chore: add dev container support for simplicity

[Tony-WLB]

This pull request introduces a development container setup to streamline onboarding and development for the Netplan project. It also completes the dependencies list.

Dev container environment:

• .devcontainer/Dockerfile - define a reproducible Ubuntu 24.04-based development environment
• .devcontainer/devcontainer.json - configure the dev container

Documentation updates:

• Updated the README.md to mention the new dev container as an alternative to manual dependency installation, and revised the dependency list to match the packages installed in the dev container.

[JegadishD]

@Tony-WLB
The approach of using a devcontainer for netplan development looks promising.
However, the following points should be considered as part of using a container-based development environment.

1. The netplan is used widely including in other debian based distributions. The original README file looks neutral and not leaning towards a specific container technology or IDE. As there are other container technologies and IDE, it is preferable to move the VSCode-container-build-environment details from the README.md to another VSC_specific file.

2. Netplan has dependency with other processes like systemd, networkd, dbus. The container definitions do not include them. While running the make-tests, the following errors are seen which are likely due to lack of dependent services.

Failed to connect to system bus: No such file or directory
System has not been booted with systemd as init system (PID 1). Can't operate.

3. Netplan code makes accesses to sys folder-files and kernel states depending on the network configurations. It needs to be seen if this limits us from running all tests from a container environment.

[Tony-WLB]

Hi @JegadishD !

Yeah, I have the same concern about the VS Code part. Since editor choice is largely up to individual developers, I’m not sure how much emphasis we should put on VS Code here.
Would it make sense to move it to a separate file, or should we remove it altogether? VS Code already provides guidance through pop-ups when users open the project, so duplicating that here might not add much value.

The current dependencies part can cover the tests triggered by make check and make check-coverage. The networkd should be contained in the systemd package, and the dbus is included by the Ubuntu image.

However, as you mentioned, this container is not running systemd as PID 1, and that does bring some troubles for realistic testing. It seems that some manual setups are needed to run realistic tests with apply.
I've tried a naive test with netplan try in a VM instead of the container, and it was working. Maybe we can achieve similar behavior in the container with further configuration. For now, the container is okay withmake, make check, and make check-coverage; realistic tests may need a more detailed setup.

[JegadishD]

Hi @JegadishD !

Yeah, I have the same concern about the VS Code part. Since editor choice is largely up to individual developers, I’m not sure how much emphasis we should put on VS Code here. Would it make sense to move it to a separate file, or should we remove it altogether? VS Code already provides guidance through pop-ups when users open the project, so duplicating that here might not add much value.

Hi @Tony-WLB
Removing the VSCode dev environment details from this repository also makes sense. But it would be useful to have the Dockerfile, the devcontainer-file and the steps accessible at an another repository. We can make use (and extend) of it where applicable.

The current dependencies part can cover the tests triggered by make check and make check-coverage. The networkd should be contained in the systemd package, and the dbus is included by the Ubuntu image.

The systemd package is not present in the ubuntu docker container. In the process list of the container, I do not see systemd or networkd running in it.

Tasks:  20 total,   1 running,  19 sleeping,   0 stopped,   0 zombie
%Cpu(s):  0.4 us,  0.4 sy,  0.0 ni, 99.3 id,  0.0 wa,  0.0 hi,  0.0 si,  0.0 st 
MiB Mem :   7935.5 total,   1588.4 free,   1782.2 used,   4875.7 buff/cache     
MiB Swap:      0.0 total,      0.0 free,      0.0 used.   6153.3 avail Mem 

    PID USER      PR  NI    VIRT    RES    SHR S  %CPU  %MEM     TIME+ COMMAND                                 
    266 ubuntu    20   0   11.3g 137080  54784 S   1.4   1.7   0:14.20 node                                    
      1 ubuntu    20   0    2800   1748   1644 S   0.0   0.0   0:06.74 sh                                      
    138 ubuntu    20   0    2800   1960   1804 S   0.0   0.0   0:00.02 sh                                      
    228 ubuntu    20   0 1047520  54940  46544 S   0.0   0.7   0:00.20 node                                    
    257 ubuntu    20   0    2800   1916   1812 S   0.0   0.0   0:00.02 sh                                      
    598 ubuntu    20   0 1132448  73820  49164 S   0.0   0.9   0:09.07 node                                    
  36725 root      20   0    2800   1916   1812 S   0.0   0.0   0:00.01 sh                                      
  36731 root      20   0    2800   1768   1668 S   0.0   0.0   0:00.00 sh                                      
  36746 ubuntu    20   0    2800   1924   1812 S   0.0   0.0   0:00.01 sh                                      
  36797 root      20   0    2800   1940   1832 S   0.0   0.0   0:00.01 sh                                      
  36833 ubuntu    20   0    2800   1964   1808 S   0.0   0.0   0:00.01 sh                                      
  36961 ubuntu    20   0 1047376  55356  46308 S   0.0   0.7   0:00.04 node                                    
  36995 ubuntu    20   0  949652  55168  44400 S   0.0   0.7   0:00.11 node                                    
  37017 ubuntu    20   0  947516  53116  44400 S   0.0   0.7   0:00.11 node                                    
  37029 ubuntu    20   0 1132000  60228  49004 S   0.0   0.7   0:00.07 node                                    
  37042 ubuntu    20   0   52.9g 686868  62352 S   0.0   8.5   0:05.34 node                                    
  37073 ubuntu    20   0    5768   5232   3472 S   0.0   0.1   0:00.02 bash                                    
  37102 ubuntu    20   0 1026812  63980  48108 S   0.0   0.8   0:00.10 node                                    
  37246 ubuntu    20   0    8844   5388   3196 R   0.0   0.1   0:00.01 top                                     
  37270 ubuntu    20   0    2696   1692   1596 S   0.0   0.0   0:00.00 sleep  

However, as you mentioned, this container is not running systemd as PID 1, and that does bring some troubles for realistic testing. It seems that some manual setups are needed to run realistic tests with apply. I've tried a naive test with netplan try in a VM instead of the container, and it was working. Maybe we can achieve similar behavior in the container with further configuration. For now, the container is okay withmake, make check, and make check-coverage; realistic tests may need a more detailed setup.

Yes, The container dev environment can be be useful to an extent and the VM can be a suitable environment to test the real changes.

[benhoyt]

Thanks. I'm happy once you've made the changes Jegadish mentioned.

[JegadishD]

Looks good. Thanks