DockerCLI/cli/command/orchestrator.go

package command

import (
	"os"
	"strings"
)

// Orchestrator type acts as an enum describing supported orchestrators.
type Orchestrator string

const (
	// OrchestratorKubernetes orchestrator
	OrchestratorKubernetes = Orchestrator("kubernetes")
	// OrchestratorSwarm orchestrator
	OrchestratorSwarm = Orchestrator("swarm")
	orchestratorUnset = Orchestrator("unset")

	defaultOrchestrator = OrchestratorSwarm
	dockerOrchestrator  = "DOCKER_ORCHESTRATOR"
)

func normalize(flag string) Orchestrator {
	switch strings.ToLower(flag) {
	case "kubernetes", "k8s":
		return OrchestratorKubernetes
	case "swarm", "swarmkit":
		return OrchestratorSwarm
	default:
		return orchestratorUnset
	}
}

// GetOrchestrator checks DOCKER_ORCHESTRATOR environment variable and configuration file
// orchestrator value and returns user defined Orchestrator.
func GetOrchestrator(orchestrator string) Orchestrator {
	// Check environment variable
	env := os.Getenv(dockerOrchestrator)
	if o := normalize(env); o != orchestratorUnset {
		return o
	}
	// Check specified orchestrator
	if o := normalize(orchestrator); o != orchestratorUnset {
		return o
	}

	// Nothing set, use default orchestrator
	return defaultOrchestrator
}