Add Viper based config loader

go.mod

@@ -13,10 +13,13 @@ require (
 	github.com/go-redis/redis/v7 v7.2.0
 	github.com/kr/pretty v0.2.0 // indirect
 	github.com/mbland/hmacauth v0.0.0-20170912233209-44256dfd4bfa
+	github.com/mitchellh/mapstructure v1.1.2
 	github.com/mreiferson/go-options v1.0.0
 	github.com/onsi/ginkgo v1.12.0
 	github.com/onsi/gomega v1.9.0
 	github.com/pquerna/cachecontrol v0.0.0-20180517163645-1555304b9b35 // indirect
+	github.com/spf13/pflag v1.0.3
+	github.com/spf13/viper v1.6.3
 	github.com/stretchr/testify v1.5.1
 	github.com/yhat/wsutil v0.0.0-20170731153501-1d66fa95c997
 	golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2

go.sum

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@@ -73,20 +123,61 @@ github.com/onsi/gomega v1.7.0/go.mod h1:ex+gbHU/CVuBBDIJjb2X0qEXbFg53c61hWP/1Cpa
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@@ -98,11 +189,14 @@ golang.org/x/lint v0.0.0-20190409202823-959b441ac422/go.mod h1:6SW0HCj/g11FgYtHl
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@@ -117,7 +211,10 @@ golang.org/x/sync v0.0.0-20181221193216-37e7f081c4d4/go.mod h1:RxMgew5VJxzue5/jJ
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@@ -131,11 +228,14 @@ golang.org/x/text v0.3.1-0.20180807135948-17ff2d5776d2/go.mod h1:NqM8EUOU14njkJ3
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@@ -152,21 +252,28 @@ google.golang.org/genproto v0.0.0-20190418145605-e7d98fc518a7/go.mod h1:VzzqZJRn
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 gopkg.in/yaml.v2 v2.2.1/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
 gopkg.in/yaml.v2 v2.2.2 h1:ZCJp+EgiOT7lHqUV2J862kp8Qj64Jo6az82+3Td9dZw=
 gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=

pkg/apis/options/load.go

@@ -0,0 +1,132 @@
+package options
+
+import (
+	"fmt"
+	"reflect"
+	"strings"
+
+	"github.com/mitchellh/mapstructure"
+	"github.com/spf13/pflag"
+	"github.com/spf13/viper"
+)
+
+// Load reads in the config file at the path given, then merges in environment
+// variables (prefixed with `OAUTH2_PROXY`) and finally merges in flags from the flagSet.
+// If a config value is unset and the flag has a non-zero value default, this default will be used.
+// Eg. A field defined:
+//    FooBar `cfg:"foo_bar" flag:"foo-bar"`
+// Can be set in the config file as `foo_bar="baz"`, in the environment as `OAUTH2_PROXY_FOO_BAR=baz`,
+// or via the command line flag `--foo-bar=baz`.
+func Load(configFileName string, flagSet *pflag.FlagSet, into interface{}) error {
+	v := viper.New()
+	v.SetConfigFile(configFileName)
+	v.SetConfigType("toml") // Config is in toml format
+	v.SetEnvPrefix("OAUTH2_PROXY")
+	v.AutomaticEnv()
+	v.SetTypeByDefaultValue(true)
+
+	if configFileName != "" {
+		err := v.ReadInConfig()
+		if err != nil {
+			return fmt.Errorf("unable to load config file: %w", err)
+		}
+	}
+
+	err := registerFlags(v, "", flagSet, into)
+	if err != nil {
+		// This should only happen if there is a programming error
+		return fmt.Errorf("unable to register flags: %w", err)
+	}
+
+	err = v.Unmarshal(into, decodeFromCfgTag)
+	if err != nil {
+		return fmt.Errorf("error unmarshalling config: %w", err)
+	}
+
+	return nil
+}
+
+// registerFlags uses `cfg` and `flag` tags to associate flags in the flagSet
+// to the fields in the options interface provided.
+// Each exported field in the options must have a `cfg` tag otherwise an error will occur.
+// - For fields, set `cfg` and `flag` so that `flag` is the name of the flag associated to this config option
+// - For exported fields that are not user facing, set the `cfg` to `,internal`
+// - For structs containing user facing fields, set the `cfg` to `,squash`
+func registerFlags(v *viper.Viper, prefix string, flagSet *pflag.FlagSet, options interface{}) error {
+	val := reflect.ValueOf(options)
+	var typ reflect.Type
+	if val.Kind() == reflect.Ptr {
+		typ = val.Elem().Type()
+	} else {
+		typ = val.Type()
+	}
+
+	for i := 0; i < typ.NumField(); i++ {
+		// pull out the struct tags:
+		//    flag - the name of the command line flag
+		//    cfg - the name of the config file option
+		field := typ.Field(i)
+		fieldV := reflect.Indirect(val).Field(i)
+		fieldName := strings.Join([]string{prefix, field.Name}, ".")
+
+		cfgName := field.Tag.Get("cfg")
+		if cfgName == ",internal" {
+			// Public but internal types that should not be exposed to users, skip them
+			continue
+		}
+
+		if isUnexported(field.Name) {
+			// Unexported fields cannot be set by a user, so won't have tags or flags, skip them
+			continue
+		}
+
+		if field.Type.Kind() == reflect.Struct {
+			if cfgName != ",squash" {
+				return fmt.Errorf("field %q does not have required cfg tag: `,squash`", fieldName)
+			}
+			err := registerFlags(v, fieldName, flagSet, fieldV.Interface())
+			if err != nil {
+				return err
+			}
+			continue
+		}
+
+		flagName := field.Tag.Get("flag")
+		if flagName == "" || cfgName == "" {
+			return fmt.Errorf("field %q does not have required tags (cfg, flag)", fieldName)
+		}
+
+		if flagSet == nil {
+			return fmt.Errorf("flagset cannot be nil")
+		}
+
+		f := flagSet.Lookup(flagName)
+		if f == nil {
+			return fmt.Errorf("field %q does not have a registered flag", flagName)
+		}
+		err := v.BindPFlag(cfgName, f)
+		if err != nil {
+			return fmt.Errorf("error binding flag for field %q: %w", fieldName, err)
+		}
+	}
+
+	return nil
+}
+
+// decodeFromCfgTag sets the Viper decoder to read the names from the `cfg` tag
+// on each struct entry.
+func decodeFromCfgTag(c *mapstructure.DecoderConfig) {
+	c.TagName = "cfg"
+}
+
+// isUnexported checks if a field name starts with a lowercase letter and therefore
+// if it is unexported.
+func isUnexported(name string) bool {
+	if len(name) == 0 {
+		// This should never happen
+		panic("field name has len 0")
+	}
+
+	first := string(name[0])
+	return first == strings.ToLower(first)
+}

pkg/apis/options/load_test.go

@@ -0,0 +1,288 @@
+package options
+
+import (
+	"fmt"
+	"io/ioutil"
+	"os"
+	"testing"
+
+	. "github.com/onsi/ginkgo"
+	. "github.com/onsi/ginkgo/extensions/table"
+	. "github.com/onsi/gomega"
+	"github.com/spf13/pflag"
+)
+
+func TestOptionsSuite(t *testing.T) {
+	RegisterFailHandler(Fail)
+	RunSpecs(t, "Options Suite")
+}
+
+var _ = Describe("Load", func() {
+	Context("with a testOptions structure", func() {
+		type TestOptionSubStruct struct {
+			StringSliceOption []string `flag:"string-slice-option" cfg:"string_slice_option"`
+		}
+
+		type TestOptions struct {
+			StringOption string              `flag:"string-option" cfg:"string_option"`
+			Sub          TestOptionSubStruct `cfg:",squash"`
+			// Check exported but internal fields do not break loading
+			Internal *string `cfg:",internal"`
+			// Check unexported fields do not break loading
+			unexported string
+		}
+
+		type MissingSquashTestOptions struct {
+			StringOption string `flag:"string-option" cfg:"string_option"`
+			Sub          TestOptionSubStruct
+		}
+
+		type MissingCfgTestOptions struct {
+			StringOption string              `flag:"string-option"`
+			Sub          TestOptionSubStruct `cfg:",squash"`
+		}
+
+		type MissingFlagTestOptions struct {
+			StringOption string              `cfg:"string_option"`
+			Sub          TestOptionSubStruct `cfg:",squash"`
+		}
+
+		var testOptionsConfigBytes = []byte(`
+			string_option="foo"
+			string_slice_option="a,b,c,d"
+		`)
+
+		var testOptionsFlagSet *pflag.FlagSet
+
+		type testOptionsTableInput struct {
+			env            map[string]string
+			args           []string
+			configFile     []byte
+			flagSet        func() *pflag.FlagSet
+			expectedErr    error
+			input          interface{}
+			expectedOutput interface{}
+		}
+
+		BeforeEach(func() {
+			testOptionsFlagSet = pflag.NewFlagSet("testFlagSet", pflag.ExitOnError)
+			testOptionsFlagSet.String("string-option", "default", "")
+			testOptionsFlagSet.StringSlice("string-slice-option", []string{"a", "b"}, "")
+		})
+
+		DescribeTable("Load",
+			func(o *testOptionsTableInput) {
+				var configFileName string
+
+				if o.configFile != nil {
+					By("Creating a config file")
+					configFile, err := ioutil.TempFile("", "oauth2-proxy-test-legacy-config-file")
+					Expect(err).ToNot(HaveOccurred())
+					defer configFile.Close()
+
+					_, err = configFile.Write(o.configFile)
+					Expect(err).ToNot(HaveOccurred())
+					defer os.Remove(configFile.Name())
+
+					configFileName = configFile.Name()
+				}
+
+				if len(o.env) > 0 {
+					By("Setting environment variables")
+					for k, v := range o.env {
+						os.Setenv(k, v)
+						defer os.Unsetenv(k)
+					}
+				}
+
+				Expect(o.flagSet).ToNot(BeNil())
+				flagSet := o.flagSet()
+				Expect(flagSet).ToNot(BeNil())
+
+				if len(o.args) > 0 {
+					By("Parsing flag arguments")
+					Expect(flagSet.Parse(o.args)).To(Succeed())
+				}
+
+				var input interface{}
+				if o.input != nil {
+					input = o.input
+				} else {
+					input = &TestOptions{}
+				}
+				err := Load(configFileName, flagSet, input)
+				if o.expectedErr != nil {
+					Expect(err).To(MatchError(o.expectedErr.Error()))
+				} else {
+					Expect(err).ToNot(HaveOccurred())
+				}
+				Expect(input).To(Equal(o.expectedOutput))
+			},
+			Entry("with just a config file", &testOptionsTableInput{
+				configFile: testOptionsConfigBytes,
+				flagSet:    func() *pflag.FlagSet { return testOptionsFlagSet },
+				expectedOutput: &TestOptions{
+					StringOption: "foo",
+					Sub: TestOptionSubStruct{
+						StringSliceOption: []string{"a", "b", "c", "d"},
+					},
+				},
+			}),
+			Entry("when setting env variables", &testOptionsTableInput{
+				configFile: testOptionsConfigBytes,
+				env: map[string]string{
+					"OAUTH2_PROXY_STRING_OPTION":       "bar",
+					"OAUTH2_PROXY_STRING_SLICE_OPTION": "a,b,c",
+				},
+				flagSet: func() *pflag.FlagSet { return testOptionsFlagSet },
+				expectedOutput: &TestOptions{
+					StringOption: "bar",
+					Sub: TestOptionSubStruct{
+						StringSliceOption: []string{"a", "b", "c"},
+					},
+				},
+			}),
+			Entry("when setting flags", &testOptionsTableInput{
+				configFile: testOptionsConfigBytes,
+				env: map[string]string{
+					"OAUTH2_PROXY_STRING_OPTION":       "bar",
+					"OAUTH2_PROXY_STRING_SLICE_OPTION": "a,b,c",
+				},
+				args: []string{
+					"--string-option", "baz",
+					"--string-slice-option", "a,b,c,d,e",
+				},
+				flagSet: func() *pflag.FlagSet { return testOptionsFlagSet },
+				expectedOutput: &TestOptions{
+					StringOption: "baz",
+					Sub: TestOptionSubStruct{
+						StringSliceOption: []string{"a", "b", "c", "d", "e"},
+					},
+				},
+			}),
+			Entry("when setting flags multiple times", &testOptionsTableInput{
+				configFile: testOptionsConfigBytes,
+				env: map[string]string{
+					"OAUTH2_PROXY_STRING_OPTION":       "bar",
+					"OAUTH2_PROXY_STRING_SLICE_OPTION": "a,b,c",
+				},
+				args: []string{
+					"--string-option", "baz",
+					"--string-slice-option", "x",
+					"--string-slice-option", "y",
+					"--string-slice-option", "z",
+				},
+				flagSet: func() *pflag.FlagSet { return testOptionsFlagSet },
+				expectedOutput: &TestOptions{
+					StringOption: "baz",
+					Sub: TestOptionSubStruct{
+						StringSliceOption: []string{"x", "y", "z"},
+					},
+				},
+			}),
+			Entry("when setting env variables without a config file", &testOptionsTableInput{
+				env: map[string]string{
+					"OAUTH2_PROXY_STRING_OPTION":       "bar",
+					"OAUTH2_PROXY_STRING_SLICE_OPTION": "a,b,c",
+				},
+				flagSet: func() *pflag.FlagSet { return testOptionsFlagSet },
+				expectedOutput: &TestOptions{
+					StringOption: "bar",
+					Sub: TestOptionSubStruct{
+						StringSliceOption: []string{"a", "b", "c"},
+					},
+				},
+			}),
+			Entry("when setting flags without a config file", &testOptionsTableInput{
+				env: map[string]string{
+					"OAUTH2_PROXY_STRING_OPTION":       "bar",
+					"OAUTH2_PROXY_STRING_SLICE_OPTION": "a,b,c",
+				},
+				args: []string{
+					"--string-option", "baz",
+					"--string-slice-option", "a,b,c,d,e",
+				},
+				flagSet: func() *pflag.FlagSet { return testOptionsFlagSet },
+				expectedOutput: &TestOptions{
+					StringOption: "baz",
+					Sub: TestOptionSubStruct{
+						StringSliceOption: []string{"a", "b", "c", "d", "e"},
+					},
+				},
+			}),
+			Entry("when setting flags without a config file", &testOptionsTableInput{
+				env: map[string]string{
+					"OAUTH2_PROXY_STRING_OPTION":       "bar",
+					"OAUTH2_PROXY_STRING_SLICE_OPTION": "a,b,c",
+				},
+				args: []string{
+					"--string-option", "baz",
+					"--string-slice-option", "a,b,c,d,e",
+				},
+				flagSet: func() *pflag.FlagSet { return testOptionsFlagSet },
+				expectedOutput: &TestOptions{
+					StringOption: "baz",
+					Sub: TestOptionSubStruct{
+						StringSliceOption: []string{"a", "b", "c", "d", "e"},
+					},
+				},
+			}),
+			Entry("when nothing is set it should use flag defaults", &testOptionsTableInput{
+				flagSet: func() *pflag.FlagSet { return testOptionsFlagSet },
+				expectedOutput: &TestOptions{
+					StringOption: "default",
+					Sub: TestOptionSubStruct{
+						StringSliceOption: []string{"a", "b"},
+					},
+				},
+			}),
+			Entry("with an invalid config file", &testOptionsTableInput{
+				configFile:     []byte(`slice_option = foo`),
+				flagSet:        func() *pflag.FlagSet { return testOptionsFlagSet },
+				expectedErr:    fmt.Errorf("unable to load config file: While parsing config: (1, 16): never reached"),
+				expectedOutput: &TestOptions{},
+			}),
+			Entry("with an invalid flagset", &testOptionsTableInput{
+				flagSet: func() *pflag.FlagSet {
+					// Missing a flag
+					f := pflag.NewFlagSet("testFlagSet", pflag.ExitOnError)
+					f.String("string-option", "default", "")
+					return f
+				},
+				expectedErr:    fmt.Errorf("unable to register flags: field \"string-slice-option\" does not have a registered flag"),
+				expectedOutput: &TestOptions{},
+			}),
+			Entry("with an struct is missing the squash tag", &testOptionsTableInput{
+				flagSet:        func() *pflag.FlagSet { return testOptionsFlagSet },
+				expectedErr:    fmt.Errorf("unable to register flags: field \".Sub\" does not have required cfg tag: `,squash`"),
+				input:          &MissingSquashTestOptions{},
+				expectedOutput: &MissingSquashTestOptions{},
+			}),
+			Entry("with a field is missing the cfg tag", &testOptionsTableInput{
+				flagSet:        func() *pflag.FlagSet { return testOptionsFlagSet },
+				expectedErr:    fmt.Errorf("unable to register flags: field \".StringOption\" does not have required tags (cfg, flag)"),
+				input:          &MissingCfgTestOptions{},
+				expectedOutput: &MissingCfgTestOptions{},
+			}),
+			Entry("with a field is missing the flag tag", &testOptionsTableInput{
+				flagSet:        func() *pflag.FlagSet { return testOptionsFlagSet },
+				expectedErr:    fmt.Errorf("unable to register flags: field \".StringOption\" does not have required tags (cfg, flag)"),
+				input:          &MissingFlagTestOptions{},
+				expectedOutput: &MissingFlagTestOptions{},
+			}),
+			Entry("with existing unexported fields", &testOptionsTableInput{
+				flagSet: func() *pflag.FlagSet { return testOptionsFlagSet },
+				input: &TestOptions{
+					unexported: "unexported",
+				},
+				expectedOutput: &TestOptions{
+					StringOption: "default",
+					Sub: TestOptionSubStruct{
+						StringSliceOption: []string{"a", "b"},
+					},
+					unexported: "unexported",
+				},
+			}),
+		)
+	})
+})