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Defining custom networks

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Overview​

When developing multiple projects simultaneously, it can be beneficial to deploy each project to a different local network for simplicity or to support different development workflows. Custom networks can be configured with dfx at both the system-wide and project-specific levels.

Defining system-wide networks in networks.json​

Canisters in any project can be deployed to system-wide networks. System-wide custom networks can be configured in the networks.json configuration file for dfx.

To locate this file on your local system, use the dfx command:

dfx info networks-json-path

This will return the file path where your system's networks.json file is located, such as:

/Users/developer/.config/dfx/networks.json

Default configuration​

By default, this file contains the following configuration:

{
    "local": {
        "replica": {
            "subnet_type": "application"
        }
    }
}

Alternatively, if a network.json file is not defined locally, dfx will by default use the above configuration.

Defining a custom network​

To define a custom network, you can define a binding address in your networks.json to be localhost or any other domain name, such as:

{
  "network_1": {
    "bind": "localhost:4943",
    "replica": {
      "subnet_type": "application"
    }
  }
}

To define multiple networks, use multiple definitions on different domain names:

{
  "network_1": {
    "bind": "localhost:4943",
    "replica": {
      "subnet_type": "application"
    }
  },
  "network_2": {
    "bind": "127.0.0.1:4943",
    "replica": {
      "subnet_type": "application"
    }
  }
}

Then, to deploy to one of these networks, use the --network flag with dfx deploy, such as:

dfx deploy --network network_2

dfx deploy will display URLs in the format <canister>.localhost:port or <network>:port/?canisterId=<canister>:

  Frontend canister via browser
    poll_frontend: http://b77ix-eeaaa-aaaaa-qaada-cai.localhost:4943/
  Backend canister via Candid interface:
    poll_backend: http://by6od-j4aaa-aaaaa-qaadq-cai.localhost:4943/?id=bw4dl-smaaa-aaaaa-qaacq-cai
URLs:
  Frontend canister via browser
    poll_frontend: http://127.0.0.1:4943/?canisterId=bd3sg-teaaa-aaaaa-qaaba-cai
  Backend canister via Candid interface:
    poll_backend: http://127.0.0.1:4943/?canisterId=be2us-64aaa-aaaaa-qaabq-cai&id=bkyz2-fmaaa-aaaaa-qaaaq-cai

Defining project-specific networks in dfx.json​

Networks can also be defined in a project's dfx.json file. Only canisters within the project can be deployed to the networks defined in dfx.json.

Network definitions in the dfx.json file can have the following configuration components:

  • providers: The network provider; can be localhost or any other domain name. Domain names must be a full URL, such as https://domain.com.
  • type: The type of network, either ephemeral or persistent. Ephemeral networks do not retain the same IDs for canisters, while persistent networks will retain the same canister IDs.

To define a project-specific network, add a "networks" section to your dfx.json file such as:

"networks": {
    "dev": {
      "providers": [
        "https://ic0.app"
      ],
      "type": "persistent"
    }
  }

If you are using a cycles wallet, be sure to deploy your cycles wallet to this custom network.

dfx identity --network dev set-wallet $(dfx identity --network ic get-wallet)

Then, deploy to the network:

dfx deploy --network dev

Resources​

You can learn more about project-specific networks in the custom testnet documentation.