prefetch: allow outputting multiple env files

[chmeliik]

1. Fix a problem that caused integration tests to test the kbc version installed in the upstream hermeto image instead of testing the one we want to test
2. Make it possible to generate multiple env files and to generate JSON env files

The plan is to immediately follow up with a PR that makes the Konflux prefetch task return cachi2.env, prefetch.env and prefetch-env.json (currently only outputs cachi2.env).

Prefetch support in the build task will be implemented as follows:

• If <prefetch-dir>/prefetch-env.json exists and buildah version >= (not yet released), inject env vars without modifying the containerfile (described more in the commit message)
• Else if <prefetch-dir>/prefetch.env or <prefetch-dir>/cachi2.env exists, modify the containerfile to source it in each RUN instruction (cachi2.env fallback needed in case the build task is used with an older version of the prefetch task)
• Possibly always mount the .env file at /cachi2/cachi2.env. It is possible that some users use the existence of the file to decide if they should do some prefetch-specific things. To be investigated.

[qodo-code-review]

Code Review by Qodo

🐞 Bugs (1) 📘 Rule violations (0) 📎 Requirement gaps (0) 📐 Spec deviations (0)

1. GenerateEnv unit test broken ☑ 🐞 Bug ✓ Correctness

Description

HermetoCli.GenerateEnv now appends --format after --output, but
TestHermetoCliGenerateEnvArgs asserts the old positional argument order, causing unit tests to
fail.

Code

pkg/cliwrappers/hermeto.go[R107-109]

+	if params.Format != "" {
+		args = append(args, "--format", params.Format)
+	}

Evidence

The implementation builds args with --output before conditionally appending --format. The unit
test still expects --format to appear before --output at fixed indices, so the assertion will
fail deterministically.

pkg/cliwrappers/hermeto.go[93-114]
pkg/cliwrappers/hermeto_test.go[81-115]

Agent prompt

The issue below was found during a code review. Follow the provided context and guidance below and implement a solution

## Issue description
`pkg/cliwrappers/hermeto.go` changed the ordering of `hermeto generate-env` arguments such that `--format` is appended after `--output`. `pkg/cliwrappers/hermeto_test.go` asserts a specific argument order and now fails.
### Issue Context
- The test currently checks fixed indices (e.g., `capturedArgs[6] == "--format"`), which no longer matches the constructed args.
### Fix Focus Areas
- Either restore the previous argument ordering in `HermetoCli.GenerateEnv` (place `--format` before `--output` when provided), or make the unit test order-insensitive (e.g., assert the presence of flag/value pairs rather than exact positions).
- pkg/cliwrappers/hermeto.go[93-114]
- pkg/cliwrappers/hermeto_test.go[81-115]

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---

2. Bare env-file silently ignored 🐞 Bug ✓ Correctness

Description

With env-file now a slice flag, a user invoking --env-file without any values can be silently
dropped by ExpandArrayParameters, causing the CLI to fall back to the default env file instead of
erroring.

Code

pkg/commands/prefetch_dependencies/params.go[R66-72]

"env-file": {
Name:         "env-file",
-		TypeKind:     reflect.String,
+		TypeKind:     reflect.Slice,
EnvVarName:   "KBC_PD_ENV_FILE",
DefaultValue: "./prefetch.env",
-		Usage:        "path to file where environment variables for hermetic build will be written",
+		Usage:        "path(s) to file(s) where environment variables for hermetic build will be written, format is inferred from file suffix",
Required:     false,

Evidence

This PR changes env-file from a string to a slice, which makes it subject to
ExpandArrayParameters’ multi-flag expansion. That function currently removes a multi-flag entirely
if no values follow it (it only appends flag,value pairs inside the loop), so a bare --env-file
is not passed to cobra/pflag and no missing-arg error can occur; since the param is optional,
ParseParameters then falls back to the default value.

pkg/commands/prefetch_dependencies/params.go[66-112]
pkg/common/array_arg.go[35-110]
cmd/root.go[19-29]

Agent prompt

The issue below was found during a code review. Follow the provided context and guidance below and implement a solution

## Issue description
After changing `--env-file` to a slice flag, the global `ExpandArrayParameters` preprocessor can now silently drop a bare `--env-file` (no values). This causes the command to proceed using defaults rather than surfacing an argument error.
### Issue Context
- `ExpandArrayParameters` expands `--flag v1 v2` into `--flag v1 --flag v2`.
- For multi-flags, if no non-flag tokens follow, it currently appends nothing (thus removing the flag entirely).
### Fix Focus Areas
- In `ExpandArrayParameters`, when encountering a multi-flag (e.g., `--env-file`) and the next token is missing / `--` / another flag, append the flag as-is so cobra/pflag can report a missing value error.
- Consider adding a small unit test for this behavior if none exists.
- pkg/common/array_arg.go[63-110]
- pkg/commands/prefetch_dependencies/params.go[66-72]
- cmd/root.go[19-29]

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[chmeliik]

@konflux-ci/prefetch @slimreaper35 PTAL if the plan makes sense

[slimreaper35]

nitpick: Maybe the name could be --env-files / KBC_PD_ENV_FILES now, but that would require a change in the environment variable in the task.

[chmeliik]

Yeah, I wanted to avoid breaking changes, but it's probably OK to do them at this point. I'm fairly sure e2e tests will catch this when build-definitions gets the hermeto image update PR

[chmeliik]

Renamed

[chmeliik]

/retest