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|
package oci
import (
"context"
"os"
"path/filepath"
"github.com/docker/docker/libnetwork/resolvconf"
"github.com/docker/docker/pkg/idtools"
"github.com/moby/buildkit/solver/pb"
"github.com/moby/buildkit/util/flightcontrol"
"github.com/pkg/errors"
)
var g flightcontrol.Group[struct{}]
var notFirstRun bool
var lastNotEmpty bool
// overridden by tests
var resolvconfPath = resolvconf.Path
type DNSConfig struct {
Nameservers []string
Options []string
SearchDomains []string
}
func GetResolvConf(ctx context.Context, stateDir string, idmap *idtools.IdentityMapping, dns *DNSConfig, netMode pb.NetMode) (string, error) {
p := filepath.Join(stateDir, "resolv.conf")
if netMode == pb.NetMode_HOST {
p = filepath.Join(stateDir, "resolv-host.conf")
}
_, err := g.Do(ctx, p, func(ctx context.Context) (struct{}, error) {
generate := !notFirstRun
notFirstRun = true
if !generate {
fi, err := os.Stat(p)
if err != nil {
if !errors.Is(err, os.ErrNotExist) {
return struct{}{}, err
}
generate = true
}
if !generate {
fiMain, err := os.Stat(resolvconfPath())
if err != nil {
if !errors.Is(err, os.ErrNotExist) {
return struct{}{}, err
}
if lastNotEmpty {
generate = true
lastNotEmpty = false
}
} else if fi.ModTime().Before(fiMain.ModTime()) {
generate = true
}
}
}
if !generate {
return struct{}{}, nil
}
dt, err := os.ReadFile(resolvconfPath())
if err != nil && !errors.Is(err, os.ErrNotExist) {
return struct{}{}, err
}
tmpPath := p + ".tmp"
if dns != nil {
var (
dnsNameservers = dns.Nameservers
dnsSearchDomains = dns.SearchDomains
dnsOptions = dns.Options
)
if len(dns.Nameservers) == 0 {
dnsNameservers = resolvconf.GetNameservers(dt, resolvconf.IP)
}
if len(dns.SearchDomains) == 0 {
dnsSearchDomains = resolvconf.GetSearchDomains(dt)
}
if len(dns.Options) == 0 {
dnsOptions = resolvconf.GetOptions(dt)
}
f, err := resolvconf.Build(tmpPath, dnsNameservers, dnsSearchDomains, dnsOptions)
if err != nil {
return struct{}{}, err
}
dt = f.Content
}
if netMode != pb.NetMode_HOST || len(resolvconf.GetNameservers(dt, resolvconf.IP)) == 0 {
f, err := resolvconf.FilterResolvDNS(dt, true)
if err != nil {
return struct{}{}, err
}
dt = f.Content
}
if err := os.WriteFile(tmpPath, dt, 0644); err != nil {
return struct{}{}, err
}
if idmap != nil {
root := idmap.RootPair()
if err := os.Chown(tmpPath, root.UID, root.GID); err != nil {
return struct{}{}, err
}
}
if err := os.Rename(tmpPath, p); err != nil {
return struct{}{}, err
}
return struct{}{}, nil
})
if err != nil {
return "", err
}
return p, nil
}
|
