fix(test): wait for microVM to boot before snapshotting

In test_vulnerabilities.py we have various tests that check whether a
condition holds after resuming from a snapshot. These checks seem to
consistently fail if we take a snapshot before letting the guest kernel
boot.

Introduce an ssh command to ensure that the guest has booted before
taking the snapshot so that we avoid the issue.

Signed-off-by: Babis Chalios <[email protected]>

Author: bchalios

tests/integration_tests/security/test_vulnerabilities.py

@@ -59,6 +59,7 @@ def configure_microvm(
     else:
         microvm = factory.build(kernel, rootfs)
 
+    microvm.help.enable_console()
     microvm.spawn()
     microvm.basic_config(vcpu_count=2, mem_size_mib=256, cpu_template=cpu_template)
     if custom_cpu_template:
@@ -122,6 +123,9 @@ def with_restore(factory, microvm_factory):
 
     def restore(firecracker=None, jailer=None):
         microvm = factory(firecracker, jailer)
+        # Ensure that we have booted before getting the snapshot.
+        rc, _, stderr = microvm.ssh.run("true")
+        assert rc == 0, stderr
         snapshot = microvm.snapshot_full()
 
         if firecracker: