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Build customization

To customize certain aspects of the build process, build environment variables can be used. You can specify them using the --build-env flag during creation or update of the application.

Setting build environment variables on app creation​

You can use the --build-env flag of the nctl create app command to set build environment variables on application creation.

--build-env=KEY=VALUE;...    Environment variables which are passed to the app build process.

$ nctl create app go-example --build-env='BP_GO_TARGETS=./cmd/app'

Multiple build time env variables can be set by using the --build-env option multiple times or by adding the variables separated by a semicolon:

$ nctl create app go-example --build-env='BP_GO_TARGETS=./cmd/app' --build-env='BP_KEEP_FILES=assets/*:public/*'

or

$ nctl create app go-example --build-env='BP_GO_TARGETS=./cmd/app;BP_KEEP_FILES=assets/*:public/*'

Updating build environment variables​

To update build environment variables on existing applications you can use the --build-env flag of the nctl update app command.

$ nctl update app go-example --build-env='BP_GO_TARGETS=./cmd/app'

More information​

All build environment variables are specific to the language and the buildpack that is being used in the backend to build your app. You can find the language specific supported build environment variables in the "Languages" section of the documentation.