Group similar instructions in a dockerfile

Optimizes a dockerfile by grouping similar consecutive instructions into single multi-command instructions where appropriate. This can reduce the number of layers in the final Docker image.

Usage

dfm_group_similar(dockerfile)

Arguments

dockerfile

A dockerfile object

Value

A new dockerfile object with similar instructions grouped

Details

This function primarily targets RUN instructions, combining them with && to create single multi-command instructions. This follows Docker best practices by reducing the number of layers in the final image. Instructions like FROM, WORKDIR, USER, ENTRYPOINT, and CMD are left as separate instructions.

See also

dfm_sort_by_instruction() for sorting instructions by type

Other dockerfile modification functions: dfm_add_line(), dfm_move_line(), dfm_remove_line(), dfm_replace_line(), dfm_sort_by_instruction()

Examples

df <- dockerfile() |>
  dfi_from("rocker/r-ver:4.4.0") |>
  dfi_run("apt-get update") |>
  dfi_run("apt-get install -y curl") |>
  dfi_run("apt-get clean")
  
# Group the three RUN instructions into one
df <- dfm_group_similar(df)