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handle dns response from cni

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when cni returns a list of dns servers, we should add them under the
right conditions.  the defined conditions are as follows:

- if the user provides dns, it and only it are added.
- if not above and you get a cni name server, it is added and a
forwarding dns instance is created for what was in resolv.conf.
- if not either above, the entries from the host's resolv.conf are used.
Signed-off-by: baude <bbaude@redhat.com>

Signed-off-by: baude <bbaude@redhat.com>
This commit is contained in:
baude
2019-08-28 13:19:15 -05:00
parent 03344fff1c
commit 8818e358bf
1 changed files with 24 additions and 6 deletions
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30
libpod/container_internal_linux.go
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@ -1039,6 +1039,11 @@ func (c *Container) makeBindMounts() error {
// generateResolvConf generates a containers resolv.conf
func (c *Container) generateResolvConf() (string, error) {
var (
nameservers []string
cniNameServers []string
)
resolvConf := "/etc/resolv.conf"
for _, namespace := range c.config.Spec.Linux.Namespaces {
if namespace.Type == spec.NetworkNamespace {
@ -1074,18 +1079,31 @@ func (c *Container) generateResolvConf() (string, error) {
return "", errors.Wrapf(err, "error parsing host resolv.conf")
}
// Make a new resolv.conf
nameservers := resolvconf.GetNameservers(resolv.Content)
// slirp4netns has a built in DNS server.
if c.config.NetMode.IsSlirp4netns() {
nameservers = append([]string{"10.0.2.3"}, nameservers...)
// Check if CNI gave back and DNS servers for us to add in
cniResponse := c.state.NetworkStatus
for _, i := range cniResponse {
if i.DNS.Nameservers != nil {
cniNameServers = append(cniNameServers, i.DNS.Nameservers...)
logrus.Debugf("adding nameserver(s) from cni response of '%q'", i.DNS.Nameservers)
}
}
// If the user provided dns, it trumps all; then dns masq; then resolv.conf
if len(c.config.DNSServer) > 0 {
// We store DNS servers as net.IP, so need to convert to string
nameservers = []string{}
for _, server := range c.config.DNSServer {
nameservers = append(nameservers, server.String())
}
} else if len(cniNameServers) > 0 {
nameservers = append(nameservers, cniNameServers...)
} else {
// Make a new resolv.conf
nameservers = resolvconf.GetNameservers(resolv.Content)
// slirp4netns has a built in DNS server.
if c.config.NetMode.IsSlirp4netns() {
nameservers = append([]string{"10.0.2.3"}, nameservers...)
}
}
search := resolvconf.GetSearchDomains(resolv.Content)