Allow the usage of mirror registries/repositories in all/most places

[mozesl-nokia]

Title

Allow the usage of mirror registries/repositories in all/most places

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Description

• What changed: You can now pass even more environment variables to replace default registries/repositories:
  • Dockerfiles
  • Make targets
  • Bash scripts
  • DB unit test suite
• Why it’s needed: So that you can work more easily behind (increasingly stricter) proxies
• How it works: Define env vars before commands or use a .env file for convenience

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Related Issue(s)

(I thought we opened (and fixed) an issue for this, but I cannot find it.)

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Type of Change

• Other: Development environment

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Checklist

• Code follows project style guidelines
• Self-reviewed changes
• Tests added/updated
• Documentation added/updated
• All tests and gating checks pass

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Testing Instructions (Optional)

1. make setup-dev-env
2. make run-in-kind-db-cache
3. Tried a few other make targets, like reload-server and reload-function-runner, but please try your favourite make targets and scripts too to make sure they all work.

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Additional Notes (Optional)

• Further improvements: Somehow add the GHCR mirror to the prefix list of the FunctionConfigs in the example deployment.
• Review notes: Added a few comments like: "TODO: do we still use this?", I am pretty sure these are unused and should be removed. Please check. Also, I am open to changing the names of the env vars.

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AI Disclosure

I have not used AI in the creation of this PR.

[Copilot]

Pull request overview

This PR adds environment-variable-driven registry/mirror overrides for development builds, deployment scripts, kpt functions, and DB tests so contributors can work behind registry/proxy restrictions.

Changes:

• Adds .env/environment support for GHCR, Docker Hub, and Maven mirror configuration.
• Replaces hardcoded kpt function and Docker base image registries with configurable prefixes.
• Extends DB tests and dev setup scripts to consume mirror-related environment variables.

Reviewed changes

Copilot reviewed 24 out of 25 changed files in this pull request and generated 12 comments.

Show a summary per file

File	Description
.env.template	Documents mirror-related environment variables.
Makefile	Exports registry mirror defaults and adds dump-env.
build/Dockerfile	Makes Docker Hub base images configurable.
build/Dockerfile.apiserver	Adds usage TODO comment.
build/Dockerfile.etcd	Adds usage TODO comment.
build/Makefile	Passes Docker Hub mirror build args.
controllers/Dockerfile	Makes builder base image configurable.
controllers/Makefile	Passes Docker Hub mirror build args.
func/Dockerfile	Makes kpt function and base image registries configurable.
func/Dockerfile-wrapperserver	Makes base images configurable.
func/Makefile	Passes mirror-related build args.
go.mod	Adds godotenv dependency.
go.sum	Adds checksums for godotenv.
make/deploy.mk	Adjusts setup-dev-env help placement.
pkg/cache/dbcache/dbcache_test.go	Loads .env and applies Maven mirror to embedded Postgres.
scripts/common.sh	Loads .env and centralizes mirror defaults.
scripts/create-deployment-blueprint.sh	Uses configurable kpt function images and env-based Docker Hub mirror.
scripts/create-deployment-config.sh	Passes GHCR prefix to deployment blueprint generation.
scripts/create-deployment-kpt.sh	Uses configurable kpt function images.
scripts/install-dev-gitea-setup.sh	Sources common config and applies mirrors to Gitea setup.
scripts/remove-controller-from-deployment-config.sh	Uses configurable kpt function image prefix.
scripts/remove-porch-server-from-deployment-config.sh	Uses configurable kpt function image prefix.
scripts/run-load-test.sh	Uses configurable kpt function image prefix.
test/Dockerfile	Adds usage TODO comment.
test/Makefile	Adds usage TODO comment.

Comments suppressed due to low confidence (1)

scripts/create-deployment-kpt.sh:136

• This is another PORCH_GHCR_PREFIX_URL use in a set -u script that never initializes the variable. A direct run without the env var fails here before deployment customization can proceed.

    --image "${PORCH_GHCR_PREFIX_URL}/starlark:v0.5.5" \