Add script for migrating from other CNI to Antrea

Add a YAML file antrea-migrator.yml to migrate clusters
with other CNIs to Antrea. It will restart all Pods in-place.

A new image "antrea-migrator" is responsible for restarting
all Pods on each Nodes. It is a DaemonSet that tries to kill
sandboxes to restart the Pods in-place.

Signed-off-by: hjiajing <hjiajing@vmware.com>

.github/workflows/build.yml

@@ -160,3 +160,22 @@ jobs:
       run: |
         echo "$DOCKER_PASSWORD" | docker login -u "$DOCKER_USERNAME" --password-stdin
         docker push antrea/flow-aggregator:latest
+
+  build-antrea-migrator:
+    needs: check-changes
+    if: ${{ needs.check-changes.outputs.has_changes == 'yes' || github.event_name == 'push' }}
+    runs-on: [ubuntu-latest]
+    steps:
+    - uses: actions/checkout@v4
+      with:
+        show-progress: false
+    - name: Build antrea-migrator Docker image
+      run: make build-migrator
+    - name: Push antrea-migrator Docker image to registry
+      if: ${{ github.repository == 'antrea-io/antrea' && github.event_name == 'push' && github.ref == 'refs/heads/main' }}
+      env:
+        DOCKER_USERNAME: ${{ secrets.DOCKER_USERNAME }}
+        DOCKER_PASSWORD: ${{ secrets.DOCKER_PASSWORD }}
+      run: |
+        echo "$DOCKER_PASSWORD" | docker login -u "$DOCKER_USERNAME" --password-stdin
+        docker push antrea/antrea-migrator:latest

Makefile

@@ -380,6 +380,16 @@ build-scale-simulator:
 	docker build -t antrea/antrea-ubuntu-simulator:$(DOCKER_IMG_VERSION) -f build/images/Dockerfile.simulator.build.ubuntu $(DOCKER_BUILD_ARGS) .
 	docker tag antrea/antrea-ubuntu-simulator:$(DOCKER_IMG_VERSION) antrea/antrea-ubuntu-simulator
 
+.PHONY: build-migrator
+build-migrator:
+	@echo "===> Building antrea/antrea-migrator Docker image <==="
+ifneq ($(NO_PULL),)
+	docker build -t antrea/antrea-migrator:$(DOCKER_IMG_VERSION) -f build/images/Dockerfile.build.migrator $(DOCKER_BUILD_ARGS) .
+else
+	docker build --pull -t antrea/antrea-migrator:$(DOCKER_IMG_VERSION) -f build/images/Dockerfile.build.migrator $(DOCKER_BUILD_ARGS) .
+endif
+	docker tag antrea/antrea-migrator:$(DOCKER_IMG_VERSION) antrea/antrea-migrator
+
 .PHONY: manifest
 manifest:
 	@echo "===> Generating dev manifest for Antrea <==="

build/images/Dockerfile.build.migrator

@@ -0,0 +1,37 @@
+# Copyright 2024 Antrea Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+FROM ubuntu:22.04
+
+LABEL maintainer="Antrea <projectantrea-dev@googlegroups.com>"
+LABEL description="The Docker image to migrate other CNIs to Antrea CNI."
+
+USER root
+
+COPY build/images/scripts/migrate_cni /usr/local/bin/
+
+ENV CRICTL_VERSION="v1.27.0"
+RUN apt update \
+    && apt install -y jq ca-certificates wget \
+    && rm -rf /var/cache/apt/* /var/lib/apt/lists/* \
+    && wget -q https://github.com/kubernetes-sigs/cri-tools/releases/download/${CRICTL_VERSION}/crictl-${CRICTL_VERSION}-linux-amd64.tar.gz \
+    && tar -xzf crictl-${CRICTL_VERSION}-linux-amd64.tar.gz \
+    && mv crictl /usr/local/bin/ \
+    && rm -f crictl-${CRICTL_VERSION}-linux-amd64.tar.gz \
+    && chmod +x /usr/local/bin/crictl \
+    && chmod +x /usr/local/bin/migrate_cni
+
+COPY --from=registry.k8s.io/pause:latest /pause /pause
+
+CMD ["/pause"]

build/images/scripts/migrate_cni

@@ -0,0 +1,50 @@
+#!/usr/bin/env bash
+
+# Copyright 2024 Antrea Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+set -e
+
+CRICTL="crictl --runtime-endpoint $RUNTIME_ENDPOINT"
+
+for file in /etc/cni/net.d/*; do
+    if [[ $file == *.conf || $file == *.conflist || $file == *.json ]]; then
+        if [[ $file != *10-antrea.conflist ]]; then
+            mv $file $file.bak
+        fi
+    fi
+done
+
+# Remove rules added by the previous CNI in CHAIN CNI-HOSTPORT-DNAT.
+# CHAIN CNI-HOSTPORT-DNAT is created by portmap for ingress controllers. It will not be deleted
+# even if the CNI is removed, so we delete the stale rules here.
+if iptables -t nat -S | grep -q "CNI-HOSTPORT-DNAT"; then
+    rules=$(iptables -t nat -L CNI-HOSTPORT-DNAT --line-numbers | grep -v "antrea" | awk 'NR>2 {print $1}')
+    chains=$(iptables -t nat -L CNI-HOSTPORT-DNAT | grep -v "antrea" | awk 'NR>2 {print $1}')
+    for rule in $rules; do
+        iptables -t nat -D CNI-HOSTPORT-DNAT "$rule"
+    done
+    for chain in $chains; do
+        iptables -t nat -F "$chain"
+        iptables -t nat -X "$chain"
+    done
+fi
+
+pods=$($CRICTL pods -q)
+for pod in $pods; do
+    network_type=$($CRICTL inspectp $pod | jq -r .status.linux.namespaces.options.network)
+    if [ "$network_type" == "POD" ]; then
+        $CRICTL stopp $pod && $CRICTL rmp $pod
+    fi
+done

build/yamls/antrea-migrator.yml

@@ -0,0 +1,57 @@
+kind: DaemonSet
+apiVersion: apps/v1
+metadata:
+  labels:
+    app: antrea
+    component: antrea-migrator
+  name: antrea-migrator
+  namespace: kube-system
+spec:
+  selector:
+    matchLabels:
+      app: antrea
+      component: antrea-migrator
+  template:
+    metadata:
+      labels:
+        app: antrea
+        component: antrea-migrator
+    spec:
+      hostPID: true
+      hostNetwork: true
+      nodeSelector:
+        kubernetes.io/os: linux
+      tolerations:
+        - key: CriticalAddonsOnly
+          operator: Exists
+        - effect: NoSchedule
+          operator: Exists
+        - effect: NoExecute
+          operator: Exists
+      volumes:
+        - name: cni-cfg
+          hostPath:
+            path: /etc/cni/net.d
+        - name: containerd
+          hostPath:
+            path: /run/containerd
+      initContainers:
+        - name: antrea-migrator-init
+          image: antrea/antrea-migrator:latest
+          imagePullPolicy: IfNotPresent
+          securityContext:
+            privileged: true
+          command:
+            - migrate_cni
+          env:
+            - name: RUNTIME_ENDPOINT
+              value: unix:///run/containerd/containerd.sock
+          volumeMounts:
+            - mountPath: /run/containerd
+              name: containerd
+            - mountPath: /etc/cni/net.d
+              name: cni-cfg
+      containers:
+        - image: antrea/antrea-migrator:latest
+          imagePullPolicy: IfNotPresent
+          name: antrea-migrator

docs/migrate-to-antrea.md

@@ -0,0 +1,74 @@
+# Migrate from another CNI to Antrea
+
+This document provides guidance on migrating from other CNIs to Antrea
+starting from version v1.15.0 onwards.
+
+NOTE: The following is a reference list of CNIs and versions for which we have
+verified the migration process. CNIs and versions that are not listed here
+might also work. Please create an issue if you run into problems during the
+migration to Antrea. During the migration process, no Kubernetes resources
+should be created or deleted, otherwise the migration process might fail or
+some unexpected problems might occur.
+
+| CNI     | Version |
+|---------|---------|
+| Calico  | v3.26   |
+| Flannel | v0.22.0 |
+
+The migration process is divided into three steps:
+
+1. Clean up the old CNI.
+2. Install Antrea in the cluster.
+3. Deploy Antrea migrator.
+
+## Clean up the old CNI
+
+The cleanup process varies across CNIs, typically you should remove
+the DaemonSet, Deployment, and CRDs of the old CNI from the cluster.
+For example, if you used `kubectl apply -f <CNI_MANIFEST>` to install
+the old CNI, you could then use `kubectl delete -f <CNI_MANIFEST>` to
+uninstall it.
+
+## Install Antrea
+
+The second step is to install Antrea in the cluster. You can follow the
+[installation guide](https://github.com/antrea-io/antrea/blob/main/docs/getting-started.md)
+to install Antrea. The following is an example of installing Antrea v1.14.1:
+
+```bash
+kubectl apply -f https://github.com/antrea-io/antrea/releases/download/v1.14.1/antrea.yml
+```
+
+## Deploy Antrea migrator
+
+After Antrea is up and running, you can now deploy Antrea migrator
+by the following command. The migrator runs as a DaemonSet, `antrea-migrator`,
+in the cluster, which will restart all non hostNetwork Pods in the cluster
+in-place and perform necessary network resource cleanup.
+
+```bash
+kubectl apply -f https://github.com/antrea-io/antrea/main/build/yamls/antrea-migrator.yml
+```
+
+The reason for restarting all Pods is that Antrea needs to take over the
+network management and IPAM from the old CNI. In order to avoid the Pods
+being rescheduled and minimize service downtime, the migrator restarts
+all non-hostNetwork Pods in-place by restarting their sandbox containers.
+Therefore, it's expected to see the `RESTARTS` count for these Pods being
+increased by 1 like below:
+
+```bash
+$ kubectl get pod -o wide
+NAME                               READY   STATUS    RESTARTS      AGE    IP          NODE          NOMINATED NODE   READINESS GATES
+migrate-example-6d6b97f96b-29qbq   1/1     Running   1 (24s ago)   2m5s   10.10.1.3   test-worker   <none>           <none>
+migrate-example-6d6b97f96b-dqx2g   1/1     Running   1 (23s ago)   2m5s   10.10.1.6   test-worker   <none>           <none>
+migrate-example-6d6b97f96b-jpflg   1/1     Running   1 (23s ago)   2m5s   10.10.1.5   test-worker   <none>           <none>
+```
+
+When the `antrea-migrator` Pods on all Nodes are in `Running` state,
+the migration process is completed. You can then remove the `antrea-migrator`
+DaemonSet safely with the following command:
+
+```bash
+kubectl delete -f https://github.com/antrea-io/antrea/main/build/yamls/antrea-migrator.yml
+```

hack/.notableofcontents

@@ -26,6 +26,7 @@ docs/maintainers/build-kubemark.md
 docs/maintainers/getting-started-gif.md
 docs/maintainers/release.md
 docs/maintainers/updating-ovs-windows.md
+docs/migrate-to-antrea.md
 docs/multicluster/api.md
 docs/multicluster/antctl.md
 docs/multicluster/architecture.md