temporalio
[Bug] CLI panics if started without a `stdout` file descriptor
Describe the bug
Since 0.12.0, launching the CLI without a stdout file descriptor causes the Printer to panic as soon as the process attempts to emit some output.
This notably happens when starting a dev server using TS SDK's TestWorkflowEnvironment.createLocal(), due to Node's setting FD_CLOEXEC on all of its standard file descriptors. This has been recently fixed on the TS SDK (to be included in upcoming v1.9.4), but previous releases will be unusable with CLI 0.12+ until we fix this on CLI side.
Minimal Reproduction
This can be easily tested using Bash or a similar shell, with any command:
$ temporal-v0.12.0 workflow start --workflow-id abcd --task-queue test --type qwerty >&-
panic: write /dev/stdout: device not configured
goroutine 1 [running]:
github.com/temporalio/cli/temporalcli/internal/printer.(*Printer).write(...)
/home/runner/work/cli/cli/temporalcli/internal/printer/printer.go:199
github.com/temporalio/cli/temporalcli/internal/printer.(*Printer).writeStr(...)
/home/runner/work/cli/cli/temporalcli/internal/printer/printer.go:204
github.com/temporalio/cli/temporalcli/internal/printer.(*Printer).Print(0x14000890320, {0x1400036e0c0?, 0x2, 0x14000b51838?})
/home/runner/work/cli/cli/temporalcli/internal/printer/printer.go:42 +0xcc
github.com/temporalio/cli/temporalcli/internal/printer.(*Printer).Println(...)
/home/runner/work/cli/cli/temporalcli/internal/printer/printer.go:49
github.com/temporalio/cli/temporalcli.(*TemporalWorkflowCommand).startWorkflow(0x140009ca000, 0x140008ae2a0, {0x12a516a08, 0x14000956000}, 0x140009cb6e0, 0x0?, 0x0?, 0x1)
/home/runner/work/cli/cli/temporalcli/commands.workflow_exec.go:226 +0x268
github.com/temporalio/cli/temporalcli.(*TemporalWorkflowStartCommand).run(0x140009cb400, 0x0?, {0x0?, 0x0?, 0x0?})
/home/runner/work/cli/cli/temporalcli/commands.workflow_exec.go:28 +0xc0
github.com/temporalio/cli/temporalcli.NewTemporalWorkflowStartCommand.func1(0x140008e9d00?, {0x1400063bce0?, 0x4?, 0x1021b4473?})
/home/runner/work/cli/cli/temporalcli/commands.gen.go:2118 +0x3c
github.com/spf13/cobra.(*Command).execute(0x140009cb408, {0x1400063bc80, 0x6, 0x6})
/home/runner/go/pkg/mod/github.com/spf13/[email protected]/command.go:987 +0x828
github.com/spf13/cobra.(*Command).ExecuteC(0x1400004fc00)
/home/runner/go/pkg/mod/github.com/spf13/[email protected]/command.go:1115 +0x344
github.com/spf13/cobra.(*Command).Execute(...)
/home/runner/go/pkg/mod/github.com/spf13/[email protected]/command.go:1039
github.com/spf13/cobra.(*Command).ExecuteContext(...)
/home/runner/go/pkg/mod/github.com/spf13/[email protected]/command.go:1032
github.com/temporalio/cli/temporalcli.Execute({0x10336df30?, 0x14000890230?}, {{0x0, 0x0, 0x0}, {0x0, 0x0}, {0x0, 0x0}, 0x0, ...})
/home/runner/work/cli/cli/temporalcli/commands.go:318 +0xec
main.main()
/home/runner/work/cli/cli/cmd/temporal/main.go:15 +0x64
Note that the >&- shell redirection operator at the end of the command instructs the shell to close the STDOUT file descriptor before executing the child process.
There is no error if the same command is run without the >&- shell redirection operator, or when using previous versions of the CLI with the redirection operator.
Hrmm, not much Go binary documentation out there on this issue. Can you confirm that this panics for every Go binary that uses os.Stdout.Write([]byte("foo")) in this situation? I am not aware of any Go binaries that account for missing descriptors as opposed to just ones forwarded to /dev/null (can check kubectl, cockroachdb, etc, etc). I think the issue is the absence of the descriptor not how the CLI reacts to it.
Stdout.Write returns an error. Printer does panic on that error.
package main
import (
"os"
)
func main() {
_, err := os.Stdout.Write([]byte("foo"))
if err != nil {
panic(err)
}
}
when I run that, I get:
$ go run test.go >&-
panic: write /dev/stdout: bad file descriptor
goroutine 1 [running]:
main.main()
/Users/jwatkins/Development/Temporal/CLI/cli/test.go:10 +0x64
exit status 2