When running smoketests in the vyos-build container, an error message similar to the following appears:
DEBUG - test_fastnetmon (__main__.TestServiceIDS.test_fastnetmon) ... [ 4213.579433] Out of memory: Killed process 543005 (fastnetmon) total-vm:2301048kB, anon-rss:7432kB, file-rss:1812608kB, shmem-rss:0kB, UID:0 pgtables:3804kB oom_score_adj:0
Further investigation reveals that the KVM created for the smoketests is limited to 3GB of memory. Increasing this to 4GB allows the test to complete successfully. Recommend that this value in the script be increased to 4GB.