Add container registry docu

_toc.yml

@@ -22,6 +22,7 @@ sections:
       - file: applications/headless_execution
       - file: applications/secret_manager
       - file: applications/eoapi
+      - file: applications/container_registry
 
   - title: Tutorials
     sections:   

applications/container_registry.md

@@ -0,0 +1,33 @@
+# Container Registry
+
+## Login in UI
+
+The credentials can be found in the secret **registry-login** in the [credentials manager](./secret_manager.md) or your workspace.
+
+```{figure} assets/credentials-manager/registry-credentials-detail.png
+---
+name: registry-credentials-detail
+---
+Credential 'registry-login' contains the login information for the container registry: registry server FQDN (URL), username & password
+```
+
+## Upload images to registry
+
+1. Login
+    ```shell
+    docker login -u <username> registry.[workspace-name].[cluster].eox.at  # e.g. registry.hub-test-ws1.hub-test.eox.at
+    ```
+   Type in the password when asked.  
+
+2. Tag your image
+    ```shell
+    docker tag my-image:latest registry.[workspace-name].[cluster].eox.at/my-image:latest
+    ```
+
+3. Push image to registry
+
+    ```shell
+    docker push registry.[workspace-name].[cluster].eox.at/my-image:latest
+    ```
+
+After a successful upload, the image is visible in the UI and in the file browser, and can be used in Argo Workflows, etc.