Add support for using base template in etc/containerd/config.toml.tmpl

[skirsten]

Proposed Changes

Right now you need copy-paste the default containerd config template from github into config.toml.tmpl only to add a few lines.

This PR allows to do 👇 instead which is much cleaner and removes the need to keep the base template up-to-date from ☝️ :

/var/lib/rancher/k3s/agent/etc/containerd/config.toml.tmpl

{{ template "base" . }}

[plugins."io.containerd.grpc.v1.cri".containerd.runtimes."custom"]
  runtime_type = "io.containerd.runc.v2"
[plugins."io.containerd.grpc.v1.cri".containerd.runtimes."custom".options]
  BinaryName = "/usr/bin/custom-container-runtime"

Types of Changes

The PR adds the base template to the template list, so that it can be used.

Verification

• Build
• Use above config.toml.tmpl
• cat config.toml

Testing

Linked Issues

• Use base template in etc/containerd/config.toml.tmpl #7992

User-Facing Change

User-provided containerd config templates may now use `{{ template "base" . }}` to include the default K3s template content. This makes it easier to maintain user configuration if the only need is to add additional sections to the file.

Further Comments

[brandond]

Thanks! Would you mind opening an issue describing the problem you're trying to solve, so that our QA folks have something to work against for validation?

[cwayne18]

Thanks for the contribution!

[codecov]

Codecov Report

Patch coverage: 100.00% and project coverage change: +4.48% 🎉

Comparison is base (be44243) 46.94% compared to head (f78a66b) 51.42%.
Report is 8 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #7991      +/-   ##
==========================================
+ Coverage   46.94%   51.42%   +4.48%     
==========================================
  Files         143      143              
  Lines       14561    14562       +1     
==========================================
+ Hits         6836     7489     +653     
+ Misses       6629     5883     -746     
- Partials     1096     1190      +94     

Flag	Coverage Δ
e2etests	49.26% <100.00%> (?)
inttests	44.40% <100.00%> (+0.07%)	⬆️
unittests	19.86% <0.00%> (-0.01%)	⬇️

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

Files Changed	Coverage Δ
pkg/agent/templates/templates_linux.go	62.50% <100.00%> (+5.35%)	⬆️

... and 44 files with indirect coverage changes

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