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launcher.go
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launcher.go
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package launch
import (
"os"
"os/exec"
"path/filepath"
"github.com/pkg/errors"
"github.com/buildpacks/lifecycle/api"
"github.com/buildpacks/lifecycle/env"
)
var (
LifecycleDir = filepath.Join(CNBDir, "lifecycle")
ProcessDir = filepath.Join(CNBDir, "process")
LauncherPath = filepath.Join(LifecycleDir, "launcher"+exe)
)
type Launcher struct {
AppDir string
Buildpacks []Buildpack
DefaultProcessType string
Env Env
Exec ExecFunc
ExecD ExecD
Shell Shell
LayersDir string
PlatformAPI *api.Version
Processes []Process
Setenv func(string, string) error
}
type ExecFunc func(argv0 string, argv []string, envv []string) error
type ExecD interface {
ExecD(path string, env Env) error
}
type Env interface {
AddEnvDir(envDir string, defaultAction env.ActionType) error
AddRootDir(baseDir string) error
Get(string) string
List() []string
Set(name, k string)
}
// Launch uses cmd to select a process and launches that process.
// For direct=false processes, self is used to set argv0 during profile script execution
func (l *Launcher) Launch(self string, cmd []string) error {
proc, err := l.ProcessFor(cmd)
if err != nil {
return errors.Wrap(err, "determine start command")
}
return l.LaunchProcess(self, proc)
}
// LaunchProcess launches the provided process.
// For direct=false processes, self is used to set argv0 during profile script execution
func (l *Launcher) LaunchProcess(self string, proc Process) error {
if err := os.Chdir(l.AppDir); err != nil {
return errors.Wrap(err, "change to app directory")
}
if err := l.doEnv(proc.Type); err != nil {
return errors.Wrap(err, "modify env")
}
if err := l.doExecD(proc.Type); err != nil {
return errors.Wrap(err, "exec.d")
}
proc.WorkingDirectory = getProcessWorkingDirectory(proc, l.AppDir)
if proc.Direct {
return l.launchDirect(proc)
}
return l.launchWithShell(self, proc)
}
func (l *Launcher) launchDirect(proc Process) error {
if err := l.Setenv("PATH", l.Env.Get("PATH")); err != nil {
return errors.Wrap(err, "set path")
}
binary, err := exec.LookPath(proc.Command.Entries[0])
if err != nil {
return errors.Wrap(err, "path lookup")
}
if err = os.Chdir(proc.WorkingDirectory); err != nil {
return errors.Wrap(err, "change directory")
}
if err := l.Exec(binary,
append(proc.Command.Entries, proc.Args...),
l.Env.List(),
); err != nil {
return errors.Wrap(err, "direct exec")
}
return nil
}
func (l *Launcher) doEnv(procType string) error {
return l.eachBuildpack(func(bpAPI *api.Version, bpDir string) error {
if err := eachLayer(bpDir, l.doLayerRoot()); err != nil {
return errors.Wrap(err, "add layer root")
}
if err := eachLayer(bpDir, l.doLayerEnvFiles(procType, env.DefaultActionType(bpAPI))); err != nil {
return errors.Wrap(err, "add layer env")
}
return nil
})
}
func (l *Launcher) doExecD(procType string) error {
return l.eachBuildpack(func(bpAPI *api.Version, bpDir string) error {
return eachLayer(bpDir, l.doLayerExecD(procType))
})
}
type bpAction func(bpAPI *api.Version, bpDir string) error
type dirAction func(layerDir string) error
func (l *Launcher) eachBuildpack(fn bpAction) error {
for _, bp := range l.Buildpacks {
dir := filepath.Join(l.LayersDir, EscapeID(bp.ID))
if _, err := os.Stat(dir); os.IsNotExist(err) {
continue
} else if err != nil {
return errors.Wrap(err, "find buildpack directory")
}
bpAPI, err := api.NewVersion(bp.API)
if err != nil {
return err
}
if err := fn(bpAPI, dir); err != nil {
return err
}
}
return nil
}
func (l *Launcher) doLayerRoot() dirAction {
return func(path string) error {
return l.Env.AddRootDir(path)
}
}
func (l *Launcher) doLayerEnvFiles(procType string, defaultAction env.ActionType) dirAction {
return func(path string) error {
if err := l.Env.AddEnvDir(filepath.Join(path, "env"), defaultAction); err != nil {
return err
}
if err := l.Env.AddEnvDir(filepath.Join(path, "env.launch"), defaultAction); err != nil {
return err
}
if procType == "" {
return nil
}
return l.Env.AddEnvDir(filepath.Join(path, "env.launch", procType), defaultAction)
}
}
func (l *Launcher) doLayerExecD(procType string) dirAction {
return func(path string) error {
if err := eachFile(filepath.Join(path, "exec.d"), func(path string) error {
return l.ExecD.ExecD(path, l.Env)
}); err != nil {
return err
}
if procType == "" {
return nil
}
return eachFile(filepath.Join(path, "exec.d", procType), func(path string) error {
return l.ExecD.ExecD(path, l.Env)
})
}
}
func eachLayer(bpDir string, action dirAction) error {
return eachInDir(bpDir, action, func(entry os.DirEntry) bool {
return entry.IsDir()
})
}
func eachFile(dir string, action dirAction) error {
return eachInDir(dir, action, func(entry os.DirEntry) bool {
return !entry.IsDir()
})
}
func eachInDir(dir string, action dirAction, predicate func(entry os.DirEntry) bool) error {
entries, err := os.ReadDir(dir)
if os.IsNotExist(err) {
return nil
}
if err != nil {
return errors.Wrapf(err, "failed to list files in dir '%s'", dir)
}
for _, entry := range entries {
if !predicate(entry) {
continue
}
if err := action(filepath.Join(dir, entry.Name())); err != nil {
return err
}
}
return nil
}