NO_LOGIN docs & default settings

README.md

@@ -34,6 +34,9 @@ The following environment variables can be set:
  * `USER_PROMPT` - Sets the default action for user prompts (non-error)
   * `true` - (_Default_) Prompts user for input/validation
   * `false` - Skips user prompt and automatically proceeds
+ * `NO_LOGIN`
+  * `true` - Skips `docker login` for the v1 and v2 registries
+  * `false` - (_Default_) Prompts user to login to the v1 and v2 registries
  * `V1_REPO_FILTER` - Search filter to limit the scope of the repositories to migrate (uses [grep basic regular expression interpretation](http://www.gnu.org/software/grep/manual/html_node/Basic-vs-Extended.html))
   * *Note*: This only filters the repositories returned from the v1 search API, not the individual tags
  * `V1_USERNAME` - Username used for `docker login` to the v1 registry

migrator.sh

@@ -26,6 +26,9 @@ initialize_migrator() {
 
   # set default to prompt user for validation
   USER_PROMPT=${USER_PROMPT:-true}
+
+  # set default to require docker login
+  NO_LOGIN=${NO_LOGIN:-false}
 }
 
 # verify requirements met for script to execute properly