add auto-discovery mode

[dogancanbakir]

Fixes #795

-ad builds aws, gcp, azure and kubernetes from environment credentials through their SDK default chains and skips providers that fail to initialize.
Kubernetes now falls back to $KUBECONFIG, ~/.kube/config, then in-cluster when no kubeconfig is configured.
Supersedes #718.

Summary by CodeRabbit

• New Features
  • Added an auto-discovery option to find providers using AWS, GCP, Azure, and Kubernetes environment credentials. Providers without usable credentials are skipped; an error is returned if none can be initialized.
• Documentation
  • Clarified that Kubernetes configuration follows kubectl’s kubeconfig lookup order when no kubeconfig is specified, and that an encoded kubeconfig takes precedence when both configuration options are set.

[coderabbitai]

Walkthrough

The runner adds an auto-discovery option for AWS, GCP, Azure, and Kubernetes providers. It initializes provider configurations individually and skips failed initializations. Kubernetes configuration also uses default kubeconfig loading when no explicit kubeconfig value is supplied.

Changes

Provider discovery and Kubernetes configuration

Layer / File(s)	Summary
Kubernetes kubeconfig resolution PROVIDERS.md, pkg/providers/k8s/kubernetes.go, pkg/providers/k8s/kubernetes_test.go	Kubernetes configuration uses default client loading rules when no encoded kubeconfig is supplied. Documentation and tests cover environment-based lookup and missing kubeconfig paths.
Auto-discovery option and runner setup internal/runner/autodiscovery.go, internal/runner/options.go, internal/runner/runner.go, README.md	The runner adds the auto-discovery option and default provider configurations. When enabled, New selects the default configuration, and Enumerate creates inventory through the runner’s discovery path.
Per-provider inventory initialization internal/runner/autodiscovery.go, internal/runner/autodiscovery_test.go	Auto-discovery initializes provider configurations separately, skips failures, and returns an error if none initialize. Tests cover mixed provider success, all-provider failure, and the disabled path.

Priority: ➖ Normal

Estimated code review effort: 3 (Moderate) | ~20 minutes

Change: Feature

Sequence Diagram(s)

sequenceDiagram
  participant Runner
  participant autoDiscoveryConfig
  participant RunnerNewInventory
  participant inventoryNew
  Runner->>autoDiscoveryConfig: Build default provider configuration
  autoDiscoveryConfig-->>Runner: Return provider configuration
  Runner->>RunnerNewInventory: Initialize inventory during Enumerate
  RunnerNewInventory->>inventoryNew: Initialize each provider configuration
  inventoryNew-->>RunnerNewInventory: Return success or initialization error
  RunnerNewInventory-->>Runner: Return inventory or no-credentials error

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Merge Risk: 🟡 Moderate · up to a5c32

A missing kubeconfig entry can select an unintended in-cluster target, while a malformed configuration can leave Kubernetes out of discovery without a normal warning. Address these cases before merging.

Pre-merge checks | 3 | 2

❌ Failed checks (2 warnings)

Check name	Status	Explanation	Resolution
Linked Issues check		Issue #795 requires -ad to discover AWS, GCP, Azure, and Kubernetes credentials, including in-cluster Kubernetes credentials. The new autoDiscoveryConfig() creates the four provider blocks and `ne…	Update pkg/providers/k8s/kubernetes.go so Kubernetes auto-discovery falls back to rest.InClusterConfig() after the configured kubeconfig sources are unavailable, while preserving the documented $KUBECONFIG, ~/.kube/config, then in-c…
Docstring Coverage		Docstring coverage is 27.27% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 11 functions across 6 files. (2 skipped: …	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check		Check skipped - CodeRabbit’s high-level summary is enabled.
Title check		The title clearly and concisely identifies the primary change: adding auto-discovery mode for provider initialization.
Out of Scope Changes check		The changed files support Issue #795. The flag, runner integration, provider discovery loop, Kubernetes loading behavior, documentation, and tests all implement or verify auto-discovery. No unrelated …

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Full details: Linked Issues check

Explanation

Issue #795 requires -ad to discover AWS, GCP, Azure, and Kubernetes credentials, including in-cluster Kubernetes credentials. The new autoDiscoveryConfig() creates the four provider blocks and newInventory() skips initialization failures. AWS, GCP, and Azure therefore use their existing default initialization paths. Kubernetes uses clientcmd.NewDefaultClientConfigLoadingRules() for $KUBECONFIG and ~/.kube/config, but buildConfigWithContext() never calls rest.InClusterConfig() after kubeconfig loading fails. The required in-cluster fallback is not implemented. The added tests cover a kubeconfig file and a missing file, but not in-cluster discovery.

Resolution

Update pkg/providers/k8s/kubernetes.go so Kubernetes auto-discovery falls back to rest.InClusterConfig() after the configured kubeconfig sources are unavailable, while preserving the documented $KUBECONFIG, ~/.kube/config, then in-cluster order. Add an automated test for the in-cluster path.

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Full details: Docstring Coverage

Explanation

Docstring coverage is 27.27% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 11 functions across 6 files. (2 skipped: 2 unsupported.)

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_{A rabbit checks the cloud-bound trail,
With kubeconfig tucked beneath its tail.
It tries each path and provider key,
Skips the ones it cannot see.
The working clouds join in the run,
Then hops back home when tasks are done.}

_{Comment @coderabbitai help to get the list of available commands.}

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Actionable comments posted: 2

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Inline comments:
Review comments at @internal/runner/autodiscovery.go:
- Around line 32-36: Update the provider initialization error handling around
inventory.New to log Kubernetes failures at a higher severity when KUBECONFIG is
explicitly set, while keeping expected missing-credential failures at Verbose;
preserve the continue behavior so discovery proceeds for other providers.

Review comments at @pkg/providers/k8s/kubernetes.go:
- Around line 113-114: Before creating the deferred client configuration, make
missing paths from an explicitly set KUBECONFIG fatal instead of allowing
client-go to return an empty configuration. Preserve the existing strict
handling of a non-empty kubeconfigPath.

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ℹ️ Review info

⚙️ Run configuration

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📥 Commits

Reviewing files that changed from the base of the PR and between 446c334 and a5c3262.

📒 Files selected for processing (8)

• PROVIDERS.md
• README.md
• internal/runner/autodiscovery.go
• internal/runner/autodiscovery_test.go
• internal/runner/options.go
• internal/runner/runner.go
• pkg/providers/k8s/kubernetes.go
• pkg/providers/k8s/kubernetes_test.go

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