#3935: Move private container registry docs to developer guide (#3965)

* #3935: Move private container registry docs to developer guide

* fix variables

* formatting tweak

* formatting tweak

config/nav.yml

@@ -68,6 +68,7 @@ nav:
             - Configuring custom domains: developer/serving/services/custom-domains.md
             - Configure resource requests and limits: developer/serving/services/configure-requests-limits-services.md
           - Traffic management: developer/serving/traffic-management.md
+          - Deploying from private registries: developer/serving/deploying-from-private-registry.md
           - Troubleshooting:
             - Debugging application issues: developer/serving/troubleshooting/debugging-application-issues.md
         - Knative Eventing:
@@ -110,7 +111,6 @@ nav:
     - Knative Serving:
       - Overview: serving/README.md
       - Developer Topics:
-        - Deploying from private registries: serving/deploying-from-private-registry.md
         - Tag resolution: serving/tag-resolution.md
         - Gradually rolling out latest Revisions: serving/rolling-out-latest-revision.md
         - Creating and using Subroutes: serving/using-subroutes.md

config/redirects.yml

@@ -1,6 +1,7 @@
 plugins:
   redirects:
     redirect_maps:
+      serving/deploying-from-private-registry.md: developer/serving/deploying-from-private-registry.md
       serving/samples/blue-green-deployment.md: developer/serving/traffic-management.md
       serving/samples/traffic-splitting/README.md: developer/serving/traffic-management.md
       admin/install/install-eventing-with-yaml.md: admin/install/eventing/install-eventing-with-yaml.md

docs/developer/serving/deploying-from-private-registry.md

@@ -0,0 +1,72 @@
+# Deploying images from a private container registry
+
+You can share access to private container images across multiple Services and Revisions by configuring your Knative cluster to deploy images from a private
+container registry.
+
+To configure using a private container registry, you must:
+
+1. Create a list of Kubernetes secrets ([`imagePullSecrets`](https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.18/#pod-v1-core)) by using your registry credentials.
+1. Add those `imagePullSecrets` to the default [service account](https://kubernetes.io/docs/tasks/configure-pod-container/configure-service-account/).
+1. Deploy those configurations to your Knative cluster.
+
+## Prerequisites
+
+- You must have a Kubernetes cluster with Knative Serving installed.
+- You must have access to credentials for the private container registry where your container images are stored.
+
+## Procedure
+
+1. Create a `imagePullSecrets` object that contains your credentials as a list of secrets:
+
+    ```bash
+    kubectl create secret docker-registry <registry-credential-secrets> \
+      --docker-server=<private-registry-url>] \
+      --docker-email=<private-registry-email> \
+      --docker-username=<private-registry-user> \
+      --docker-password=<private-registry-password>
+    ```
+
+    Where:
+
+    - `<registry-credential-secrets>` is the name that you want to use for your secrets (the `imagePullSecrets` object). For example, `container-registry`.
+
+    - `<private-registry-url>` is the URL of the private registry where your container images are stored. Examples include [Google Container Registry](https://gcr.io/) or [DockerHub](https://docker.io/).
+
+    * `<private-registry-email>` is the email address that is associated with
+      the private registry.
+
+    * `<private-registry-user>` is the username that you use to access the
+      private container registry.
+
+    * `<private-registry-password>` is the password that you use to access
+      the private container registry.
+
+    Example:
+
+    ```bash
+    kubectl create secret container-registry \
+      --docker-server=https://gcr.io/ \
+      --docker-email=my-account-email@address.com \
+      --docker-username=my-grc-username \
+      --docker-password=my-gcr-password
+    ```
+
+    !!! tip
+        After you have created the `imagePullSecrets` object, you can view the secrets by running:
+
+        ```bash
+        kubectl get secret <registry-credential-secrets> -o=yaml
+        ```
+
+1. Add the `imagePullSecrets` to the `default` service account in the `default` namespace.
+
+    !!! note
+        By default, the `default` service account in each of the [namespaces](https://kubernetes.io/docs/concepts/overview/working-with-objects/namespaces/) of your Knative cluster are used by your Revisions, unless the [`serviceAccountName`](https://github.com/knative/specs/blob/main/specs/serving/knative-api-specification-1.0.md#revision-2) is specified.
+
+    For example, if have you named your secrets `container-registry`, you can run the following command to modify the `default` service account:
+
+    ```bash
+    kubectl patch serviceaccount default -p "{\"imagePullSecrets\": [{\"name\": \"container-registry\"}]}"
+    ```
+
+    New pods that are created in the `default` namespace now include your credentials and have access to your container images in the private registry.