Fix running cargo test in parallel for Jailer

[sudanl0]

Description:

The unit tests in jailer fail when run in parallel, the result of cargo test --package jailer is as below:

failures:

---- env::tests::test_copy_cache_info stdout ----
thread 'env::tests::test_copy_cache_info' panicked at src/jailer/src/env.rs:860:31:
called `Result::unwrap()` on an `Err` value: CgroupHierarchyMissing("No hierarchy found for this cgroup version.")

---- cgroup::tests::test_cgroup_builder_v1 stdout ----
thread 'cgroup::tests::test_cgroup_builder_v1' panicked at src/jailer/src/cgroup.rs:580:17:
called `Result::unwrap()` on an `Err` value: CgroupHierarchyMissing("No hierarchy found for this cgroup version.")

---- cgroup::tests::test_cgroup_builder_v2 stdout ----
thread 'cgroup::tests::test_cgroup_builder_v2' panicked at src/jailer/src/cgroup.rs:588:17:
called `Result::unwrap()` on an `Err` value: CgroupHierarchyMissing("No hierarchy found for this cgroup version.")

---- cgroup::tests::test_cgroup_v2_write_value stdout ----
thread 'cgroup::tests::test_cgroup_v2_write_value' panicked at src/jailer/src/cgroup.rs:649:17:
called `Result::unwrap()` on an `Err` value: CgroupHierarchyMissing("No hierarchy found for this cgroup version.")

---- cgroup::tests::test_cgroup_build stdout ----
thread 'cgroup::tests::test_cgroup_build' panicked at src/jailer/src/cgroup.rs:614:54:
called `Result::unwrap()` on an `Err` value: CgroupHierarchyMissing("No hierarchy found for this cgroup version.")
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

---- env::tests::test_new_env stdout ----
thread 'env::tests::test_new_env' panicked at src/jailer/src/env.rs:874:35:
This new environment should be created successfully.: FileOpen("/tmp/firecracker/test/jailer/proc/mounts", Os { code: 2, kind: NotFound, message: "No such file or directory" })

---- cgroup::tests::test_cgroup_build_invalid stdout ----
thread 'cgroup::tests::test_cgroup_build_invalid' panicked at src/jailer/src/cgroup.rs:633:54:
called `Result::unwrap()` on an `Err` value: FileOpen("/tmp/firecracker/test/jailer/proc/mounts", Os { code: 2, kind: NotFound, message: "No such file or directory" })

---- env::tests::test_save_exec_file_pid stdout ----
thread 'env::tests::test_save_exec_file_pid' panicked at src/jailer/src/env.rs:860:31:
called `Result::unwrap()` on an `Err` value: FileOpen("/tmp/firecracker/test/jailer/proc/mounts", Os { code: 2, kind: NotFound, message: "No such file or directory" })

---- env::tests::test_userfaultfd_dev stdout ----
thread 'env::tests::test_userfaultfd_dev' panicked at src/jailer/src/env.rs:860:31:
called `Result::unwrap()` on an `Err` value: FileOpen("/tmp/firecracker/test/jailer/proc/mounts", Os { code: 2, kind: NotFound, message: "No such file or directory" })

---- env::tests::test_mknod_and_own_dev stdout ----
thread 'env::tests::test_mknod_and_own_dev' panicked at src/jailer/src/env.rs:860:31:
called `Result::unwrap()` on an `Err` value: FileOpen("/tmp/firecracker/test/jailer/proc/mounts", Os { code: 2, kind: NotFound, message: "No such file or directory" })

---- env::tests::test_setup_jailed_folder stdout ----
thread 'env::tests::test_setup_jailed_folder' panicked at src/jailer/src/env.rs:860:31:
called `Result::unwrap()` on an `Err` value: FileOpen("/tmp/firecracker/test/jailer/proc/mounts", Os { code: 2, kind: NotFound, message: "No such file or directory" })

---- env::tests::test_copy_exec_to_chroot stdout ----
thread 'env::tests::test_copy_exec_to_chroot' panicked at src/jailer/src/env.rs:1215:9:
assertion `left == right` failed
  left: []
 right: [115, 111, 109, 101, 95, 99, 111, 110, 116, 101, 110, 116]

---- env::tests::test_cgroups_parsing stdout ----
thread 'env::tests::test_cgroups_parsing' panicked at src/jailer/src/env.rs:1298:31:
called `Result::unwrap()` on an `Err` value: FileOpen("/tmp/firecracker/test/jailer/proc/mounts", Os { code: 2, kind: NotFound, message: "No such file or directory" })

---- cgroup::tests::test_cgroup_builder_v2_with_v1_mounts stdout ----
thread 'cgroup::tests::test_cgroup_builder_v2_with_v1_mounts' panicked at src/jailer/src/cgroup.rs:596:17:
called `Result::unwrap_err()` on an `Ok` value: CgroupBuilder { version: 2, hierarchies: {"unified": "/tmp/firecracker/test/jailer/sys_cgroup/unified"}, mount_points: [] }


failures:
    cgroup::tests::test_cgroup_build
    cgroup::tests::test_cgroup_build_invalid
    cgroup::tests::test_cgroup_builder_v1
    cgroup::tests::test_cgroup_builder_v2
    cgroup::tests::test_cgroup_builder_v2_with_v1_mounts
    cgroup::tests::test_cgroup_v2_write_value
    env::tests::test_cgroups_parsing
    env::tests::test_copy_cache_info
    env::tests::test_copy_exec_to_chroot
    env::tests::test_mknod_and_own_dev
    env::tests::test_new_env
    env::tests::test_save_exec_file_pid
    env::tests::test_setup_jailed_folder
    env::tests::test_userfaultfd_dev

test result: FAILED. 17 passed; 14 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.26s

error: test failed, to rerun pass `-p jailer --bin jailer`
root@cff916670245:/firecracker# 

The tests run successfully when run serially with this command : cargo test --package jailer -- --test-threads=1

Action item

To fix the unit tests so they can run in parallel.

Acceptance criteria

PR with the fix to run cargo test --package jailer command without any errors.

[cm-iwata]

I'm interested in working on this issue.
May I work on it?

[sudanl0]

@cm-iwata thank you for sharing your interest on this. Please feel free to work on it and post a PR when you are ready.