feat: Command that generates a private key with well known params.

internal/clis/hmpki/generate.go

@@ -0,0 +1,28 @@
+package hmpki
+
+import (
+	"github.com/spf13/cobra"
+)
+
+var Output string
+
+func init() {
+	rootCmd.AddCommand(generateCmd)
+
+	// All "generate" commands output an artifact to a file,
+	// be it a key or a cert, etc.
+	generateCmd.PersistentFlags().StringVarP(
+		&Output,
+		"output",
+		"o",
+		"",
+		"output filename",
+	)
+	generateCmd.MarkPersistentFlagRequired("output")
+	generateCmd.MarkPersistentFlagFilename("output")
+}
+
+var generateCmd = &cobra.Command{
+	Use:   "generate",
+	Short: "Generate pki resources (keys/certs)",
+}

internal/clis/hmpki/generate_key.go

@@ -0,0 +1,56 @@
+package hmpki
+
+import (
+	"crypto/ecdsa"
+	"crypto/elliptic"
+	"crypto/rand"
+	"crypto/x509"
+	"encoding/pem"
+	"os"
+
+	"git.handmadecities.com/HMC/shhh/pkg/pki"
+	"github.com/spf13/cobra"
+)
+
+func init() {
+	generateCmd.AddCommand(generateKeyCmd)
+}
+
+var generateKeyCmd = &cobra.Command{
+	Use:   "key",
+	Short: "Generate a private key and save it to a file",
+	RunE: func(cmd *cobra.Command, args []string) error {
+		priv, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
+		if err != nil {
+			return err
+		}
+
+		der, err := x509.MarshalPKCS8PrivateKey(priv)
+		if err != nil {
+			return err
+		}
+
+		pemBytes := pem.EncodeToMemory(&pem.Block{
+			Type:  "PRIVATE KEY",
+			Bytes: der,
+		})
+
+		kf, err := os.OpenFile(
+			Output,
+			// Write only, and fail if it alreay exists.
+			os.O_WRONLY|os.O_CREATE|os.O_EXCL,
+			pki.PrivateKeyFilePerms,
+		)
+		if err != nil {
+			return err
+		}
+		if _, err = kf.Write(pemBytes); err != nil {
+			return err
+		}
+		if err = kf.Close(); err != nil {
+			return err
+		}
+
+		return nil
+	},
+}

internal/clis/hmpki/rootcmd.go

@@ -0,0 +1,29 @@
+package hmpki
+
+import (
+	"fmt"
+	"os"
+
+	"github.com/spf13/cobra"
+)
+
+// Get a root cobra command going, then code for generating:
+// - Generate CA key
+// - Generate CA cert
+// - Generate server cert/key
+// - Generate client cert/key
+
+var rootCmd = &cobra.Command{
+	Use:   "hmpki",
+	Short: "Generate keys/certs with set roles for mTLS auth between services",
+	// Run: func(cmd *cobra.Command, args []string) {
+	// 	fmt.Println("I'm a cobra command!")
+	// },
+}
+
+func Execute() {
+	if err := rootCmd.Execute(); err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		os.Exit(1)
+	}
+}