package docker import ( "fmt" "github.com/dotcloud/docker/iptables" "path" "strings" ) type Link struct { ParentIP string ChildIP string Name string BridgeInterface string ChildEnvironment []string Ports []Port IsEnabled bool } func NewLink(parent, child *Container, name, bridgeInterface string) (*Link, error) { if parent.ID == child.ID { return nil, fmt.Errorf("Cannot link to self: %s == %s", parent.ID, child.ID) } if !child.State.Running { return nil, fmt.Errorf("Cannot link to a non running container: %s AS %s", child.Name, name) } ports := make([]Port, len(child.Config.ExposedPorts)) var i int for p := range child.Config.ExposedPorts { ports[i] = p i++ } l := &Link{ BridgeInterface: bridgeInterface, Name: name, ChildIP: child.NetworkSettings.IPAddress, ParentIP: parent.NetworkSettings.IPAddress, ChildEnvironment: child.Config.Env, Ports: ports, } return l, nil } func (l *Link) Alias() string { _, alias := path.Split(l.Name) return alias } func (l *Link) ToEnv() []string { env := []string{} alias := strings.ToUpper(l.Alias()) if p := l.getDefaultPort(); p != nil { env = append(env, fmt.Sprintf("%s_PORT=%s://%s:%s", alias, p.Proto(), l.ChildIP, p.Port())) } // Load exposed ports into the environment for _, p := range l.Ports { env = append(env, fmt.Sprintf("%s_PORT_%s_%s=%s://%s:%s", alias, p.Port(), strings.ToUpper(p.Proto()), p.Proto(), l.ChildIP, p.Port())) env = append(env, fmt.Sprintf("%s_PORT_%s_%s_ADDR=%s", alias, p.Port(), strings.ToUpper(p.Proto()), l.ChildIP)) env = append(env, fmt.Sprintf("%s_PORT_%s_%s_PORT=%s", alias, p.Port(), strings.ToUpper(p.Proto()), p.Port())) env = append(env, fmt.Sprintf("%s_PORT_%s_%s_PROTO=%s", alias, p.Port(), strings.ToUpper(p.Proto()), p.Proto())) } // Load the linked container's name into the environment env = append(env, fmt.Sprintf("%s_NAME=%s", alias, l.Name)) if l.ChildEnvironment != nil { for _, v := range l.ChildEnvironment { parts := strings.Split(v, "=") if len(parts) != 2 { continue } // Ignore a few variables that are added during docker build if parts[0] == "HOME" || parts[0] == "PATH" { continue } env = append(env, fmt.Sprintf("%s_ENV_%s=%s", alias, parts[0], parts[1])) } } return env } // Default port rules func (l *Link) getDefaultPort() *Port { var p Port i := len(l.Ports) if i == 0 { return nil } else if i > 1 { sortPorts(l.Ports, func(ip, jp Port) bool { // If the two ports have the same number, tcp takes priority // Sort in desc order return ip.Int() < jp.Int() || (ip.Int() == jp.Int() && strings.ToLower(ip.Proto()) == "tcp") }) } p = l.Ports[0] return &p } func (l *Link) Enable() error { if err := l.toggle("-I", false); err != nil { return err } l.IsEnabled = true return nil } func (l *Link) Disable() { // We do not care about errors here because the link may not // exist in iptables l.toggle("-D", true) l.IsEnabled = false } func (l *Link) toggle(action string, ignoreErrors bool) error { for _, p := range l.Ports { if err := iptables.Raw(action, "FORWARD", "-i", l.BridgeInterface, "-o", l.BridgeInterface, "-p", p.Proto(), "-s", l.ParentIP, "--dport", p.Port(), "-d", l.ChildIP, "-j", "ACCEPT"); !ignoreErrors && err != nil { return err } if err := iptables.Raw(action, "FORWARD", "-i", l.BridgeInterface, "-o", l.BridgeInterface, "-p", p.Proto(), "-s", l.ChildIP, "--sport", p.Port(), "-d", l.ParentIP, "-j", "ACCEPT"); !ignoreErrors && err != nil { return err } } return nil }