In r-lib/pak: Another Approach to Package Installation

library(pillar)
pkgload::load_all()
options(asciicast_timeout = 600)
if (exists(".knitr_asciicast_process", envir = .GlobalEnv)) {
  rm(list = ".knitr_asciicast_process", envir = .GlobalEnv)
}

asciicast::init_knitr_engine(
  echo = TRUE,
  echo_input = FALSE,
  interactive = FALSE,
  timeout = as.integer(Sys.getenv("ASCIICAST_TIMEOUT", 300)),
  startup = quote({
    options(width = 72)
    options(cli.width = 72)
    options(cli.progress_show_after = 0)
    options(cli.progress_clear = FALSE)
    library(cli)
    pkgload::load_all()
    set.seed(1)
  })
)

knitr::opts_chunk$set(
  cache = TRUE,
  asciicast_knitr_output = "html",
  asciicast_include_style = FALSE,
  asciicast_theme = "pkgdown",
  asciicast_width = 72,
  asciicast_cols = 72
)

```{asciicast asciicast-setup, include = FALSE, cache = FALSE} pkgload::load_all() library(pillar) dir.create(lib <- file.path(tempdir(), "lib")) .libPaths(c(lib, .libPaths()))

# Introduction

Many R packages need external software to be present on the machine,
otherwise they do not work, or not even load.
For example the RPostgres R package uses the PostgreSQL client library,
and by default dynamically links to it on Linux systems.
This means that you (or the administrators of your system) need to install
this library, typically in the form of a system package: `libpq-dev` on
Ubuntu and Debian systems, or `postgresql-server-devel` or `postgresql-devel`
on RedHat, Fedora, etc. systems.

The good news is that pak helps you with this:
- it looks up the required system packages when installing R packages,
- it checks if the required system packages are installed, and
- it installs them automatically, if you are a superuser, or you can use
  password-less `sudo` to start a superuser shell.

In addition, pak also has some functions to query system requirements and
system packages.

# Requirements, supported platforms

Call `pak::sysreqs_platforms()` to list all platforms that support system
requirements:
```{asciicast sysreqs-platforms}
pak::sysreqs_platforms()

Call pak::sysreqs_is_supported() to see if your system is supported: ```{asciicast sysreqs-is-supported} pak::sysreqs_is_supported()

This vignette was built on `r sessionInfo()$running`, which is a platform
pak `r if (sysreqs_is_supported()) "does" else "does not"` support. So in the
following you will `r if (sysreqs_is_supported()) "" else "not"` see the output
of the code.

# R package installation

If you are using pak as a superuser, on a supported platform, then pak
will look up system requirements, and install the missing ones. Here is
an example:
```{asciicast pkg-inst-setup, include=FALSE, cache = FALSE}
system("apt-get remove -y libpq5")
try(pak::pkg_remove("RPostres"))

```{asciicast pkg-inst} pak::pkg_install("RPostgres")

## Running R as a regular user

If you don't want to use R as the superuser, but you can set up `sudo`
without a password, that works as well.
pak will automatically detect the password-less `sudo` capability, and use
it to install system packages, as needed.

If you run R as a regular (not root) user, and password-less `sudo` is
not available, then pak will print the system requirements, but it will
not try to install or update them.
If you are installing source packages that need to link to system
libraries, then their installation will probably fail, until you install
these system packages.
If you are installing binary R packages, then the installation typically
succeeds, but you won't be able to load these packages into R, until you
install the required system packages. Here is an example, on a system that
does not have the required system package installed for RPostgres.
If you are installing a source R package, the installation already fails:

```{asciicast pkg-inst-user-setup, include=FALSE, cache = FALSE}
system("apt-get remove -y libpq5")
try(pak::pkg_remove("RPostgres"))
options(pkg.sysreqs = FALSE)

```{asciicast pkg-install-user-src, error = TRUE} pak::pkg_install("RPostgres?source")

On the other hand, if you are installing binary packages, e.g. from the
Posit Package Manager, then the installation typically succeeds, but then
loading the package fails:

```{asciicast pkg-inst-user, error = TRUE}
pak::pkg_install("RPostgres")
library(RPostgres)

Query system requirements without installation

If you only want to query system requirements, without installing any packages, use the pkg_sysreqs() function. This is similar to pkg_deps() but in addition to looking up package dependencies, it also looks up system dependencies, and only reports the latter:

```{asciicast pkg-sysreqs} pak::pkg_sysreqs(c("curl", "xml2", "devtools", "CHRONOS"))

See the manual of `pkg_sysreqs()` to see how to programmatically extract
information from its return value.

# Other queries

In addition to the automatic system package lookup and installation, pak
also has some other functions to help you with system dependencies.
The `sysreqs_db_list()` function lists all system requirements pak knows
about.
```{asciicast db-list}
pak::sysreqs_db_list()

sysreqs_db_match() manually matches SystemREquirements fields againts these system requirements: ```{asciicast db-match} sq <- pak::sysreqs_db_match("Needs libcurl and also Java.") sq

```{asciicast db-match-2}
sq[[1]]$packages

You can also use it to query system requirements for other platforms: ```{asciicast db-match-3} sqrhel9 <- pak::sysreqs_db_match("Needs libcurl and also Java.", "redhat-9") sqrhel9

```{asciicast db-match-4}
sqrhel9[[1]]$packages

sysreqs_list_system_packages() is a cross-platform way of listing all installed system packages and capabilities: ```{asciicast list-system-packages} pak::sysreqs_list_system_packages()

`sysreqs_check_installed()` is a handy function that checks if all
system requirements are installed for some or all R packages that are
installed in your library:
```{asciicast check-installed-setup, include = FALSE}
.libPaths(.libPaths()[-1])

{asciicast check-installed} pak::sysreqs_check_installed()

sysreqs_fix_installed() goes one step further and also tries to install the missing system requirements.

Build-time and run-time dependencies

The system requirements database that pak uses does not currently differentiate between build-time and run-time dependencies. A build-time dependency is a system package that you need when installing an R package from source. A run-time dependency is a system package that you need when using an R package. Most Linux distribution create (at least) two packages for each software library: a runtime package and a development package. For an R package that uses such a software library, the runtime package is a run-time dependency and the development package is a build-time dependency. However, pak does not currently know the difference between build-time and run-time dependencies, and it will install both types of dependencies, always. This means that pak usually installs system packages that are not strictly necessary. These are typically development packages of libraries, i.e. header files, and typically do not cause any issues. If you are short on disk space, then you can try removing them.

How it works

pak uses the database of system requirements at https://github.com/rstudio/r-system-requirements. It has its own copy of the database embedded into the package, and it also tries to download updated versions of the database from GitHub, if its current copy is older than one day. You can explicitly update the database from GitHub using the sysreqs_db_update() function.

For CRAN packages, it downloads the SystemRequirements fields from https://cran.r-pkg.org/metadata/, which is a database updated daily. For Bioconductor packages, it downloads then from GitHub. (We are planning on moving CRAN database to GitHub as well.)

For packages sources that require pak to obtain a package DESCRIPTION file (e.g. github::, git::, etc.), pak obtains SystemRequirements directly from the DESCRIPTION file.

Once having the SystemRequirements fields, pak matches them to the database, to obtain the cacnonized list of system requirements.

Then pak queries the local platform, to see the exact system packages needed. It also queries the installed system packages, to avoid trying to install system packages that are already installed.

Configuration

There are several pak configuration options you can use to adjust how system requirements are handled. We will list some of them here, please see the options with a sysreqs prefix in the ?pak-config manual page for a complete and current list.

• sysreqs: whether to install system requirements. The default is TRUE if the platform is supported and the user can install system packages, either because it is the superuser, or via sudo. If it is FALSE (or the user cannot install system packages), but the platform is supported, system requirements are printed, but not installed.
• sysreqs_db_update: whether to try to update the system requirements database from GitHub.
• sysreqs_db_update_timeout: timeout for the system requirements update from GitHub.
• sysreqs_dry_run: if TRUE then pak only prints the install commands, but does not actually run them.
• sysreqs_platform: the platform name to use for determining system requirements. Defaults to the current platform. If you are using a Linux distribution that is compatible with some distribution that pak supports, then you can set this option manually. E.g. Ubuntu-based distros can set it to ubuntu-22.04, or the appropriate Ubuntu version.
• sysreqs_sudo: whether to use sudo to install system packages. If this is not set, then pak tries to auto-detect if sudo is needed or not.
• sysreqs_update: whether to try to update system packages that are already installed. pak does not know which version of a system package is required, and it does not try to update system packages by default. If you think that you need newer system packages, then you can set this option to TRUE.
• sysreqs_verbose: whether to print the output of the system package installation commands. Useful for debugging, and it is TRUE by default in a CI environment.

About other OSes

Windows

While the system requirements database has some information about system dependencies on Windows, pak does not use this information and it does not try to install system software on Windows. CRAN, PPM and Bioconductor have Windows binary packages available for the majority of R packages they serve, and these packages practically always link to system libraries statically, so they don't need any external software.

If you wish to compile Windows packages from source, then you need to install the appropriate version of Rtools, and possibly extra packages using the pacman tool of Rtools4x.

Rtools42 and newer Rtools versions bundle lots of libraries, so most likely no extra pacman packages are needed. Rtools40 has a leaner default installation, and you'll probably need to install packages manually: https://github.com/r-windows/docs/blob/master/rtools40.md#readme

We are planning on adding better Windows system software support to pak in the future.

macOS

pak does not currently have system requirement information for macOS. macOS is similar to Windows, in that most repositories will serve statically linked macOS binary packages that do not need system software.

If you do need to compile packages from source, then you possibly need to install some sytem libraries, either via Homebrew, or by downloading CRAN's static library builds from https://mac.r-project.org/bin/

We are planning on adding better macOS system software support to pak in the future.

r-lib/pak documentation built on Nov. 9, 2024, 2:34 a.m.