executor: allow setting DNSConfig to be used by resolvconf

cmd/buildkitd/config/config.go

@@ -26,6 +26,8 @@ type Config struct {
 	} `toml:"worker"`
 
 	Registries map[string]RegistryConfig `toml:"registry"`
+
+	DNS *DNSConfig `toml:"dns"`
 }
 
 type GRPCConfig struct {
@@ -85,6 +87,12 @@ type GCPolicy struct {
 	Filters      []string `toml:"filters"`
 }
 
+type DNSConfig struct {
+	Nameservers   []string `toml:"nameservers"`
+	Options       []string `toml:"options"`
+	SearchDomains []string `toml:"searchDomains"`
+}
+
 func Load(r io.Reader) (Config, *toml.MetaData, error) {
 	var c Config
 	md, err := toml.DecodeReader(r, &c)

cmd/buildkitd/config/config_test.go

@@ -51,6 +51,11 @@ keepDuration=7200
 [registry."docker.io"]
 mirrors=["hub.docker.io"]
 http=true
+
+[dns]
+nameservers=["1.1.1.1","8.8.8.8"]
+options=["edns0"]
+searchDomains=["example.com"]
 `
 
 	cfg, md, err := Load(bytes.NewBuffer([]byte(testConfig)))
@@ -98,4 +103,9 @@ http=true
 
 	require.Equal(t, cfg.Registries["docker.io"].PlainHTTP, true)
 	require.Equal(t, cfg.Registries["docker.io"].Mirrors[0], "hub.docker.io")
+
+	require.NotNil(t, cfg.DNS)
+	require.Equal(t, cfg.DNS.Nameservers, []string{"1.1.1.1", "8.8.8.8"})
+	require.Equal(t, cfg.DNS.SearchDomains, []string{"example.com"})
+	require.Equal(t, cfg.DNS.Options, []string{"edns0"})
 }

cmd/buildkitd/main.go

@@ -31,6 +31,7 @@ import (
 	"github.com/moby/buildkit/client"
 	"github.com/moby/buildkit/cmd/buildkitd/config"
 	"github.com/moby/buildkit/control"
+	"github.com/moby/buildkit/executor/oci"
 	"github.com/moby/buildkit/frontend"
 	dockerfile "github.com/moby/buildkit/frontend/dockerfile/builder"
 	"github.com/moby/buildkit/frontend/gateway"
@@ -685,3 +686,15 @@ func getGCPolicy(cfg config.GCConfig, root string) []client.PruneInfo {
 	}
 	return out
 }
+
+func getDNSConfig(cfg *config.DNSConfig) *oci.DNSConfig {
+	var dns *oci.DNSConfig
+	if cfg != nil {
+		dns = &oci.DNSConfig{
+			Nameservers:   cfg.Nameservers,
+			Options:       cfg.Options,
+			SearchDomains: cfg.SearchDomains,
+		}
+	}
+	return dns
+}

cmd/buildkitd/main_containerd_worker.go

@@ -172,7 +172,9 @@ func containerdWorkerInitializer(c *cli.Context, common workerInitializerOpt) ([
 		return nil, nil
 	}
 
-	opt, err := containerd.NewWorkerOpt(common.config.Root, cfg.Address, ctd.DefaultSnapshotter, cfg.Namespace, cfg.Labels, ctd.WithTimeout(60*time.Second))
+	dns := getDNSConfig(common.config.DNS)
+
+	opt, err := containerd.NewWorkerOpt(common.config.Root, cfg.Address, ctd.DefaultSnapshotter, cfg.Namespace, cfg.Labels, dns, ctd.WithTimeout(60*time.Second))
 	if err != nil {
 		return nil, err
 	}

cmd/buildkitd/main_oci_worker.go

@@ -192,7 +192,9 @@ func ociWorkerInitializer(c *cli.Context, common workerInitializerOpt) ([]worker
 		processMode = oci.NoProcessSandbox
 	}
 
-	opt, err := runc.NewWorkerOpt(common.config.Root, snFactory, cfg.Rootless, processMode, cfg.Labels, idmapping)
+	dns := getDNSConfig(common.config.DNS)
+
+	opt, err := runc.NewWorkerOpt(common.config.Root, snFactory, cfg.Rootless, processMode, cfg.Labels, idmapping, dns)
 	if err != nil {
 		return nil, err
 	}

executor/containerdexecutor/executor.go

@@ -30,10 +30,11 @@ type containerdExecutor struct {
 	root             string
 	networkProviders map[pb.NetMode]network.Provider
 	cgroupParent     string
+	dnsConfig        *oci.DNSConfig
 }
 
 // New creates a new executor backed by connection to containerd API
-func New(client *containerd.Client, root, cgroup string, networkProviders map[pb.NetMode]network.Provider) executor.Executor {
+func New(client *containerd.Client, root, cgroup string, networkProviders map[pb.NetMode]network.Provider, dnsConfig *oci.DNSConfig) executor.Executor {
 	// clean up old hosts/resolv.conf file. ignore errors
 	os.RemoveAll(filepath.Join(root, "hosts"))
 	os.RemoveAll(filepath.Join(root, "resolv.conf"))
@@ -43,13 +44,14 @@ func New(client *containerd.Client, root, cgroup string, networkProviders map[pb
 		root:             root,
 		networkProviders: networkProviders,
 		cgroupParent:     cgroup,
+		dnsConfig:        dnsConfig,
 	}
 }
 
 func (w containerdExecutor) Exec(ctx context.Context, meta executor.Meta, root cache.Mountable, mounts []executor.Mount, stdin io.ReadCloser, stdout, stderr io.WriteCloser) (err error) {
 	id := identity.NewID()
 
-	resolvConf, err := oci.GetResolvConf(ctx, w.root, nil)
+	resolvConf, err := oci.GetResolvConf(ctx, w.root, nil, w.dnsConfig)
 	if err != nil {
 		return err
 	}

executor/oci/resolvconf.go

@@ -8,14 +8,21 @@ import (
 
 	"github.com/docker/docker/pkg/idtools"
 	"github.com/docker/libnetwork/resolvconf"
+	"github.com/docker/libnetwork/types"
 	"github.com/moby/buildkit/util/flightcontrol"
 )
 
 var g flightcontrol.Group
 var notFirstRun bool
 var lastNotEmpty bool
 
-func GetResolvConf(ctx context.Context, stateDir string, idmap *idtools.IdentityMapping) (string, error) {
+type DNSConfig struct {
+	Nameservers   []string
+	Options       []string
+	SearchDomains []string
+}
+
+func GetResolvConf(ctx context.Context, stateDir string, idmap *idtools.IdentityMapping, dns *DNSConfig) (string, error) {
 	p := filepath.Join(stateDir, "resolv.conf")
 	_, err := g.Do(ctx, stateDir, func(ctx context.Context) (interface{}, error) {
 		generate := !notFirstRun
@@ -61,9 +68,34 @@ func GetResolvConf(ctx context.Context, stateDir string, idmap *idtools.Identity
 			dt = f.Content
 		}
 
-		f, err = resolvconf.FilterResolvDNS(dt, true)
-		if err != nil {
-			return "", err
+		if dns != nil {
+			var (
+				dnsNameservers   = resolvconf.GetNameservers(dt, types.IP)
+				dnsSearchDomains = resolvconf.GetSearchDomains(dt)
+				dnsOptions       = resolvconf.GetOptions(dt)
+			)
+			if len(dns.Nameservers) > 0 {
+				dnsNameservers = dns.Nameservers
+			}
+			if len(dns.SearchDomains) > 0 {
+				dnsSearchDomains = dns.SearchDomains
+			}
+			if len(dns.Options) > 0 {
+				dnsOptions = dns.Options
+			}
+
+			f, err = resolvconf.Build(p+".tmp", dnsNameservers, dnsSearchDomains, dnsOptions)
+			if err != nil {
+				return "", err
+			}
+		} else {
+			// Logic seems odd here: why are we filtering localhost IPs
+			// only if neither of the DNS configs were specified?
+			// Logic comes from https://github.com/docker/libnetwork/blob/164a77ee6d24fb2b1d61f8ad3403a51d8453899e/sandbox_dns_unix.go#L230-L269
+			f, err = resolvconf.FilterResolvDNS(f.Content, true)
+			if err != nil {
+				return "", err
+			}
 		}
 
 		tmpPath := p + ".tmp"

executor/runcexecutor/executor.go

@@ -43,6 +43,7 @@ type Opt struct {
 	IdentityMapping *idtools.IdentityMapping
 	// runc run --no-pivot (unrecommended)
 	NoPivot bool
+	DNS     *oci.DNSConfig
 }
 
 var defaultCommandCandidates = []string{"buildkit-runc", "runc"}
@@ -57,6 +58,7 @@ type runcExecutor struct {
 	processMode      oci.ProcessMode
 	idmap            *idtools.IdentityMapping
 	noPivot          bool
+	dns              *oci.DNSConfig
 }
 
 func New(opt Opt, networkProviders map[pb.NetMode]network.Provider) (executor.Executor, error) {
@@ -115,6 +117,7 @@ func New(opt Opt, networkProviders map[pb.NetMode]network.Provider) (executor.Ex
 		processMode:      opt.ProcessMode,
 		idmap:            opt.IdentityMapping,
 		noPivot:          opt.NoPivot,
+		dns:              opt.DNS,
 	}
 	return w, nil
 }
@@ -134,7 +137,7 @@ func (w *runcExecutor) Exec(ctx context.Context, meta executor.Meta, root cache.
 		logrus.Info("enabling HostNetworking")
 	}
 
-	resolvConf, err := oci.GetResolvConf(ctx, w.root, w.idmap)
+	resolvConf, err := oci.GetResolvConf(ctx, w.root, w.idmap, w.dns)
 	if err != nil {
 		return err
 	}

vendor/modules.txt

@@ -151,8 +151,8 @@ github.com/docker/go-events
 github.com/docker/go-units
 # github.com/docker/libnetwork v0.8.0-dev.2.0.20190604151032-3c26b4e7495e
 github.com/docker/libnetwork/resolvconf
-github.com/docker/libnetwork/resolvconf/dns
 github.com/docker/libnetwork/types
+github.com/docker/libnetwork/resolvconf/dns
 # github.com/gofrs/flock v0.7.0
 github.com/gofrs/flock
 # github.com/gogo/googleapis v1.1.0

worker/containerd/containerd.go

@@ -13,6 +13,7 @@ import (
 	"github.com/containerd/containerd/snapshots"
 	"github.com/moby/buildkit/cache/metadata"
 	"github.com/moby/buildkit/executor/containerdexecutor"
+	"github.com/moby/buildkit/executor/oci"
 	"github.com/moby/buildkit/identity"
 	containerdsnapshot "github.com/moby/buildkit/snapshot/containerd"
 	"github.com/moby/buildkit/util/leaseutil"
@@ -26,16 +27,16 @@ import (
 )
 
 // NewWorkerOpt creates a WorkerOpt.
-func NewWorkerOpt(root string, address, snapshotterName, ns string, labels map[string]string, opts ...containerd.ClientOpt) (base.WorkerOpt, error) {
+func NewWorkerOpt(root string, address, snapshotterName, ns string, labels map[string]string, dns *oci.DNSConfig, opts ...containerd.ClientOpt) (base.WorkerOpt, error) {
 	opts = append(opts, containerd.WithDefaultNamespace(ns))
 	client, err := containerd.New(address, opts...)
 	if err != nil {
 		return base.WorkerOpt{}, errors.Wrapf(err, "failed to connect client to %q . make sure containerd is running", address)
 	}
-	return newContainerd(root, client, snapshotterName, ns, labels)
+	return newContainerd(root, client, snapshotterName, ns, labels, dns)
 }
 
-func newContainerd(root string, client *containerd.Client, snapshotterName, ns string, labels map[string]string) (base.WorkerOpt, error) {
+func newContainerd(root string, client *containerd.Client, snapshotterName, ns string, labels map[string]string, dns *oci.DNSConfig) (base.WorkerOpt, error) {
 	if strings.Contains(snapshotterName, "/") {
 		return base.WorkerOpt{}, errors.Errorf("bad snapshotter name: %q", snapshotterName)
 	}
@@ -106,7 +107,7 @@ func newContainerd(root string, client *containerd.Client, snapshotterName, ns s
 		ID:            id,
 		Labels:        xlabels,
 		MetadataStore: md,
-		Executor:      containerdexecutor.New(client, root, "", network.Default()),
+		Executor:      containerdexecutor.New(client, root, "", network.Default(), dns),
 		Snapshotter:   containerdsnapshot.NewSnapshotter(snapshotterName, client.SnapshotService(snapshotterName), cs, md, ns, gc, nil),
 		ContentStore:  cs,
 		Applier:       winlayers.NewFileSystemApplierWithWindows(cs, df),

worker/runc/runc.go

@@ -34,7 +34,7 @@ type SnapshotterFactory struct {
 }
 
 // NewWorkerOpt creates a WorkerOpt.
-func NewWorkerOpt(root string, snFactory SnapshotterFactory, rootless bool, processMode oci.ProcessMode, labels map[string]string, idmap *idtools.IdentityMapping) (base.WorkerOpt, error) {
+func NewWorkerOpt(root string, snFactory SnapshotterFactory, rootless bool, processMode oci.ProcessMode, labels map[string]string, idmap *idtools.IdentityMapping, dns *oci.DNSConfig) (base.WorkerOpt, error) {
 	var opt base.WorkerOpt
 	name := "runc-" + snFactory.Name
 	root = filepath.Join(root, name)
@@ -52,6 +52,7 @@ func NewWorkerOpt(root string, snFactory SnapshotterFactory, rootless bool, proc
 		Rootless:        rootless,
 		ProcessMode:     processMode,
 		IdentityMapping: idmap,
+		DNS:             dns,
 	}, network.Default())
 	if err != nil {
 		return opt, err

worker/runc/runc_test.go

@@ -39,7 +39,7 @@ func newWorkerOpt(t *testing.T, processMode oci.ProcessMode) (base.WorkerOpt, fu
 		},
 	}
 	rootless := false
-	workerOpt, err := NewWorkerOpt(tmpdir, snFactory, rootless, processMode, nil, nil)
+	workerOpt, err := NewWorkerOpt(tmpdir, snFactory, rootless, processMode, nil, nil, nil)
 	require.NoError(t, err)
 
 	return workerOpt, cleanup