grpc/grpc-go · error

failed to create temp file

Error message

failed to create temp file: %v

What it means

NewTempFileSink creates an OS temp file under /tmp to buffer binary log entries (sink.go:59-66). If os.CreateTemp fails, the error is wrapped and returned to the caller. The sink is typically wired in during program initialization via binarylog.SetSink.

Solutions

1. Ensure /tmp exists and is writable by the process, or run in an environment with a writable temp directory.
2. Free disk space if /tmp is full.
3. If /tmp is not usable, implement your own binarylog.Sink (e.g., writing to a path you control) and pass it to binarylog.SetSink instead of using NewTempFileSink.

Example fix

// before
sink, err := binarylog.NewTempFileSink() // requires writable /tmp
// after: write to your own file
f, err := os.OpenFile("/var/log/grpc.binlog", os.O_CREATE|os.O_WRONLY, 0644)
if err != nil { log.Fatal(err) }
binarylog.SetSink(iblog.NewBufferedSink(f))

sink, err := binarylog.NewTempFileSink()
if err != nil {
    // fall back to your own sink or disable binary logging
    log.Printf("binary log temp file unavailable: %v", err)
} else {
    binarylog.SetSink(sink)
}

When it happens

Trigger: Calling binarylog.NewTempFileSink() when /tmp is not writable, does not exist, is full, or the process lacks permission. os.CreateTemp("/tmp", "grpcgo_binarylog_*.txt") returns a non-nil error.

Common situations: Running in a container/sandbox without /tmp or with a read-only filesystem; exhausted disk space; restrictive SELinux/AppArmor policy; a custom OS where TMPDIR is honored but /tmp is hardcoded here.

Related errors

• could not get resolver for default scheme
• empty string is not a valid method binary logging config
• failed to create JWT call credentials
• policyFile( ) read failed
• token file access error

AI-assisted analysis of grpc/grpc-go@0c51461d27 (2026-08-11). Data as JSON: /api/errors/a3d7c3cd0896979e. Report an issue: GitHub.

Appendix: source

Thrown at binarylog/sink.go:65

	// is not specified, but should have sufficient information to rebuild the
	// entry. Some options are: proto bytes, or proto json.
	//
	// Note this function needs to be thread-safe.
	Write(*binlogpb.GrpcLogEntry) error
	// Close closes this sink and cleans up resources (e.g. the flushing
	// goroutine).
	Close() error
}

// NewTempFileSink creates a temp file and returns a Sink that writes to this
// file.
func NewTempFileSink() (Sink, error) {
	// Two other options to replace this function:
	// 1. take filename as input.
	// 2. export NewBufferedSink().
	tempFile, err := os.CreateTemp("/tmp", "grpcgo_binarylog_*.txt")
	if err != nil {
		return nil, fmt.Errorf("failed to create temp file: %v", err)
	}
	return iblog.NewBufferedSink(tempFile), nil
}

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