{"record":{"id":"416fab4815f17b5a","repo":"kubernetes/kops","slug":"error-visiting-container-v-w","errorCode":null,"errorMessage":"error visiting container %v: %w","messagePattern":"error visiting container (.+?): %w","errorType":"exception","errorClass":null,"httpStatus":null,"severity":"error","filePath":"pkg/kubemanifest/containerargs.go","lineNumber":49,"sourceCode":"\tif err != nil {\n\t\treturn err\n\t}\n\treturn nil\n}\n\ntype containerVisitor struct {\n\tvisitorBase\n\tvisitor ContainerVisitorFunction\n}\n\nfunc (m *containerVisitor) VisitMap(path []string, v map[string]interface{}) error {\n\tn := len(path)\n\tif n < 2 || path[n-2] != \"containers\" || !strings.HasPrefix(path[n-1], \"[\") {\n\t\treturn nil\n\t}\n\n\tif err := m.visitor(v); err != nil {\n\t\treturn fmt.Errorf(\"error visiting container %v: %w\", v, err)\n\t}\n\n\treturn nil\n}\n","sourceCodeStart":31,"sourceCodeEnd":54,"githubUrl":"https://github.com/kubernetes/kops/blob/4c8573c808a73d578c5eadc86d410646ea0b0d73/pkg/kubemanifest/containerargs.go#L31-L54","documentation":"containerargs VisitMap fires when the visitor path indicates a containers list entry (`containers[i]` in a PodSpec). Before invoking the visitor function it wraps any error from the inner visitor with 'error visiting container'. The wrapped error is the underlying failure (e.g. YAML/JSON coercion, or an error set inside the visitor callback), with v (the visitor closure) printed for context.","triggerScenarios":"Iterating a manifest whose path is `...containers[N]` and the visitor function `v` passed to visit() returns an error — e.g. container argument mutation failing, nested manifests invalid, or an inner error propagated by the callback.","commonSituations":"Rewriting container args/images in addon manifests or YAML manifests with kubemanifest tools (e.g. during `kops toolbox`, addon remapping); malformed container spec sections in a multi-document YAML.","solutions":["Read the wrapped %w cause for the real error (use errors.Unwrap / %v print)","Validate the manifest parses cleanly (`kubectl apply --dry-run=client -f file.yaml` or yamllint) to rule out malformed sections","Check the visitor callback for errors it may return on unexpected container shapes (missing image/args fields)","Ensure the target fields exist in each container entry before the visitor mutates them"],"exampleFix":null,"handlingStrategy":"try-catch","validationCode":"// ensure each container entry has the fields your visitor needs\nfor _, c := range podSpec[\"containers\"].([]interface{}) {\n\tm := c.(map[string]interface{})\n\tif _, ok := m[\"image\"]; !ok { return fmt.Errorf(\"container missing image\") }\n}\n","typeGuard":null,"tryCatchPattern":"if err := manifest.Visit(...); err != nil {\n\tvar wrapped error\n\tif errors.As(err, &wrapped) { /* inspect errors.Unwrap chain for root cause */ }\n\treturn fmt.Errorf(\"container rewrite failed: %w\", err)\n}\n","preventionTips":["Validate manifests with kubectl --dry-run before rewriting","Handle missing container fields defensively in the visitor","Log the full error chain (%+v) to see the wrapped cause","Test visitors against multi-document manifests"],"tags":["yaml-manifest","visitor-pattern","go"],"backgroundTag":"manifest-visitor-error","analyzedSha":"4c8573c808a73d578c5eadc86d410646ea0b0d73","analyzedAt":"2026-09-05T04:13:19.212Z","contentChangedAt":"2026-09-05T04:13:19.212Z","schemaVersion":2},"datasetVersion":"2026-09-12T07:17:12.445Z"}