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Installing simple Hello World App on Pantavisor Device

In this tutorial, we are going to install a simple hello world Application to our previously installed and claimed Pantavisor device.

What you will need

To install Application on your Pantavisor device on Pantacor Hub:

  • Any x86_64 based target board (we are using Odroid-H2 in our example)
  • Power cable for target board
  • Internet-facing Ethernet cable
  • Your computer


Compile a Hello World C Program

What we are going to do now, is to compile a hello world app that will just print Hello Pantacor Hub on console continously in a forever loop with some delay. First, create a directory anywhere you wish, execute the following commands:

mkdir Hello_World_App
cd Hello_World_App

Now open a new file hello_world.c in your favourite text editor and copy and paste the following code:

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
int main(void) {
    unsigned long long int i = 0;
    while(1) {
        printf("Hello Pantacor Hub %llu\n", i);

Save the file and quit the text editor. Now compile the C program, make sure to link the libc library statically, execute the follwing command:
$ gcc hello_world.c -o hello_world -static
This will produce a binary hello_world, make sure the binary is statically linked libc libary, to check execute the following command, it should produce output:
$ not a dynamic executable

$ ldd hello_world
        not a dynamic executable

Create a Dockerfile to build a docker image of your application

A dockerfile is required to build a docker image, create a dockerfile
$ vi Dockerfile
Copy and paste the following content in your dockerfile:

FROM scratch
ADD hello_world /usr/bin/hello_world
ENTRYPOINT [ "/usr/bin/hello_world" ]

Save the file and quit the text editor. To build a docker image of your application, execute the following command:
$ docker build -t helloworldbin -f Dockerfile ./
helloworldbin is the name of the image, you can give any name of your choice for the image.
Verify that the image is available under the list of images, run:
$ docker images
$ docker image ls
The above command will list all the available docker images on your host computer.

Verify the docker image

Verify that the docker image is working correctly, execute the following command to run the docker image:
$ docker run --rm-t helloworldbin
If the above command doesn’t produce any error, it means the image is build succssfully.
The above command won’t get terminated with ctrl+c, it needs to be stopped via docker, open a new terminal window or tab and execute the follwing command:

docker rm -f $(docker ps -a -q -f "ancestor=helloworldbin")

Install the Hello World App

To install the Hello world app to your Pantacor Hub device we are going to use the pvr tool from your host computer, execute the following commands:

cd ../<clone-checkout> #your cloned device repesentation
fakeroot pvr app add --arg PV_RUN_TMPFS_DISABLE=yes --from helloworldbin hello_binary
pvr add .
pvr commit
pvr post

This will automatically commit the new app and post it to the device, which will then process the update. You can follow this process on Pantacor Hub, checking out the console of your device. Once the device is in done state, you can view the logs from console choose hello_binary-console from Filter Logs dropdown.