// updateNameservers assigns each container the same nameservers as the host.
func updateNameservers(dk docker.Client, containers []db.Container) {
hostResolv, err := ioutil.ReadFile("/etc/resolv.conf")
if err != nil {
log.WithError(err).Error("failed to read /etc/resolv.conf")
}
nsRE := regexp.MustCompile("nameserver\\s([0-9]{1,3}\\.){3}[0-9]{1,3}\\s+")
matches := nsRE.FindAllString(string(hostResolv), -1)
newNameservers := strings.Join(matches, "\n")
for _, dbc := range containers {
id := dbc.DockerID
currNameservers, err := dk.GetFromContainer(id, "/etc/resolv.conf")
if err != nil {
log.WithError(err).Error("failed to get /etc/resolv.conf")
return
}
if newNameservers != currNameservers {
err = dk.WriteToContainer(id, newNameservers, "/etc",
"resolv.conf", 0644)
if err != nil {
log.WithError(err).Error(
"failed to update /etc/resolv.conf")
}
}
}
}
func updateEtcHosts(dk docker.Client, containers []db.Container, labels []db.Label,
connections []db.Connection) {
/* Map label name to its IP. */
labelIP := make(map[string]string)
/* Map label to a list of all labels it connect to. */
conns := make(map[string][]string)
for _, l := range labels {
labelIP[l.Label] = l.IP
}
for _, conn := range connections {
if conn.To == stitch.PublicInternetLabel ||
conn.From == stitch.PublicInternetLabel {
continue
}
conns[conn.From] = append(conns[conn.From], conn.To)
}
for _, dbc := range containers {
id := dbc.DockerID
currHosts, err := dk.GetFromContainer(id, "/etc/hosts")
if err != nil {
log.WithError(err).Error("Failed to get /etc/hosts")
return
}
newHosts := generateEtcHosts(dbc, labelIP, conns)
if newHosts != currHosts {
err = dk.WriteToContainer(id, newHosts, "/etc", "hosts", 0644)
if err != nil {
log.WithError(err).Error("Failed to update /etc/hosts")
}
}
}
}