Configuring a BigchainDB Node

The BigchainDB configuration settings for a particular node are stored on that node in a configuration file at $HOME/.bigchaindb. That file doesn't exist by default. (It's not created when installing BigchainDB.) One could create it using a text editor, but it's easiest to use the bigchaindb configure command:

$ bigchaindb configure

It will ask some questions and generate a new keypair (i.e. a private key and corresponding public key for the node). See below for some additional explanation of the settings and their meanings. To accept a suggested default value, press Enter or Return. If you want to accept all the default values, use the -y option when running the command, that is:

$ bigchaindb -y configure

Using a Different Path for the Configuration File

By default, the configuration settings are stored in $HOME/.bigchaindb. If you want to specify a different path for your configuration file, you can use the -c parameter. This works for every subcommand under the bigchaindb executable.

For example, if you want to generate a new configuration file under a specific path, you can run:

$ bigchaindb -c local.json configure
$ bigchaindb -c test.json configure

This will create two new files named local.json and test.json in your current working directory.

From now on, you can refer to those configuration files using the -c parameter; for example:

$ bigchaindb -c local.json show-config

will show the configuration for local.json.

If you want to start BigchainDB with the test.json configuration file, you can use:

$ bigchaindb -c test.json start

Using Environment Variables to Configure the Node

Sometimes it's more convenient to use environment variables to configure the system, for example when using Docker or Heroku. In that case you can configure the system using environment variables.

Every configuration parameter can be mapped to an environment variable. The environment variables available are:

BIGCHAINDB_DATABASE_HOST defines the RethinkDB database hostname to connect to.
BIGCHAINDB_DATABASE_PORT defines the RethinkDB database port to connect to.
BIGCHAINDB_DATABASE_NAME defines the RethinkDB database name to use.
BIGCHAINDB_KEYPAIR_PUBLIC defines the public key of the BigchainDB node.
BIGCHAINDB_KEYPAIR_PRIVATE defines the private key of the BigchainDB node.
BIGCHAINDB_KEYRING is a colon-separated list of the public keys of all other nodes in the cluster.
BIGCHAINDB_STATSD_HOST defines the hostname of the statsd server for monitoring.
BIGCHAINDB_STATSD_PORT defines the port of the statsd server for monitoring.
BIGCHAINDB_STATSD_RATE is a float between 0 and 1 that defines the fraction of transaction operations sampled.
BIGCHAINDB_API_ENDPOINT defines the API endpoint to use (e.g. http://localhost:9984/api/v1).
BIGCHAINDB_CONSENSUS_PLUGIN defines the name of the consensus plugin to use.
BIGCHAINDB_SERVER_BIND defines where to bind the server socket, the format is addr:port (e.g. localhost:9984).
BIGCHAINDB_SERVER_WORKERS defines the number of workers to start for the server API.
BIGCHAINDB_SERVER_THREADS defines the number of threads to start for the server API.

Configuring the API Server

The API Server is powered by Gunicorn, a Python WSGI HTTP Server for UNIX. If you need to tweak some settings for the API server you can manually edit your .bigchaindb config file: the server section accepts all the options specified in the Gunicorn settings documentation.

Order of Precedence in Determining Configuration Values

All configuration values start with their default values (defined in bigchaindb.__init__), but a default value can be overriden by an environment variable, and a value set by an environment variable can be overriden by a value in a local configuration file ($HOME/.bigchaindb or the location specified by the -c command-line option).

In summary, there is an order of precedence in reading configuration values:

local configuration file
environment variables
default configuration file (defined in bigchaindb.__init__)

This means that if the default configuration contains:

{
    "database": {
        "host": "localhost",
        "port": 28015
    }
}

while the local file local.json contains:

{
    "database": {
        "host": "ec2-xx-xx-xxx-xxx.eu-central-1.compute.amazonaws.com"
    }
}

and you run this command:

$ BIGCHAINDB_DATABASE_HOST=anotherhost.com \
  BIGCHAINDB_DATABASE_PORT=4242 \
  BIGCHAINDB_KEYRING=pubkey0:pubkey1 \
  bigchaindb -c local.json show-config

you will get the following values for all the configuration settings:

{
    "api_endpoint": "http://localhost:8008/api/v1",
    "consensus_plugin": "default",
    "database": {
        "host": "ec2-xx-xx-xxx-xxx.eu-central-1.compute.amazonaws.com",
        "name": "bigchain",
        "port": 4242
    },
    "keypair": {
        "private": "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx",
        "public": "nJq6EmdUkvFjQRB5hFvDmvZtv1deb3W3RgmiAq6dyygC"
    },
    "keyring": [
        "pubkey0",
        "pubkey1"
    ],
    "server": {
        "bind": "localhost:9984",
        "threads": null,
        "workers": null
    },
    "statsd": {
        "host": "localhost",
        "port": 8125,
        "rate": 0.01
    }
}

Another Example

As another example, let's assume we don't have any configuration file stored in $HOME/.bigchaindb. As you can see, show-config displays the default configuration (and a warning):

$ bigchaindb show-config
WARNING:bigchaindb.config_utils:Cannot find config file `/home/vrde/.bigchaindb`.
{
    "api_endpoint": "http://localhost:9984/api/v1",
    "consensus_plugin": "default",
    "database": {
        "host": "localhost",
        "name": "bigchain",
        "port": 28015
    },
    "keypair": {
        "private": null,
        "public": null
    },
    "keyring": [],
    "server": {
        "bind": "localhost:9984",
        "threads": null,
        "workers": null
    },
    "statsd": {
        "host": "localhost",
        "port": 8125,
        "rate": 0.01
    }
}

If we try to run the node, the command will fail:

$ bigchaindb start
WARNING:bigchaindb.config_utils:Cannot find config file `/home/vrde/.bigchaindb`.
Cannot start BigchainDB, no keypair found. Did you run `bigchaindb configure`?

This is failing as expected: a BigchainDB node needs at least a key pair to work. We can pass the key pair using environment variables:

$ BIGCHAINDB_KEYPAIR_PUBLIC=26y9EuyGP44JXxqcvF8GbCJGqkiqFXddZzxVjLU3rWbHp \
  BIGCHAINDB_KEYPAIR_PRIVATE=9PkLfHbzXnSSNnb1sSBL73C2MydzKLs5fAHoA4Q7otrG \
  bigchaindb start

We can also run show-config to see how the configuration looks:

$ BIGCHAINDB_KEYPAIR_PUBLIC=26y9EuyGP44JXxqcvF8GbCJGqkiqFXddZzxVjLU3rWbHp \
  BIGCHAINDB_KEYPAIR_PRIVATE=9PkLfHbzXnSSNnb1sSBL73C2MydzKLs5fAHoA4Q7otrG \
  bigchaindb show-config

WARNING:bigchaindb.config_utils:Cannot find config file `/home/vrde/.bigchaindb`.
{
    "api_endpoint": "http://localhost:9984/api/v1",
    "consensus_plugin": "default",
    "database": {
        "host": "localhost",
        "name": "bigchain",
        "port": 28015
    },
    "keypair": {
        "private": "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx",
        "public": "26y9EuyGP44JXxqcvF8GbCJGqkiqFXddZzxVjLU3rWbHp"
    },
    "keyring": [],
    "server": {
        "bind": "localhost:9984",
        "threads": null,
        "workers": null
    },
    "statsd": {
        "host": "localhost",
        "port": 8125,
        "rate": 0.01
    }
}

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