Add cli package with envconfig parser

Makefile

@@ -10,8 +10,6 @@ license-check:
 	licensed cache
 	licensed status
 
-
-
 .PHONY: help
 help:
 	@grep -E '^[a-zA-Z_-]+:.*?## .*$$' $(MAKEFILE_LIST) | sort | awk 'BEGIN {FS = ":.*?## "}; {printf "\033[36m%-30s\033[0m %s\n", $$1, $$2}'

cli/envconfig.go

@@ -0,0 +1,34 @@
+package cli
+
+import (
+	"github.com/kelseyhightower/envconfig"
+	"github.com/spf13/pflag"
+)
+
+// EnvconfigProcessWithPflags can be used to run envconfig.Process without stomping on flags
+// passed to the command line, since explicit flags should take precedence over the environment.
+func EnvconfigProcessWithPflags(prefix string, flags *pflag.FlagSet, obj any) error {
+	// discover all non-default flags before processing envconfig
+	var changedFlags = map[string]string{}
+
+	flags.VisitAll(func(f *pflag.Flag) {
+		// only include non-default flags
+		if f.Changed {
+			changedFlags[f.Name] = f.Value.String()
+		}
+	})
+
+	// apply envconfig values
+	if err := envconfig.Process(prefix, obj); err != nil {
+		return err
+	}
+
+	// re-apply changed flags to override environment
+	for name, value := range changedFlags {
+		if err := flags.Lookup(name).Value.Set(value); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}

cli/envconfig_test.go

@@ -0,0 +1,160 @@
+package cli_test
+
+import (
+	"os"
+	"testing"
+
+	"github.com/kanopy-platform/go-library/cli"
+	"github.com/spf13/cobra"
+	"github.com/stretchr/testify/assert"
+)
+
+type testCLI struct {
+	String           string
+	Int              int
+	SubString        string `split_words:"true"`
+	OverrideFlagRoot string `split_words:"true"`
+	OverrideFlagSub  string `split_words:"true"`
+}
+
+func (c *testCLI) RootCmd() *cobra.Command {
+	emptyRun := func(_ *cobra.Command, _ []string) {}
+
+	root := &cobra.Command{
+		Use: "root",
+		Run: emptyRun,
+		PersistentPreRunE: func(cmd *cobra.Command, _ []string) error {
+			return cli.EnvconfigProcessWithPflags("APP", cmd.Flags(), c)
+		},
+	}
+
+	root.PersistentFlags().StringVar(&c.String, "string", "default", "")
+	root.PersistentFlags().IntVar(&c.Int, "int", 1, "")
+	root.PersistentFlags().StringVar(&c.OverrideFlagRoot, "override", "root", "")
+
+	sub := &cobra.Command{Use: "sub", Run: emptyRun}
+	sub.Flags().StringVar(&c.SubString, "substring", "default", "")
+	sub.PersistentFlags().StringVar(&c.OverrideFlagSub, "override", "sub", "")
+
+	root.AddCommand(sub)
+
+	return root
+}
+
+// checks that the correct order of precedence is adhered to: flag > env > default
+func TestPrecedence(t *testing.T) {
+	tests := []struct {
+		desc string
+		env  map[string]string
+		args []string
+		want testCLI
+	}{
+		{
+			desc: "test root defaults",
+			want: testCLI{
+				String:           "default",
+				Int:              1,
+				SubString:        "default",
+				OverrideFlagRoot: "root",
+				OverrideFlagSub:  "sub",
+			},
+		},
+		{
+			desc: "test root override",
+			args: []string{"--override=flag"},
+			want: testCLI{
+				String:           "default",
+				Int:              1,
+				SubString:        "default",
+				OverrideFlagRoot: "flag",
+				OverrideFlagSub:  "sub",
+			},
+		},
+		{
+			desc: "test sub defaults",
+			args: []string{"sub"},
+			want: testCLI{
+				String:           "default",
+				Int:              1,
+				SubString:        "default",
+				OverrideFlagRoot: "root",
+				OverrideFlagSub:  "sub",
+			},
+		},
+		{
+			desc: "test sub env",
+			args: []string{"sub"},
+			env: map[string]string{
+				"APP_STRING":            "env",
+				"APP_INT":               "2",
+				"APP_SUB_STRING":        "env",
+				"APP_OVERRIDE_FLAG_SUB": "env",
+			},
+			want: testCLI{
+				String:           "env",
+				Int:              2,
+				SubString:        "env",
+				OverrideFlagRoot: "root",
+				OverrideFlagSub:  "env",
+			},
+		},
+		{
+			desc: "test sub flags",
+			args: []string{
+				"sub",
+				"--string=flag",
+				"--int=3",
+				"--substring=flag",
+				"--override=flag",
+			},
+			want: testCLI{
+				String:           "flag",
+				Int:              3,
+				SubString:        "flag",
+				OverrideFlagRoot: "root",
+				OverrideFlagSub:  "flag",
+			},
+		},
+		{
+			desc: "test sub flags > env",
+			env: map[string]string{
+				"APP_STRING":             "env",
+				"APP_INT":                "2",
+				"APP_SUB_STRING":         "env",
+				"APP_OVERRIDE_FLAG_ROOT": "env",
+				"APP_OVERRIDE_FLAG_SUB":  "env",
+			},
+			args: []string{
+				"sub",
+				"--string=flag",
+				"--int=3",
+				"--substring=flag",
+				"--override=flag",
+			},
+			want: testCLI{
+				String:           "flag",
+				Int:              3,
+				SubString:        "flag",
+				OverrideFlagRoot: "env",
+				OverrideFlagSub:  "flag",
+			},
+		},
+	}
+
+	for _, test := range tests {
+		for k, v := range test.env {
+			assert.NoError(t, os.Setenv(k, v))
+		}
+
+		cli := &testCLI{}
+		cmd := cli.RootCmd()
+		cmd.SetArgs(test.args)
+		assert.NoError(t, cmd.Execute())
+
+		assert.Equal(t, test.want, *cli, test.desc)
+
+		for k := range test.env {
+			assert.NoError(t, os.Unsetenv(k))
+		}
+	}
+}

go.mod

@@ -3,13 +3,17 @@ module github.com/kanopy-platform/go-library
 go 1.23.0
 
 require (
+	github.com/kelseyhightower/envconfig v1.4.0
 	github.com/sirupsen/logrus v1.9.3
+	github.com/spf13/cobra v1.8.1
+	github.com/spf13/pflag v1.0.6
 	github.com/stretchr/testify v1.10.0
 )
 
 require (
-	github.com/davecgh/go-spew v1.1.1 // indirect
-	github.com/pmezard/go-difflib v1.0.0 // indirect
-	golang.org/x/sys v0.0.0-20220715151400-c0bba94af5f8 // indirect
+	github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc // indirect
+	github.com/inconshreveable/mousetrap v1.1.0 // indirect
+	github.com/pmezard/go-difflib v1.0.1-0.20181226105442-5d4384ee4fb2 // indirect
+	golang.org/x/sys v0.27.0 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect
 )

go.sum

@@ -1,16 +1,30 @@
+github.com/cpuguy83/go-md2man/v2 v2.0.4/go.mod h1:tgQtvFlXSQOSOSIRvRPT7W67SCa46tRHOmNcaadrF8o=
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
-github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
-github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc h1:U9qPSI2PIWSS1VwoXQT9A3Wy9MM3WgvqSxFWenqJduM=
+github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/inconshreveable/mousetrap v1.1.0 h1:wN+x4NVGpMsO7ErUn/mUI3vEoE6Jt13X2s0bqwp9tc8=
+github.com/inconshreveable/mousetrap v1.1.0/go.mod h1:vpF70FUmC8bwa3OWnCshd2FqLfsEA9PFc4w1p2J65bw=
+github.com/kelseyhightower/envconfig v1.4.0 h1:Im6hONhd3pLkfDFsbRgu68RDNkGF1r3dvMUtDTo2cv8=
+github.com/kelseyhightower/envconfig v1.4.0/go.mod h1:cccZRl6mQpaq41TPp5QxidR+Sa3axMbJDNb//FQX6Gg=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/pmezard/go-difflib v1.0.1-0.20181226105442-5d4384ee4fb2 h1:Jamvg5psRIccs7FGNTlIRMkT8wgtp5eCXdBlqhYGL6U=
+github.com/pmezard/go-difflib v1.0.1-0.20181226105442-5d4384ee4fb2/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/russross/blackfriday/v2 v2.1.0/go.mod h1:+Rmxgy9KzJVeS9/2gXHxylqXiyQDYRxCVz55jmeOWTM=
 github.com/sirupsen/logrus v1.9.3 h1:dueUQJ1C2q9oE3F7wvmSGAaVtTmUizReu6fjN8uqzbQ=
 github.com/sirupsen/logrus v1.9.3/go.mod h1:naHLuLoDiP4jHNo9R0sCBMtWGeIprob74mVsIT4qYEQ=
+github.com/spf13/cobra v1.8.1 h1:e5/vxKd/rZsfSJMUX1agtjeTDf+qv1/JdBF8gg5k9ZM=
+github.com/spf13/cobra v1.8.1/go.mod h1:wHxEcudfqmLYa8iTfL+OuZPbBZkmvliBWKIezN3kD9Y=
+github.com/spf13/pflag v1.0.5/go.mod h1:McXfInJRrz4CZXVZOBLb0bTZqETkiAhM9Iw0y3An2Bg=
+github.com/spf13/pflag v1.0.6 h1:jFzHGLGAlb3ruxLB8MhbI6A8+AQX/2eW4qeyNZXNp2o=
+github.com/spf13/pflag v1.0.6/go.mod h1:McXfInJRrz4CZXVZOBLb0bTZqETkiAhM9Iw0y3An2Bg=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
 github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
 github.com/stretchr/testify v1.10.0 h1:Xv5erBjTwe/5IxqUQTdXv5kgmIvbHo3QQyRwhJsOfJA=
 github.com/stretchr/testify v1.10.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
-golang.org/x/sys v0.0.0-20220715151400-c0bba94af5f8 h1:0A+M6Uqn+Eje4kHMK80dtF3JCXC4ykBgQG4Fe06QRhQ=
 golang.org/x/sys v0.0.0-20220715151400-c0bba94af5f8/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.27.0 h1:wBqf8DvsY9Y/2P8gAfPDEYNuS30J4lPHJxXSb/nJZ+s=
+golang.org/x/sys v0.27.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=