Split off cli into separate binaries (#37)

* 🎨 Split off cli into separate binaries

This commit splits off the cli into 3 binaries:
- agent
- cli
- provider

The provider now is a separate component that can be tested by itself
and have its own lifecycle. This paves the way to a ligher c3os variant,
HA support and other features that can be provided on runtime.

This is working, but still there are low hanging fruit to care about.

Fixes #14

* 🤖 Add provider bin to releases

* ⚙️ Handle signals

* ⚙️ Reduce buildsize footprint

* 🎨 Scan for providers also in /system/providers

* 🤖 Run goreleaser

* 🎨 Refactoring

internal/machine/machine.go

@@ -0,0 +1,103 @@
+package machine
+
+import (
+	"fmt"
+	"os"
+
+	"github.com/c3os-io/c3os/internal/machine/openrc"
+	"github.com/c3os-io/c3os/internal/machine/systemd"
+	"github.com/denisbrodbeck/machineid"
+
+	"github.com/c3os-io/c3os/internal/utils"
+)
+
+type Service interface {
+	WriteUnit() error
+	Start() error
+	OverrideCmd(string) error
+	Enable() error
+	Restart() error
+}
+
+func EdgeVPN(instance, rootDir string) (Service, error) {
+	if utils.IsOpenRCBased() {
+		return openrc.NewService(
+			openrc.WithName("edgevpn"),
+			openrc.WithUnitContent(openrc.EdgevpnUnit),
+			openrc.WithRoot(rootDir),
+		)
+	} else {
+		return systemd.NewService(
+			systemd.WithName("edgevpn"),
+			systemd.WithInstance(instance),
+			systemd.WithUnitContent(systemd.EdgevpnUnit),
+			systemd.WithRoot(rootDir),
+		)
+	}
+}
+
+const EdgeVPNDefaultInstance string = "c3os"
+
+type fakegetty struct{}
+
+func (fakegetty) Restart() error           { return nil }
+func (fakegetty) Enable() error            { return nil }
+func (fakegetty) OverrideCmd(string) error { return nil }
+func (fakegetty) SetEnvFile(string) error  { return nil }
+func (fakegetty) WriteUnit() error         { return nil }
+func (fakegetty) Start() error {
+	utils.SH("chvt 2")
+	return nil
+}
+
+func Getty(i int) (Service, error) {
+	if utils.IsOpenRCBased() {
+		return &fakegetty{}, nil
+	} else {
+		return systemd.NewService(
+			systemd.WithName("getty"),
+			systemd.WithInstance(fmt.Sprintf("tty%d", i)),
+		)
+	}
+}
+
+func K3s() (Service, error) {
+	if utils.IsOpenRCBased() {
+		return openrc.NewService(
+			openrc.WithName("k3s"),
+		)
+	} else {
+		return systemd.NewService(
+			systemd.WithName("k3s"),
+		)
+	}
+}
+
+func K3sAgent() (Service, error) {
+	if utils.IsOpenRCBased() {
+		return openrc.NewService(
+			openrc.WithName("k3s-agent"),
+		)
+	} else {
+		return systemd.NewService(
+			systemd.WithName("k3s-agent"),
+		)
+	}
+}
+
+func K3sEnvUnit(unit string) string {
+	if utils.IsOpenRCBased() {
+		return fmt.Sprintf("/etc/rancher/k3s/%s.env", unit)
+	} else {
+		return fmt.Sprintf("/etc/sysconfig/%s", unit)
+	}
+}
+
+func UUID() string {
+	if os.Getenv("UUID") != "" {
+		return os.Getenv("UUID")
+	}
+	id, _ := machineid.ID()
+	hostname, _ := os.Hostname()
+	return fmt.Sprintf("%s-%s", id, hostname)
+}