refactor: expose kubeconform as a module

cmd/kubeconform/validate.go

@@ -1,4 +1,4 @@
-package main
+package kubeconform
 
 import (
 	"context"
@@ -15,8 +15,6 @@ import (
 	"github.com/yannh/kubeconform/pkg/validator"
 )
 
-var version = "development"
-
 func processResults(cancel context.CancelFunc, o output.Output, validationResults <-chan validator.Result, exitOnError bool) <-chan bool {
 	success := true
 	result := make(chan bool)
@@ -28,7 +26,7 @@ func processResults(cancel context.CancelFunc, o output.Output, validationResult
 			}
 			if o != nil {
 				if err := o.Write(res); err != nil {
-					fmt.Fprint(os.Stderr, "failed writing log\n")
+					log.Fatal("failed writing log: ", err)
 				}
 			}
 			if !success && exitOnError {
@@ -46,27 +44,19 @@ func processResults(cancel context.CancelFunc, o output.Output, validationResult
 	return result
 }
 
-func realMain() int {
-	cfg, out, err := config.FromFlags(os.Args[0], os.Args[1:])
+func Validate(cfg config.Config, out string) error {
+
 	if out != "" {
-		o := os.Stderr
-		errCode := 1
 		if cfg.Help {
-			o = os.Stdout
-			errCode = 0
+			fmt.Fprintln(cfg.Stream.Output, out)
+			return nil
 		}
-		fmt.Fprintln(o, out)
-		return errCode
+		return fmt.Errorf("config out is not empty")
 	}
 
 	if cfg.Version {
-		fmt.Println(version)
-		return 0
-	}
-
-	if err != nil {
-		fmt.Fprintf(os.Stderr, "failed parsing command line: %s\n", err.Error())
-		return 1
+		fmt.Fprintln(cfg.Stream.Output, out)
+		return nil
 	}
 
 	cpuProfileFile := os.Getenv("KUBECONFORM_CPUPROFILE_FILE")
@@ -93,13 +83,11 @@ func realMain() int {
 		useStdin = true
 	}
 
-	var o output.Output
-	if o, err = output.New(cfg.OutputFormat, cfg.Summary, useStdin, cfg.Verbose); err != nil {
-		fmt.Fprintln(os.Stderr, err)
-		return 1
+	o, err := output.New(cfg.Stream.Output, cfg.OutputFormat, cfg.Summary, useStdin, cfg.Verbose)
+	if err != nil {
+		return fmt.Errorf("failed to get output: %s", err.Error())
 	}
-	var v validator.Validator
-	v, err = validator.New(cfg.SchemaLocations, validator.Opts{
+	v, err := validator.New(cfg.SchemaLocations, validator.Opts{
 		Cache:                cfg.Cache,
 		Debug:                cfg.Debug,
 		SkipTLS:              cfg.SkipTLS,
@@ -110,8 +98,7 @@ func realMain() int {
 		IgnoreMissingSchemas: cfg.IgnoreMissingSchemas,
 	})
 	if err != nil {
-		fmt.Fprintln(os.Stderr, err)
-		return 1
+		return fmt.Errorf("failed to validate: %s", err.Error())
 	}
 
 	validationResults := make(chan validator.Result)
@@ -121,7 +108,7 @@ func realMain() int {
 	var resourcesChan <-chan resource.Resource
 	var errors <-chan error
 	if useStdin {
-		resourcesChan, errors = resource.FromStream(ctx, "stdin", os.Stdin)
+		resourcesChan, errors = resource.FromStream(ctx, "stdin", cfg.Stream.Input)
 	} else {
 		resourcesChan, errors = resource.FromFiles(ctx, cfg.Files, cfg.IgnoreFilenamePatterns)
 	}
@@ -171,12 +158,8 @@ func realMain() int {
 	o.Flush()
 
 	if !success {
-		return 1
+		return fmt.Errorf("failed to process results")
 	}
 
-	return 0
-}
-
-func main() {
-	os.Exit(realMain())
+	return nil
 }

main.go

@@ -0,0 +1,24 @@
+package main
+
+import (
+	"fmt"
+	"os"
+
+	"github.com/yannh/kubeconform/cmd/kubeconform"
+	"github.com/yannh/kubeconform/pkg/config"
+)
+
+var version = "development"
+
+func main() {
+	cfg, out, err := config.FromFlags(os.Args[0], os.Args[1:])
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "failed parsing command line: %s\n", err.Error())
+		os.Exit(1)
+	}
+
+	if err = kubeconform.Validate(cfg, out); err != nil {
+		fmt.Fprintf(os.Stderr, "failed validating resources: %s - %s\n", err.Error(), out)
+		os.Exit(1)
+	}
+}

pkg/config/config.go

@@ -4,9 +4,17 @@ import (
 	"bytes"
 	"flag"
 	"fmt"
+	"io"
+	"os"
 	"strings"
 )
 
+type Stream struct {
+	Input  io.Reader
+	Output io.Writer
+	Error  io.Writer
+}
+
 type Config struct {
 	Cache                  string
 	Debug                  bool
@@ -26,6 +34,7 @@ type Config struct {
 	IgnoreFilenamePatterns []string
 	Help                   bool
 	Version                bool
+	Stream                 *Stream
 }
 
 type arrayParam []string
@@ -62,7 +71,9 @@ func FromFlags(progName string, args []string) (Config, string, error) {
 
 	c := Config{}
 	c.Files = []string{}
+	c.Stream = &Stream{os.Stdin, os.Stdout, os.Stderr}
 
+	flags.SetOutput(c.Stream.Output)
 	flags.StringVar(&c.KubernetesVersion, "kubernetes-version", "master", "version of Kubernetes to validate against, e.g.: 1.18.0")
 	flags.Var(&schemaLocationsParam, "schema-location", "override schemas location search path (can be specified multiple times)")
 	flags.StringVar(&skipKindsCSV, "skip", "", "comma-separated list of kinds or GVKs to ignore")

pkg/output/output.go

@@ -2,7 +2,7 @@ package output
 
 import (
 	"fmt"
-	"os"
+	"io"
 
 	"github.com/yannh/kubeconform/pkg/validator"
 )
@@ -12,9 +12,7 @@ type Output interface {
 	Flush() error
 }
 
-func New(outputFormat string, printSummary, isStdin, verbose bool) (Output, error) {
-	w := os.Stdout
-
+func New(w io.Writer, outputFormat string, printSummary, isStdin, verbose bool) (Output, error) {
 	switch {
 	case outputFormat == "json":
 		return jsonOutput(w, printSummary, isStdin, verbose), nil