dfx build
Use the dfx build command to compile your program into a WebAssembly module that can be deployed on the IC. You can use this command to compile all of the programs that are defined for a project in the project’s dfx.json configuration file or a specific canister.
Note that you can only run this command from within the project directory structure. For example, if your project name is hello_world, your current working directory must be the hello_world top-level project directory or one of its subdirectories.
The dfx build command looks for the source code to compile using the information you have configured under the canisters section in the dfx.json configuration file.
Basic usage
dfx build [flag] [option] [--all | canister_name]
Flags
You can use the following optional flags with the dfx build command.
| Flag | Description |
|---|---|
--check | Builds canisters using a temporary, hard-coded, locally-defined canister identifier for testing that your program compiles without connecting to the IC. |
Options
You can specify the following options for the dfx build command.
| Option | Description |
|---|---|
--network <network> | Specifies the network alias or URL you want to connect to. You can use this option to override the network specified in the dfx.json configuration file. |
--output-env-file | Writes dfx environment variables to a provided path. Overrides the output_env_file configuration from dfx.json if passed. |
Arguments
You can specify the following arguments for the dfx build command.
| Argument | Description |
|---|---|
--all | Builds all of the canisters configured in the project’s dfx.json file. |
canister_name | Specifies the name of the canister you want to build. If you are not using the --all option, you can continue to use dfx build or provide a canister name as an argument (the canister name must match at least one name that you have configured in the canisters section of the dfx.json configuration file for your project.) |
Examples
You can use the dfx build command to build one or more WebAssembly modules from the programs specified in the dfx.json configuration file under the canisters key. For example, if your dfx.json configuration file defines one hello_world_backend canister and one hello_world_frontend canister, then running dfx build compiles two WebAssembly modules.
Note that the file name and path to the programs on your file system must match the information specified in the dfx.json configuration file.
In this example, the hello_world_backend canister contains the main program code and the hello_world_frontend canister store frontend code and assets. If you want to keep the hello_world_frontend canister defined in the dfx.json file, but only build the backend program, you could run the following command:
dfx build hello_world_backend
Building a specific canister is useful when you have multiple canisters defined in the dfx.json file, but want to test and debug operations for canisters independently.
To test whether a canister compiles without connecting to the IC or the local canister execution environment, you would run the following command:
dfx build --check
Management canister
If dfx detects that your Motoko project is importing the Management Canister (e.g. import Management "ic:aaaaa-aa";) it will automatically provide the Candid interface for the Management Canister during the build.