Add credentials via environment variable.

README.md

@@ -68,6 +68,14 @@ Variable Name             | Default          | Notes
 `BRANCH         `         | N/A (Optional) | Branch to fetch manifest from and open pull requests against.
 `PULL_REQUESTS_ASSIGNEE`  | N/A (Optional) | User to assign to the created pull request.
 `OPTIONS`                 | `{}`           | JSON options to customize the operation of Dependabot
+`CREDENTIALS`             | `[]`            | JSON array containing credentials that can be used to specify what additional resources Dependabot can access and how it can access them.
+
+The content of both the OPTIONS and CREDENTIALS variables depend on the selected package manager. For example, when using "maven", the CREDENTIALS variable can be used to specify an
+additional repository or to completely replace the default maven central repository with a custom one:
+
+```shell
+export CREDENTIALS='[{"type": "maven_repository", "url": "https://example.com/maven", "replaces-base": true}]'
+```
 
 There are other variables that you must pass to your container that will depend on the Git source you use:
 

generic-update-script.rb

@@ -10,14 +10,15 @@
 require "gitlab"
 require "json"
 
-credentials = [
-  {
-    "type" => "git_source",
-    "host" => "github.com",
-    "username" => "x-access-token",
-    "password" => ENV["GITHUB_ACCESS_TOKEN"] # A GitHub access token with read access to public repos
-  }
-]
+# Get optional credentials from the environment variable called CREDENTIALS (json array).
+credentials = JSON.parse(ENV["CREDENTIALS"] || "[]")
+
+credentials << {
+  "type" => "git_source",
+  "host" => "github.com",
+  "username" => "x-access-token",
+  "password" => ENV["GITHUB_ACCESS_TOKEN"] # A GitHub access token with read access to public repos
+}
 
 # Full name of the repo you want to create pull requests for.
 repo_name = ENV["PROJECT_PATH"] # namespace/project