15370: Re-enable docker tests.

[arvados.git] / lib / crunchrun / background.go

diff --git a/lib/crunchrun/background.go b/lib/crunchrun/background.go
index 4bb249380fd98b2e340bc4bd3bacb2b78d5f0a47..8a919bc5e2ba3080283d39a9f9784b1eddbec37d 100644 (file)
--- a/lib/crunchrun/background.go
+++ b/lib/crunchrun/background.go
@@ -36,10 +36,10 @@ type procinfo struct {
 //
 // Stdout and stderr in the child process are sent to the systemd
 // journal using the systemd-cat program.
-func Detach(uuid string, prog string, args []string, stdout, stderr io.Writer) int {
-       return exitcode(stderr, detach(uuid, prog, args, stdout, stderr))
+func Detach(uuid string, prog string, args []string, stdin io.Reader, stdout, stderr io.Writer) int {
+       return exitcode(stderr, detach(uuid, prog, args, stdin, stdout))
 }
-func detach(uuid string, prog string, args []string, stdout, stderr io.Writer) error {
+func detach(uuid string, prog string, args []string, stdin io.Reader, stdout io.Writer) error {
        lockfile, err := func() (*os.File, error) {
                // We must hold the dir-level lock between
                // opening/creating the lockfile and acquiring LOCK_EX
@@ -77,20 +77,24 @@ func detach(uuid string, prog string, args []string, stdout, stderr io.Writer) e
                // invoked as "/path/to/crunch-run"
                execargs = append([]string{prog}, execargs...)
        }
-       execargs = append([]string{
-               // Here, if the inner systemd-cat can't exec
-               // crunch-run, it writes an error message to stderr,
-               // and the outer systemd-cat writes it to the journal
-               // where the operator has a chance to discover it. (If
-               // we only used one systemd-cat command, it would be
-               // up to us to report the error -- but we are going to
-               // detach and exit, not wait for something to appear
-               // on stderr.)  Note these systemd-cat calls don't
-               // result in additional processes -- they just connect
-               // stderr/stdout to sockets and call exec().
-               "systemd-cat", "--identifier=crunch-run",
-               "systemd-cat", "--identifier=crunch-run",
-       }, execargs...)
+       if _, err := exec.LookPath("systemd-cat"); err == nil {
+               execargs = append([]string{
+                       // Here, if the inner systemd-cat can't exec
+                       // crunch-run, it writes an error message to
+                       // stderr, and the outer systemd-cat writes it
+                       // to the journal where the operator has a
+                       // chance to discover it. (If we only used one
+                       // systemd-cat command, it would be up to us
+                       // to report the error -- but we are going to
+                       // detach and exit, not wait for something to
+                       // appear on stderr.)  Note these systemd-cat
+                       // calls don't result in additional processes
+                       // -- they just connect stderr/stdout to
+                       // sockets and call exec().
+                       "systemd-cat", "--identifier=crunch-run",
+                       "systemd-cat", "--identifier=crunch-run",
+               }, execargs...)
+       }
 
        cmd := exec.Command(execargs[0], execargs[1:]...)
        // Child inherits lockfile.
@@ -99,10 +103,26 @@ func detach(uuid string, prog string, args []string, stdout, stderr io.Writer) e
        // from parent (sshd) while sending lockfile content to
        // caller.
        cmd.SysProcAttr = &syscall.SysProcAttr{Setpgid: true}
+       // We need to manage our own OS pipe here to ensure the child
+       // process reads all of our stdin pipe before we return.
+       piper, pipew, err := os.Pipe()
+       if err != nil {
+               return err
+       }
+       defer pipew.Close()
+       cmd.Stdin = piper
        err = cmd.Start()
        if err != nil {
                return fmt.Errorf("exec %s: %s", cmd.Path, err)
        }
+       _, err = io.Copy(pipew, stdin)
+       if err != nil {
+               return err
+       }
+       err = pipew.Close()
+       if err != nil {
+               return err
+       }
 
        w := io.MultiWriter(stdout, lockfile)
        return json.NewEncoder(w).Encode(procinfo{