eclair/docs/Configure.md

Configuring Eclair

Eclair reads its configuration file, and writes its logs, to ~/.eclair by default. You can change this behavior with the eclair.datadir parameter:

eclair-node.sh -Declair.datadir="/path/to/custom/eclair/data/folder"

Change your node's configuration

The first step is to actually create the configuration file. Go to eclair.datadir and create a file named eclair.conf. The encoding should be UTF-8.

Options are set as key-value pairs and follow the HOCON syntax. Values do not need to be surrounded by quotes, except if they contain special characters.

Options reference

Here are some of the most common options:

name	description	default value
eclair.chain	Which blockchain to use: regtest, testnet or mainnet	mainnet
eclair.server.port	Lightning TCP port	9735
eclair.api.port	API HTTP port	8080
eclair.api.enabled	Enables the JSON API	false
eclair.api.password	Password protecting the API (BASIC auth)	no default
eclair.bitcoind.rpcuser	Bitcoin Core RPC user	foo
eclair.bitcoind.rpcpassword	Bitcoin Core RPC password	bar
eclair.bitcoind.zmqblock	Bitcoin Core ZMQ block address	"tcp://127.0.0.1:29000"
eclair.bitcoind.zmqtx	Bitcoin Core ZMQ tx address	"tcp://127.0.0.1:29000"
eclair.bitcoind.wallet	Bitcoin Core wallet name	""
eclair.server.public-ips	List of node public ip	no default

→ see reference.conf for full reference. There are many more options!

Customize features

Eclair ships with a set of features that are activated by default, and some experimental or optional features that can be activated by users. The list of supported features can be found in the reference configuration.

To enable a non-default feature, you simply need to add the following to your eclair.conf:

eclair.features {
    official_feature_name = optional|mandatory
}

For example, to activate option_static_remotekey:

eclair.features {
    option_static_remotekey = optional
}

Note that you can also disable some default features:

eclair.features {
    option_support_large_channel = disabled
}

It's usually risky to activate non-default features or disable default features: make sure you fully understand a feature (and the current implementation status, detailed in the release notes) before doing so.

Eclair supports per-peer features. Suppose you are connected to Alice and Bob, you can use a different set of features with Alice than the one you use with Bob. When experimenting with non-default features, we recommend using this to scope the peers you want to experiment with.

This is done with the override-features configuration parameter in your eclair.conf:

eclair.override-features = [
    {
        nodeId = "03864ef025fde8fb587d989186ce6a4a186895ee44a926bfc370e2c366597a3f8f"
        features {
            option_support_large_channel = disabled
            option_static_remotekey = optional
        }
    },
    {
        nodeId = "<another nodeId>"
        features {
            option_static_remotekey = optional
            option_support_large_channel = optional
        }
    },
]

Customize feerate tolerance

In order to secure your channels' funds against attacks, your eclair node keeps an up-to-date estimate of on-chain feerates (based on your Bitcoin node's estimations). When that estimate deviates from what your peers estimate, eclair may automatically close channels that are at risk to guarantee the safety of your funds.

Since predicting the future is hard and imperfect, eclair has a tolerance for deviations, governed by the following parameters:

on-chain-fees {
    feerate-tolerance {
      ratio-low = 0.5 // will allow remote fee rates as low as half our local feerate
      ratio-high = 10.0 // will allow remote fee rates as high as 10 times our local feerate
    }
}

We do not recommend changing these values unless you really know what you're doing. However, if you have a trust relationship with some specific peers, and you know they will never try to cheat you, you can increase the tolerance specifically for those peers. On the other hand, if you have channels with peers you suspect may try to attack you, you can decrease the tolerance specifically for those peers.

on-chain-fees {
    override-feerate-tolerance = [
        {
            nodeid = "<nodeId of a trusted peer>"
            feerate-tolerance {
                ratio-low = 0.1 // will allow remote fee rates as low as 10% our local feerate
                ratio-high = 15.0 // will allow remote fee rates as high as 15 times our local feerate
            }
        },
        {
            nodeid = "<nodeId of a peer we don't trust at all>"
            feerate-tolerance {
                // will only allow remote fees between 75% and 200% of our local feerate
                ratio-low = 0.75
                ratio-high = 2.0
            }
        }
    ]
}

Examples

Basic configuration

This is a common configuration file which overrides the default server port, node's label and node's color and enables the API (needed to interact with your node with eclair-cli):

# server port
eclair.server.port=9737

# node's label
eclair.node-alias="my node"
# rgb node's color
eclair.node-color=49daaa

eclair.api.enabled=true
# You should set a real password here.
eclair.api.password=foobar
# Make sure this port isn't accessible from the internet!
eclair.api.port=8080

Regtest mode

To run with Bitcoin's regtest mode, you need to set the chain reference:

eclair.chain = "regtest"

You usually also need to disable the feerate mismatch

Public node

To make your node public, add a public ip:

eclair.server.public-ips=[x.x.x.x]

You'll also have to make sure the node is accessible from the outside world (port forwarding, firewall,...).