✨ Add kantra multiple inputs enhancement (#198)

* Add kantra multiple inputs enhancement

Adding multiple inputs support for kantra analyze command.

Fixes: #194

Signed-off-by: Marek Aufart <maufart@redhat.com>

* Update summary, cleanup

Signed-off-by: Marek Aufart <maufart@redhat.com>

* Update with feedback part 1

Signed-off-by: Marek Aufart <maufart@redhat.com>

* Update design details

Signed-off-by: Marek Aufart <maufart@redhat.com>

---------

Signed-off-by: Marek Aufart <maufart@redhat.com>

enhancements/kantra/multiple-inputs/README.md

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+---
+title: kantra-analyze-multiple-inputs
+authors:
+  - "@aufi" (maufart)
+reviewers:
+  - "@dymurray"
+  - "@brunoborges"
+  - "@pranavgaikwad"
+  - "@rromannissen"
+  - "@shawn-hurley"
+approvers:
+  - TBD
+creation-date: 2024-08-13
+last-updated: 2024-09-04
+status: implementable
+see-also:
+  - "https://github.com/konveyor/enhancements/issues/194"  
+---
+
+# Kantra analyze multiple inputs
+
+This enhancement introduces feature of kantra to analyze multiple input applications with a single kantra command execution with results (issues&incidents) combined into a single static-report.
+
+## Release Signoff Checklist
+
+- [x] Enhancement is `implementable`
+- [x] Design details are appropriately documented from clear requirements
+- [x] Test plan is defined
+- [ ] User-facing documentation is created
+
+
+## Summary
+
+Konveyor consists of the main cloud-native installation driven by _Hub_ that provides advanced features of application analysis execution including analysis task scheduling, parallel tasks executions. And more lighweight command line tool called _kantra_, that can analyze just a single input application on its command execution.
+
+We want to add support for multiple inputs to kantra, that would match to previous _mta-cli_ tool multiple inputs feature. In order to accomplish that, kantra will be updated to accept multiple ```--input``` args and handle analysis for all those inputs.
+
+## Motivation
+
+This enhancement should close a feature gap to "original" mta-cli multiple input option and help users with a large portfolio of applications, who run kantra on these individually.
+
+That is time a consuming process that leads them to have multiple different static reports. So, having a single static report for all the local applications they are working on will greatly increase the visability of known issues across the local portfolio.
+
+### Goals
+
+Analyze multiple applications with a single kantra command execution.
+
+### Non-Goals
+
+Implement an analysis task scheduler within the kantra or parallel application analysis execution similar to Hub features.
+
+Support `--input-bin-dir` option, however it could be added later.
+
+## Proposal
+
+Extend kantra to accept multiple ```--input``` args, execute all needed steps to analyze those input applications and provide static-report with results for all provided inputs.
+
+### User Stories
+
+As a user, I want to be able execute kantra analyze command with multiple inputs and get static-report with all provided inputs.
+
+Example:
+```
+$ kantra analyze --input ApplicationA --input ApplicationB --input ApplicationC --output=<path/to/output/applicationsABC>
+```
+
+### Implementation Details/Notes/Constraints
+
+### Security, Risks, and Mitigations
+
+There is a possibility to overload local machine (CPU or memory) that executes the analysis. That could be caused by size of the application(s) itself or chosen rules. User need to keep in mind, that kantra analyze execution might consume significant resources on their machine. 
+
+## Design Details
+
+It would be nice to generate static-report after each input application analysis completion to have some static-report available before finishing all inputs or for a case that analysis crash or an unexpected termination.
+
+When analysis of one of inputs fails, kantra will stop its execution. Potential following inputs will not be analyzed (however static report and results generated before the failure will be kept).
+
+The analyze loop over multiple inputs might re-create provider containers, volumes etc. which introdudes some inefficiency, however allows easier maintenance of the codebase in future kantra development.
+
+### Limitations
+
+All analysis options are the same for all input applications and there is no plan to implement different source/targets/... for different input applications. This limitation needs to be mentioned in docs.
+
+### Test Plan
+
+Run kantra analyze with multiple (different) input applications and check output for:
+- static-report contains
+- - all input applications
+- - issues and incidents for each input application
+- - issues and incidents for all input applications together
+- output.yaml and optionally dependencies.yaml files for input applications look sane
+- analysis.log file content to look sane
+
+## Drawbacks
+
+This feature overlaps with Konveyor Hub features that is preffered way to run Konveyor and brings a logic to kantra, that doesn't fit naturally to the tool itself (from engineering team point of view).
+
+## Alternatives
+
+### kantra```--batch```
+
+There is already an option to analyze multiple input applications with `--batch` option and get static-report that contains issues&incidents for all applications. However, that requires call `kantra analyze` for each input application.
+
+On the other hand, this solution has a minimal impact on kantra codebase complexity and maintenance.
+
+Example:
+```
+kantra analyze --bulk --input=ApplicationA --output=<path/to/output/applicationsABC>
+kantra analyze --bulk --input=ApplicationB --output=<path/to/output/applicationsABC>
+kantra analyze --bulk --input=ApplicationC --output=<path/to/output/applicationsABC>
+```