// Execute a formula in a specified directory. MAY PANIC.
func (e *Executor) Execute(f def.Formula, j def.Job, d string, result *def.JobResult, outS, errS io.WriteCloser, journal log15.Logger) {
// Dedicated rootfs folder to distinguish container from nsinit noise
rootfs := filepath.Join(d, "rootfs")
// nsinit wants to have a logfile
logFile := filepath.Join(d, "nsinit-debug.log")
// Prep command
args := []string{}
// Global options:
// --root will place the 'nsinit' folder (holding a state.json file) in d
// --log-file does much the same with a log file (unsure if care?)
// --debug allegedly enables debug output in the log file
args = append(args, "--root", d, "--log-file", logFile, "--debug")
// Subcommand, and tell nsinit to not desire a JSON file (instead just use many flergs)
args = append(args, "exec", "--create")
// Use the host's networking (no bridge, no namespaces, etc)
args = append(args, "--net=host")
// Where our system image exists
args = append(args, "--rootfs", rootfs)
// Set cwd
args = append(args, "--cwd", f.Accents.Cwd)
// Add all desired environment variables
for k, v := range f.Accents.Env {
args = append(args, "--env", k+"="+v)
}
// Unroll command args
args = append(args, f.Accents.Entrypoint...)
// Prepare command to exec
cmd := exec.Command("nsinit", args...)
cmd.Stdin = nil
cmd.Stdout = outS
cmd.Stderr = errS
// Prepare filesystem
transmat := util.DefaultTransmat()
assembly := util.ProvisionInputs(
transmat,
util.BestAssembler(),
f.Inputs, rootfs, journal,
)
defer assembly.Teardown() // What ever happens: Disassemble filesystem
util.ProvisionOutputs(f.Outputs, rootfs, journal)
// launch execution.
// transform gosh's typed errors to repeatr's hierarchical errors.
// this is... not untroubled code: since we're invoking a helper that's then
// proxying the exec even further, most errors are fatal (the mapping here is
// very different than in e.g. chroot executor, and provides much less meaning).
var proc gosh.Proc
try.Do(func() {
proc = gosh.ExecProcCmd(cmd)
}).CatchAll(func(err error) {
switch err.(type) {
case gosh.NoSuchCommandError:
panic(executor.ConfigError.New("nsinit binary is missing"))
case gosh.NoArgumentsError:
panic(executor.UnknownError.Wrap(err))
case gosh.NoSuchCwdError:
panic(executor.UnknownError.Wrap(err))
case gosh.ProcMonitorError:
panic(executor.TaskExecError.Wrap(err))
default:
panic(executor.UnknownError.Wrap(err))
}
}).Done()
// Wait for the job to complete
// REVIEW: consider exposing `gosh.Proc`'s interface as part of repeatr's job tracking api?
result.ExitCode = proc.GetExitCode()
// Horrifyingly ambiguous attempts to detect failure modes from inside nsinit.
// This can only be made correct by pushing patches into nsinit to use another channel for control data reporting that is completely separated from user data flows.
// (Or, arguably, putting another layer of control processes as the first parent inside nsinit, but that's ducktape within a ducktape mesh; let's not.)
// Certain program outputs may be incorrectly attributed as launch failure, though this should be... "unlikely".
// Also note that if we ever switch to non-blocking execution, this will become even more of a mess: we won't be able to tell if exec failed, esp. in the case of e.g. a long running process with no output, and so we won't know when it's safe to return.
// TODO handle the following leading strings:
// - "exec: \"%s\": executable file not found in $PATH\n"
// - "no such file or directory\n"
// this will probably require rejiggering a whole bunch of stuff so that the streamer is reachable down here.
// Save outputs
result.Outputs = util.PreserveOutputs(transmat, f.Outputs, rootfs, journal)
}
// Execute a formula in a specified directory. MAY PANIC.
func (e *Executor) Execute(f def.Formula, j def.Job, d string, result *def.JobResult, stdin io.Reader, outS, errS io.WriteCloser, journal log15.Logger) {
// Prepare filesystem
rootfs := filepath.Join(d, "rootfs")
transmat := util.DefaultTransmat()
assembly := util.ProvisionInputs(
transmat,
util.BestAssembler(),
f.Inputs, rootfs, journal,
)
defer assembly.Teardown() // What ever happens: Disassemble filesystem
util.ProvisionOutputs(f.Outputs, rootfs, journal)
// chroot's are pretty easy.
cmdName := f.Accents.Entrypoint[0]
cmd := exec.Command(cmdName, f.Accents.Entrypoint[1:]...)
cmd.SysProcAttr = &syscall.SysProcAttr{
Chroot: rootfs,
Pdeathsig: syscall.SIGKILL,
}
// except handling cwd is a little odd.
// see comments in gosh tests with chroot for information about the odd behavior we're hacking around here;
// we're comfortable making this special check here, but not upstreaming it to gosh, because in our context we "know" we're not racing anyone.
if externalCwdStat, err := os.Stat(filepath.Join(rootfs, f.Accents.Cwd)); err != nil {
panic(executor.TaskExecError.New("cannot set cwd to %q: %s", f.Accents.Cwd, err.(*os.PathError).Err))
} else if !externalCwdStat.IsDir() {
panic(executor.TaskExecError.New("cannot set cwd to %q: not a dir", f.Accents.Cwd))
}
cmd.Dir = f.Accents.Cwd
// set env.
// initialization already required by earlier 'validate' calls.
cmd.Env = envToSlice(f.Accents.Env)
cmd.Stdin = stdin
cmd.Stdout = outS
cmd.Stderr = errS
// launch execution.
// transform gosh's typed errors to repeatr's hierarchical errors.
var proc gosh.Proc
try.Do(func() {
proc = gosh.ExecProcCmd(cmd)
}).CatchAll(func(err error) {
switch err.(type) {
case gosh.NoSuchCommandError:
panic(executor.NoSuchCommandError.Wrap(err))
case gosh.NoArgumentsError:
panic(executor.NoSuchCommandError.Wrap(err))
case gosh.NoSuchCwdError: // included for clarity and completeness, but we'll never actually see this; see comments in gosh about the interaction of chroot and cwd error handling.
panic(executor.TaskExecError.Wrap(err))
case gosh.ProcMonitorError:
panic(executor.TaskExecError.Wrap(err))
default:
panic(executor.UnknownError.Wrap(err))
}
}).Done()
// Wait for the job to complete
// REVIEW: consider exposing `gosh.Proc`'s interface as part of repeatr's job tracking api?
result.ExitCode = proc.GetExitCode()
// Save outputs
result.Outputs = util.PreserveOutputs(transmat, f.Outputs, rootfs, journal)
}