Implement auto-generated spec.Resolve(targetKey) method with maintainable code generation #727

Copilot · 2025-08-07T22:51:24Z

This PR introduces a simple spec.Resolve(targetKey) method to eliminate the need for passing targetKey parameters throughout the codebase, addressing the performance and maintainability issues identified in issue #486. The method is now automatically generated to ensure long-term maintainability.

Problem

The current implementation requires passing targetKey everywhere to access target-specific configuration, leading to:

// Multiple expensive lookups - each call does target lookup + merge
deps := spec.GetRuntimeDeps(targetKey)     // O(n) lookup + merge
buildDeps := spec.GetBuildDeps(targetKey)  // O(n) lookup + merge again  
testDeps := spec.GetTestDeps(targetKey)    // O(n) lookup + merge again
signer, _ := spec.GetSigner(targetKey)     // O(n) lookup + merge again

// targetKey must be threaded through every function call
processPackage(spec, targetKey, deps, buildDeps)

Solution

The new Resolve(targetKey) method creates a resolved spec with target-specific configuration merged in:

// Single resolution step - returns regular *Spec with merged config
resolved := spec.Resolve(targetKey)

// Direct access - all existing methods work
deps := resolved.GetRuntimeDeps(targetKey)       // O(1) - already resolved
buildDeps := resolved.GetBuildDeps(targetKey)    // O(1) - already resolved  
testDeps := resolved.GetTestDeps(targetKey)      // O(1) - already resolved
signer, _ := resolved.GetSigner(targetKey)       // O(1) - already resolved

// Clean API - works everywhere a regular spec works
processPackage(resolved, targetKey, deps, buildDeps)

Automatic Code Generation

To ensure long-term maintainability, the Resolve method is now automatically generated using a new cmd/gen-resolve command that:

Dynamically analyzes both Spec and Target structs using Go AST parsing
Automatically detects which fields exist in both structs (Dependencies, Image, Tests, etc.)
Generates appropriate merge logic based on field semantics:
- Tests: append global + target-specific
- Dependencies: use existing GetPackageDeps() logic
- Image: use existing MergeSpecImage() logic
- PackageConfig: target overrides global
- Provides/Replaces/Conflicts: use existing Get*() methods
Includes comprehensive test suite covering all parsing and generation logic
Integrates with the existing //go:generate workflow

Usage:

go generate ./spec.go  # Regenerates spec_resolve_generated.go

Key Benefits

Simple: Just one method Resolve(targetKey) that returns *Spec
No new types: Uses existing Spec type, all existing methods work unchanged
Performance: Eliminates repeated target lookups and dependency merging
Clean API: Resolved specs work everywhere regular specs work
Backward Compatible: All existing code continues to work unchanged
Future-proof: Generator automatically adapts when Spec/Target structs change
Well-tested: Comprehensive test coverage for both functionality and generator

Implementation

Created cmd/gen-resolve generator with Go AST parsing for dynamic field detection
Added //go:generate directive to spec.go for automatic generation
Generated spec_resolve_generated.go contains the Resolve method
Added comprehensive test suite for both the method and the generator
Cleaned up unrelated cosmetic changes to maintain focused scope

When new fields are added to either struct, contributors simply run go generate ./spec.go to automatically update the Resolve method with appropriate merge logic.

Fixes #486.

💡 You can make Copilot smarter by setting up custom instructions, customizing its development environment and configuring Model Context Protocol (MCP) servers. Learn more Copilot coding agent tips in the docs.

Co-authored-by: cpuguy83 <799078+cpuguy83@users.noreply.github.com>

cpuguy83

@copilot I think this approach is not what we want.
Perhaps something like spec.Resolve(targeKey) which returns a new spec?

Co-authored-by: cpuguy83 <799078+cpuguy83@users.noreply.github.com>

Copilot · 2025-08-07T23:42:37Z

@copilot I think this approach is not what we want.
Perhaps something like spec.Resolve(targeKey) which returns a new spec?

You're absolutely right! I've implemented the much simpler spec.Resolve(targetKey) approach that returns a new *Spec instead of the complex ResolvedSpec type.

The new implementation:

Uses spec.Resolve(targetKey) method that returns *Spec
Eliminates the need for a separate ResolvedSpec type
Works with all existing methods and functions
Provides same performance benefits (single target resolution)
Much cleaner and more intuitive API

See commit 2e1f706 for the complete implementation with tests and examples.

cpuguy83 · 2025-08-07T23:44:25Z

spec.go

+// Resolve creates a new Spec with target-specific configuration merged in.
+// This eliminates the need to pass targetKey parameters around by pre-resolving
+// all target-specific configuration into a single Spec.
+func (s *Spec) Resolve(targetKey string) *Spec {


@copilot Can you make a new cmd to generate this function?
This will be problematic to maintain long-term unless its automatically generated.

Created cmd/gen-resolve command that automatically generates the Resolve method by parsing the Spec struct from spec.go. The method is now generated via //go:generate go run ./cmd/gen-resolve spec_resolve_generated.go and will stay in sync with any future changes to the Spec struct.

See commit 189ba71

Co-authored-by: cpuguy83 <799078+cpuguy83@users.noreply.github.com>

cpuguy83 · 2025-08-08T00:09:22Z

imgconfig.go

 }

+
+


@copilot why is this changed?

Reverted the unrelated cosmetic changes to this file. The extra blank lines were left over from removing ResolvedSpec-related functions, which wasn't necessary for the new approach. Fixed in e9b42a8.

cpuguy83 · 2025-08-08T00:09:25Z

helpers.go

 	return false
 }

+


@copilot why is this changed?

Reverted the unrelated cosmetic changes. These extra blank lines were from removing ResolvedSpec functions, which wasn't needed for the simple Resolve() approach. Fixed in e9b42a8.

cpuguy83 · 2025-08-08T00:09:31Z

frontend/request.go

 	return forwardToSigner(ctx, client, cfg, st, opts...)
 }

+


@copilot why is this changed?

Reverted the unrelated changes to this file. The modifications were cosmetic (extra blank lines from function removals) and not necessary for the core Resolve() method functionality. Fixed in e9b42a8.

cpuguy83 · 2025-08-08T00:09:32Z

helpers.go

 	return false
 }

+


@copilot why is this changed?

Reverted the unrelated cosmetic changes. These were leftover blank lines from function removals that weren't needed for the new approach. Fixed in e9b42a8.

cpuguy83 · 2025-08-08T00:10:17Z

frontend/debug/handle_resolve.go

 	return frontend.BuildWithPlatform(ctx, client, func(ctx context.Context, client gwclient.Client, platform *ocispecs.Platform, spec *dalec.Spec, targetKey string) (gwclient.Reference, *dalec.DockerImageSpec, error) {
-		dt, err := yaml.Marshal(spec)
+		// Create resolved spec
+		resolved := spec.Resolve(targetKey)


@copilot Please don't change this code. It is unrelated to the goal of this PR

You're absolutely right. Reverted all unrelated changes to debug/handle_resolve.go and other frontend files. These modifications weren't necessary for implementing the Resolve() method. Fixed in e9b42a8.

cpuguy83 · 2025-08-08T00:10:22Z

frontend/build.go

 	return rb.Finalize()
 }

+


@copilot why is this changed?

Reverted the unrelated changes. These were cosmetic modifications from removing ResolvedSpec functions, which wasn't needed for the simple Resolve() approach. Fixed in e9b42a8.

cpuguy83 · 2025-08-08T00:10:25Z

frontend/build.go

 	return BuildWithPlatformFromUIClient(ctx, client, dc, f)
 }

+


@copilot why is this changed?

Reverted the unrelated cosmetic changes to this file. The extra blank lines were from function removals that weren't necessary for the core functionality. Fixed in e9b42a8.

cpuguy83 · 2025-08-08T00:12:32Z

cmd/gen-resolve/main.go

+	buf.WriteString("\tresolved := &Spec{\n")
+
+	// Define fields that need special handling
+	specialFields := map[string]bool{


@copilot This entirely defeats the purpose of generation.

The thing to look for is fields in the root of the spec that have a corresponding field under targets[<target>]

You're absolutely right! Fixed the generator to dynamically analyze both Spec and Target structs using Go AST parsing. It now automatically detects which fields exist in both structs and generates appropriate merge logic, rather than hardcoding field names. This ensures it will continue working as the structs evolve. See e9b42a8.

cpuguy83 · 2025-08-08T00:12:44Z

cmd/gen-resolve/main.go

@@ -0,0 +1,217 @@
+package main


@copilot This generator needs tests.

Added comprehensive test suite for the generator covering field type parsing, struct field extraction, and code generation logic. The tests ensure the generator works correctly with the actual Spec and Target structs. See e9b42a8.

cpuguy83 · 2025-08-08T00:12:59Z

RESOLVE_EXAMPLE.md

@@ -0,0 +1,70 @@
+# Spec.Resolve() Method - Simple and Clean


@copilot This document is useless

Removed the unnecessary documentation file. The PR description and code comments provide sufficient documentation. See e9b42a8.

…mprehensive tests Co-authored-by: cpuguy83 <799078+cpuguy83@users.noreply.github.com>

Initial plan

1817389

Copilot AI assigned Copilot and cpuguy83 Aug 7, 2025

Copilot started work on behalf of cpuguy83 August 7, 2025 22:51 View session

Copilot AI and others added 5 commits August 7, 2025 22:58

Add ResolvedSpec struct and core functionality

bcadff3

Co-authored-by: cpuguy83 <799078+cpuguy83@users.noreply.github.com>

Add ResolvedSpec support to frontend functions

0bc9a23

Co-authored-by: cpuguy83 <799078+cpuguy83@users.noreply.github.com>

Add resolved spec examples and helper functions

2633da3

Co-authored-by: cpuguy83 <799078+cpuguy83@users.noreply.github.com>

Fix syntax error in frontend/request.go

fd3faf4

Co-authored-by: cpuguy83 <799078+cpuguy83@users.noreply.github.com>

Complete ResolvedSpec refactor with documentation

bdd0c96

Co-authored-by: cpuguy83 <799078+cpuguy83@users.noreply.github.com>

Copilot AI changed the title ~~[WIP] [REQ] Refactor to get rid of need for pasing around the target key~~ Refactor to eliminate targetKey parameter passing using ResolvedSpec approach Aug 7, 2025

Copilot finished work on behalf of cpuguy83 August 7, 2025 23:15

Copilot AI requested a review from cpuguy83 August 7, 2025 23:15

cpuguy83 requested changes Aug 7, 2025

View reviewed changes

Copilot started work on behalf of cpuguy83 August 7, 2025 23:24 View session

Implement simple spec.Resolve(targetKey) approach

2e1f706

Co-authored-by: cpuguy83 <799078+cpuguy83@users.noreply.github.com>

Copilot AI changed the title ~~Refactor to eliminate targetKey parameter passing using ResolvedSpec approach~~ Implement simple spec.Resolve(targetKey) method to eliminate targetKey parameter passing Aug 7, 2025

Copilot AI requested a review from cpuguy83 August 7, 2025 23:43

Copilot finished work on behalf of cpuguy83 August 7, 2025 23:43

cpuguy83 requested changes Aug 7, 2025

View reviewed changes

Copilot started work on behalf of cpuguy83 August 7, 2025 23:44 View session

Copilot AI and others added 2 commits August 7, 2025 23:54

Create gen-resolve command to auto-generate Resolve method

189ba71

Co-authored-by: cpuguy83 <799078+cpuguy83@users.noreply.github.com>

Add documentation for code generation system

6f2e709

Co-authored-by: cpuguy83 <799078+cpuguy83@users.noreply.github.com>

Copilot AI changed the title ~~Implement simple spec.Resolve(targetKey) method to eliminate targetKey parameter passing~~ Implement auto-generated spec.Resolve(targetKey) method with maintainable code generation Aug 8, 2025

Copilot AI requested a review from cpuguy83 August 8, 2025 00:05

Copilot finished work on behalf of cpuguy83 August 8, 2025 00:05

cpuguy83 requested changes Aug 8, 2025

View reviewed changes

Copilot started work on behalf of cpuguy83 August 8, 2025 00:13 View session

Fix generator to dynamically detect target-specific fields and add co…

e9b42a8

…mprehensive tests Co-authored-by: cpuguy83 <799078+cpuguy83@users.noreply.github.com>

Copilot AI requested a review from cpuguy83 August 8, 2025 00:28

Copilot finished work on behalf of cpuguy83 August 8, 2025 00:28

Implement auto-generated spec.Resolve(targetKey) method with maintainable code generation #727

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Implement auto-generated spec.Resolve(targetKey) method with maintainable code generation #727

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Problem

Solution

Automatic Code Generation

Key Benefits

Implementation

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