4_Python.md

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Debugging Python applications remotely

In my "embedded native remote development environment" approach plays Microsoft Visual Studio Code Insider the primary roll as development IDE with a SSH-connection to the SoC-FPGA development board. VS Code can not only be used for Python development but for C++ application development and debugging and for Webinterface design, as well. For every use case please follow this guide to see how you can establish a remote connection between VS Code and rsyocto.

My pre-configured and preferred Linux application development approach for C++,Python and Web

This guide describes how to install and configure Visual Studio Code Insiders to access the Linux system remotely over a ssh-connection. Later on is shown how to use Visual Studio Code to remote debug Phyton applications.

Visual Studio Code is a code editor built by Microsoft. It is an universal binary application and runs on Windows, Linux and macOS. Visual Studio Code Insider is a special version and extended Visual Studio Code with advanced plugin support. For instance, only Visual Studio Code Insider enables a remote access via SSH to ARMv7-A and ARMv8-A Linux devices.

Visual Studio Code Insider does allow only SSH access with a SSH-Keygen. The key must be regenerated after every Board-, SD-card or IP-Address switch. A static IPv4-Address or an indexed MAC address of the board inside the DHCP-Server can prevent the OpenSSH server to request a new keygen after a reboot.

The following step by step guide shows how to setup Visual Studio Code Insider for Python application remote development and debugging on a Windows 10 PC. For other systems please follow Microsoft's instructions: Visual Studio Code Remote Development Troubleshooting Tips and Tricks (Chapter: Improving your security with a dedicated key)

With the following guide Microsoft describes the remote debugging function of Visual Studio Code Insider: Developing on Remote Machines using SSH and Visual Studio Code

I. Generation of the SSH Key with Windows 10 / Linux

• Open the Windows "Command Prompt" or the Linux Terminal Window (admin rights not required)
• Execute the following commands

1. Generate a new SSH Key
   • Windows stores the key inside the following directory: C:\Users\<USER Name>\.ssh
   • Linux here: ~/.ssh

   ssh-keygen -t rsa -b 4096

   
   • Always press ENTER (do not enter an extra password or another name):
2. Set the IPv4 Address of the board

   SET [email protected]

   • Here for example with the IP address 192.168.2.105
3. Copy the generated SSH-Key via SSH to the board
   • After this command the rsyocto splash screen appears and the Linux Distribution asks for the password: eit

   scp %USERPROFILE%\.ssh\id_rsa.pub %REMOTEHOST%:~/tmp.pub

4. Authenticate and activate the SSH key
   • Again, after this following command should the rsyocto splash screen appear and the Linux Distribution should ask for the password: eit

   ssh %REMOTEHOST% "mkdir -p ~/.ssh && chmod 700 ~/.ssh && cat ~/tmp.pub >>  ~/.ssh/authorized_keys && chmod 600 ~/.ssh/authorized_keys && rm -f ~/tmp.pub"

II. Installation of Visual Studio Code Insider and configuration of remote access

• Download and install the latest version of Visual Studio Code Insider: Download Visual Studio Code Insiders

• Follow the installation instructions

• After a successful installation open Visual Studio Code Insider

• On the sidebar (toolbar on the left hand side) click the Extension-icon

• Search for the extension:"Remote Development" (by Microsoft) (Remote Development - Visual Studio Marketplace) and press the install-button to install this extension

  

• Restart Visual Studio Code Insider to accept the changes

• Click on the side bar "Remote Explorer"

• Choose in the Drop Down Menu "REMOTE EXPLORER" and the SSH Target

• Move the mouse of the title "SSH TARGETS" and click on the gear-icon

  

• Select in the appeared Dropdown menu: "C:\Users<USER Name>.ssh\config"

  

• Configure the name and IPv4-Address by adding the following jason-configuration file (change the "HostName" with the IPv4-Address of your board):

Host rsyocto
    ForwardAgent yes
    HostName 192.168.2.105
    User root
    IdentityFile ~/.ssh/id_rsa

• Save and close this configuration file
• If an error occurred close and restart Visual Studio Code Insider and try it again

III. Connection of the rsyocto with Visual Studio Code Insider

• Open Visual Studio Code Insider

• Select on the side bar "Remote SSH"

• Under the tap "Connections" an entry with the name "rsyocto" appears

• Right click on this entry and choose "Connect Host in current Window"

  

  • The first attach attempt takes a little bit longer, because the Visual Studio Code downloads and installs the Visual Studio Code Server
  • Note: Be sure that the board is connected to the internet and the system time is correct (use date to check it)
  • In case that the connection to the board is established successfully a green icon with a connected symbol should appear

IV. Accessing the rootfs files remotely

• Visual Studio Code Insider can access the rootfs (root file system) of the embedded Linux Distribution
• Some Python sample applications are pre-installed on rsyocto
• Navigate on the sidebar to "Explorer" click the blue "Open Folder" icon
• Visual Studio Code Insider should now ask for a remote directory to open
  • Default: "/home/root/" --> User root folder with the Python examples
  • Web sever: "/usr/share/apache2/default-site/htdocs" --> Every file inside this folder will be accessible with a web browser
• Click "okay"

• Now the rootfs of the embedded Linux is accessible with the Visual Studio Code Insider File explorer

V. Preparing the Python remote development

• Select inside the sidebar "Extension"
• Choose the previously installed extension "Python" (by Microsoft)
• Press the green button:"Install on SSH:rsyocto"

• With this input Visual Studio Code Server starts with the installation of the required remote Python debugging components
• Press "reload required" to activate this changes

VI. Debugging Python Code remotely

• Open any pre-installed Python sample located on the home directory (~) of rsyocto (also available inside examples/python of this repo)
• Navigate to the sidebar icon "Debug and Run" and click on the "Debug with Python" Button
• Choose in the Drop Down Menu "Python File"

• Or use the following json-file to configure the debugger:

        {
        "version": "0.2.0",
        "configurations": [
              {
                  "type": "python",
                  "request": "launch",
                  "name": "Python curent file remotly",
                  "program": "${file}",
                  "console":"integratedTerminal"
              }
            ]
        }

• The remote Debugging should start

• If not: press the "Start Debugging" button or F5

• Now Microsoft Visual Studio Code is configured to write and debug any Python Code directly on the embedded Linux via a network interface over SSH and SFTP

  

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VII. Use of the Python Package Manager pip (PyPI)

• The pre-installed example "serialEchoDemo.py" requires the pySerial-module

• "rsyocto" has a full support for all Python pip package index versions

• Use the PiP Homepage to find a module to download and install

• Run the following command to download and install this module with rsyocto:

  pip3 install "module_name"

• Now it is possible to use Python packages, which are designed by a large community (e.g. Raspberry Pi-community), on a powerful Intel SoC-FPGA

• To show all pre-installed Python PiP packages

  pip list

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Example: Debugging the Python script "gsensorDemo.py" on a DE10 Standard Board

Continue with the next level: Analyzation of applications with the ARM Development Studio (DS-5) Streamline