Function resolveAndMergeBuildArgs

pkg/compose/build.go:252–267

resolveAndMergeBuildArgs returns the final set of build arguments to use for the service image build. First, args directly defined via `build.args` in YAML are considered. Then, any explicitly passed args in opts (e.g. via `--build-arg` on the CLI) are merged, overwriting any keys that already exis

(proxyConfig map[string]string, project *types.Project, service types.ServiceConfig, opts api.BuildOptions)

// Finally, standard proxy variables based on the Docker client configuration are added, but will not overwrite
// any values if already present.
func resolveAndMergeBuildArgs(proxyConfig map[string]string, project *types.Project, service types.ServiceConfig, opts api.BuildOptions) types.MappingWithEquals {
	result := make(types.MappingWithEquals).
		OverrideBy(service.Build.Args).
		OverrideBy(opts.Args).
		Resolve(envResolver(project.Environment))

	// proxy arguments do NOT override and should NOT have env resolution applied,
	// so they're handled last
	for k, v := range proxyConfig {
		if _, ok := result[k]; !ok {
			v := v
			result[k] = &v
		}
	}
	return result
}

func getImageBuildLabels(project *types.Project, service types.ServiceConfig) types.Labels {
	ret := make(types.Labels)