feat: add documentation for Plugin Store Authentication

products/paas/shopware/fundamentals/plugins-store-authentication.md

@@ -0,0 +1,49 @@
+---
+nav:
+  title: Plugin Store Authentication
+  position: 100
+---
+
+# Plugin Store Authentication
+The build process might needs to authentication against plugins stores (Shopware official and any other one), this document explain how configure this authentication.
+
+We rely on `composer` to fecth plugin during build time configured with two environment variables: `SHOPWARE_PACKAGES_TOKEN` and `COMPOSER_AUTH`.
+
+## Shopware plugin store
+Under normal circumstances, during the provisioning of your organization we automatically create the secret `SHOPWARE_PACKAGES_TOKEN`.
+This secret contains the token to authenticate against the official Shopware plugin store.
+
+If this secret is not present you can recreate it:
+```
+sw-paas vault create --type buildenv --key SHOPWARE_PACKAGES_TOKEN
+```
+Then just put the token provided by Shopware.
+
+## Third party plugin store
+To authenticate against third party plugin store or plugin repository you need to create a secret named `COMPOSER_AUTH`.
+The content need to be the json string required for the store/repository, run the following command:
+```
+sw-paas vault create --type buildenv --key COMPOSER_AUTH
+```
+
+The content of the secret needs to be a json string compatible with composer, for instance:
+- basic auth string:
+```json
+{
+  "http-basic": {
+    "git.mycompany.com": {
+      "password": "mypassword",
+      "username": "myuser"
+    }
+  }
+}
+```
+
+- a bearer token:
+```json
+{
+  "bearer": {
+    "git.mycompany.com": "mytoken"
+  }
+}
+```