Show actual distro info instead of "Ubuntu Core 18"?

snapcraft
1

Hi,

I made a snap for my app, and everything is working perfectly except on thing, which is:

If I run my tool locally without snap, this line will read like:

Linux distro: Ubuntu 19.10 eoan

while on snap this same line will say:

Linux distro: Ubuntu Core 18

I understand this correct as in snap that’s the actual environment information. However, I was wondering is there any way to get it to display my host distro information?

Thanks

2

if you use the system-observe plug you should be able to read:

/var/lib/snapd/hostfs/etc/os-release

which has the info from the host machine …

1 Like
3

Perfect, exactly what I was looking for.

Thanks!

4

I’m about to release my snap, and I was planning to use classic confinement which I thought has unrestricted access to all system resources.

However, after building my snap and then installing it with:
snap install auto-cpufreq_1.0_amd64.snap --classic --dangerous

After I run the app, I get an error, i.e:

sudo auto-cpufreq --live

----------------------------- System information ------------------------------

Traceback (most recent call last):
  File "/snap/auto-cpufreq/x1/bin/auto-cpufreq", line 108, in <module>
    main()
  File "/snap/auto-cpufreq/x1/lib/python3.6/site-packages/click/core.py", line 764, in __call__
    return self.main(*args, **kwargs)
  File "/snap/auto-cpufreq/x1/lib/python3.6/site-packages/click/core.py", line 717, in main
    rv = self.invoke(ctx)
  File "/snap/auto-cpufreq/x1/lib/python3.6/site-packages/click/core.py", line 956, in invoke
    return ctx.invoke(self.callback, **ctx.params)
  File "/snap/auto-cpufreq/x1/lib/python3.6/site-packages/click/core.py", line 555, in invoke
    return callback(*args, **kwargs)
  File "/snap/auto-cpufreq/x1/bin/auto-cpufreq", line 73, in main
    sysinfo()
  File "/snap/auto-cpufreq/x1/lib/python3.6/site-packages/source/core.py", line 324, in sysinfo
    searchfile = open("/var/lib/snapd/hostfs/etc/os-release", "r")
FileNotFoundError: [Errno 2] No such file or directory: '/var/lib/snapd/hostfs/etc/os-release'

Building the snap in devmode confinement and installing it as such shows no errors. Do you know why this is the case?

5

classic snaps behave differently and do not use interfaces at all when you use --devmode you set a strict snap into a lose confinement mode so that you can catch any denials in your system log to fix the confinement … if you use classic confinement, all of the confinement features (including interfaces) get turned off …

that said, you should be able to just access /etc/os-release directly under classic confinement. …

6

Right, that’s what I thought as well. This is what my snapcraft file looks like.

Building and installing it with snap install auto-cpufreq_1.0_amd64.snap --classic --dangerous will result in error above, as /var/lib/snapd/hostfs/etc/os-release file really doesn’t exist in classic confinement.

But if I changed confinement to devmode, build and install it with snap install auto-cpufreq_1.0_amd64.snap --dangerous I won’t get any errors and file will be available.

Update

I set to use /usr/lib/os-release which is available and works on both devmode and classic confinement.

7

Right, the hostfs is directly accessible to classic snaps so you don’t need to use the /var/lib/snapd/hostfs prefix because you can just go direct to the file. That’s why snapd doesn’t even set the /var/lib/snapd/hostfs mount up for a classic snap at all, making your attempt to access it result in a not found error.

8

Okay, that’s good to know.