{"record":{"id":"82515574b65ed81a","repo":"kubernetes/kops","slug":"error-while-hashing-resource-v","errorCode":null,"errorMessage":"error while hashing resource: %v","messagePattern":"error while hashing resource: (.+?)","errorType":"exception","errorClass":null,"httpStatus":null,"severity":"error","filePath":"util/pkg/hashing/hash.go","lineNumber":132,"sourceCode":"\tswitch len(s) {\n\tcase 32:\n\t\tha = HashAlgorithmMD5\n\tcase 40:\n\t\tha = HashAlgorithmSHA1\n\tcase 64:\n\t\tha = HashAlgorithmSHA256\n\tdefault:\n\t\treturn nil, fmt.Errorf(\"cannot determine algorithm for hash length: %d\", len(s))\n\t}\n\n\treturn ha.FromString(s)\n}\n\nfunc (ha HashAlgorithm) Hash(r io.Reader) (*Hash, error) {\n\thasher := ha.NewHasher()\n\t_, err := copyToHasher(hasher, r)\n\tif err != nil {\n\t\treturn nil, fmt.Errorf(\"error while hashing resource: %v\", err)\n\t}\n\treturn &Hash{Algorithm: ha, HashValue: hasher.Sum(nil)}, nil\n}\n\nfunc (ha HashAlgorithm) HashFile(p string) (*Hash, error) {\n\tf, err := os.OpenFile(p, os.O_RDONLY, 0)\n\tif err != nil {\n\t\tif os.IsNotExist(err) {\n\t\t\treturn nil, err\n\t\t}\n\t\treturn nil, fmt.Errorf(\"error opening file %q: %v\", p, err)\n\t}\n\tdefer try.CloseFile(f)\n\treturn ha.Hash(f)\n}\n\nfunc copyToHasher(dest io.Writer, src io.Reader) (int64, error) {\n\tn, err := io.Copy(dest, src)","sourceCodeStart":114,"sourceCodeEnd":150,"githubUrl":"https://github.com/kubernetes/kops/blob/4c8573c808a73d578c5eadc86d410646ea0b0d73/util/pkg/hashing/hash.go#L114-L150","documentation":"HashAlgorithm.Hash streams an io.Reader through the algorithm's hasher; this error wraps any failure that occurs while copying the reader's data into the hasher. Because hashing itself cannot fail for in-memory data, the cause is almost always an I/O read error from the underlying source (network body, pipe, file reader).","triggerScenarios":"Calling HashAlgorithm.Hash(r) with a reader whose Read fails mid-stream — e.g. an HTTP response body cut off during transferFile, a closed file, or a broken pipe from a subprocess.","commonSituations":"Network flakiness while hashing a downloaded CNI/utility asset; reading from a file being concurrently truncated; disk I/O errors on the node running the tool.","solutions":["Retry the operation; transient reader/network errors usually clear on re-run","Verify the source of the reader is fully available before hashing (e.g. download completes first)","Inspect the wrapped %v cause to identify the underlying read failure","Read the source fully into memory (io.ReadAll) first to separate download errors from hashing"],"exampleFix":"// before\nh, err := algo.Hash(resp.Body)\n// after\ndata, err := io.ReadAll(resp.Body)\nif err != nil { return fmt.Errorf(\"downloading asset: %w\", err) }\nh, err := algo.Hash(bytes.NewReader(data))","handlingStrategy":"try-catch","validationCode":"null","typeGuard":"null","tryCatchPattern":"h, err := algo.Hash(r)\nif err != nil {\n\tvar netErr net.Error\n\tif errors.As(err, &netErr) || isRetryable(err) {\n\t\treturn retryHash(r)\n\t}\n\treturn fmt.Errorf(\"hashing failed: %w\", err)\n}","preventionTips":["Fully download/buffer data before hashing so read errors surface as download errors","Retry transient I/O failures with backoff","Check disk and network health if failures recur","Log the wrapped cause — the real error is inside the %v"],"tags":["hashing","io","reader"],"backgroundTag":"io-read-failure","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"}