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Testing

All of these tests have been automated in sanity.rs.

The examples directory contains several programs used for testing this library.

  • simple.rs: A program that demonstrates the usage of the pid1-rs library.
  • zombie.rs: Creates a zombie process.
  • sigterm_handler.rs: A program that has a SIGTERM handler and exits upon receiving the signal.
  • sigterm_loop.rs: A buggy program that does not exit on SIGTERM.
  • dumb_shell.rs: An alternative shell for testing, since bash automatically reaps child processes.

Environment setup

  • Run the test program via the just recipe: build-image
  • You can get shell access to it via the recipe: exec-shell
❯ just exec-shell
docker exec -it pid1rs sh
/ # ps aux
PID   USER     TIME  COMMAND
    1 root      0:05 /simple
    7 root      0:00 /simple
    8 root      0:00 sh
   14 root      0:00 [date]
   15 root      0:00 ps aux

Tests

Basic functionality

❯ just test
...
docker run --name pid1rs -t pid1rstest
pid1-rs: Process running as PID 1
pid1-rs: Process not running as Pid 1: PID 7
In the simple process, going to sleep. Process ID is 7
Args: ["/simple"]
Wed Sep 27 08:29:35 UTC 2023
Wed Sep 27 08:29:37 UTC 2023
Wed Sep 27 08:29:39 UTC 2023

Ensure that the process exits with a status code of 0. The test above confirms the following:

  • The simple program was executed as PID 1.
  • It relaunched itself as PID 7, which then executed various child processes.

Zombie process

❯ just run-image
...
docker rm pid1rs || exit 0
pid1rs
docker run --name pid1rs -t pid1rstest /simple --sleep
pid1-rs: Process running as PID 1
pid1-rs: Process not running as Pid 1: PID 7
In the simple process, going to sleep. Process ID is 7
Args: ["/simple", "--sleep"]
Wed Sep 27 08:34:57 UTC 2023
Wed Sep 27 08:34:59 UTC 2023
Wed Sep 27 08:35:01 UTC 2023
Going to sleep 500 seconds
Wed Sep 27 08:35:03 UTC 2023

While it's executing, open a new shell and run the recipe to create a zombie process:

❯ just run-zombie
docker exec -t pid1rs zombie
Process ID is 9
Parent process: going to sleep and exit

You should see the following logs from the simple process, indicating that a process has been reaped:

...
Wed Sep 27 09:40:56 UTC 2023
Reaped pid: 15

Child Exit code status propagation

  • Run the run-image recipe:
❯ just run-image
...
docker rm pid1rs || exit 0
pid1rs
docker run --name pid1rs -t pid1rstest /simple --sleep
pid1-rs: Process running as PID 1
pid1-rs: Process not running as Pid 1: PID 7
In the simple process, going to sleep. Process ID is 7
Args: ["/simple", "--sleep"]
Wed Sep 27 08:34:57 UTC 2023
Wed Sep 27 08:34:59 UTC 2023
Wed Sep 27 08:35:01 UTC 2023
Going to sleep 500 seconds
Wed Sep 27 08:35:03 UTC 2023
  • Run the exec-shell recipe and perform the test:
❯ just exec-shell
docker exec -it pid1rs sh
/ # ps -aux
USER         PID %CPU %MEM    VSZ   RSS TTY      STAT START   TIME COMMAND
root           1  0.0  0.0    996     4 pts/0    Ss+  12:34   0:00 /simple --sleep
root           7  0.0  0.0    976     4 pts/0    S+   12:34   0:00 /simple --sleep
root           8  0.0  0.0      0     0 pts/0    Z+   12:34   0:00 [date] <defunct>
root           9  0.0  0.0   1672  1048 pts/1    Ss   12:34   0:00 sh
root          14  0.0  0.0      0     0 pts/0    Z+   12:34   0:00 [date] <defunct>
root          15  0.0  0.0      0     0 pts/0    Z+   12:34   0:00 [date] <defunct>
root          16  0.0  0.0      0     0 pts/0    Z+   12:34   0:00 [date] <defunct>
root          17  0.0  0.0   2460  1608 pts/1    R+   12:34   0:00 ps -aux
/ # kill -12 7
  • Check the logs of the run-image recipe to find the exit status code:
...
error: Recipe `run-image` failed on line 21 with exit code 140

The exit code 140 is correct (128 + 12).

SIGINT/SIGTERM handling

The goal of this test is to verify that the child process's SIGTERM handler is called if it is defined.

These are the signal codes:

  • SIGINT: 2
  • SIGTERM: 15

Execute the recipe sigterm-test:

❯ just sigterm-test
docker rm pid1rs || exit 0
pid1rs
docker run --name pid1rs -t pid1rstest sigterm_handler
pid1-rs: Process running as PID 1
pid1-rs: Process not running as Pid 1: PID 7
This APP can be killed by SIGTERM (15)

Now, send SIGTERM to the PID 1 process:

❯ just send-sigterm

Confirm from the logs that the SIGTERM handler was called and that the process exited with a status of 0:

App got SIGTERM 15, going to exit

Now, perform the same test with SIGINT. You can confirm that nothing is printed, as this signal is not handled by the application.

SIGTERM ignore

This test is for an application that ignores SIGTERM and continues running. This library should be able to forcibly kill such processes.

Execute the recipe sigloop-test:

❯ just sigloop-test
docker rm pid1rs || exit 0
pid1rs
docker run --name pid1rs -t pid1rstest sigterm_loop
pid1-rs: Process running as PID 1
pid1-rs: Process not running as Pid 1: PID 7
This APP ignores SIGTERM (15)

Now, send SIGTERM to the PID 1 process:

❯ just send-sigterm

You will see that it would have exited:

App got SIGTERM 15, but will not exit
App got SIGTERM 15, but will not exit
error: Recipe `sigloop-test` failed on line 44 with exit code 137

You can confirm from the status code (137) that the child process was killed by SIGKILL (signal 9, exit code 128 + 9), because the application ignored SIGTERM.