ci: Upgrade test-vm to debian bullseye

This change updates the test VM to debian bullseye, primarily to enable
io_uring features that are not available in the 4.16 kernel shipping
with debian buster.

We are not updating the builder containers to bullseye, as newer
versions of qemu fail to start on kokoro. See b/181359683

Since it was needed for debugging this CL, it includes a feature to
debug kokoro builders via SSH. It can be enabled by setting
DEBUG_SSH_KEY from the fusion2 UI.

BUG=b:178228512
TEST=./test_all passes

Change-Id: I22f1678577183a0aace80245a87c31907221cc09
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosvm/+/2721062
Reviewed-by: Daniel Verkamp <dverkamp@chromium.org>
Reviewed-by: Zach Reizner <zachr@chromium.org>
Tested-by: kokoro <noreply+kokoro@google.com>
Commit-Queue: Dennis Kempin <denniskempin@google.com>

ci/crosvm_test_vm/Dockerfile

@@ -24,7 +24,7 @@ RUN apt-get update && apt-get install --yes \
 WORKDIR /workspace/vm
 
 RUN curl -sSfL -o rootfs.qcow2 \
-    "https://cdimage.debian.org/cdimage/cloud/buster/20201214-484/debian-10-generic-${VM_ARCH}-20201214-484.qcow2"
+    "http://cloud.debian.org/images/cloud/bullseye/daily/20210208-542/debian-11-generic-${VM_ARCH}-daily-20210208-542.qcow2"
 
 # Package `cloud_init_data.yaml` to be loaded during `first_boot.expect`
 COPY build/cloud_init_data.yaml ./

ci/crosvm_test_vm/build/cloud_init_data.yaml

@@ -12,12 +12,6 @@ users:
         crosvm@localhost
     groups: kvm, disk, tty
 
-apt:
-  sources:
-    testing:
-      source: "deb $MIRROR bullseye main"
-  conf: APT::Default-Release "stable";
-
 # Store working data on tmpfs to reduce unnecessary disk IO
 mounts:
   - [swap, null]
@@ -37,18 +31,6 @@ packages:
   - rsync
 
 runcmd:
-  # Install testing (debian bullseye) versions of some libraries.
-  - [
-      apt-get,
-      install,
-      --yes,
-      -t,
-      testing,
-      --no-install-recommends,
-      libdrm2,
-      libepoxy0,
-    ]
-
   # Trim some fat
   - [apt-get, remove, --yes, vim-runtime, iso-codes, perl, grub-common]
   - [apt-get, autoremove, --yes]

ci/image_tag

@@ -1 +1 @@
-r0001
+r0002

ci/kokoro/common.sh

@@ -5,6 +5,19 @@
 
 crosvm_root="${KOKORO_ARTIFACTS_DIR}"/git/crosvm
 
+# Enable SSH access to the kokoro builder.
+# Use the fusion2/ UI to trigger a build and set the DEBUG_SSH_KEY environment
+# variable to your public key, that will allow you to connect to the builder
+# via SSH.
+# Note: Access is restricted to the google corporate network.
+# Details: https://yaqs.corp.google.com/eng/q/6628551334035456
+if [[ ! -z "${DEBUG_SSH_KEY}" ]]; then
+  echo "${DEBUG_SSH_KEY}" >> ~/.ssh/authorized_keys
+  external_ip=$(curl -s -H "Metadata-Flavor: Google"
+    http://metadata/computeMetadata/v1/instance/network-interfaces/0/access-configs/0/external-ip)
+  echo "SSH Debug enabled. Connect to: kbuilder@${external_ip}"
+fi
+
 setup_source() {
   if [ -z "${KOKORO_ARTIFACTS_DIR}" ]; then
     echo "This script must be run in kokoro"
@@ -45,6 +58,12 @@ setup_source() {
 }
 
 cleanup() {
+  # Sleep after the build to allow for SSH debugging to continue.
+  if [[ ! -z "${DEBUG_SSH_KEY}" ]]; then
+    echo "Build done. Blocking for SSH debugging."
+    sleep 1h
+  fi
+
   if command -v bindfs >/dev/null; then
     fusermount -uz "${KOKORO_ARTIFACTS_DIR}/cros/src/platform/crosvm"
   else