Carlos Florêncio
92 lines
1.9 KiB
Go
92 lines
1.9 KiB
Go
package launcher
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import (
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"fmt"
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"math/rand"
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"net"
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"os"
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"strconv"
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"time"
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)
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type portConfig struct {
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BackendPort int
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AgentctlPort int
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BackendURL string
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}
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func resolvePorts(opts Options) (int, error) {
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backend := opts.BackendPort
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if backend == 0 {
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if p, err := envPort("KANDEV_BACKEND_PORT"); err != nil {
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return 0, err
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} else if p != 0 {
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backend = p
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} else if p, err := envPort("KANDEV_PORT"); err != nil {
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return 0, err
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} else {
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backend = p
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}
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}
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return backend, nil
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}
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func envPort(name string) (int, error) {
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raw, ok := os.LookupEnv(name)
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if !ok {
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return 0, nil
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}
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n, err := strconv.Atoi(raw)
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if raw == "" || err != nil || n < 1 || n > 65535 {
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return 0, ParseError{Message: fmt.Sprintf("%s must be an integer between 1 and 65535, got %q", name, raw)}
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}
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return n, nil
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}
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func pickPorts(backendPort int) (portConfig, error) {
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used := map[int]bool{}
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backend := backendPort
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if backend == 0 {
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p, err := pickAvailablePortExcept(defaultBackendPort, used)
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if err != nil {
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return portConfig{}, err
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}
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backend = p
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}
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used[backend] = true
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agentctl, err := pickAvailablePortExcept(defaultAgentctlPort, used)
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if err != nil {
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return portConfig{}, err
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}
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return portConfig{
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BackendPort: backend,
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AgentctlPort: agentctl,
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BackendURL: fmt.Sprintf("http://localhost:%d", backend),
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}, nil
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}
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func pickAvailablePortExcept(preferred int, used map[int]bool) (int, error) {
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if canBind(preferred) {
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if !used[preferred] {
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return preferred, nil
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}
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}
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r := rand.New(rand.NewSource(time.Now().UnixNano()))
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for i := 0; i < 10; i++ {
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candidate := randomPortMin + r.Intn(randomPortMax-randomPortMin+1)
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if !used[candidate] && canBind(candidate) {
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return candidate, nil
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}
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}
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return 0, fmt.Errorf("unable to find a free port")
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}
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func canBind(port int) bool {
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ln, err := net.Listen("tcp", fmt.Sprintf("127.0.0.1:%d", port))
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if err != nil {
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return false
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}
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_ = ln.Close()
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return true
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}
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