[ci] fix linux runners running out of disk space (fixed #6635)

.vsts-ci.yml

@@ -50,6 +50,35 @@ resources:
       tasks: true
 jobs:
 ###########################################
+- job: Maintenance
+###########################################
+  pool: mariner-20240410-0
+  container: ubuntu-latest
+  # routine maintenance (like periodically deleting old files),
+  # to be run on 1 random CI runner in the self-hosted pool each runner
+  steps:
+  - script: |
+      print-diagnostics(){
+        echo "---- df -h -m ----"
+        df -h -m
+        echo "---- docker system df ----"
+        /tmp/docker system df
+        echo "---- docker images ----"
+        /tmp/docker images
+      }
+      # check disk usage
+      print-diagnostics
+      # remove old containers, container images, volumes
+      # ref: https://stackoverflow.com/a/32723127/3986677)
+      echo "---- running 'docker system prune' ----"
+      /tmp/docker system prune \
+        --all \
+        --force \
+        --filter until=720h
+      # check disk usage again
+      print-diagnostics
+    displayName: clean
+###########################################
 - job: Linux
 ###########################################
   variables: