Build antrea-cni binary and release binaries without cgo

[antoninbas]

antrea-cni can be installed (by the initContainer) on systems with
incompatible system libraries. To increase portability, we build
antrea-cni without cgo by setting CG_ENABLED to 0.

Same goes for release binaries (e.g. antctl). Note that when
cross-compiling, cgo is disabled by default, so there is no change there
(e.g. antctl binary for macOS). It's only for native Linux amd64 builds
that there is an actual change.

Fixes #2095

[antoninbas]

Surprisingly, the antrea-cni binary is actually smaller with cgo disabled... I was expecting the opposite...

$ make antrea-cni
GOOS=linux CGO_ENABLED=0 go build -o /home/abas/vmware/antrea/bin  -ldflags ' -X antrea.io/antrea/pkg/version.Version=v1.1.0-dev -X antrea.io/antrea/pkg/version.GitSHA=3134f7ee -X antrea.io/antrea/pkg/version.GitTreeState=dirty -X antrea.io/antrea/pkg/version.ReleaseStatus=unreleased' antrea.io/antrea/cmd/antrea-cni
abas@ubuntu:~/vmware/antrea$ ls -l bin/antrea-cni
-rwxr-xr-x 1 abas abas 11673235 May 18 16:44 bin/antrea-cni

$ make antrea-cni
GOOS=linux CGO_ENABLED=1 go build -o /home/abas/vmware/antrea/bin  -ldflags ' -X antrea.io/antrea/pkg/version.Version=v1.1.0-dev -X antrea.io/antrea/pkg/version.GitSHA=3134f7ee -X antrea.io/antrea/pkg/version.GitTreeState=dirty -X antrea.io/antrea/pkg/version.ReleaseStatus=unreleased' antrea.io/antrea/cmd/antrea-cni
abas@ubuntu:~/vmware/antrea$ ls -l bin/antrea-cni
-rwxr-xr-x 1 abas abas 11741710 May 18 16:45 bin/antrea-cni

[codecov-commenter]

Codecov Report

Merging #2189 (1e53e11) into main (5c5cae5) will increase coverage by 20.07%.
The diff coverage is n/a.

❗ Current head 1e53e11 differs from pull request most recent head 7865e2c. Consider uploading reports for the commit 7865e2c to get more accurate results

@@             Coverage Diff             @@
##             main    #2189       +/-   ##
===========================================
+ Coverage   41.02%   61.09%   +20.07%     
===========================================
  Files         134      273      +139     
  Lines       16683    20646     +3963     
===========================================
+ Hits         6844    12614     +5770     
+ Misses       9253     6713     -2540     
- Partials      586     1319      +733     

Flag	Coverage Δ
e2e-tests	∅ <ø> (?)
kind-e2e-tests	52.03% <ø> (?)
unit-tests	41.04% <ø> (+0.02%)	⬆️

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

Impacted Files	Coverage Δ
pkg/apiserver/handlers/webhook/mutation_labels.go	24.71% <0.00%> (ø)
...er/crdmirroring/crdhandler/clusternetworkpolicy.go	13.46% <0.00%> (ø)
...lientset/versioned/typed/security/v1alpha1/tier.go	27.39% <0.00%> (ø)
...ormers/externalversions/core/v1alpha2/interface.go	100.00% <0.00%> (ø)
pkg/apiserver/apiserver.go	89.51% <0.00%> (ø)
...formers/externalversions/security/v1alpha1/tier.go	64.28% <0.00%> (ø)
pkg/features/antrea_features.go	16.66% <0.00%> (ø)
pkg/legacyapis/system/v1beta1/register.go	90.00% <0.00%> (ø)
pkg/agent/metrics/prometheus.go	27.27% <0.00%> (ø)
...s/externalversions/clusterinformation/interface.go	0.00% <0.00%> (ø)
... and 229 more

[tnqn]

LGTM, a question left

[tnqn]

Doesn't antrea-agent run as a process on windows? Should it also have cgo disabled, assuming it could be complied on windows OS (so no cross-compiling)?

[antoninbas]

Thanks for the reminder, you are correct. In the case of the antrea/antrea-windows Docker image, we actually build the binaries without cross-compilation. Then when running on Windows in the "Docker mode" (as opposed to "containerd mode"...) we copy the antrea-agent binary to the host and run it as a host process:

antrea/build/yamls/antrea-windows.yml

Line 7 in 971d66c

cp /k/antrea/bin/* /host/k/antrea/bin/

. So it's definitely a valid assumption.

[tnqn]

LGTM

[antoninbas]

/test-all

[antoninbas]

@tnqn oops I forgot to sign my commit, shame on me :P I need another approval...

[antoninbas]

/test-all

[jianjuns]

LGTM.