Update install script with option to skip reload

[dramich]

Proposed Changes

Add a new envvar INSTALL_RKE2_SKIP_RELOAD that skips the systemctl
daemon-reload call. This is useful when using the install script
to build images that contain rke2 but init has not run yet.

Types of Changes

Enhancement

Verification

Run the script with and without the new flag set. On a fresh box systemctl won't see the rke2 services until after the reload is called, so running the script with and without the flag should show the difference. Or run in a container before init is called and watch systemctl bomb 😄

Linked Issues

#3247

[brandond]

Is the issue that systemd isn't installed yet when building the image? In the K3s installer we wrap things in a check to see if systemctl is available, perhaps we should do that here as well?

https://github.com/k3s-io/k3s/blob/master/install.sh#L694-L698

[dramich]

systemctl does exist at this point but systemd is not running since init has not run yet, so the check passes but still fails in the same way as before.

[brandond]

one nit; makes sense otherwise

[dramich]

@brandond Can you run the workflows?

[codecov-commenter]

Codecov Report

Merging #3248 (51ce86b) into master (f8f9e45) will decrease coverage by 0.07%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #3248      +/-   ##
==========================================
- Coverage   18.96%   18.88%   -0.08%     
==========================================
  Files          25       25              
  Lines        2289     2287       -2     
==========================================
- Hits          434      432       -2     
  Misses       1817     1817              
  Partials       38       38              

Flag	Coverage Δ
unittests	18.88% <ø> (-0.08%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
pkg/rke2/rke2_linux.go	84.08% <0.00%> (-0.15%)	⬇️
pkg/cli/defaults/defaults.go	93.54% <0.00%> (+0.21%)	⬆️

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[mdrahman-suse]

@dramich can I get some assistance on how to test this? I tried installing rke2 on fresh node by running curl -sfL https://get.rke2.io | sudo INSTALL_RKE2_VERSION=v1.25.0-rc4+rke2r1 INSTALL_RKE2_SKIP_RELOAD=true sh - and when I try to check the status of the service using $ systemctl status rke2-server, I do see the service getting loaded... same happens if I dont use the var INSTALL_RKE2_SKIP_RELOAD=true

rke2-server.service - Rancher Kubernetes Engine v2 (server)
     Loaded: loaded (/usr/local/lib/systemd/system/rke2-server.service; disabled; vendor preset: enabled)
     Active: inactive (dead)
       Docs: https://github.com/rancher/rke2#readme

CC: @brandond