn it on for just the node where a specific type of transaction is processed.

During development it can be beneficial to write deltas to the database using the db option, where they can easily be viewed or cleared out using PhpMyadin.

DynamoDB is a fast alternative to the database for production environments, and provides fallback transaction state information in case of a database failure.

Also, the none option is useful during performance testing, to determine which part of system load is caused by saving transaction deltas.

# datp.description

A string to describe this node group.

# datp.development

ZZZZZ

# datp.headersTimeout

(default=66000)
This is related to keepAliveTimeout. To prevent the reported 502 errors, this value must be longer than keepAliveTimeout, which must be longer than the timeout of your AWS ALB.

# datp.host

e.g. localhost

The domain name MONDAT should use to access DATP endpoints.

# datp.keepAliveTimeout

(default=65000)
This value is used to configure Node to not shut down socket of the API endpoint within the specified number of milliseconds. We've added this to provide a workaround for a bug that causes Express, Restify and some other frameworks to occassionally return 502 errors under load, when behind an AWS load balancer.

For more details and a full description of the problem, see Dealing with Intermittent 502's between an AWS ALB and Express Web Server (opens new window).

To prevent these errors make sure keepAliveTimeout is greater than the AWS timeout for the ALB (Application Load Balancer).

# datp.logDestination

db | datadog | none

This defines where DATP will write log entries.

During development it's easiest to write logs to the database using the db option, where they can easily be viewed or cleared out using PhpMyadin.

Datadog is a fast alternative to the database for production environments.

The none option is useful during performance testing, to determine which part of system load is caused by the logging.

# datp.logHealthcheck

true|false
When true, each call to the healthcheck URL will be logged to the console. This is useful to isolate errors when debugging errors with a load balancer or AWS target group.

# datp.maxWebhookAttempts

(default=5)
This value specifies how many times DATP will attempt to call the webhook for a transaction before giving up.

# datp.name

(deprecated)
Name of the current node.

# datp.nodeGroup

String (default="master")

When you divide your application into multiple types of DATP node, this value is used to group instances of each node type.

"datp": {
  "nodeGroup": "master"
}

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# datp.port

e.g. 4000

The HTTP port that MONDAT should use to access DATP endpoints.

# datp.protocol

(default https) The protocol MONDAT should use to access DATP endpoints.

# datp.serveMondat

(default=false)
If true the API server will also act as the website hosting MONDAT. This requires that the MONDAT server be generated into the dist directory.

# datp.serveMondatApi

(default=false)
When true, the server will enable the API endpoints used by MONDAT. Note that this is different to datp.serveMondat, which causes the server to serve up the MONDAT clint/website.

# datp.statePersistanceInterval

(default=15 seconds)

DATP normally stores transaction state in REDIS, but if it is not accessed for a long time it is assumed the transaction has been put to sleep for an extended period, and the state will be persisted to long term storage.

The statePersistanceInterval is the minimum number of seconds until DATP schedules the state to be moved to this long term storage.

# datp.webhook-credentials

When DATP calls a client's webhook to notify the status of a transaction, the result is signed with a digital signature. This section of the config file defines the credentials to sign and check those signatures.

See [./DZDwebhook-background.html]! for details. See the Web Hooks section for details.

  "datp": {
    "webhook-credentials": {
      "publicKey": "-----BEGIN PUBLIC KEY-----\n....\n-----END PUBLIC KEY-----\n",
      "privateKey": "-----BEGIN PRIVATE KEY-----\n....\n-----END PRIVATE KEY-----\n"
    },
    ...
  }

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# datadog.apikey

The APIKey provided by Datadog. Only required if you are logging to Datadog.

# datadog.appkey

The Application Key provided by Datadog. Only required if you are logging to Datadog.

# db.host

Domain name for reading from the DATP database.

# db.writeHost

The endpoint for writing to the DATP database.

# db.port

(default=3306)

Port for DATP's database endpoint.

# db.user

Database user name.

# db.password

Database password.

# db.database

(default=datp_master)

The name of the database used by this DATP node group.

# db.connectionLimit

(default=10)

This is the maximum number of connections in each connnection pool for the DATP database. Note that there are two connection pools - one for reading and one for writing - so DATP will ultimately use double this number of connections.

When specifying this value consider the number of nodes you will have running, across all node groups, and ensure you do not exceed the maximum number of connections allowed by the database.

# redis.host

(default=localhost)

Domain name of the REDIS endpoint.

# redis.port

(default=6379)

Port of the REDIS endpoint.

# redis.username

(default=null)

User name used to access REDIS.

# redis.password

(default=null)

Password used to access REDIS.

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