Fix generation of default config

This change ensures that the nvidia-ctk config default command
generates a config file that is compatible with the official documentation
to, for example, disable cgroups in the NVIDIA Container CLI.

This requires that whitespace around comments is stripped before outputing the
contets.

This also adds an option to load a config and modify it in-place instead. This can
be triggered as a post-install step, for example.

Signed-off-by: Evan Lezar <elezar@nvidia.com>

cmd/nvidia-ctk/config/create-default/create-default.go

@@ -17,12 +17,16 @@
 package defaultsubcommand
 
 import (
+	"bytes"
 	"fmt"
 	"io"
 	"os"
+	"path/filepath"
+	"regexp"
 
-	nvctkConfig "github.com/NVIDIA/nvidia-container-toolkit/internal/config"
+	"github.com/NVIDIA/nvidia-container-toolkit/internal/config"
 	"github.com/NVIDIA/nvidia-container-toolkit/internal/logger"
+	"github.com/pelletier/go-toml"
 	"github.com/urfave/cli/v2"
 )
 
@@ -32,7 +36,9 @@ type command struct {
 
 // options stores the subcommand options
 type options struct {
-	output string
+	config  string
+	output  string
+	inPlace bool
 }
 
 // NewCommand constructs a default command with the specified logger
@@ -61,9 +67,20 @@ func (m command) build() *cli.Command {
 	}
 
 	c.Flags = []cli.Flag{
+		&cli.StringFlag{
+			Name:        "config",
+			Usage:       "Specify the config file to process; The contents of this file overrides the default config",
+			Destination: &opts.config,
+		},
+		&cli.BoolFlag{
+			Name:        "in-place",
+			Aliases:     []string{"i"},
+			Usage:       "Modify the config file in-place",
+			Destination: &opts.inPlace,
+		},
 		&cli.StringFlag{
 			Name:        "output",
-			Usage:       "Specify the file to output the generated configuration for to. If this is '' the configuration is ouput to STDOUT.",
+			Usage:       "Specify the output file to write to; If not specified, the output is written to stdout",
 			Destination: &opts.output,
 		},
 	}
@@ -72,31 +89,98 @@ func (m command) build() *cli.Command {
 }
 
 func (m command) validateFlags(c *cli.Context, opts *options) error {
+	if opts.inPlace {
+		if opts.output != "" {
+			return fmt.Errorf("cannot specify both --in-place and --output")
+		}
+		opts.output = opts.config
+	}
 	return nil
 }
 
 func (m command) run(c *cli.Context, opts *options) error {
-	defaultConfig, err := nvctkConfig.GetDefaultConfigToml()
-	if err != nil {
-		return fmt.Errorf("unable to get default config: %v", err)
+	if err := opts.ensureOutputFolder(); err != nil {
+		return fmt.Errorf("unable to create output directory: %v", err)
 	}
 
+	contents, err := opts.getFormattedConfig()
+	if err != nil {
+		return fmt.Errorf("unable to fix comments: %v", err)
+	}
+
+	if _, err := opts.Write(contents); err != nil {
+		return fmt.Errorf("unable to write to output: %v", err)
+	}
+
+	return nil
+}
+
+// getFormattedConfig returns the default config formatted as required from the specified config file.
+// The config is then formatted as required.
+// No indentation is used and comments are modified so that there is no space
+// after the '#' character.
+func (opts options) getFormattedConfig() ([]byte, error) {
+	cfg, err := config.Load(opts.config)
+	if err != nil {
+		return nil, fmt.Errorf("unable to load or create config: %v", err)
+	}
+
+	buffer := bytes.NewBuffer(nil)
+	enc := toml.NewEncoder(buffer).Indentation("")
+
+	if err := enc.Encode(cfg); err != nil {
+		return nil, fmt.Errorf("invalid config: %v", err)
+	}
+
+	return fixComments(buffer.Bytes())
+}
+
+func fixComments(contents []byte) ([]byte, error) {
+	r, err := regexp.Compile(`(\n*)\s*?#\s*(\S.*)`)
+	if err != nil {
+		return nil, fmt.Errorf("unable to compile regexp: %v", err)
+	}
+	replaced := r.ReplaceAll(contents, []byte("$1#$2"))
+
+	return replaced, nil
+}
+
+func (opts options) outputExists() (bool, error) {
+	if opts.output == "" {
+		return false, nil
+	}
+	_, err := os.Stat(opts.output)
+	if err == nil {
+		return true, nil
+	} else if !os.IsNotExist(err) {
+		return false, fmt.Errorf("unable to stat output file: %v", err)
+	}
+	return false, nil
+}
+
+func (opts options) ensureOutputFolder() error {
+	if opts.output == "" {
+		return nil
+	}
+	if dir := filepath.Dir(opts.output); dir != "" {
+		return os.MkdirAll(dir, 0755)
+	}
+	return nil
+}
+
+// Write writes the contents to the output file specified in the options.
+func (opts options) Write(contents []byte) (int, error) {
 	var output io.Writer
 	if opts.output == "" {
 		output = os.Stdout
 	} else {
 		outputFile, err := os.Create(opts.output)
 		if err != nil {
-			return fmt.Errorf("unable to create output file: %v", err)
+			return 0, fmt.Errorf("unable to create output file: %v", err)
 		}
 		defer outputFile.Close()
 		output = outputFile
 	}
 
-	_, err = defaultConfig.WriteTo(output)
-	if err != nil {
-		return fmt.Errorf("unable to write to output: %v", err)
-	}
-
-	return nil
+	return output.Write(contents)
 }

cmd/nvidia-ctk/config/create-default/create-default_test.go

@@ -0,0 +1,82 @@
+/**
+# Copyright (c) NVIDIA CORPORATION.  All rights reserved.
+#
+# 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.
+**/
+
+package defaultsubcommand
+
+import (
+	"strings"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestFixComment(t *testing.T) {
+	testCases := []struct {
+		input    string
+		expected string
+	}{
+		{
+			input:    "# comment",
+			expected: "#comment",
+		},
+		{
+			input:    " #comment",
+			expected: "#comment",
+		},
+		{
+			input:    " # comment",
+			expected: "#comment",
+		},
+		{
+			input: strings.Join([]string{
+				"some",
+				"# comment",
+				" # comment",
+				" #comment",
+				"other"}, "\n"),
+			expected: strings.Join([]string{
+				"some",
+				"#comment",
+				"#comment",
+				"#comment",
+				"other"}, "\n"),
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.input, func(t *testing.T) {
+			actual, _ := fixComments([]byte(tc.input))
+			require.Equal(t, tc.expected, string(actual))
+		})
+	}
+}
+
+func TestGetFormattedConfig(t *testing.T) {
+	expectedLines := []string{
+		"#no-cgroups = false",
+		"#debug = \"/var/log/nvidia-container-toolkit.log\"",
+		"#debug = \"/var/log/nvidia-container-runtime.log\"",
+	}
+
+	opts := &options{}
+	contents, err := opts.getFormattedConfig()
+	require.NoError(t, err)
+	lines := strings.Split(string(contents), "\n")
+
+	for _, line := range expectedLines {
+		require.Contains(t, lines, line)
+	}
+}