Add preCommand option to support configuring experimental environment by user

[J-shang]

It can be used in remote mode by set preCommand in experiment config. It is an optional key with string value.
An example is as below:

...
machineList:
  - ip: ${replace_to_your_remote_machine_ip}
    username: ${replace_to_your_remote_machine_username}
    sshKeyPath: ${replace_to_your_remote_machine_sshKeyPath}
    # Pre-command will be executed before the remote machine executes other commands.
    # Below is an example of specifying python path.
    # If you want to execute multiple commands, please use "&&" to connect them.
    preCommand: export PATH=${replace_to_python_environment_path_in_your_remote_machine}:$PATH
...

[QuanluZhang]

export PATH=${replace_to_python_environment_path_in_your_remote_machine}:$PATH. since only this part replace_to_python_environment_path_in_your_remote_machine can be changed, why not directly write this part in this field without export PATH=...

[J-shang]

@QuanluZhang The example may not be particularly clear. It is an example for export python path directly, but not only ${replace_to_python_environment_path_in_your_remote_machine} can be changed.
Maybe you want to use
preCommand: source "${replace_absolute_path_recommended_here}/bin/activate" to activate a virtualenv
or
preCommand: source /${replace_to_conda_path}/bin/activate ${replace_to_conda_env_name} to activate a conda env
User can use any commands they need to configure the experimental environment.

[QuanluZhang]

@QuanluZhang The example may not be particularly clear. It is an example for export python path directly, but not only ${replace_to_python_environment_path_in_your_remote_machine} can be changed.
Maybe you want to use
preCommand: source "${replace_absolute_path_recommended_here}/bin/activate" to activate a virtualenv
or
preCommand: source /${replace_to_conda_path}/bin/activate ${replace_to_conda_env_name} to activate a conda env
User can use any commands they need to configure the experimental environment.

got it. so it is not specifically for specifying python environment, it is a general command which is executed before trial code. suggest to make it clear how to specify python environment with this command in doc

[J-shang]

Indeed, I will add more detailed instructions in the doc.

[SparkSnail]

It can be used in remote mode by set preCommand in experiment config. It is an optional key with string value.
An example is as below:

...
machineList:
  - ip: ${replace_to_your_remote_machine_ip}
    username: ${replace_to_your_remote_machine_username}
    sshKeyPath: ${replace_to_your_remote_machine_sshKeyPath}
    # Pre-command will be executed before the remote machine executes other commands.
    # Below is an example of specifying python path.
    # If you want to execute multiple commands, please use "&&" to connect them.
    preCommand: export PATH=${replace_to_python_environment_path_in_your_remote_machine}:$PATH
...

This preCommand is added per machine, and only works when the machine is set preCommand? In remote mode, the trial is scheduled randomly on different machine, then the trial code will be executed randomly in different preCommand?

[J-shang]

It can be used in remote mode by set preCommand in experiment config. It is an optional key with string value.
An example is as below:

...
machineList:
  - ip: ${replace_to_your_remote_machine_ip}
    username: ${replace_to_your_remote_machine_username}
    sshKeyPath: ${replace_to_your_remote_machine_sshKeyPath}
    # Pre-command will be executed before the remote machine executes other commands.
    # Below is an example of specifying python path.
    # If you want to execute multiple commands, please use "&&" to connect them.
    preCommand: export PATH=${replace_to_python_environment_path_in_your_remote_machine}:$PATH
...

This preCommand is added per machine, and only works when the machine is set preCommand? In remote mode, the trial is scheduled randomly on different machine, then the trial code will be executed randomly in different preCommand?

Yes, if user don't set preCommand, the process will run in the default environment as before.
I think the trial code will be executed randomly in different preCommand, this may be mainly caused by different configuration methods in different machines. Like source /YOUR_CONDA_PATH/bin/activate your_env in Linux and call activate your_env in Windows.

[QuanluZhang]

suggest to use a subsection to explain how to config python environment with preCommand

[chicm-ms]

Please add UT and/or IT test cases.

[chicm-ms]

Since this preCommand will be added to all commands executed on remote machine, so in doc/config example, please mention that: user should not use those commands may make changes to system, like mkdir, touch, etc

[chicm-ms]

remote machine support windows as local / remote system, have we checked whether it works on windows?

[J-shang]

Please add UT and/or IT test cases.

Got it.

Since this preCommand will be added to all commands executed on remote machine, so in doc/config example, please mention that: user should not use those commands may make changes to system, like mkdir, touch, etc

This should indeed remind users. I will add note for it.

remote machine support windows as local / remote system, have we checked whether it works on windows?

Yes, it works on windows.

[QuanluZhang]

this doc is very clear!

[QuanluZhang]

"If there are multiple commands want to execute" -> "If you want multiple commands to be executed"