feat: implement container network attaching

Containers can be attached:

- after they are created, but before they are started
- after a successful deploy, but before the proxy reloads

This allows folks to have flexibility around when they would like a container to be made available to a network.

plugins/network/network.go

@@ -1,6 +1,8 @@
 package network
 
 import (
+	"bytes"
+	"errors"
 	"fmt"
 	"io/ioutil"
 	"os"
@@ -19,9 +21,55 @@ var (
 	// DefaultProperties is a map of all valid network properties with corresponding default property values
 	DefaultProperties = map[string]string{
 		"bind-all-interfaces": "false",
+		"attach-post-create":  "",
+		"attach-post-deploy":  "",
+		"tld":                 "",
 	}
 )
 
+// AttachAppToNetwork attaches a container to a network
+func AttachAppToNetwork(containerID string, networkName string, appName string, phase string, processType string) {
+	cmdParts := []string{
+		common.DockerBin(),
+		"network",
+		"connect",
+	}
+
+	if phase == "deploy" {
+		property := "tld"
+		defaultValue := GetDefaultValue(property)
+		tld := common.PropertyGetDefault("network", appName, property, defaultValue)
+
+		networkAlias := fmt.Sprintf("%v.%v", appName, processType)
+		if tld != "" {
+			networkAlias = fmt.Sprintf("%v.%v", networkAlias, tld)
+		}
+
+		cmdParts = append(cmdParts, "--alias")
+		cmdParts = append(cmdParts, networkAlias)
+
+		hostname, err := common.DockerInspect(containerID, "{{ .Config.Hostname }}")
+		if err != nil {
+			common.LogWarn(err.Error())
+		} else {
+			cmdParts = append(cmdParts, "--alias")
+			cmdParts = append(cmdParts, fmt.Sprintf("%v.%v", hostname, networkAlias))
+		}
+	}
+
+	cmdParts = append(cmdParts, networkName)
+	cmdParts = append(cmdParts, containerID)
+	attachCmd := common.NewShellCmd(strings.Join(cmdParts, " "))
+	var stderr bytes.Buffer
+	attachCmd.ShowOutput = false
+	attachCmd.Command.Stderr = &stderr
+	_, err := attachCmd.Output()
+	if err != nil {
+		err = errors.New(strings.TrimSpace(stderr.String()))
+		common.LogFail(fmt.Sprintf("Unable to attach container to network: %v", err.Error()))
+	}
+}
+
 // BuildConfig builds network config files
 func BuildConfig(appName string) {
 	if err := common.VerifyAppName(appName); err != nil {
@@ -186,6 +234,21 @@ func HasNetworkConfig(appName string) bool {
 	return common.FileExists(ipfile) && common.FileExists(portfile)
 }
 
+// ListNetworks returns a list of docker networks
+func ListNetworks() ([]string, error) {
+	b, err := sh.Command(common.DockerBin(), "network", "list", "--format", "{{ .Name }}").Output()
+	output := strings.TrimSpace(string(b[:]))
+
+	networks := []string{}
+	if err != nil {
+		common.LogVerboseQuiet(output)
+		return networks, err
+	}
+
+	networks = strings.Split(output, "\n")
+	return networks, nil
+}
+
 // PostAppCloneSetup removes old IP and PORT files for a newly cloned app
 func PostAppCloneSetup(appName string) bool {
 	dokkuRoot := common.MustGetEnv("DOKKU_ROOT")
@@ -217,6 +280,8 @@ func ReportSingleApp(appName, infoFlag string) {
 
 	infoFlags := map[string]string{
 		"--network-bind-all-interfaces": common.PropertyGet("network", appName, "bind-all-interfaces"),
+		"--network-attach-post-create":  common.PropertyGet("network", appName, "attach-post-create"),
+		"--network-attach-post-deploy":  common.PropertyGet("network", appName, "attach-post-deploy"),
 		"--network-listeners":           strings.Join(GetListeners(appName), " "),
 	}