feat(docker): Add core data structures for Dockerfile parsing

[shivasurya]

Executive Summary

This PR introduces the foundational data structures needed for Dockerfile parsing and analysis. It contains ZERO behavioral changes to the existing codebase - only new type definitions, constructors, and tests.

File Structure

Following the existing pattern (java/, python/), files are organized in:

sast-engine/graph/docker/
├── node.go           (DockerfileNode - unified instruction representation)
├── graph.go          (DockerfileGraph + BuildStage - multi-stage support)
├── node_test.go      (Comprehensive tests)
└── graph_test.go     (Comprehensive tests)

Why This is Safe

• ✅ No modifications to existing files
• ✅ No integration with existing logic
• ✅ All new code is isolated in new package
• ✅ 100% test coverage on all new code
• ✅ All tests pass: gradle buildGo && gradle testGo && gradle lintGo

Quality Metrics

Metric	Result
Build Status	✅ BUILD SUCCESSFUL
Test Coverage	✅ 100%
Linting	✅ 0 issues
Test Execution	✅ All tests PASS

Code Examples

Creating a FROM instruction node:

node := docker.NewDockerfileNode("FROM", 1)
node.BaseImage = "ubuntu"
node.ImageTag = "20.04"
node.StageAlias = "builder"

Building a Dockerfile graph:

graph := docker.NewDockerfileGraph("/path/to/Dockerfile")
graph.AddInstruction(fromNode)
graph.AddInstruction(runNode)

// Security check
if graph.IsRunningAsRoot() {
    // Container runs as root
}

Multi-stage build analysis:

stages := graph.GetStages()
for _, stage := range stages {
    fmt.Printf("Stage %s: %s:%s\n", 
        stage.Alias, stage.BaseImage, stage.ImageTag)
}

Part of Stack

Dockerfile & Docker Compose Support implementation:

• ✅ PR Tree-Sitter Implementation with Source Sink Analysis #1: Core Data Structures (this PR)
• ⏳ PR Parse full method name as identifier #2: Tree-sitter Integration
• ⏳ PR Added support for method query like interface #3: AST Conversion Layer
• ⏳ PR Feature: Add Method Declaration filter based on attributes #4: Python DSL Extensions

Testing Coverage

• ✅ Constructor and initialization tests
• ✅ Flag operations (GetFlag, HasFlag)
• ✅ Helper methods (IsRootUser, UsesLatestTag)
• ✅ Graph operations (AddInstruction, GetInstructions)
• ✅ Multi-stage analysis (AnalyzeBuildStages, GetStageByAlias)
• ✅ Edge cases (empty graph, single stage, no USER instruction)

[shivasurya]

• feat(docker): Expand container security rules from 18 to 47 (+29 new rules) #428
• feat(docker): Container security rule executor and infrastructure (PR 7/8) #422
• feat(docker): Add Python DSL advanced features #421
• feat(docker): Add Python DSL core for container rules #420
• feat(docker): Add docker-compose parser with security queries #419
• feat(docker): Add comprehensive instruction converters for all 18 Dockerfile instructions #418
• feat(docker): Add tree-sitter Dockerfile parsing integration #417
• feat(docker): Add core data structures for Dockerfile parsing #416 👈 (View in Graphite)
• main

This stack of pull requests is managed by Graphite. Learn more about stacking.

[safedep]

SafeDep Report Summary

No dependency changes detected. Nothing to scan.

_{This report is generated by SafeDep Github App}

[codecov]

Codecov Report

❌ Patch coverage is 93.10345% with 6 lines in your changes missing coverage. Please review.
✅ Project coverage is 80.61%. Comparing base (3004338) to head (097fbb0).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
sast-engine/graph/docker/node.go	82.60%	2 Missing and 2 partials ⚠️
sast-engine/graph/docker/graph.go	96.87%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #416      +/-   ##
==========================================
+ Coverage   80.47%   80.61%   +0.13%     
==========================================
  Files          77       79       +2     
  Lines        7763     7850      +87     
==========================================
+ Hits         6247     6328      +81     
- Misses       1269     1272       +3     
- Partials      247      250       +3     

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[shivasurya]

Merge activity

• Dec 10, 6:17 AM UTC: A user started a stack merge that includes this pull request via Graphite.
• Dec 10, 6:17 AM UTC: @shivasurya merged this pull request with Graphite.