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Switch to using libnetwork's resolvconf package

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Libnetwork provides a well-tested package for generating
resolv.conf from the host's that has some features our current
implementation does not. Swap to using their code and remove our
built-in implementation.

Signed-off-by: Matthew Heon <matthew.heon@gmail.com>
This commit is contained in:
Matthew Heon
2018-09-25 11:35:16 -04:00
parent 094b8b7350
commit e4ded6ce7f
10 changed files with 1449 additions and 72 deletions
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104
libpod/container_internal.go
View File

@ -17,11 +17,12 @@ import (
"github.com/containers/libpod/pkg/hooks/exec"
"github.com/containers/libpod/pkg/rootless"
"github.com/containers/libpod/pkg/secrets"
"github.com/containers/libpod/pkg/util"
"github.com/containers/storage"
"github.com/containers/storage/pkg/archive"
"github.com/containers/storage/pkg/chrootarchive"
"github.com/containers/storage/pkg/mount"
"github.com/docker/libnetwork/netutils"
"github.com/docker/libnetwork/resolvconf"
spec "github.com/opencontainers/runtime-spec/specs-go"
"github.com/opencontainers/runtime-tools/generate"
"github.com/opencontainers/selinux/go-selinux/label"
@ -1017,12 +1018,6 @@ func (c *Container) writeStringToRundir(destFile, output string) (string, error)
return filepath.Join(c.state.DestinationRunDir, destFile), nil
}
type resolvConf struct {
nameServers []string
searchDomains []string
options []string
}
// generateResolvConf generates a containers resolv.conf
func (c *Container) generateResolvConf() (string, error) {
// Determine the endpoint for resolv.conf in case it is a symlink
@ -1030,86 +1025,51 @@ func (c *Container) generateResolvConf() (string, error) {
if err != nil {
return "", err
}
orig, err := ioutil.ReadFile(resolvPath)
contents, err := ioutil.ReadFile(resolvPath)
if err != nil {
return "", errors.Wrapf(err, "unable to read %s", resolvPath)
}
if len(c.config.DNSServer) == 0 && len(c.config.DNSSearch) == 0 && len(c.config.DNSOption) == 0 {
return c.writeStringToRundir("resolv.conf", fmt.Sprintf("%s", orig))
// Process the file to remove localhost nameservers
// TODO: set ipv6 enable bool more sanely
resolv, err := resolvconf.FilterResolvDNS(contents, true)
if err != nil {
return "", errors.Wrapf(err, "error parsing host resolv.conf")
}
// Read and organize the hosts /etc/resolv.conf
resolv := createResolv(string(orig[:]))
// Populate the resolv struct with user's dns search domains
if len(c.config.DNSSearch) > 0 {
resolv.searchDomains = nil
// The . character means the user doesnt want any search domains in the container
if !util.StringInSlice(".", c.config.DNSSearch) {
resolv.searchDomains = append(resolv.searchDomains, c.Config().DNSSearch...)
}
}
// Populate the resolv struct with user's dns servers
// Make a new resolv.conf
nameservers := resolvconf.GetNameservers(resolv.Content, netutils.IP)
if len(c.config.DNSServer) > 0 {
resolv.nameServers = nil
for _, i := range c.config.DNSServer {
resolv.nameServers = append(resolv.nameServers, i.String())
// 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())
}
}
// Populate the resolve struct with the users dns options
search := resolvconf.GetSearchDomains(resolv.Content)
if len(c.config.DNSSearch) > 0 {
search = c.config.DNSSearch
}
options := resolvconf.GetOptions(resolv.Content)
if len(c.config.DNSOption) > 0 {
resolv.options = nil
resolv.options = append(resolv.options, c.Config().DNSOption...)
options = c.config.DNSOption
}
return c.writeStringToRundir("resolv.conf", resolv.ToString())
}
// createResolv creates a resolv struct from an input string
func createResolv(input string) resolvConf {
var resolv resolvConf
for _, line := range strings.Split(input, "\n") {
if strings.HasPrefix(line, "search") {
fields := strings.Fields(line)
if len(fields) < 2 {
logrus.Debugf("invalid resolv.conf line %s", line)
continue
}
resolv.searchDomains = append(resolv.searchDomains, fields[1:]...)
} else if strings.HasPrefix(line, "nameserver") {
fields := strings.Fields(line)
if len(fields) < 2 {
logrus.Debugf("invalid resolv.conf line %s", line)
continue
}
resolv.nameServers = append(resolv.nameServers, fields[1])
} else if strings.HasPrefix(line, "options") {
fields := strings.Fields(line)
if len(fields) < 2 {
logrus.Debugf("invalid resolv.conf line %s", line)
continue
}
resolv.options = append(resolv.options, fields[1:]...)
}
}
return resolv
}
destPath := filepath.Join(c.state.RunDir, "resolv.conf")
//ToString returns a resolv struct in the form of a resolv.conf
func (r resolvConf) ToString() string {
var result string
// Populate the output string with search domains
result += fmt.Sprintf("search %s\n", strings.Join(r.searchDomains, " "))
// Populate the output string with name servers
for _, i := range r.nameServers {
result += fmt.Sprintf("nameserver %s\n", i)
if err := os.Remove(destPath); err != nil && !os.IsNotExist(err) {
return "", errors.Wrapf(err, "error removing resolv.conf for container %s", c.ID())
}
// Populate the output string with dns options
for _, i := range r.options {
result += fmt.Sprintf("options %s\n", i)
// Build resolv.conf
if _, err = resolvconf.Build(destPath, nameservers, search, options); err != nil {
return "", errors.Wrapf(err, "error building resolv.conf for container %s")
}
return result
return destPath, nil
}
// generateHosts creates a containers hosts file