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unit.go
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unit.go
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package fleet
import (
"fmt"
"io/ioutil"
"os"
"path"
"strconv"
"strings"
"github.com/coreos/fleet/unit"
)
// path hierarchy for finding systemd service templates
var templatePaths = []string{
os.Getenv("DEISCTL_UNITS"),
path.Join(os.Getenv("HOME"), ".deis", "units"),
"/var/lib/deis/units",
}
// Units returns a list of units filtered by target
func (c *FleetClient) Units(target string) (units []string, err error) {
allUnits, err := c.Fleet.Units()
if err != nil {
return
}
for _, u := range allUnits {
if strings.Contains(u.Name, target) {
units = append(units, u.Name)
}
}
if len(units) == 0 {
err = fmt.Errorf("could not find unit: %s", target)
}
return
}
// nextUnit returns the next unit number for a given component
func (c *FleetClient) nextUnit(component string) (num int, err error) {
units, err := c.Units(component)
if err != nil {
return
}
num, err = nextUnitNum(units)
if err != nil {
return
}
return
}
// lastUnit returns the last unit number for a given component
func (c *FleetClient) lastUnit(component string) (num int, err error) {
units, err := c.Units(component)
if err != nil {
return
}
num, err = lastUnitNum(units)
if err != nil {
return
}
return
}
// NewUnit takes a component type and returns a Fleet unit
// that includes the relevant systemd service template
func NewUnit(component string) (uf *unit.UnitFile, err error) {
template, err := readTemplate(component)
if err != nil {
return
}
uf, err = unit.NewUnitFile(string(template))
if err != nil {
return
}
return
}
// formatUnitName returns a properly formatted systemd service name
// using the given component type and number
func formatUnitName(component string, num int) (unitName string, err error) {
component = strings.TrimPrefix(component, "deis-")
if num == 0 {
return "deis-" + component + ".service", nil
}
return "deis-" + component + "@" + strconv.Itoa(num) + ".service", nil
}
// readTemplate returns the contents of a systemd template for the given component
func readTemplate(component string) (out []byte, err error) {
templateName := "deis-" + component + ".service"
var templateFile string
// look in $DEISCTL_UNITS env var, then the local and global root paths
for _, p := range templatePaths {
if p == "" {
continue
}
filename := path.Join(p, templateName)
if _, err := os.Stat(filename); err == nil {
templateFile = filename
break
}
}
if templateFile == "" {
return nil, fmt.Errorf("Could not find unit template for %v", component)
}
out, err = ioutil.ReadFile(templateFile)
if err != nil {
return
}
return
}