{"record":{"id":"2bae7db3a639e273","repo":"vxcontrol/pentagi","slug":"failed-to-copy-file-w","errorCode":null,"errorMessage":"failed to copy file: %w","messagePattern":"failed to copy file: %w","errorType":"exception","errorClass":null,"httpStatus":null,"severity":"error","filePath":"backend/pkg/tools/terminal.go","lineNumber":376,"sourceCode":"\n// readFileFromContainer copies path out of the flow's container and returns\n// its content. It performs no terminal-log writes, so callers that need the\n// content only as an intermediate step (e.g. EditFile, before reapplying a\n// diff and writing back) don't echo a spurious \"cat\" transcript entry.\nfunc (t *terminal) readFileFromContainer(ctx context.Context, flowID int64, path string) (string, error) {\n\tcontainerName := PrimaryTerminalName(t.tenantPrefix, flowID)\n\n\tisRunning, err := t.dockerClient.IsContainerRunning(ctx, t.containerLID)\n\tif err != nil {\n\t\treturn \"\", fmt.Errorf(\"runtime verification failed: %w\", err)\n\t}\n\tif !isRunning {\n\t\treturn \"\", fmt.Errorf(\"container runtime is not operational\")\n\t}\n\n\treader, stats, err := t.dockerClient.CopyFromContainer(ctx, containerName, path)\n\tif err != nil {\n\t\treturn \"\", fmt.Errorf(\"failed to copy file: %w\", err)\n\t}\n\tdefer reader.Close()\n\n\tvar buffer strings.Builder\n\ttarReader := tar.NewReader(reader)\n\tfor {\n\t\ttarHeader, err := tarReader.Next()\n\t\tif err == io.EOF {\n\t\t\tbreak\n\t\t}\n\t\tif err != nil {\n\t\t\treturn \"\", fmt.Errorf(\"failed to read tar header: %w\", err)\n\t\t}\n\n\t\tif tarHeader.FileInfo().IsDir() {\n\t\t\tcontinue\n\t\t}\n","sourceCodeStart":358,"sourceCodeEnd":394,"githubUrl":"https://github.com/vxcontrol/pentagi/blob/ea665308baaff015b226f308438a68d929d0f29b/backend/pkg/tools/terminal.go#L358-L394","documentation":"Wraps any error returned by dockerClient.CopyFromContainer, which streams the file at `path` out of the container as a tar archive. The error originates in the Docker SDK / daemon layer — most often the path does not exist, the container is gone, or the daemon rejected the copy request — and is wrapped so the Docker cause is preserved via %w.","triggerScenarios":"ReadFile or EditFile called with a `path` that does not exist in the container, points outside an accessible scope, or when the Docker daemon cannot service CopyFromContainer (container removed mid-call, daemon restarting, permission denied on the path).","commonSituations":"Typo'd or wrong-container-relative path (path must be absolute inside the container); file deleted between listing and read; read-only volume mount rejecting access; container was recreated with a new name so the old name no longer resolves; Docker daemon socket permission issues.","solutions":["Verify the path exists inside the container: `docker exec <container> ls -la <path>`; use an absolute path","Confirm the container is running and the container name (PrimaryTerminalName(tenantPrefix, flowID)) still matches the actual container","Inspect the wrapped %w cause (`errors.Unwrap` or the log output) — if it's 404 the path is wrong, if it's a daemon/transport error check `docker info`","If the file lives on a mounted volume, check host-side mount permissions (uid/gid) inside the container","Retry the operation if the cause is transient (daemon restart)"],"exampleFix":"// before\nreader, stats, err := t.dockerClient.CopyFromContainer(ctx, containerName, path)\n// after (caller-side)\nvar nfe *docker.NotFoundError // or errors.As on the wrapped cause\nif err != nil && strings.Contains(err.Error(), \"No such file\") {\n    return \"\", fmt.Errorf(\"file %q does not exist in container %s\", path, containerName)\n}","handlingStrategy":"try-catch","validationCode":"if path == \"\" || !filepath.IsAbs(path) {\n    return fmt.Errorf(\"path must be a non-empty absolute path\")\n}\n_, err := executor.Run(ctx, flowID, fmt.Sprintf(\"test -e %s && echo ok\", path)) // existence probe","typeGuard":null,"tryCatchPattern":"reader, stats, err := dockerClient.CopyFromContainer(ctx, name, path)\nif err != nil {\n    var nf objectNotFoundError\n    if errors.As(err, &nf) {\n        return fmt.Errorf(\"file %q not found in container %s\", path, name)\n    }\n    return fmt.Errorf(\"failed to copy file: %w\", err)\n}","preventionTips":["Always use absolute paths inside the container","Probe file existence with a cheap `test -e` exec before copying","Keep container names/IDs in sync with the flow lifecycle","Check wrapped error causes to distinguish 404 from daemon failures"],"tags":["docker","file-copy","tar"],"backgroundTag":"docker-copy-failed","analyzedSha":"ea665308baaff015b226f308438a68d929d0f29b","analyzedAt":"2026-09-01T14:16:31.421Z","contentChangedAt":null,"schemaVersion":2},"datasetVersion":"2026-09-08T10:18:20.063Z"}