feat: Implement Issue #1779: Add MinReplicas option to SetCanaryScale

[ssanders1449]

Implements issue #1779
See #1779 for Use Cases

[codecov]

Codecov Report

Base: 81.55% // Head: 81.55% // Decreases project coverage by -0.00% ⚠️

Coverage data is based on head (edb6dca) compared to base (93c2520).
Patch coverage: 88.88% of modified lines in pull request are covered.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1938      +/-   ##
==========================================
- Coverage   81.55%   81.55%   -0.01%     
==========================================
  Files         124      124              
  Lines       18931    18947      +16     
==========================================
+ Hits        15439    15452      +13     
- Misses       2702     2703       +1     
- Partials      790      792       +2     

Impacted Files	Coverage Δ
utils/rollout/rolloututil.go	90.15% <0.00%> (-2.16%)	⬇️
utils/replicaset/canary.go	92.95% <100.00%> (+0.22%)	⬆️

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[sonarcloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

No Coverage information
3.5% Duplication

[sonarcloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

No Coverage information
3.5% Duplication

[ssanders1449]

@jessesuen - can you please review this? We need this in order to ensure high availability when using TrafficRoutedCanary

@nissy34 - FYI

[github-actions]

This PR is stale because it has been open 90 days with no activity.

[ssanders1449]

I'm surprised that no one else has this issue. We worked around it so far, by adding a default-backend service to the nginx ingress which routes to all of pods (both stable and canary), so that if one of the replicasets has only one POD and it goes down (e.g. it is being moved to another node), the requests will get routed to the other pods via the default-backend.

However, I'm not sure that other traffic-routing options (e.g. ALB) have a similar 'default-backend' concept

[github-actions]

Go Published Test Results

1 800 tests   1 800 ✔️  2m 30s ⏱️
   102 suites         0 💤
       1 files           0 ❌

Results for commit edb6dca.

♻️ This comment has been updated with latest results.

[github-actions]

E2E Tests Published Test Results

    2 files      2 suites   1h 29m 46s ⏱️
  89 tests   82 ✔️ 3 💤 4 ❌
184 runs  172 ✔️ 6 💤 6 ❌

For more details on these failures, see this check.

Results for commit edb6dca.

♻️ This comment has been updated with latest results.

[sonarcloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

No Coverage information
3.4% Duplication

[ssanders1449]

@zachaller - can you take a look at this? We are currently building from a fork, and would like this to be eventually included

[ssanders1449]

Based on #1779 (comment), this can be replaced by

#2410

[ssanders1449]

closing in favor of #2448