dockerfile: expose add-hosts

Signed-off-by: Tonis Tiigi <tonistiigi@gmail.com>

frontend/dockerfile/builder/build.go

@@ -4,8 +4,10 @@ import (
 	"archive/tar"
 	"bytes"
 	"context"
+	"encoding/csv"
 	"encoding/json"
 	"fmt"
+	"net"
 	"regexp"
 	"strconv"
 	"strings"
@@ -36,6 +38,7 @@ const (
 	keyTargetPlatform     = "platform"
 	keyMultiPlatform      = "multi-platform"
 	keyImageResolveMode   = "image-resolve-mode"
+	keyGlobalAddHosts     = "add-hosts"
 )
 
 var httpPrefix = regexp.MustCompile("^https?://")
@@ -64,6 +67,11 @@ func Build(ctx context.Context, c client.Client) (*client.Result, error) {
 		return nil, err
 	}
 
+	extraHosts, err := parseExtraHosts(opts[keyGlobalAddHosts])
+	if err != nil {
+		return nil, errors.Wrap(err, "failed to parse additional hosts")
+	}
+
 	filename := opts[keyFilename]
 	if filename == "" {
 		filename = defaultDockerfileName
@@ -250,6 +258,7 @@ func Build(ctx context.Context, c client.Client) (*client.Result, error) {
 					BuildPlatforms:   buildPlatforms,
 					ImageResolveMode: resolveMode,
 					PrefixPlatform:   exportMap,
+					ExtraHosts:       extraHosts,
 				})
 
 				if err != nil {
@@ -413,3 +422,29 @@ func parseResolveMode(v string) (llb.ResolveMode, error) {
 		return 0, errors.Errorf("invalid image-resolve-mode: %s", v)
 	}
 }
+
+func parseExtraHosts(v string) ([]llb.HostIP, error) {
+	if v == "" {
+		return nil, nil
+	}
+	out := make([]llb.HostIP, 0)
+	csvReader := csv.NewReader(strings.NewReader(v))
+	fields, err := csvReader.Read()
+	if err != nil {
+		return nil, err
+	}
+	for _, field := range fields {
+		parts := strings.SplitN(field, "=", 2)
+		if len(parts) != 2 {
+			return nil, errors.Errorf("invalid key-value pair %s", field)
+		}
+		key := strings.ToLower(parts[0])
+		val := strings.ToLower(parts[1])
+		ip := net.ParseIP(val)
+		if ip == nil {
+			return nil, errors.Errorf("failed to parse IP %s", val)
+		}
+		out = append(out, llb.HostIP{Host: key, IP: ip})
+	}
+	return out, nil
+}

frontend/dockerfile/dockerfile2llb/convert.go

@@ -52,6 +52,7 @@ type ConvertOpt struct {
 	TargetPlatform   *specs.Platform
 	BuildPlatforms   []specs.Platform
 	PrefixPlatform   bool
+	ExtraHosts       []llb.HostIP
 }
 
 func Dockerfile2LLB(ctx context.Context, dt []byte, opt ConvertOpt) (*llb.State, *Image, error) {
@@ -294,6 +295,7 @@ func Dockerfile2LLB(ctx context.Context, dt []byte, opt ConvertOpt) (*llb.State,
 			cacheIDNamespace:  opt.CacheIDNamespace,
 			buildPlatforms:    platformOpt.buildPlatforms,
 			targetPlatform:    platformOpt.targetPlatform,
+			extraHosts:        opt.ExtraHosts,
 		}
 
 		if err = dispatchOnBuild(d, d.image.Config.OnBuild, opt); err != nil {
@@ -397,6 +399,7 @@ type dispatchOpt struct {
 	cacheIDNamespace  string
 	targetPlatform    specs.Platform
 	buildPlatforms    []specs.Platform
+	extraHosts        []llb.HostIP
 }
 
 func dispatch(d *dispatchState, cmd command, opt dispatchOpt) error {
@@ -584,6 +587,9 @@ func dispatchRun(d *dispatchState, c *instructions.RunCommand, proxy *llb.ProxyE
 	}
 	opt = append(opt, runMounts...)
 	opt = append(opt, llb.WithCustomName(prefixCommand(d, uppercaseCmd(processCmdEnv(dopt.shlex, c.String(), d.state.Run(opt...).Env())), d.prefixPlatform, d.state.GetPlatform())))
+	for _, h := range dopt.extraHosts {
+		opt = append(opt, llb.AddExtraHost(h.Host, h.IP))
+	}
 	d.state = d.state.Run(opt...).Root()
 	return commitToHistory(&d.image, "RUN "+runCommandString(args, d.buildArgs), true, &d.state)
 }