fix: declare container identity for systemd nodes (#59)

Signed-off-by: Tianyu Zhou <albert.zty@antgroup.com>

Author: tianyuzhou95

.github/workflows/ci.yml

@@ -132,12 +132,26 @@ jobs:
               IMAGE_TAG="${GITHUB_SHA}" \
               RUNTIME_PROFILE=rrt
 
+      - name: Verify systemd container identity in the image
+        run: |
+          docker image inspect "akernel-ci/all-in-one:${GITHUB_SHA}" \
+            --format '{{json .Config.Env}}' | \
+            python -c 'import json, sys; assert "container=oci" in json.load(sys.stdin)'
+
       - name: Start standalone AKernel
         run: |
           IMAGE="akernel-ci/all-in-one:${GITHUB_SHA}" \
             AKERNEL_NAT_BACKEND=iptables \
             ./deploy/standalone/start.sh
 
+      - name: Verify PID 1 detects its container
+        run: |
+          docker exec akernel-node bash -euo pipefail -c '
+            tr "\0" "\n" < /proc/1/environ | grep -x "container=oci"
+            test "$(cat /run/systemd/container)" = oci
+            systemd-detect-virt --container
+          '
+
       - name: Run SDK end-to-end examples
         run: |
           gateway_ip="$(docker inspect \

AGENTS.md

@@ -183,6 +183,13 @@ Use [`deploy/README.md`](./deploy/README.md) as the deployment entry point.
 AKernel supports standalone, existing Kubernetes clusters via Helm, and
 Terraform-based cloud provisioning.
 
+The all-in-one image and node launchers declare lowercase `container=oci`
+for PID 1 systemd. Preserve this in the final image, Helm node environment,
+and standalone launcher: without container detection, privileged systemd
+shutdown can remount shared host filesystems read-only. See
+[`deploy/README.md#systemd-container-identity`](./deploy/README.md#systemd-container-identity)
+for deployment implications.
+
 Aliyun's aggregate Pod PID budget is configurable independently of the
 per-sandbox limit; see `deploy/terraform/aliyun/README.md#pod-pid-budget`.
 

builder/node.Dockerfile

@@ -233,6 +233,9 @@ COPY ./src/distill-fs/ ./
 RUN cargo build --locked --release --bin distill_fs
 
 FROM ${AKERNEL_NODE_BASE_IMAGE}
+# Let PID 1 systemd avoid remounting shared host filesystems during shutdown.
+ENV container=oci
+
 ARG AKERNEL_ENABLE_KATA
 ARG AKERNEL_ENABLE_RUNC
 ARG AKERNEL_ENABLE_FIRECRACKER

deploy/README.md

@@ -71,6 +71,14 @@ The node must support TC eBPF and bpffs. bpfnat does not manage host firewall
 policy, so custom host-network deployments must allow forwarding to and from
 the sandbox bridge when their `FORWARD` policy is `DROP`.
 
+### systemd container identity
+
+The all-in-one image, Helm node template, and standalone launcher set
+`container=oci` so PID 1 systemd recognizes the container and does not remount
+shared host filesystems read-only during shutdown. Preserve this variable in
+custom launchers. Applying the fix requires replacing the node Pod or
+standalone container; it does not repair an already read-only filesystem.
+
 ### Network ACLs
 
 The bundled standalone, Helm, and Terraform sandboxd configurations enable

deploy/akernel/charts/core/templates/node/daemonset.yaml

@@ -76,6 +76,9 @@ spec:
         resources:
           {{- toYaml .Values.node.resources | nindent 10 }}
         env:
+        # Required for systemd shutdown safety, including with older images.
+        - name: container
+          value: "oci"
         - name: AKERNEL_ROLE
           value: "node"
         - name: RUNSC_AKERNEL

deploy/standalone/start.sh

@@ -361,6 +361,7 @@ start_node_container() {
         --privileged \
         --net bridge \
         --restart always \
+        -e container=oci \
         -e AKS_LOCAL_MODE="true" \
         -e YR_RRT_CONTROL_SOCKET_PATH="/run/akernel" \
         -e YR_IMAGE_PROCESS_CONFIG="${YR_IMAGE_PROCESS_CONFIG}" \