docs: Add how to run cilium-cli e2e tests locally

Signed-off-by: Martynas Pumputis <m@lambda.lt>

Documentation/contributing/testing/e2e.rst

@@ -8,3 +8,95 @@
 
 End-To-End Connectivity Testing
 ===============================
+
+Introduction
+~~~~~~~~~~~~
+
+Cilium uses `cilium-cli connectivity tests
+<https://github.com/cilium/cilium-cli/#connectivity-check>`_
+for implementing and running end-to-end tests which test Cilium all the way
+from the API level (for example, importing policies, CLI) to the datapath (in order words, whether
+policy that is imported is enforced accordingly in the datapath).
+
+Running End-To-End Connectivity Tests
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The connectivity tests are implemented in such a way that they can be run against
+any K8s cluster running Cilium. The built-in feature detection allows the testing 
+framework to automatically skip tests when a required test condition cannot be met
+(for example, skip the Egress Gateway tests if the Egress Gateway feature is disabled).
+
+Running tests locally
+^^^^^^^^^^^^^^^^^^^^^
+
+Before running the connectivity tests you need to install `Cilium CLI <https://github.com/cilium/cilium-cli#installation>`_.
+Alternatively, ``Cilium CLI`` can be manually built and installed by fetching
+``https://github.com/cilium/cilium-cli``, and then running ``make install``.
+
+Next, you need a Kubernetes cluster to run Cilium. The easiest way to create one
+is to use `kind <https://github.com/kubernetes-sigs/kind>`_. Cilium provides
+a wrapper script which simplifies creating K8s cluster with ``kind``. For example,
+to create a cluster consisting of 1 control-plane node, 3 worker nodes, without
+kube-proxy, and with ``DualStack`` enabled:
+
+.. code-block:: shell-session
+
+    $ cd cilium/
+    $ ./contrib/scripts/kind.sh "" 3 "" "" "none" "dual"
+    ...
+    Kind is up! Time to install cilium:
+    make kind-image
+    make kind-install-cilium
+
+Afterwards, you need to install Cilium. The preferred way is to use
+`cilium-cli install <https://github.com/cilium/cilium-cli/#install-cilium>`_,
+as it is able to automate some steps (e.g., detecting ``kube-apiserver`` endpoint
+address which otherwise needs to be specified when running w/o ``kube-proxy``, or
+set an annotation to a K8s worker node to prevent Cilium from being scheduled on it).
+
+Assuming that Cilium was built with:
+
+.. code-block:: shell-session
+
+    $ cd cilium/
+    $ make kind-image
+    ...
+    ^^^ Images pushed, multi-arch manifest should be above. ^^^
+
+You can install Cilium with the following:
+
+.. code_block:: shell-session
+
+    $ cilium install --wait --rollback=false \
+        --chart-directory=$GOPATH/src/github.com/cilium/cilium/install/kubernetes/cilium \
+        --helm-set=image.override=localhost:5000/cilium/cilium-dev:local \
+        --helm-set=image.pullPolicy=Never \
+        --helm-set=operator.image.override=localhost:5000/cilium/operator-generic:local \
+        --helm-set=operator.image.pullPolicy=Never \
+        --helm-set-string=tunnel=vxlan \
+        --nodes-without-cilium=kind-worker3
+    ...
+    ⌛ Waiting for Cilium to be installed and ready...
+    ✅ Cilium was successfully installed! Run 'cilium status' to view installation health
+
+Finally, to run tests:
+
+.. code_block:: shell-session
+
+    $ cilium connectivity test
+    ...
+    ✅ All 32 tests (263 actions) successful, 2 tests skipped, 1 scenarios skipped.
+
+Alternatively, you can select which tests to run:
+
+.. code_block:: shell-session
+
+    $ cilium connectivity test --test north-south-loadbalancing
+    ...
+    [=] Test [north-south-loadbalancing]
+    ......
+
+Running tests in VM
+^^^^^^^^^^^^^^^^^^^
+
+TODO

Documentation/contributing/testing/index.rst

@@ -24,6 +24,7 @@ information about Cilium's CI infrastructure.
    :glob:
 
    ci
+   e2e
    e2e_legacy
    unit
    bpf