Update OpenFaaS Pro docs for mirroring images

Update the section on mirroring images for OpenFaaS Pro into your own
regsitry to reflect the latest changes to the airfaas cli.

Signed-off-by: Han Verstraete (OpenFaaS Ltd) <han@openfaas.com>

Author: welteki

docs/openfaas-pro/airgap.md

@@ -1,10 +1,10 @@
-## Air Gap with Kubernetes
+# Air Gap with Kubernetes
 
 OpenFaaS Standard and OpenFaaS for Enterprises are licensed for use within an airgap when purchased on an annual basis via invoice.
 
 You can use your own choice of tooling to mirror images and bundle the Helm chart(s) required for your installations, or you can use our own purpose-built airfaas tool.
 
-### Mirror OpenFaaS images into your own registry
+## Mirror OpenFaaS images into your own registry
 
 If your organisation has a policy of mirroring all consumed images from vendors into a private registry, then `airfaas mirror` can help you with this, even if you don't install OpenFaaS into an airgapped environment.
 
@@ -15,38 +15,32 @@ faas-cli plugin get airfaas
 Mirror all images for the given chart/index to a custom registry:
 
 ```bash
-faas-cli airfaas download images \
-        openfaas/openfaas \
-        --registry-prefix ttl.sh
+faas-cli airfaas mirror \
+    openfaas/openfaas \
+    --registry ttl.sh
 ```
 
 Mirror the Kafka-connector's images:
 
 ```bash
-faas-cli airfaas download images \
-        openfaas/kafka-connector \
-        --registry-prefix ttl.sh
+faas-cli airfaas mirror \
+    openfaas/kafka-connector \
+    --registry ttl.sh
 ```
 
+The `-f/--file` flag can be used to write a `values.yaml` file with the mirrored image names, which can be used as an overlay to your existing `values.yaml` file when deploying OpenFaaS.
 The `--url` flag can be used to specify a different Helm chart repository. The only requirement is that images are stored in the same format as OpenFaaS: i.e. `image:` or `componentName.image:`.
 
 Note: if you receive an access denied error from ghcr.io, it's most likely because you have an old, expired access token in your local Docker config or keychain. Run `docker logout ghcr.io` to clear the token and try again.
 
-## Consume the mirrored images from your own registry
-
-After the mirroring is complete, you'll receive output in the format of a values.yaml file, which you can add to your `helm upgrade --install` command.
-
-```bash
-$ faas-cli airfaas mirror openfaas/openfaas --to https://aws_account_id.dkr.ecr.us-west-2.amazonaws.com/openfaas
-Mirrored 18 images in 3m7.242s
-```
+### Consume the mirrored images from your own registry
 
 There are two options for consuming the mirrored images:
 
 1. Use the `registryPrefix` setting to add a prefixed string i.e. your registry to the image name across all images i.e. `registryPrefix: aws_account_id.dkr.ecr.us-west-2.amazonaws.com/openfaas`
-2. Use the generated text produced by `airfaas` as an overlay to your existing `values.yaml` file.
+2. Use the generated generated values.yaml file produced by running `arifaas mirror` with the `--file` flag as an overlay to your existing `values.yaml` file.
 
-### Option 1 - Use the `registryPrefix` setting
+#### Option 1 - Use the `registryPrefix` setting
 
 ```yaml
 registryPrefix: aws_account_id.dkr.ecr.us-west-2.amazonaws.com/openfaas
@@ -61,9 +55,18 @@ imagePullSecrets:
 
 For certain registries such as AWS ECR, it's possible to use the ambient AWS IAM credentials to authenticate the registry without overriding the default `imagePullSecrets` setting.
 
-### Option 2 - Use the generated text produced by `airfaas` as an overlay to your existing `values.yaml` file.
+#### Option 2 - Use the generated values file produced by `airfaas` as an overlay to your existing `values.yaml` file.
+
+Run `faas-cli airfaas mirror` with the `--file` flag to generate a values.yaml file with the mirrored image names e.g:
+
+```bash
+faas-cli airfaas mirror \
+    openfaas/openfaas \
+    --registry aws_account_id.dkr.ecr.us-west-2.amazonaws.com/openfaas \
+    --file values-mirror.yaml
+```
 
-Then copy the below to i.e. `values-mirror.yaml`:
+The resuling file should looke like this, with all images updated to point to the mirrored registry:
 
 ```yaml
 gatewayPro:
@@ -85,7 +88,7 @@ helm upgrade --install openfaas \
   -f values-mirror.yaml
 ```
 
-### Perform an offline installation
+## Perform an offline installation
 
 Airfaas can perform an offline installation of OpenFaaS into an airgapped environment. It will bundle the Helm chart(s) and images required for the installation, then restore the images into an offline registry, and install OpenFaaS using the Helm chart(s) from the local filesystem.
 
@@ -95,4 +98,4 @@ Airfaas can perform an offline installation of OpenFaaS into an airgapped enviro
 ![Conceptual upload process](https://www.openfaas.com/images/2024-04-airgap/restore.png)
 > The upload / installation process
 
-Follow the instructions in: [Deploy airgapped Serverless Functions with OpenFaaS](https://www.openfaas.com/blog/airgap-serverless-functions/)
+Follow the instructions in: [Deploy airgapped Serverless Functions with OpenFaaS](https://www.openfaas.com/blog/airgap-serverless-functions/)