ci: Use same date for all images

Export date to artifact on one task which other tasks are depended.
Then download this artifact on other tasks and use it to set date.

.cirrus.yml

@@ -17,6 +17,16 @@ env:
   # GCP_REGION
   # GCP_REPO
 
+# To use same date for the all tasks, download date artifact from
+# create_date task and use it. Another method is used at the
+# Windows docker-builder task because $CIRRUS_ENV can't
+# be updated and this method is not working on PowerShell.
+export_date_unix_shell: &export_date_unix_shell
+  export_date_script: |
+    ARTIFACT_URL=https://api.cirrus-ci.com/v1/artifact/build/${CIRRUS_BUILD_ID}/create_date/date/date.txt
+    curl -fsSLO ${ARTIFACT_URL}
+    DATE=$(cat date.txt)
+    echo "DATE=${DATE}" | tee -a ${CIRRUS_ENV}
 
 # central definition for the tasks interacting with gcp
 
@@ -78,6 +88,24 @@ gcp_docker_auth_win: &gcp_docker_auth_win
   gcp_docker_auth_script:
     - gcloud auth configure-docker --quiet %GCP_REGION%-docker.pkg.dev
 
+# To export date and to use this date on other tasks, have a minimal task
+# that all others depend on.
+task:
+  name: create_date
+
+  container:
+    image: debian:latest
+    cpu: 0.5
+    memory: 256Mi
+
+  export_date_script: |
+    DATE=$(date --utc +'%Y-%m-%dt%H-%M-%S')
+    echo "${DATE}" | tee -a date.txt
+
+  date_artifacts:
+    path: "date.txt"
+    type: text/plain
+
 
 task:
   matrix:
@@ -116,9 +144,7 @@ task:
   info_script:
     - packer --version
 
-  export_date_script: |
-    DATE=$(date --utc +'%Y-%m-%dt%H-%M-%S')
-    echo "DATE=${DATE}" | tee -a $CIRRUS_ENV
+  <<: *export_date_unix_shell
 
   build_image_script: |
     packer build \
@@ -178,9 +204,7 @@ task:
   info_script:
     - packer --version
 
-  export_date_script: |
-    DATE=$(date --utc +'%Y-%m-%dt%H-%M-%S')
-    echo "DATE=${DATE}" | tee -a $CIRRUS_ENV
+  <<: *export_date_unix_shell
 
   build_image_script: |
     export PACKER_LOG=1
@@ -275,6 +299,8 @@ task:
     - docker buildx use multibuilder
     - docker buildx inspect --bootstrap
 
+  <<: *export_date_unix_shell
+
   # XXX: would be nicer to split into multiple steps, so that e.g. build vs
   # upload time are visible
   #
@@ -287,8 +313,6 @@ task:
   #
   # Disabled linux/arm64, fails currently due to reasons outside of our control
   build_script: |
-    DATE=$(date --utc +'%Y-%m-%dt%H-%M-%S')
-
     docker buildx build \
       --platform linux/amd64 \
       --build-arg DATE=$DATE \
@@ -330,7 +354,9 @@ docker_builder:
     # switched to the powershell
     - ps: |
         echo "gcp_password = `"$(gcloud auth print-access-token)`"" | Out-File -Append -Encoding ASCII ${Env:PKRVARFILE}
-        $DATE=[datetime]::Utcnow.Tostring("yyyy-MM-dd't'HH-mm-ss")
+        $ARTIFACT_URL="https://api.cirrus-ci.com/v1/artifact/build/${Env:CIRRUS_BUILD_ID}/create_date/date/date.txt"
+        curl.exe -fsSLO ${ARTIFACT_URL}
+        $DATE=$(cat date.txt)
 
         packer build `
           -only "*.${Env:CIRRUS_TASK_NAME}" `