Merge pull request #1219 from manugupt1/fallback-containerfile

Fallback to Containerfile when Dockerfile is not present.

Author: AkihiroSuda

cmd/nerdctl/build.go

@@ -41,8 +41,10 @@ import (
 
 func newBuildCommand() *cobra.Command {
 	var buildCommand = &cobra.Command{
-		Use:           "build",
-		Short:         "Build an image from a Dockerfile. Needs buildkitd to be running.",
+		Use:   "build",
+		Short: "Build an image from a Dockerfile. Needs buildkitd to be running.",
+		Long: `Build an image from a Dockerfile. Needs buildkitd to be running.
+If Dockerfile is not present and -f is not specified, it will look for Containerfile and build with it. `,
 		RunE:          buildAction,
 		SilenceUsage:  true,
 		SilenceErrors: true,
@@ -355,13 +357,11 @@ func generateBuildctlArgs(cmd *cobra.Command, buildkitHost string, platform, arg
 			dir = "."
 		}
 	}
-	absDir, err := filepath.Abs(dir)
+	dir, file, err = buildkitutil.BuildKitFile(dir, file)
 	if err != nil {
 		return "", nil, false, "", nil, nil, err
 	}
-	if _, err := os.Lstat(filepath.Join(absDir, file)); err != nil {
-		return "", nil, false, "", nil, nil, err
-	}
+
 	buildctlArgs = append(buildctlArgs, "--local=dockerfile="+dir)
 	buildctlArgs = append(buildctlArgs, "--opt=filename="+file)
 

cmd/nerdctl/build_test.go

@@ -287,3 +287,54 @@ CMD ["echo", "nerdctl-build-test-string"]
 	base.Cmd("run", "--rm", imgWithNoTag).AssertOutExactly("nerdctl-build-test-string\n")
 	base.Cmd("run", "--rm", imgWithCustomTag).AssertOutExactly("nerdctl-build-test-string\n")
 }
+
+func TestBuildWithContainerfile(t *testing.T) {
+	testutil.RequiresBuild(t)
+	testutil.DockerIncompatible(t)
+	base := testutil.NewBase(t)
+	defer base.Cmd("builder", "prune").Run()
+	imageName := testutil.Identifier(t)
+	defer base.Cmd("rmi", imageName).Run()
+
+	containerfile := fmt.Sprintf(`FROM %s
+CMD ["echo", "nerdctl-build-test-string"]
+	`, testutil.CommonImage)
+
+	buildCtx := t.TempDir()
+
+	var err = os.WriteFile(filepath.Join(buildCtx, "Containerfile"), []byte(containerfile), 0644)
+	assert.NilError(t, err)
+	base.Cmd("build", "-t", imageName, buildCtx).AssertOK()
+	base.Cmd("run", "--rm", imageName).AssertOutExactly("nerdctl-build-test-string\n")
+}
+
+func TestBuildWithDockerFileAndContainerfile(t *testing.T) {
+	testutil.RequiresBuild(t)
+	base := testutil.NewBase(t)
+	defer base.Cmd("builder", "prune").Run()
+	imageName := testutil.Identifier(t)
+	defer base.Cmd("rmi", imageName).Run()
+
+	dockerfile := fmt.Sprintf(`FROM %s
+CMD ["echo", "dockerfile"]
+	`, testutil.CommonImage)
+
+	containerfile := fmt.Sprintf(`FROM %s
+	CMD ["echo", "containerfile"]
+		`, testutil.CommonImage)
+
+	tmpDir := t.TempDir()
+
+	var err = os.WriteFile(filepath.Join(tmpDir, "Dockerfile"), []byte(dockerfile), 0644)
+	assert.NilError(t, err)
+
+	err = os.WriteFile(filepath.Join(tmpDir, "Containerfile"), []byte(containerfile), 0644)
+	assert.NilError(t, err)
+
+	buildCtx, err := createBuildContext(dockerfile)
+	assert.NilError(t, err)
+	defer os.RemoveAll(buildCtx)
+
+	base.Cmd("build", "-t", imageName, buildCtx).AssertOK()
+	base.Cmd("run", "--rm", imageName).AssertOutExactly("dockerfile\n")
+}

pkg/buildkitutil/buildkitutil.go

@@ -24,10 +24,12 @@
 package buildkitutil
 
 import (
+	"bytes"
 	"encoding/json"
 	"errors"
 	"fmt"
 	"io"
+	"io/fs"
 	"os"
 	"os/exec"
 	"path/filepath"
@@ -41,6 +43,7 @@ import (
 const (
 	// DefaultDockerfileName is the Default filename, read by nerdctl build
 	DefaultDockerfileName string = "Dockerfile"
+	ContainerfileName     string = "Containerfile"
 
 	TempDockerfileName string = "docker-build-tempdockerfile-"
 )
@@ -181,3 +184,51 @@ func WriteTempDockerfile(rc io.Reader) (dockerfileDir string, err error) {
 	}
 	return dockerfileDir, nil
 }
+
+// Buildkit file returns the values for the following buildctl args
+// --localfilename=dockerfile={absDir}
+// --opt=filename={file}
+func BuildKitFile(dir, inputfile string) (absDir string, file string, err error) {
+	file = inputfile
+	if file == "" || file == "." {
+		file = DefaultDockerfileName
+	}
+	absDir, err = filepath.Abs(dir)
+	if err != nil {
+		return "", "", err
+	}
+	if file != DefaultDockerfileName {
+		if _, err := os.Lstat(filepath.Join(absDir, file)); err != nil {
+			return "", "", err
+		}
+	} else {
+		_, dErr := os.Lstat(filepath.Join(absDir, file))
+		_, cErr := os.Lstat(filepath.Join(absDir, ContainerfileName))
+		if dErr == nil && cErr == nil {
+			// both files exist, prefer Dockerfile.
+			dockerfile, err := os.ReadFile(filepath.Join(absDir, DefaultDockerfileName))
+			if err != nil {
+				return "", "", err
+			}
+			containerfile, err := os.ReadFile(filepath.Join(absDir, ContainerfileName))
+			if err != nil {
+				return "", "", err
+			}
+			if !bytes.Equal(dockerfile, containerfile) {
+				logrus.Warnf("%s and %s have different contents, building with %s", DefaultDockerfileName, ContainerfileName, DefaultDockerfileName)
+			}
+		}
+		if dErr != nil {
+			if errors.Is(dErr, fs.ErrNotExist) {
+				logrus.Warnf("%s, using %s as fallback", dErr, ContainerfileName)
+				file = ContainerfileName
+			} else {
+				return "", "", dErr
+			}
+			if cErr != nil {
+				return "", "", cErr
+			}
+		}
+	}
+	return absDir, file, nil
+}

pkg/buildkitutil/buildkitutil_test.go

@@ -0,0 +1,165 @@
+/*
+   Copyright The containerd Authors.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+/*
+   Portions from https://github.com/docker/cli/blob/v20.10.9/cli/command/image/build/context.go
+   Copyright (C) Docker authors.
+   Licensed under the Apache License, Version 2.0
+   NOTICE: https://github.com/docker/cli/blob/v20.10.9/NOTICE
+*/
+
+package buildkitutil
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+
+	"gotest.tools/v3/assert"
+)
+
+func TestBuildKitFile(t *testing.T) {
+	var tmp = t.TempDir()
+	var wd, err = os.Getwd()
+	assert.NilError(t, err)
+	err = os.Chdir(tmp)
+	assert.NilError(t, err)
+	defer os.Chdir(wd)
+	type args struct {
+		dir       string
+		inputfile string
+	}
+	tests := []struct {
+		name       string
+		args       args
+		prepare    func(t *testing.T) error
+		wantAbsDir string
+		wantFile   string
+		wantErr    bool
+	}{
+		{
+			name: "only Dockerfile is present",
+			prepare: func(t *testing.T) error {
+				return os.WriteFile(filepath.Join(tmp, DefaultDockerfileName), []byte{}, 0644)
+			},
+			args:       args{".", ""},
+			wantAbsDir: tmp,
+			wantFile:   DefaultDockerfileName,
+			wantErr:    false,
+		},
+		{
+			name: "only Containerfile is present",
+			prepare: func(t *testing.T) error {
+				return os.WriteFile(filepath.Join(tmp, "Containerfile"), []byte{}, 0644)
+			},
+			args:       args{".", ""},
+			wantAbsDir: tmp,
+			wantFile:   ContainerfileName,
+			wantErr:    false,
+		},
+		{
+			name: "both Dockerfile and Containerfile are present",
+			prepare: func(t *testing.T) error {
+				var err = os.WriteFile(filepath.Join(tmp, "Dockerfile"), []byte{}, 0644)
+				if err != nil {
+					return err
+				}
+				return os.WriteFile(filepath.Join(tmp, "Containerfile"), []byte{}, 0644)
+			},
+			args:       args{".", ""},
+			wantAbsDir: tmp,
+			wantFile:   DefaultDockerfileName,
+			wantErr:    false,
+		},
+		{
+			name: "Dockerfile and Containerfile have different contents",
+			prepare: func(t *testing.T) error {
+				var err = os.WriteFile(filepath.Join(tmp, "Dockerfile"), []byte{'d'}, 0644)
+				if err != nil {
+					return err
+				}
+				return os.WriteFile(filepath.Join(tmp, "Containerfile"), []byte{'c'}, 0644)
+			},
+			args:       args{".", ""},
+			wantAbsDir: tmp,
+			wantFile:   DefaultDockerfileName,
+			wantErr:    false,
+		},
+		{
+			name: "Custom file is specfied",
+			prepare: func(t *testing.T) error {
+				return os.WriteFile(filepath.Join(tmp, "CustomFile"), []byte{}, 0644)
+			},
+			args:       args{".", "CustomFile"},
+			wantAbsDir: tmp,
+			wantFile:   "CustomFile",
+			wantErr:    false,
+		},
+		{
+			name: "Absolute path is specified along with custom file",
+			prepare: func(t *testing.T) error {
+				return os.WriteFile(filepath.Join(tmp, "CustomFile"), []byte{}, 0644)
+			},
+			args:       args{tmp, "CustomFile"},
+			wantAbsDir: tmp,
+			wantFile:   "CustomFile",
+			wantErr:    false,
+		},
+		{
+			name: "Absolute path is specified along with Docker file",
+			prepare: func(t *testing.T) error {
+				return os.WriteFile(filepath.Join(tmp, "Dockerfile"), []byte{}, 0644)
+			},
+			args:       args{tmp, "."},
+			wantAbsDir: tmp,
+			wantFile:   DefaultDockerfileName,
+			wantErr:    false,
+		},
+		{
+			name: "Absolute path is specified with Container file in the path",
+			prepare: func(t *testing.T) error {
+				return os.WriteFile(filepath.Join(tmp, ContainerfileName), []byte{}, 0644)
+			},
+			args:       args{tmp, "."},
+			wantAbsDir: tmp,
+			wantFile:   ContainerfileName,
+			wantErr:    false,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			tt.prepare(t)
+			gotAbsDir, gotFile, err := BuildKitFile(tt.args.dir, tt.args.inputfile)
+			if (err != nil) != tt.wantErr {
+				t.Errorf("BuildKitFile() error = %v, wantErr %v", err, tt.wantErr)
+				return
+			}
+			if gotAbsDir != tt.wantAbsDir {
+				t.Errorf("BuildKitFile() gotAbsDir = %v, want %v", gotAbsDir, tt.wantAbsDir)
+			}
+			if gotFile != tt.wantFile {
+				t.Errorf("BuildKitFile() gotFile = %v, want %v", gotFile, tt.wantFile)
+			}
+
+			entry, err := os.ReadDir(tmp)
+			assert.NilError(t, err)
+			for _, f := range entry {
+				err = os.Remove(f.Name())
+				assert.NilError(t, err)
+			}
+		})
+	}
+}