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Overview

A simple, cron-like Windows service with an http interface. I use this tool to manage our deployment servers, gitlab runners (all VM's are running Windows), test automation VM's, etc. A client tool n1.exe is also available to interface with this service.

Main functions

Schedule commands to run periodically

Prior to this service, I have been using the task scheduler for running periodic tasks. Over time, it proved to be cumbersome to manage especially with lots of VM's involved.

This service runs command lines periodically as its main function. A run.conf configuration file is provided. The lowest timer tick value support is 1 minute.

┌───────────── min (0 - 59)
│ ┌─────────── hour (0 - 23)
│ │ ┌───────── day of month (1 - 31)
│ │ │ ┌─────── month (1 - 12)
│ │ │ │ ┌───── day of week (0 - 6) (0 to 6 are Sunday to Saturday
│ │ │ │ │
* * * * * command to execute

Examples:

Run every minute:
* * * * * cmd.exe /arg1 /arg2 "arg with space" /sampledir "path\to\something"

Run every 5 minutes:
*/5 * * * * cmd.exe /arg1 /arg2 "arg with space" /sampledir "path\to\something"

Run every 2 hours:
* */2 * * * cmd.exe /arg1 /arg2 "arg with space" /sampledir "path\to\something"

Run every Aug 28 at 8:00am:
0 8 28 8 * file.exe -arg1 -arg2

Run every Saturday at 10 mins interval:
*/10 * * * 6 file.exe --arg1 --arg2

Check out run.conf configuration for more information.

Update self

This is the main reason why I wrote this service; to rid of logging in to every VM and do stuff.

You can use n1.exe to upload a new version of this service to itself.

n1.exe update --file [new-service-exe] --hosts [ip1, ip2, ip3, ...] self

With this command, n1.exe will upload the file, service saves it, then call MoveFileEx API with the MOVEFILE_DELAY_UNTIL_REBOOT flag to ask Windows to overwrite the running binary with the newly uploaded one after system reboot. By default, the service will reboot the system after calling MoveFileEx.

Update all gitlab runners

Another useful feature; updating all gitlab runner services. Currently, all our runners are installed in c:\runner folder so this path is hardcoded.

n1.exe update --file [new-gitlab-runner-exe] --hosts [ip1, ip2, ip3, ...] runner

Update run.conf

Same with updating the service itself, without the reboot.

n1.exe update --file [new-run-conf-file] --hosts [ip1, ip2, ip3, ...] conf

Upload file

I use this to upload additional tools/executables to add to run.conf but you can upload any file to any location using this command.

n1.exe upload --file [any-file] --path [location/path-to-copy-the-file] --host [ip]

File stats

n1.exe stat --files [comma-separated files/dirs] --host [ip]

Read file

I use this mainly to confirm whether the run.conf update process is successful or not.

n1.exe read --file [file-to-read] --host [ip]

Execute commands remotely

Quite a dangerous feature, though. Remember that this service runs under SYSTEM account in session 0.

n1.exe exec --cmd [cmd-to-execute] --host [ip]

The service will also capture the console output (if cmd is console-based) and sent it back to client.

Since cmd will be executed from service session, it is not interactive by default. To run an interactive command, use n1.exe's --interactive=true option.

n1.exe exec --cmd [cmd-to-execute] --host [ip] --interactive=true --wait=true --waitms=5000

The service will run cmd within the same session as winlogon.exe (not session 0) via the CreateProcessAsUser API. This is done through an external function StartSystemUserProcess hosted in libcore.dll.

Query service version

I use this mainly to confirm whether the service update process is successful or not.

n1.exe version --host [ip]

Installation

Run the following commands as administrator:

holly.exe install
holly.exe start

Uninstall

Run the following commands as administrator:

holly.exe stop
holly.exe remove

Troubleshooting

Service cannot start

  • disptrace.dll is built using VS2015 so you need to install VC++ 2015 redistributable.

Cannot access http interface

  • Add holly.exe file to 'Allowed apps' in your Windows Firewall. You can also enable port 8080 as well.

ETW logging

Logging uses ETW. For more information, check out this project or this blog series.

Quickstart guide to view ETW logs (to aid in service debugging)

  • Install manifest file
admin_prompt> wevtutil.exe im jytrace.man /mf:"full_path_to_disptrace.dll" /rf:"full_path_to_disptrace.dll"
  • Use mftrace.exe to view real-time logs from service from command line/Powershell. You can find mftrace.exe from the Windows SDK/WDK installation folder (i.e. C:\Program Files (x86)\Windows Kits\10\bin\x86\). Note that mftrace.exe needs mfdetours.dll (from the same location) to run, in case you want to copy the two files to a separate location. For more information about mftrace.exe, check out this link.
admin_prompt> mftrace.exe -c config.xml

If you're forking/contributing/modifying the service and you want more logs from the service, use the provided trace() wrapper function.

License

The MIT License

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Simple cron-like service with http interface.

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