autoupdate-v1-tests

README

Upgrade Exec Service Testing

This is a test program to explore update functionality, primarily focuses on windows.It pairs with the [Autoupdate ADR](/ docs/architecture/2019-03-11_autoupdate.md)

Observations

You cannot remove an exe that's linked to a running service. You can rename it. You can't overwrite it. This manifests as a permission error. If the service is loaded, but stopped, you can overwrite.

Note that if you're using the restart-on-failure, this can create a small race condition. If the service manager attempts a restart while there is no binary on the expected path, the service transitions to a stopped state. This timing is effected by the restart delay settings.

Windows Services Restart On Failure

Windows Service Manager can restart services on failure. This is controlled by the Recovery portion of the settings. Behavior seems the same regardless of exit code. Process does get a new PID on launch

These configs can be examined using the sc.exe tool. (Note: you might need an extra param to adjust the buffer size.)

For example:

PS C:\Users\example> sc.exe qfailure upgradetest 5000
[SC] QueryServiceConfig2 SUCCESS

SERVICE_NAME: upgradetest
        RESET_PERIOD (in seconds)    : 0
        REBOOT_MESSAGE               :
        COMMAND_LINE                 :

Further Reading:

• WiX ServiceConfig
• go configs
• StackExchange

Note: The MSI options to configure this are broken. The recommendation is to use a Custom Action to call out to sc.exe. Instead, we handle inside the service start.

Replace before restart

Manually testing the idea of moving a binary aside, and dropping in a new one and then calling Exit(0) and letting the service manager restart... This seems to work

Test Process:

1. Use my test case of run 5s, exit.
2. svc manager restarts
3. Observe new PIDs.
4. During a 5s loop, move old binary aside and scp new binary in
5. Observe the format of the log messages change on restart

Shell Debugging Snippets

Viewing Event Log:

# Old interface
Get-EventLog -LogName Application -Newest 10

# New interface, with full bodies
Get-WinEvent -LogName System -MaxEvents 10
Get-WinEvent -LogName Application -MaxEvents 10 | Format-Table TimeCreated,Message -wrap

Various ways to see service status:

Get-Service upgradetest

sc.exe query upgradetest
sc.exe qc  upgradetest
sc.exe qfailure upgradetest 5000