exec-logger

Purpose of exec-logger

This project is purely a "wrapper" around a normal command-line application. It adds functionality like timeouts, abort requests, time-stamp logging, etc

Quick Start

Execute the command

Specify the -task and then lastly the actual command-line (like ping in the below example).

Windows:

go get -u github.com/golang-devops/exec-logger
cd %Temp% & mkdir test-exec-logger & cd test-exec-logger
exec-logger -task exec ping 127.0.0.1 -n 3

Linux:

go get -u github.com/golang-devops/exec-logger
cd $Temp && mkdir test-exec-logger && cd ./test-exec-logger
exec-logger -task exec ping 127.0.0.1 -c 3

Inspect created files

There should now be four files withing a subfolder exec-logger of this temp dir, namely:

• local-context.json - gets written out at the start and includes the UserName and HostName of the machine on which it runs
• alive.txt - gets written out every 2 seconds to inform "external observers" that the process is alive and responding.
• exited.json - gets written out when the process finished and contains the ExitCode, Error (if any), ExitTime (of exit) and Duration (in golang native time.Duration format). These fields are contained in the ExitStatusDto struct
• log.log - contains the stdout/stderr of the "wrapped command" which is that of the ping command in the above example

Note that the log.log file added time-stamp prefixes to each line received from ping. It also has additional information like the last line that should read "Command exited with code 0".

The exited.json file should contain a zero ExitCode.

Failure example

Delete the above three files if they already exist.

Change the above command to a "broken" one (for example by removing the number passed to the -n flag for windows or -c flag for linux. Broken windows command exec-logger -task exec ping 127.0.0.1 -n. Broken linux command exec-logger -task exec ping 127.0.0.1 -c.

Now the three files will be created again. This time the exited.json file should contain a non-zero ExitCode with an Error. The log.log file will contain a line or two with EASY_EXEC_ERROR: prefix after the timestamp. Those lines are the Stderr lines received by the ping command. The last of those error lines would also contain Unable to run command which is generated by the exec-logger itself.

Abort the process prematurely

Delete the above three files if they already exist.

If an "external observer" of this process wants to abort it, it could just create a file called must-abort.txt inside this folder.

Run the same example from above but change the number flag (-n for windows or -c for linux) to something huge, like 3000. This means it will ping 3000 times. But we will abort this process using this mentioned file.

After running that 3000 command open another console window in the same temp directory and call echo "" > must-abort.txt to create the empty file. Now watch the first console windows should shortly after that abort the ping command. After aborting the log.log file will contain a line with Got ABORT message and another with Successfully killed process with PID. The exited.json will also contain a non-zero ExitCode.

Auto time-out using a duration

Delete the above three files if they already exist.

Now to only allow the command to run for a certain time we can use the -timeout-kill flag. Change the above command to something like:

• windows: exec-logger -timeout-kill 5s -task exec ping 127.0.0.1 -n 3000
• linux: exec-logger -timeout-kill 5s -task exec ping 127.0.0.1 -c 3000

Note the added flag -timeout-kill 5s. This will attempt to run ping for 3000 seconds but we tell it to abort after 5s. This timeout flag is in the format of native golang time.Duration.

After 5 seconds it should automatically abort and our usual three files should be there. The exited.json file should again have a non-zero ExitCode with its error being something like "The command timed out after '5s'". The log.log will also contain a line reading Timeout of 5s reached, now aborting as well as Successfully killed process with PID.

Acknowledgments

• shirou/gopsutil - Used for Linux to obtain process children to be killed

Contribution

Pull requests are welcome.