Convert legacy `.qs` files via a Docker R 4.5 container (deprecated)

Recursively converts every `.qs` file under `dir_path` to a `.qs2` sibling by running the conversion inside a `rocker/r-ver:4.5` container, where the legacy `qs` package still builds. Designed for users on R 4.6 (or later) for whom `qs` is no longer installable. Requires Docker on `PATH`; no other setup.

Usage

margot_convert_qs_dir_docker(
  dir_path,
  recursive = TRUE,
  compress_level = 4,
  delete_qs = FALSE,
  overwrite = FALSE,
  image = "rocker/r-ver:4.5",
  qs_source_url = "https://cran.r-project.org/src/contrib/Archive/qs/qs_0.27.3.tar.gz",
  ppm_snapshot = "https://packagemanager.posit.co/cran/2024-12-01",
  quiet = FALSE
)

Arguments

dir_path: Character; directory to scan. Mounted into the container at `/data`.
recursive: Logical; recurse into subdirectories. Default `TRUE`.
compress_level: Integer; zstd compression level for the new `.qs2` files. Default `4`.
delete_qs: Logical; if TRUE, delete each `.qs` file after a successful `.qs2` round-trip read. Default `FALSE`.
overwrite: Logical; if a `.qs2` sibling already exists, overwrite it. Default `FALSE` (skip).
image: Character; Docker image to use. Default `"rocker/r-ver:4.5"`.
qs_source_url: Character; CRAN archive URL for the `qs` source tarball. Pinned to `qs_0.27.3.tar.gz` by default. Override only if a future version supersedes this.
ppm_snapshot: Character; Posit Package Manager snapshot URL pinned to a date when `qs` 0.27.3 still built against the contemporaneous `stringfish`. Default `2024-12-01`. Override only if that snapshot is ever retired.
quiet: Logical; if TRUE, suppress per-file output. Default `FALSE`.

Value

Invisible integer, the docker process exit status (0 on success).

Details

On the first run Docker pulls the R 4.5 image (~600 MB) and compiles `qs` from CRAN's archive. Subsequent runs reuse the local image and the cached library, so they are fast.

Originals are kept by default. Re-run with `delete_qs = TRUE` once you have read-verified some `.qs2` files.

This function is a temporary bridge for old archives. It keeps the unsupported `qs` package inside the container so margot does not depend on it in the host R session.

For prerequisites (installing Docker / Colima, verifying the daemon, Linux/Windows setup), see the package vignette vignette("migrating-qs-to-qs2", package = "margot").

Steps:

Confirms `docker` is on `PATH`.
Writes a small R script to a temp file containing the conversion logic.
Invokes `docker run –rm` mounting `dir_path` at `/data` and the script at `/migrate.R`.
Inside the container, installs `qs2` (CRAN) and `qs` (CRAN archive source), then walks `/data` recursively and converts every `.qs`.
Returns when the container exits. The status code is propagated.

Examples