rm unauthenticated, rm impossible flag combinations, better err msgs

- The unauthenticated mode no longer exists. The unauthenticated mode caused a
  lot of confusion as it was randomly triggered when missing some flags. Now, if
  you don't provide the required flags, the command will fail with a helpful
  error showing you what you missed.
- I have removed an impossible combination (that did not work): you can
  no longer use `--private-key-path` along with `--credentials-path`.
  Previously, `--private-key-path` would be ignored if
  `--credentials-path` was provided. Now, the two options are mutually
  exclusive and a helpful message is shown when trying to use both.
- The field `uploader_id` in the configuration file is deprecated. Setting this
  field will no longer do anything. A warning is now shown when using this
  field. The reason this field was deprecated is that it was never used by the
  Venafi Cloud API. Behind the scenes, the uploader_id is arbitrarily set to
  `no` so that the API doesn't complain.
- The --private-key-path flag now defaults to the empty string. Previously, it
  defaulted to `/etc/venafi/agent/key/privatekey.pem`. This location wasn't used
  by any of our deployment options, and was confusing to users trying to use
  `--client-id`. A helpful message is now shown when trying to run `--client-id`
  without `--private-key-path`.
- The `--period` flag was required even though the `period` field in the config
  was set. You can now set the period using the `period` field in the config
  file without having to also pass `--period` or `-p`. Note that the `--period`
  flag takes precedence over the config file.

Author: maelvls

cmd/agent.go

@@ -4,10 +4,11 @@ import (
 	"fmt"
 	"os"
 
+	"github.com/spf13/cobra"
+
 	"github.com/jetstack/preflight/pkg/agent"
 	"github.com/jetstack/preflight/pkg/logs"
 	"github.com/jetstack/preflight/pkg/permissions"
-	"github.com/spf13/cobra"
 )
 
 var agentCmd = &cobra.Command{
@@ -39,11 +40,16 @@ var agentRBACCmd = &cobra.Command{
 		if err != nil {
 			logs.Log.Fatalf("Failed to read config file: %s", err)
 		}
-		cfg, err := agent.ParseConfig(b, false)
+		cfg, err := agent.ParseConfig(b)
 		if err != nil {
 			logs.Log.Fatalf("Failed to parse config file: %s", err)
 		}
 
+		err = agent.ValidateDataGatherers(cfg.DataGatherers)
+		if err != nil {
+			logs.Log.Fatalf("Failed to validate data gatherers: %s", err)
+		}
+
 		out := permissions.GenerateFullManifest(cfg.DataGatherers)
 		fmt.Print(out)
 	},

cmd/echo.go

@@ -1,8 +1,9 @@
 package cmd
 
 import (
-	"github.com/jetstack/preflight/pkg/echo"
 	"github.com/spf13/cobra"
+
+	"github.com/jetstack/preflight/pkg/echo"
 )
 
 var echoCmd = &cobra.Command{