feat(add): Default public key to <private key>.pub if not given

Author: milkpirate

README.md

@@ -86,28 +86,30 @@ Injects SSL keys to `ssh-agent` stored in 1Password, Bitwarden and AWS S3.
 
 ## How to use it
 
-1. Login to Bitwarden or 1Password with `bw` or `op`. If you are using S3, set your credentials.
+1. Login to Bitwarden (and export its session key) or 1Password with `bw` or `op`. If you are using S3, set your credentials.
 1. Add your key pairs to your password manager.
 
+> **NOTE:** If not public key is given, the private one, postfixed with `.pub`, will be used.
+
 For 1Password
 ---
 
 ```shell
-ssh-manager add --name my-another-server --private-key $PK_PATH --public-key $PUB_KEY_PATH --provider op
+ssh-manager add --name my-another-server --private-key $PK_PATH [ --public-key $PUB_KEY_PATH ] --provider op
 ```
 
 For Bitwarden
 ---
 
 ```shell
-ssh-manager add --name my-server --private-key $PK_PATH --public-key $PUB_KEY_PATH --provider bw
+ssh-manager add --name my-server --private-key $PK_PATH [ --public-key $PUB_KEY_PATH ] --provider bw
 ```
 
 For AWS S3
 ---
 
 ```shell
-ssh-manager add --name my-another-server --private-key $PK_PATH --public-key $PUB_KEY_PATH --provider s3 --bucket my-bucket
+ssh-manager add --name my-another-server --private-key $PK_PATH [ --public-key $PUB_KEY_PATH ] --provider s3 --bucket my-bucket
 ```
 
 ## Improvements to be made

cmd/add.go

@@ -21,10 +21,6 @@ func setupAddCommand(cmd *cobra.Command) {
 
 	cmd.Flags().String("public-key", "", "Public Key file")
 
-	if err := cmd.MarkFlagRequired("public-key"); err != nil {
-		log.Fatalf("Lethal damage: %s\n\n", err)
-	}
-
 	cmd.Flags().String("private-key", "", "Private Key file")
 
 	if err := cmd.MarkFlagRequired("private-key"); err != nil {
@@ -47,10 +43,13 @@ func Add() *cobra.Command {
 		Short: "Add Manager key to given provider.",
 		RunE: func(cmd *cobra.Command, args []string) error {
 			name, _ := cmd.Flags().GetString("name")
-			publicKeyFileName, _ := cmd.Flags().GetString("public-key")
-			privateKeyFileName, _ := cmd.Flags().GetString("private-key")
 			providerName, _ := cmd.Flags().GetString("provider")
 			bucket, _ := cmd.Flags().GetString("bucket")
+			privateKeyFileName, _ := cmd.Flags().GetString("private-key")
+			publicKeyFileName, err := cmd.Flags().GetString("public-key")
+			if err != nil {
+				publicKeyFileName = privateKeyFileName + ".pub"
+			}
 
 			publicKey, err := readFile(publicKeyFileName)
 			if err != nil {