[CI] Adding CPU docker pipeline

This patch adds the pipeline for CPU docker image

Signed-off-by: Yuan Zhou <[email protected]>

Author: zhouyuan

.buildkite/release-pipeline.yaml

@@ -55,3 +55,18 @@ steps:
           password-env: DOCKERHUB_TOKEN
     env:
       DOCKER_BUILDKIT: "1"
+
+  - label: "Build and publish CPU release image"
+    depends_on: ~
+    if: build.tag != null
+    agents:
+      queue: cpu_queue_postmerge
+    commands:
+      - "DOCKER_BUILDKIT=1 docker build --build-arg max_jobs=16 --build-arg GIT_REPO_CHECK=1 --tag vllm/vllm-cpu:$BUILDKITE_TAG --progress plain -f Dockerfile.cpu ."
+      - "docker push vllm/vllm-cpu:$BUILDKITE_TAG"
+    plugins:
+      - docker-login#v3.0.0:
+          username: vllm
+          password-env: DOCKERHUB_TOKEN
+    env:
+      DOCKER_BUILDKIT: "1"