Support .d directory for k3s config file (#3162)

Configuration will be loaded from config.yaml and then config.yaml.d/*.(yaml|yml) in
alphanumeric order.  The merging is done by just taking the last value of
a key found, so LIFO for keys.  Slices are not merged but replaced.

Signed-off-by: Darren Shepherd <darren@rancher.com>

pkg/configfilearg/parser.go

@@ -6,8 +6,10 @@ import (
 	"net/http"
 	"net/url"
 	"os"
+	"path/filepath"
 	"strings"
 
+	"github.com/rancher/k3s/pkg/agent/util"
 	"github.com/rancher/wrangler/pkg/data/convert"
 	"gopkg.in/yaml.v2"
 )
@@ -19,7 +21,7 @@ type Parser struct {
 	DefaultConfig string
 }
 
-// Parser will parse an os.Args style slice looking for Parser.FlagNames after Parse.After.
+// Parse will parse an os.Args style slice looking for Parser.FlagNames after Parse.After.
 // It will read the parameter value of Parse.FlagNames and read the file, appending all flags directly after
 // the Parser.After value. This means a the non-config file flags will override, or if a slice append to, the config
 // file values.
@@ -110,31 +112,69 @@ func (p *Parser) findStart(args []string) ([]string, []string, bool) {
 	return args, nil, false
 }
 
+func dotDFiles(basefile string) (result []string, _ error) {
+	files, err := ioutil.ReadDir(basefile + ".d")
+	if os.IsNotExist(err) {
+		return nil, nil
+	} else if err != nil {
+		return nil, err
+	}
+	for _, file := range files {
+		if file.IsDir() || !util.HasSuffixI(file.Name(), ".yaml", ".yml") {
+			continue
+		}
+		result = append(result, filepath.Join(basefile+".d", file.Name()))
+	}
+	return
+}
+
 func readConfigFile(file string) (result []string, _ error) {
-	bytes, err := readConfigFileData(file)
+	files, err := dotDFiles(file)
 	if err != nil {
 		return nil, err
 	}
 
-	data := yaml.MapSlice{}
-	if err := yaml.Unmarshal(bytes, &data); err != nil {
+	_, err = os.Stat(file)
+	if os.IsNotExist(err) && len(files) > 0 {
+	} else if err != nil {
 		return nil, err
+	} else {
+		files = append([]string{file}, files...)
 	}
 
-	for _, i := range data {
-		k, v := convert.ToString(i.Key), i.Value
-		prefix := "--"
-		if len(k) == 1 {
-			prefix = "-"
+	keySeen := map[string]bool{}
+	for i := len(files) - 1; i >= 0; i-- {
+		file := files[i]
+		bytes, err := readConfigFileData(file)
+		if err != nil {
+			return nil, err
+		}
+
+		data := yaml.MapSlice{}
+		if err := yaml.Unmarshal(bytes, &data); err != nil {
+			return nil, err
 		}
 
-		if slice, ok := v.([]interface{}); ok {
-			for _, v := range slice {
-				result = append(result, prefix+k+"="+convert.ToString(v))
+		for _, i := range data {
+			k, v := convert.ToString(i.Key), i.Value
+			if keySeen[k] {
+				continue
+			}
+			keySeen[k] = true
+
+			prefix := "--"
+			if len(k) == 1 {
+				prefix = "-"
+			}
+
+			if slice, ok := v.([]interface{}); ok {
+				for _, v := range slice {
+					result = append(result, prefix+k+"="+convert.ToString(v))
+				}
+			} else {
+				str := convert.ToString(v)
+				result = append(result, prefix+k+"="+str)
 			}
-		} else {
-			str := convert.ToString(v)
-			result = append(result, prefix+k+"="+str)
 		}
 	}
 

pkg/configfilearg/parser_test.go

@@ -150,8 +150,9 @@ func TestConfigFile(t *testing.T) {
 
 func TestParse(t *testing.T) {
 	testDataOutput := []string{
-		"--foo-bar=baz",
+		"--foo-bar=bar-foo",
 		"--a-slice=1",
+		"--a-slice=1.5",
 		"--a-slice=2",
 		"--a-slice=",
 		"--a-slice=three",
@@ -205,7 +206,7 @@ func TestParse(t *testing.T) {
 			input:  []string{"server", "-c=missing"},
 			output: []string{"server", "-c=missing"},
 			what:   "fail when missing config",
-			err:    "open missing: no such file or directory",
+			err:    "stat missing: no such file or directory",
 		},
 		{
 			parser: Parser{
@@ -217,6 +218,16 @@ func TestParse(t *testing.T) {
 			output: append(append([]string{"before", "server"}, testDataOutput...), "before", "-c", "./testdata/data.yaml", "after"),
 			what:   "read config file",
 		},
+		{
+			parser: Parser{
+				After:         []string{"server", "agent"},
+				FlagNames:     []string{"-c", "--config"},
+				DefaultConfig: "missing",
+			},
+			input:  []string{"before", "server", "before", "-c", "./testdata/data.yaml.d/02-data.yaml", "after"},
+			output: []string{"before", "server", "--foo-bar=bar-foo", "before", "-c", "./testdata/data.yaml.d/02-data.yaml", "after"},
+			what:   "read single config file",
+		},
 	}
 
 	for _, testCase := range testCases {

pkg/configfilearg/testdata/data.yaml.d/01-data.yml

@@ -0,0 +1,7 @@
+foo-bar: get-overriden
+a-slice:
+- 1
+- "1.5"
+- "2"
+- ""
+- three

pkg/configfilearg/testdata/data.yaml.d/02-data-ignore-this.txt

@@ -0,0 +1 @@
+foo-bar: ignored

pkg/configfilearg/testdata/data.yaml.d/02-data.yaml

@@ -0,0 +1 @@
+foo-bar: bar-foo