feat(cmd): Add vet Command to CLI Tool (#253)

cmd/substation/vet.go

@@ -0,0 +1,194 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"os"
+	"path/filepath"
+	"regexp"
+
+	"github.com/brexhq/substation/v2"
+	"github.com/spf13/cobra"
+)
+
+func init() {
+	rootCmd.AddCommand(vetCmd)
+	vetCmd.PersistentFlags().BoolP("recursive", "R", false, "recursively vet all files")
+	vetCmd.PersistentFlags().StringToString("ext-str", nil, "set external variables")
+}
+
+// vetTransformRe captures the transform ID from a Substation error message.
+// Example: `transform 324f1035-10a51b9a: object_target_key: missing required option` -> `324f1035-10a51b9a`
+var vetTransformRe = regexp.MustCompile(`transform ([a-f0-9-]+):`)
+
+var vetCmd = &cobra.Command{
+	Use:   "vet [path]",
+	Short: "report config errors",
+	Long: `'substation vet' reports errors in configuration files.
+
+The 'recursive' flag can be used to vet all files in a 
+directory, and the current directory is used if no arg is 
+provided.
+
+If an error is found, then the output always includes the
+file path and error message. If the location of the error
+is known, then the output also includes the line number
+where the error occurred.
+
+'vet' checks for two types of errors:
+  - Jsonnet syntax errors
+  - Substation configuration errors
+
+Jsonnet syntax errors look like this, and include the line
+number and column range where the error occurred:
+  vet.jsonnet:19:36-38 Unknown variable: st
+
+    sub.tf.obj.insert({obj: { trg: st.format('%s.-1', 'bar') }, value: 'baz'}),
+
+Substation config errors look like this, and include the
+line number where the error occurred in the 'transforms'
+array:
+  vet.jsonnet:3 transform 324f1035-10a51b9a: object_target_key: missing required option
+
+    {"type":"hash_sha256","settings":{"id":"324f1035-10a51b9a","object":{"source_key":"foo"}}}
+`,
+	// Examples:
+	//  substation vet [-R]
+	//  substation vet [-R] /path/to/configs
+	//  substation vet /path/to/config.json
+	//  substation vet /path/to/config.jsonnet
+	//  substation vet /path/to/my.libsonnet
+	Example: `  substation vet [-R]
+  substation vet [-R] /path/to/configs
+  substation vet /path/to/config.json
+  substation vet /path/to/config.jsonnet
+  substation vet /path/to/my.libsonnet
+`,
+	Args: cobra.MaximumNArgs(1),
+	RunE: func(cmd *cobra.Command, args []string) error {
+		// Default to current directory if no path is provided.
+		path := "."
+		if len(args) > 0 {
+			path = args[0]
+		}
+
+		// Catches an edge case where the user is looking for help.
+		if path == "help" {
+			fmt.Printf("warning: %q matched no files\n", path)
+			return nil
+		}
+
+		extStr, err := cmd.PersistentFlags().GetStringToString("ext-str")
+		if err != nil {
+			return err
+		}
+
+		recursive, err := cmd.Flags().GetBool("recursive")
+		if err != nil {
+			return err
+		}
+
+		return vetPath(path, extStr, recursive)
+	},
+}
+
+func vetFile(arg string, extVars map[string]string) error {
+	// This uses the custom config from the `test` command.
+	var cfg customConfig
+
+	switch filepath.Ext(arg) {
+	case ".jsonnet", ".libsonnet":
+		mem, err := compileFile(arg, extVars)
+		if err != nil {
+			// This is an error in the Jsonnet syntax.
+			// The line number and column range are included.
+			//
+			// Example: `vet.jsonnet:19:36-38 Unknown variable: st`
+			fmt.Printf("%v\n", err)
+
+			return nil
+		}
+
+		cfg, err = memConfig(mem)
+		if err != nil {
+			return err
+		}
+	case ".json":
+		fi, err := fiConfig(arg)
+		if err != nil {
+			return err
+		}
+
+		cfg = fi
+	}
+
+	ctx := context.Background() // This doesn't need to be canceled.
+	if _, err := substation.New(ctx, cfg.Config); err != nil {
+		r := vetTransformRe.FindStringSubmatch(err.Error())
+
+		// Cannot determine which transform failed. This should almost
+		// never happen, unless something has modified the configuration
+		// after it was compiled by Jsonnet.
+		if len(r) == 0 {
+			// Substation uses the transform name as a static transform ID.
+			//
+			// Example: `vet.json: transform hash_sha256: object_target_key: missing required option``
+			fmt.Printf("%s: %v\n", arg, err)
+
+			return nil
+		}
+
+		tfID := r[1] // The transform ID (e.g., `324f1035-10a51b9a`).
+		for idx, tf := range cfg.Config.Transforms {
+			if tf.Settings["id"] == tfID {
+				// Example: `vet.jsonnet:3 transform 324f1035-10a51b9a: object_target_key: missing required option``
+				fmt.Printf("%s:%d %v\n", arg, idx+1, err) // The line number is 1-based.
+				fmt.Printf("\n    %s\n\n", tf)
+
+				return nil
+			}
+		}
+	}
+
+	// No errors were found.
+	//
+	// Example: `vet.jsonnet`
+	fmt.Printf("%s\n", arg)
+	return nil
+}
+
+func vetPath(arg string, extVars map[string]string, recursive bool) error {
+	fi, err := os.Stat(arg)
+	if err != nil {
+		return err
+	}
+
+	if !fi.IsDir() {
+		return vetFile(arg, extVars)
+	}
+
+	if err := filepath.WalkDir(arg, func(path string, d os.DirEntry, err error) error {
+		if err != nil {
+			return err
+		}
+
+		if d.IsDir() {
+			if !recursive && path != arg {
+				return filepath.SkipDir
+			}
+
+			return nil
+		}
+
+		ext := filepath.Ext(path)
+		if ext != ".jsonnet" && ext != ".libsonnet" && ext != ".json" {
+			return nil
+		}
+
+		return vetFile(path, extVars)
+	}); err != nil {
+		return err
+	}
+
+	return nil
+}

config/config.go

@@ -1,6 +1,10 @@
 // Package config provides structures for building configurations.
 package config
 
+import (
+	"encoding/json"
+)
+
 // Config is a template used by Substation interface factories to produce new
 // instances. Type refers to the type of instance and Settings contains options
 // used in the instance. Examples of this are found in the condition and transforms
@@ -9,3 +13,8 @@ type Config struct {
 	Type     string                 `json:"type"`
 	Settings map[string]interface{} `json:"settings"`
 }
+
+func (c Config) String() string {
+	b, _ := json.Marshal(c)
+	return string(b)
+}