feat(config): support multi-file KUBECONFIG and honor --context

[Joibel]

Summary

• --context was defined but never plumbed into the Argo client — the kubeconfig's current-context always won. It now flows through internal/config → argo.Config → clientcmd.ConfigOverrides{CurrentContext: ...}.
• KUBECONFIG containing multiple files joined by the OS path-list separator (the kubectl convention, e.g. eks.yaml:k3d.yaml:home.yaml) was being treated as a single literal path. The loader now uses Precedence: filepath.SplitList(kubeconfig) so each file is merged.
• The resolved context and cluster are logged at startup so operators can confirm which cluster the server is bound to before running tools.

Test plan

• go test ./... passes (new TestBuildLoadingRules covers empty / single / multi-path)
• make lint passes
• Smoke-tested locally with a 9-file KUBECONFIG:
  • default startup picks up current-context (e.g. k3d-pipeline-mono)
  • --context=eks-internal overrides and resolves to the correct cluster
  • all 9 source files appear in the startup log

🤖 Generated with Claude Code

Summary by CodeRabbit

• New Features

  • Added support for specifying Kubernetes contexts in configuration
  • Enhanced kubeconfig handling to support multiple path lists in KUBECONFIG format
  • Improved context resolution with enhanced logging

• Tests

  • Added tests for kubeconfig path loading behavior

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

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📥 Commits

Reviewing files that changed from the base of the PR and between a9180d7 and cef948c.

⛔ Files ignored due to path filters (1)

• README.md is excluded by !**/*.md

📒 Files selected for processing (4)

• internal/config/config.go
• pkg/argo/client.go
• pkg/argo/client_test.go
• pkg/argo/config.go

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Walkthrough

The PR adds kubeconfig context selection and KUBECONFIG environment variable support to the Argo configuration. The Config struct gains a Context field for context selection and improved Kubeconfig documentation. Kubeconfig path loading is refactored to handle path lists via a new buildLoadingRules helper, with context/cluster resolution and logging added via logResolvedContext. Configuration propagation includes the new context field.

Changes

Kubeconfig Context and Path Selection

Layer / File(s)	Summary
Data Shape pkg/argo/config.go	Config struct adds exported Context field to select a kubeconfig context; Kubeconfig field is documented to accept single path or KUBECONFIG-style path list.
Environment Loading pkg/argo/config.go	NewConfigFromEnv initializes Kubeconfig from the KUBECONFIG environment variable.
Path and Context Resolution pkg/argo/client.go	New buildLoadingRules helper parses kubeconfig paths using filepath.SplitList or defaults to standard discovery. New logResolvedContext helper resolves the kubeconfig and logs selected context/cluster, with fallback to current-context.
Client Initialization pkg/argo/client.go	Direct Kubernetes API mode now builds loading rules via buildLoadingRules, applies context override via clientcmd.ConfigOverrides{CurrentContext: config.Context}, and logs resolved context.
Configuration Propagation internal/config/config.go	(*Config).ToArgoConfig() now sets the Context field in the returned argo.Config.
Tests pkg/argo/client_test.go	New TestBuildLoadingRules validates path parsing for empty, single, and multiple kubeconfig paths.

Sequence Diagram

sequenceDiagram
    participant Env as Environment/<br/>Config
    participant Config as argo.Config<br/>Structure
    participant Rules as buildLoadingRules<br/>Helper
    participant Resolver as logResolvedContext<br/>Helper
    participant KubeAPI as Kubernetes<br/>Client

    Env->>Config: Read KUBECONFIG env var<br/>and Context field
    Config->>Rules: Pass Kubeconfig paths
    Rules->>Rules: Split paths (KUBECONFIG style)<br/>or use defaults
    Config->>Resolver: Provide loading rules<br/>and context override
    Resolver->>Resolver: Resolve kubeconfig<br/>Select context
    Resolver->>Resolver: Extract cluster info<br/>and log metadata
    Config->>KubeAPI: Build client config<br/>with context override
    KubeAPI->>KubeAPI: Initialize API client

Loading

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Poem

🐰 A kubeconfig rabbit hops with glee,
Context-aware paths, wild and free!
Split those lists like lettuce leaves so fine,
Logging clusters—every hop's divine!
From env to client, the journey's clear,
Configuration blooms, oh what good cheer! 🌿

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 60.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and specifically describes the main changes: multi-file KUBECONFIG support and --context flag handling, matching the primary objectives.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch feat/multi-kubeconfig-context

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