{"record":{"id":"c07a7b3ec1c9da6d","repo":"slimtoolkit/slim","slug":"failed-to-read-file-into-the-tar-w","errorCode":null,"errorMessage":"failed to read file into the tar: %w","messagePattern":"failed to read file into the tar: %w","errorType":"exception","errorClass":null,"httpStatus":null,"severity":"error","filePath":"pkg/imagebuilder/internalbuilder/engine.go","lineNumber":316,"sourceCode":"\n\t\tif info.Mode().IsDir() {\n\t\t\thdr.Typeflag = tar.TypeDir\n\t\t} else if info.Mode().IsRegular() {\n\t\t\thdr.Typeflag = tar.TypeReg\n\t\t} else {\n\t\t\treturn fmt.Errorf(\"not implemented archiving file type %s (%s)\", info.Mode(), rel)\n\t\t}\n\n\t\tif err := tw.WriteHeader(hdr); err != nil {\n\t\t\treturn fmt.Errorf(\"failed to write tar header: %w\", err)\n\t\t}\n\t\tif !info.IsDir() {\n\t\t\tf, err := os.Open(fp)\n\t\t\tif err != nil {\n\t\t\t\treturn err\n\t\t\t}\n\t\t\tif _, err := io.Copy(tw, f); err != nil {\n\t\t\t\treturn fmt.Errorf(\"failed to read file into the tar: %w\", err)\n\t\t\t}\n\t\t\tf.Close()\n\t\t}\n\t\treturn nil\n\t})\n\n\tif err != nil {\n\t\treturn nil, fmt.Errorf(\"failed to scan files: %w\", err)\n\t}\n\tif err := tw.Close(); err != nil {\n\t\treturn nil, fmt.Errorf(\"failed to finish tar: %w\", err)\n\t}\n\n\treturn tarball.LayerFromReader(&b)\n}\n","sourceCodeStart":298,"sourceCodeEnd":332,"githubUrl":"https://github.com/slimtoolkit/slim/blob/81940d17fa112cc678e32209214bcb2355cb3004/pkg/imagebuilder/internalbuilder/engine.go#L298-L332","documentation":"After writing the tar header for a regular file, io.Copy(tw, f) failed while streaming the file contents into the archive. This wraps read/write errors — the file could not be read from disk or the tar writer rejected the data mid-copy. The raw os.Open error is returned unwrapped separately, so this specifically covers copy-stage failures.","triggerScenarios":"A file that opened successfully becomes unreadable during copy — deleted/truncated concurrently, disk I/O error, or permission change between open and copy.","commonSituations":"Another process deleting or truncating files in the layer directory during the build, failing disk/IO errors, or files on flaky network mounts.","solutions":["Re-run the build; ensure no concurrent process mutates the layer directory.","Check disk health and free space (dmesg / filesystem errors).","If the layer is on a network mount, copy it to local disk before building."],"exampleFix":"// before\n// build reads /mnt/nfs/rootfs directly\nlayerFromDir(LayerDataInfo{Source: \"/mnt/nfs/rootfs\"})\n// after\nos.CopyFS(\"/tmp/rootfs-snapshot\", os.DirFS(\"/mnt/nfs/rootfs\"))\nlayerFromDir(LayerDataInfo{Source: \"/tmp/rootfs-snapshot\"})","handlingStrategy":"retry","validationCode":"f, err := os.Open(fp)\nif err != nil { return err }\nst, err := f.Stat()\nif err != nil || !st.Mode().IsRegular() { f.Close(); return fmt.Errorf(\"file changed during archive: %s\", fp) }","typeGuard":null,"tryCatchPattern":"if err != nil && strings.Contains(err.Error(), \"failed to read file into the tar\") {\n    // retry the build after ensuring no concurrent writes to the layer dir\n}","preventionTips":["Build from a stable snapshot of the layer directory","Keep layers on reliable local storage, not network mounts","Check disk health/free space if failures persist"],"tags":["io","tar","filesystem","image-build"],"backgroundTag":"file-read-failed","analyzedSha":"81940d17fa112cc678e32209214bcb2355cb3004","analyzedAt":"2026-08-31T23:06:12.682Z","contentChangedAt":null,"schemaVersion":2},"datasetVersion":"2026-09-08T05:18:18.240Z"}