feat: add support for config struct validate tags (#1015)

config/config.go

@@ -2,13 +2,15 @@ package config
 
 import (
 	"bytes"
+	"errors"
 	"fmt"
 	"io"
 	"os"
 	"path/filepath"
 	"strings"
 	"text/template"
 
+	"github.com/go-playground/validator/v10"
 	"github.com/mitchellh/mapstructure"
 	"github.com/spf13/viper"
 )
@@ -47,7 +49,6 @@ func WithConfigYamlDir[T any](dir string) ConfigOption[T] {
 func LoadConfiguration[T any](cfg *T, opts ...ConfigOption[T]) error {
 	configYamlDir := defaultConfigYamlDir
 	if len(os.Getenv("CONFIG_YAML_DIRECTORY")) > 0 {
-		fmt.Println("CONFIG_YAML_DIRECTORY", os.Getenv("CONFIG_YAML_DIRECTORY"))
 		configYamlDir = os.Getenv("CONFIG_YAML_DIRECTORY")
 	}
 
@@ -72,7 +73,7 @@ func LoadConfiguration[T any](cfg *T, opts ...ConfigOption[T]) error {
 		}
 	}
 
-	return nil
+	return validateConfiguration(cfg)
 }
 
 func (c *ConfigLoader[T]) populateConfiguration(cfg *T) error {
@@ -170,7 +171,7 @@ func evaluateConfigWithEnv(configFile io.Reader, writers ...io.Writer) (io.Reade
 		return nil, fmt.Errorf("unable to read the config file: %w", err)
 	}
 
-	t := template.New("appConfigTemplate")
+	t := template.New("appConfigTemplate").Option("missingkey=zero")
 	tmpl, err := t.Parse(string(b))
 	if err != nil {
 		return nil, fmt.Errorf("unable to parse template from: \n%s: %w", string(b), err)
@@ -193,3 +194,15 @@ func getAppEnv() string {
 	}
 	return env
 }
+
+func validateConfiguration[T any](cfg *T) error {
+	validate := validator.New()
+	err := validate.Struct(*cfg)
+	if err != nil {
+		errSlice := &validator.ValidationErrors{}
+		errors.As(err, errSlice)
+		return errSlice
+	}
+
+	return nil
+}

config/config_test.go

@@ -23,7 +23,7 @@ func TestEnvToMap(t *testing.T) {
 	r.Contains(m, "ENV2")
 }
 
-func TesEvaluateConfigWithEnv(t *testing.T) {
+func TestEvaluateConfigWithEnv(t *testing.T) {
 	r := require.New(t)
 	test := `blah={{.ENV1}}
 blah2={{.ENV2}}`
@@ -39,3 +39,114 @@ blah2=test2`
 	r.NoError(err)
 	r.Equal(expected, string(b))
 }
+
+func TestEvaluateConfigWithMissingEnv(t *testing.T) {
+	r := require.New(t)
+	test := `blah={{.ENV1}}
+blah2={{.ENV2}}`
+	os.Setenv("ENV1", "test1")
+	defer os.Unsetenv("ENV1")
+
+	eval, err := evaluateConfigWithEnv(strings.NewReader(test))
+	r.NoError(err)
+	expected := `blah=test1
+blah2=`
+	b, err := io.ReadAll(eval)
+	r.NoError(err)
+	r.Equal(expected, string(b))
+}
+
+type nestedConfig struct {
+	Value1 string `json:"value1"`
+}
+
+type testConfig struct {
+	Value1 string       `json:"value1"`
+	Value2 string       `json:"value2"`
+	Nested nestedConfig `json:"nested"`
+}
+
+func TestLoadConfigurationBasic(t *testing.T) {
+	r := require.New(t)
+
+	cfg := &testConfig{}
+	err := LoadConfiguration(cfg, WithConfigYamlDir[testConfig]("./testData/basic"))
+	r.NoError(err)
+
+	r.Equal("foo", cfg.Value1)
+	r.Equal("bar", cfg.Value2)
+	r.Equal("zap", cfg.Nested.Value1)
+}
+
+func TestLoadConfigurationOverlay(t *testing.T) {
+	r := require.New(t)
+
+	// Set the deployment stage to test so it overlays the app-config.test.yaml file
+	os.Setenv("DEPLOYMENT_STAGE", "test")
+	defer os.Unsetenv("DEPLOYMENT_STAGE")
+
+	cfg := &testConfig{}
+	err := LoadConfiguration(cfg, WithConfigYamlDir[testConfig]("./testData/overlay"))
+	r.NoError(err)
+
+	r.Equal("testval1", cfg.Value1)
+	r.Equal("testval2", cfg.Value2)
+	r.Equal("zap", cfg.Nested.Value1)
+}
+
+type validatedConfig struct {
+	Value1 string `json:"value1" validate:"required"`
+	Value2 string `json:"value2" validate:"required"`
+	Value3 string `json:"value3"`
+}
+
+// this should fail because the values are missing from the yaml file
+func TestLoadConfigurationValidatedFail(t *testing.T) {
+	r := require.New(t)
+
+	cfg := &validatedConfig{}
+	err := LoadConfiguration(cfg, WithConfigYamlDir[validatedConfig]("./testData/validation"))
+	r.Error(err)
+
+	r.Contains(err.Error(), "Value1")
+	r.Contains(err.Error(), "Value2")
+	r.Equal("zap", cfg.Value3)
+}
+
+// this should succeed because the values are supplied by the editor function
+func TestLoadConfigurationValidatedSucceedWithConfigEditor(t *testing.T) {
+	r := require.New(t)
+
+	cfg := &validatedConfig{}
+	err := LoadConfiguration(
+		cfg,
+		WithConfigYamlDir[validatedConfig]("./testData/validation"),
+		WithConfigEditorFn(func(cfg *validatedConfig) error {
+			cfg.Value1 = "edited-value1"
+			cfg.Value2 = "edited-value2"
+			return nil
+		}),
+	)
+	r.NoError(err)
+
+	r.Equal("edited-value1", cfg.Value1)
+	r.Equal("edited-value2", cfg.Value2)
+	r.Equal("zap", cfg.Value3)
+}
+
+// this should succeed because the values are supplied by the overlay file
+func TestLoadConfigurationValidatedSucceedWithOverlay(t *testing.T) {
+	r := require.New(t)
+
+	// Set the deployment stage to test so it overlays the app-config.test.yaml file
+	os.Setenv("DEPLOYMENT_STAGE", "withvalues")
+	defer os.Unsetenv("DEPLOYMENT_STAGE")
+
+	cfg := &validatedConfig{}
+	err := LoadConfiguration(cfg, WithConfigYamlDir[validatedConfig]("./testData/validation"))
+	r.NoError(err)
+
+	r.Equal("foo", cfg.Value1)
+	r.Equal("bar", cfg.Value2)
+	r.Equal("zap", cfg.Value3)
+}

config/go.mod

@@ -1,8 +1,9 @@
 module github.com/chanzuckerberg/go-misc/config/v2
 
-go 1.21.1
+go 1.21
 
 require (
+	github.com/go-playground/validator/v10 v10.19.0
 	github.com/mitchellh/mapstructure v1.5.0
 	github.com/spf13/viper v1.18.2
 	github.com/stretchr/testify v1.8.4
@@ -11,7 +12,11 @@ require (
 require (
 	github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc // indirect
 	github.com/fsnotify/fsnotify v1.7.0 // indirect
+	github.com/gabriel-vasile/mimetype v1.4.3 // indirect
+	github.com/go-playground/locales v0.14.1 // indirect
+	github.com/go-playground/universal-translator v0.18.1 // indirect
 	github.com/hashicorp/hcl v1.0.0 // indirect
+	github.com/leodido/go-urn v1.4.0 // indirect
 	github.com/magiconair/properties v1.8.7 // indirect
 	github.com/pelletier/go-toml/v2 v2.1.0 // indirect
 	github.com/pmezard/go-difflib v1.0.1-0.20181226105442-5d4384ee4fb2 // indirect
@@ -24,8 +29,10 @@ require (
 	github.com/subosito/gotenv v1.6.0 // indirect
 	go.uber.org/atomic v1.9.0 // indirect
 	go.uber.org/multierr v1.9.0 // indirect
+	golang.org/x/crypto v0.19.0 // indirect
 	golang.org/x/exp v0.0.0-20230905200255-921286631fa9 // indirect
-	golang.org/x/sys v0.15.0 // indirect
+	golang.org/x/net v0.21.0 // indirect
+	golang.org/x/sys v0.17.0 // indirect
 	golang.org/x/text v0.14.0 // indirect
 	gopkg.in/ini.v1 v1.67.0 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect

config/go.sum

@@ -6,6 +6,16 @@ github.com/frankban/quicktest v1.14.6 h1:7Xjx+VpznH+oBnejlPUj8oUpdxnVs4f8XU8WnHk
 github.com/frankban/quicktest v1.14.6/go.mod h1:4ptaffx2x8+WTWXmUCuVU6aPUX1/Mz7zb5vbUoiM6w0=
 github.com/fsnotify/fsnotify v1.7.0 h1:8JEhPFa5W2WU7YfeZzPNqzMP6Lwt7L2715Ggo0nosvA=
 github.com/fsnotify/fsnotify v1.7.0/go.mod h1:40Bi/Hjc2AVfZrqy+aj+yEI+/bRxZnMJyTJwOpGvigM=
+github.com/gabriel-vasile/mimetype v1.4.3 h1:in2uUcidCuFcDKtdcBxlR0rJ1+fsokWf+uqxgUFjbI0=
+github.com/gabriel-vasile/mimetype v1.4.3/go.mod h1:d8uq/6HKRL6CGdk+aubisF/M5GcPfT7nKyLpA0lbSSk=
+github.com/go-playground/assert/v2 v2.2.0 h1:JvknZsQTYeFEAhQwI4qEt9cyV5ONwRHC+lYKSsYSR8s=
+github.com/go-playground/assert/v2 v2.2.0/go.mod h1:VDjEfimB/XKnb+ZQfWdccd7VUvScMdVu0Titje2rxJ4=
+github.com/go-playground/locales v0.14.1 h1:EWaQ/wswjilfKLTECiXz7Rh+3BjFhfDFKv/oXslEjJA=
+github.com/go-playground/locales v0.14.1/go.mod h1:hxrqLVvrK65+Rwrd5Fc6F2O76J/NuW9t0sjnWqG1slY=
+github.com/go-playground/universal-translator v0.18.1 h1:Bcnm0ZwsGyWbCzImXv+pAJnYK9S473LQFuzCbDbfSFY=
+github.com/go-playground/universal-translator v0.18.1/go.mod h1:xekY+UJKNuX9WP91TpwSH2VMlDf28Uj24BCp08ZFTUY=
+github.com/go-playground/validator/v10 v10.19.0 h1:ol+5Fu+cSq9JD7SoSqe04GMI92cbn0+wvQ3bZ8b/AU4=
+github.com/go-playground/validator/v10 v10.19.0/go.mod h1:dbuPbCMFw/DrkbEynArYaCwl3amGuJotoKCe95atGMM=
 github.com/google/go-cmp v0.5.9 h1:O2Tfq5qg4qc4AmwVlvv0oLiVAGB7enBSJ2x2DqQFi38=
 github.com/google/go-cmp v0.5.9/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
 github.com/hashicorp/hcl v1.0.0 h1:0Anlzjpi4vEasTeNFn2mLJgTSwt0+6sfsiTG8qcWGx4=
@@ -14,6 +24,8 @@ github.com/kr/pretty v0.3.1 h1:flRD4NNwYAUpkphVc1HcthR4KEIFJ65n8Mw5qdRn3LE=
 github.com/kr/pretty v0.3.1/go.mod h1:hoEshYVHaxMs3cyo3Yncou5ZscifuDolrwPKZanG3xk=
 github.com/kr/text v0.2.0 h1:5Nx0Ya0ZqY2ygV366QzturHI13Jq95ApcVaJBhpS+AY=
 github.com/kr/text v0.2.0/go.mod h1:eLer722TekiGuMkidMxC/pM04lWEeraHUUmBw8l2grE=
+github.com/leodido/go-urn v1.4.0 h1:WT9HwE9SGECu3lg4d/dIA+jxlljEa1/ffXKmRjqdmIQ=
+github.com/leodido/go-urn v1.4.0/go.mod h1:bvxc+MVxLKB4z00jd1z+Dvzr47oO32F/QSNjSBOlFxI=
 github.com/magiconair/properties v1.8.7 h1:IeQXZAiQcpL9mgcAe1Nu6cX9LLw6ExEHKjN0VQdvPDY=
 github.com/magiconair/properties v1.8.7/go.mod h1:Dhd985XPs7jluiymwWYZ0G4Z61jb3vdS329zhj2hYo0=
 github.com/mitchellh/mapstructure v1.5.0 h1:jeMsZIYE/09sWLaz43PL7Gy6RuMjD2eJVyuac5Z2hdY=
@@ -53,10 +65,14 @@ go.uber.org/atomic v1.9.0 h1:ECmE8Bn/WFTYwEW/bpKD3M8VtR/zQVbavAoalC1PYyE=
 go.uber.org/atomic v1.9.0/go.mod h1:fEN4uk6kAWBTFdckzkM89CLk9XfWZrxpCo0nPH17wJc=
 go.uber.org/multierr v1.9.0 h1:7fIwc/ZtS0q++VgcfqFDxSBZVv/Xo49/SYnDFupUwlI=
 go.uber.org/multierr v1.9.0/go.mod h1:X2jQV1h+kxSjClGpnseKVIxpmcjrj7MNnI0bnlfKTVQ=
+golang.org/x/crypto v0.19.0 h1:ENy+Az/9Y1vSrlrvBSyna3PITt4tiZLf7sgCjZBX7Wo=
+golang.org/x/crypto v0.19.0/go.mod h1:Iy9bg/ha4yyC70EfRS8jz+B6ybOBKMaSxLj6P6oBDfU=
 golang.org/x/exp v0.0.0-20230905200255-921286631fa9 h1:GoHiUyI/Tp2nVkLI2mCxVkOjsbSXD66ic0XW0js0R9g=
 golang.org/x/exp v0.0.0-20230905200255-921286631fa9/go.mod h1:S2oDrQGGwySpoQPVqRShND87VCbxmc6bL1Yd2oYrm6k=
-golang.org/x/sys v0.15.0 h1:h48lPFYpsTvQJZF4EKyI4aLHaev3CxivZmv7yZig9pc=
-golang.org/x/sys v0.15.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
+golang.org/x/net v0.21.0 h1:AQyQV4dYCvJ7vGmJyKki9+PBdyvhkSd8EIx/qb0AYv4=
+golang.org/x/net v0.21.0/go.mod h1:bIjVDfnllIU7BJ2DNgfnXvpSvtn8VRwhlsaeUTyUS44=
+golang.org/x/sys v0.17.0 h1:25cE3gD+tdBA7lp7QfhuV+rJiE9YXTcS3VG1SqssI/Y=
+golang.org/x/sys v0.17.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
 golang.org/x/text v0.14.0 h1:ScX5w1eTa3QqT8oi6+ziP7dTV1S2+ALU0bI+0zXKWiQ=
 golang.org/x/text v0.14.0/go.mod h1:18ZOQIKpY8NJVqYksKHtTdi31H5itFRjB5/qKTNYzSU=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=

config/testData/basic/app-config.yaml

@@ -0,0 +1,4 @@
+value1: foo
+value2: bar
+nested:
+  value1: zap

config/testData/overlay/app-config.test.yaml

@@ -0,0 +1,2 @@
+value1: testval1
+value2: testval2

config/testData/overlay/app-config.yaml

@@ -0,0 +1,3 @@
+value1: foo
+nested:
+  value1: zap

config/testData/validation/app-config.withvalues.yaml

@@ -0,0 +1,4 @@
+value1: foo
+value2: bar
+value3: zap
+

config/testData/validation/app-config.yaml

@@ -0,0 +1 @@
+value3: zap