Merge pull request #25 from cego/dest-network-detach

Attach/detach to network

README.md

@@ -1,2 +1,9 @@
 # Container manager
-Used to ensure that containers is running.
+Used to ensure that containers listed in config.yml is running and
+is connected to Docker networks.
+
+- Start/stop containers listed in config.yml
+- Add to network listed in config.yml
+- Detach from network if it is not being used (attachAllNetwork only)
+
+See config.example.yaml for configutation example.

main.go

@@ -32,7 +32,7 @@ import (
 var Build string
 
 const (
-	appName = "container-manager"
+	appName string = "container-manager"
 )
 
 var (
@@ -190,7 +190,16 @@ func NewManager(l *logrus.Logger) (*manager, error) {
 }
 
 func (m *manager) run(config *Config) {
-	networkNames, err := m.getNetworkNames()
+	// Create a list of container-manager containers
+	containerNames := []string{}
+	for _, c := range config.Containers {
+		if c.AttachAllNetwork {
+			containerNames = append(containerNames, c.Name)
+		}
+	}
+
+	// Returns a list of networks with more than 0 containers attached
+	networkNames, err := m.getNetworkNames(containerNames)
 	if err != nil {
 		m.l.Error(err)
 		return
@@ -253,9 +262,31 @@ func (m *manager) ensureContainer(config Container, networks []string) error {
 
 		m.l.WithField("name", config.Name).Debugf("Networks expected: %s", networks)
 		m.l.WithField("name", config.Name).Debugf("Networks current: %s", networkNames)
+
 		if !reflect.DeepEqual(networks, networkNames) {
-			m.l.WithField("name", config.Name).Debugf("Network config differ, recreate %s", config.Name)
-			reCreate = true
+			m.l.WithField("name", config.Name).Debugf("Network config differ, attach/detach %s", config.Name)
+
+			// New networks attach
+			for _, network := range networks {
+				// Inspect each network to get attached containers
+				attached, err := m.cli.NetworkInspect(m.ctx, network, types.NetworkInspectOptions{})
+				if err != nil {
+					m.l.Error(err)
+				}
+
+				// If container is not already attached to network
+				if !containerInNetworks(config.Name, attached) {
+					m.attachNetwork(network, config.Name)
+				}
+			}
+
+			m.l.WithField("name", config.Name).Debugf("Network detach diff: %s\n", difference(networkNames, networks))
+
+			// Old networks detach
+			for _, network := range difference(networkNames, networks) {
+				// Detach from network diff
+				m.detachNetwork(network, config.Name)
+			}
 		}
 
 		volumesExpected := make([]string, len(config.Volumes))
@@ -442,7 +473,7 @@ func (m *manager) stopContainers(config *Config) {
 	}
 }
 
-func (m *manager) getNetworkNames() ([]string, error) {
+func (m *manager) getNetworkNames(containerNames []string) ([]string, error) {
 	names := []string{}
 
 	networks, err := m.cli.NetworkList(m.ctx, types.NetworkListOptions{})
@@ -451,8 +482,18 @@ func (m *manager) getNetworkNames() ([]string, error) {
 	}
 
 	for _, network := range networks {
-		if (network.Attachable || network.Scope == "local") && !containsString(ignoredNetworkNames, network.Name) {
-			names = append(names, network.Name)
+		// Inspect each network to get attached containers
+		attached, err := m.cli.NetworkInspect(m.ctx, network.Name, types.NetworkInspectOptions{})
+		if err != nil {
+			return nil, err
+		}
+		for _, endpoint := range attached.Containers {
+			if !containsString(containerNames, endpoint.Name) &&
+				(network.Attachable || network.Scope == "local") &&
+				!containsString(ignoredNetworkNames, network.Name) {
+				names = append(names, network.Name)
+				break
+			}
 		}
 	}
 
@@ -461,6 +502,51 @@ func (m *manager) getNetworkNames() ([]string, error) {
 	return names, nil
 }
 
+// validate if a container is in a given network
+func containerInNetworks(containerName string, attached types.NetworkResource) bool {
+	for _, c := range attached.Containers {
+		if containerName == c.Name {
+			return true
+		}
+	}
+	return false
+}
+
+// difference returns the elements in `a` that aren't in `b`.
+func difference(a, b []string) []string {
+	mb := make(map[string]struct{}, len(b))
+	for _, x := range b {
+		mb[x] = struct{}{}
+	}
+	var diff []string
+	for _, x := range a {
+		if _, found := mb[x]; !found {
+			diff = append(diff, x)
+		}
+	}
+	return diff
+}
+
+// detach from network from container
+func (m *manager) detachNetwork(network string, container string) {
+	err := m.cli.NetworkDisconnect(m.ctx, network, container, true)
+
+	m.l.Debugf("Detaching %s from network %s\n", container, network)
+
+	if err != nil {
+		m.l.Error(err)
+	}
+}
+
+// attach from network from container
+func (m *manager) attachNetwork(network string, container string) {
+	err := m.cli.NetworkConnect(m.ctx, network, container, nil)
+	if err != nil {
+		m.l.Error(err)
+	}
+	m.l.Debugf("Attaching %s to network %s\n", container, network)
+}
+
 func containsString(strings []string, s string) bool {
 	for _, a := range strings {
 		if s == a {