Fixes #4008 by retrieving environment variables prefixed with "CONTAINERD_"

[nicolasbrechet]

Proposed Changes

This PR simply modifies the install script to retrieve the environment variables that are prefixed with "CONTAINERD_",thus allowing to configure containerd at installation

Types of Changes

Bugfix

Verification

Install K3s master node with this change and variables prefixed with "CONTAINERD_"
On the master node, check the content of the /etc/systemd/system/k3s.service.env

Linked Issues

#4008

User-Facing Change

NONE

Further Comments

[rancher-max]

LGTM. I confirmed this works using the below. Note this didn't pull because I didn't have my proxy setup, but it is showing the expected values and using the environment variables correctly:

curl -fL https://raw.githubusercontent.com/nicolasbrechet/k3s/patch-1/install.sh | INSTALL_K3S_EXEC="--write-kubeconfig-mode 644" CONTAINERD_HTTP_PROXY="http://this.is.my.fake.proxy/" CONTAINERD_HTTPS_PROXY="https://this.is.my.fake.proxy/" INSTALL_K3S_COMMIT=699ea165231cf6d665425c50ff5c75e1831f4afb sh -

...
$ sudo cat /etc/systemd/system/k3s.service.env
CONTAINERD_HTTP_PROXY=http://this.is.my.fake.proxy/
CONTAINERD_HTTPS_PROXY=https://this.is.my.fake.proxy/

$ k describe -n kube-system pod/coredns-85cb69466-mpk6s
...
Events:
  Type     Reason                  Age                From               Message
  ----     ------                  ----               ----               -------
  Normal   Scheduled               42s                default-scheduler  Successfully assigned kube-system/coredns-85cb69466-mpk6s to ip-172-31-26-123
  Warning  FailedCreatePodSandBox  14s (x3 over 42s)  kubelet            Failed to create pod sandbox: rpc error: code = Unknown desc = failed to get sandbox image "rancher/mirrored-pause:3.1": failed to pull image "rancher/mirrored-pause:3.1": failed to pull and unpack image "docker.io/rancher/mirrored-pause:3.1": failed to resolve reference "docker.io/rancher/mirrored-pause:3.1": failed to do request: Head "https://registry-1.docker.io/v2/rancher/mirrored-pause/manifests/3.1": proxyconnect tcp: dial tcp: lookup this.is.my.fake.proxy: no such host

[cwayne18]

@nicolasbrechet thank you for this and welcome to contributing to k3s! I just have one ask, can you please follow the instructions here to make sure your commits are signed off so that the DCO check can pass? https://github.com/k3s-io/k3s/pull/4009/checks?check_run_id=3600207069

Thanks again, we really appreciate the PR!

[codecov-commenter]

Codecov Report

Merging #4009 (57ad2f6) into master (699ea16) will decrease coverage by 0.44%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #4009      +/-   ##
==========================================
- Coverage   11.61%   11.16%   -0.45%     
==========================================
  Files         131      132       +1     
  Lines        8860     8928      +68     
==========================================
- Hits         1029      997      -32     
- Misses       7606     7715     +109     
+ Partials      225      216       -9     

Flag	Coverage Δ
inttests	?
unittests	11.16% <ø> (-0.09%)	⬇️

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

Impacted Files	Coverage Δ
tests/util/cmd.go	0.00% <0.00%> (-42.03%)	⬇️
pkg/flock/flock_unix.go	0.00% <0.00%> (-20.00%)	⬇️
pkg/etcd/etcd.go	16.26% <0.00%> (-0.26%)	⬇️
pkg/server/server.go	0.00% <0.00%> (ø)
pkg/daemons/config/types.go	50.00% <0.00%> (ø)
pkg/daemons/control/server.go	0.00% <0.00%> (ø)
pkg/etcd/controller.go
pkg/etcd/member_controller.go	0.00% <0.00%> (ø)
pkg/etcd/metadata_controller.go	0.00% <0.00%> (ø)

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[brandond]

This is ready to go once the DCO is taken care of.

[nicolasbrechet]

Sorry about that! DCO is taken care of, now.