TT-7219 implement HPA resource for tyk-gateway

[rakkhin]

Description

This PR implements Horizontal Pod Autoscaler resource for tyk-gateway chart, allowing users to easily enable automatic scaling and preventing situations described in #115.

Related Issue

#115

Motivation and Context

Currently tyk-gateway chart doesn't have any configuration regarding automatic scaling of deployments. While it could probably be fine in dev/test environments or environments will low traffic volume variance, it's generally better to have the ability to scale your env to meet current demands. Without built-in support for HPA users are forced to manually create those resources and in some cases running the risk of destabilizing their environments, described in #115.

Test Coverage For This Change

Screenshots (if appropriate)

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Refactoring or add test (improvements in base code or adds test coverage to functionality)
• Documentation updates or improvements.

Checklist

• Make sure you are requesting to pull a topic/feature/bugfix branch (right side). If PRing from your fork, don't come from your master!
• Make sure you are making a pull request against our master branch (left side). Also, it would be best if you started your change off our latest master.
• My change requires a change to the documentation.
  • I have manually updated the README(s)/documentation accordingly.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.

[caroltyk]

Thank you for raising the PR @rakkhin . We'll have an engineer from the team to review this.

[komalsukhani]

@rakkhin Can you add autoscaling in other umbrella charts(tyk-oss, tyk-mdcb-data-plane, tyk-single-dc) too?
Once done I will move the PR in the QA's backlog for testing.

[rakkhin]

@komalsukhani I've updated those charts, let me know if there's anything else left.

[komalsukhani]

@rakkhin Looks perfect. Thank you!
Have added your ticket in QA's backlog. PR will be merge once QA tests it.

[buraksekili]

@rakkhin thanks for your valuable contribution. We greatly appreciate your effort. However, it appears that there is a minor conflict in one of the files. Could you please take a moment to resolve it? If you are currently unavailable to address this matter, kindly inform us, and we will be happy to assist in resolving the conflict.

[rakkhin]

@buraksekili I resolved the conflict, should be good to go now.

[buraksekili]

thank you for this great contribution @rakkhin 🙏