added license readme

README.md

@@ -81,6 +81,12 @@ To connect with SSH to the `r1` node, use `ssh [email protected]` command.
 kind load docker-image srlinux:0.0.0-38566 --name kne
 ```
 
+## Using license files
+
+To remove the packets-per-second limit of a public container image or to launch chassis-based variants of SR Linux (ixr-6e/10e) KNE users should provide a valid license file to the `srl-controller`.
+
+Navigate to [Using license files](docs/using-licenses.md) document to have a detailed explanation on that topic.
+
 ## Controller operations
 
 The controller is designed to manage the `Srlinux` custom resource defined with [the following CRD](https://doc.crds.dev/github.com/srl-labs/srl-controller).
@@ -104,7 +110,7 @@ When a deletion happens on `Srlinux` resource, the reconcile loop does nothing.
 
 This repo contains a clientset for API access to the `Srlinux` custom resource. Check [kne repo](https://github.com/openconfig/kne/blob/fc195a73035bcbf344791979ca3e067be47a249c/topo/node/srl/srl.go#L46) to see how this can be done.
 
-## Building srl-controller container image
+## Building `srl-controller` container image
 
 To build `srl-controller` container image execute:
 

docs/using-licenses.md

@@ -0,0 +1,49 @@
+# Using license files
+
+To remove the packets-per-second limit of a public container image or to launch chassis-based variants of SR Linux (ixr-6e/10e) KNE users should provide a valid license file to the `srl-controller`.
+
+License file provisioning is handled by the `srl-controller`. Users should create a k8s secret with license text blobs stored as keys for a controller to pick it up and use with SR Linux pods. In the next sections, we provide examples for the complete workflow of license provisioning.
+
+## Creating a secret with licenses
+
+SR Linux license file can contain a single license blob for a certain release or pack multiple license blobs for several versions. SR Linux NOS can conveniently find a matching license in a file that contains several licenses automatically.
+
+A license file with multiple licenses can look similar to that:
+
+```text
+#
+# srl
+#
+00000000-0000-0000-0000-000000000000 aACUAsYXC0NTA1NERLABiSBETTERtHAnKNEAAAAA  # srl_rel_22_03_*
+00000000-0000-0000-0000-000000000000 aACUAsYXC0NTA1NERLABiSBETTERtHAnKNEAAAAA  # srl_rel_22_06_*
+00000000-0000-0000-0000-000000000000 aACUAsYXC0NTA1NERLABiSBETTERtHAnKNEAAAAA  # srl_rel_22_11_*
+```
+
+A file like that contains licenses for SR Linux releases `22.3.*`, `22.6.*`, `22.11.*`, but, for instance, not for `21.11.*`.
+
+Because a single license file can contain multiple license blob, users can maintain a single file and append license blobs to it as the new releases come out.
+
+For the sake of an argument, let's assume that a license file that contains license blobs is named `licenses.key` and exists in a current working directory. With a license file available, users should create a Secret in the `srlinux-controller` namespace with a license file blob contained under the `all.key` key.
+
+```bash
+kubectl create namespace srlinux-controller; \
+kubectl create -n srlinux-controller \
+    secret generic srlinux-licenses --from-file=all.key=licenses.key \
+    --dry-run=client --save-config -o yaml | \
+    kubectl apply -f -
+```
+
+> **Note**  
+> The above snippet ensures that `srlinux-controller` namespace exists, and then creates a Secret object from `licenses.key` file and puts its content under `all.key` key.
+
+Now you should have a Secret object in `srlinux-controller` namespace that contains SR Linux licenses.
+
+## License mount
+
+Once a Secret with license information is created, SR Linux pods will have a new volume mounted by the controller with the contents of the original license file by the path `/opt/srlinux/etc/license.key`.
+
+SR Linux NOS then will read this file at startup and will use a license if a valid string is found in that file. If no valid license is found the system will boot as if no license file was provided.
+
+## Updating licenses
+
+If you wish to add/remove a license to/from your collection of licenses you simply modify the existing file which you used to create a Secret object from and reinvoke the same command.