A bootleg puppet

install.sh

# -*- mode: bash; indent-tabs-mode: nil; sh-basic-offset: 2; fill-column: 100; -*-

# About
# ==============================
# A bootleg dotfiles installer.
#
# Usage
# ==============================
#
# $FORCE - if non-empty then install.sh will happily clobber existing files/dirs
# $DEBUG - if non-empty then install.sh will be verbose about what gets moved where
#
# $ bash ./install.sh
#
# Expects a repository of the following configuration:
# $ROOT/
# $ROOT/install.sh
# $ROOT/profiles.d
# $ROOT/packages.d
# $ROOT/hosts.d
#
# packages.d is expected to be a directory of packages.
# profiles.d and hosts.d are expected to be directories of profiles.
#
# Packages
# --------------------
#
# Packages consist of one or more directories of files to be installed, by default to ~/
# Packages may provide a README.*, an install and a build which are ignored
#
# If a build file is present, the build will be executed before the package is installed. This
# allows packages the opportunity to build platform-specific files and/or binaries.
#
# If an install file is present, that file will be executed with no arguments and is expected to
# install the package. This allows packages to provide arbitrary installation behavior, such as
# placing files elsewhere than ~, or just installing packages.
#
# If no install file is present, then all directories in the package directory will be recursively
# created under ~, and all files in the package directories will be symlinked into place. This
# behavior is used so that multiple packages can place files in the same directories.
#
# Profiles
# --------------------
#
# Profiles are a way to group together multiple packages, as well as to require packages.
#
# Profiles consist of a directory, containing an optional README.*, a requirements file, and zero or
# more package directories.
#
# The requirements file may consist of # comments, or lines of the format "profiles.d/$PROFILE" or
# "packages.d/$PACKAGE". All required packages and profiles will be installed before the packages
# included in the profile are installed.
#
# Example
# --------------------
#
# $ hostname
# test
# $ ls hosts.d/test
# requirements vim
# $ cat host.d/test/requirements
# profiles.d/default
# packages.d/git
#
# When install.sh is executed, the host profile named test will be installed. It consists of the
# default profile and the git package, as well as a vim package bundled in the host. These packages
# will be installed in that order.

function arrdem_installf () {
  # $1 is the logical name of the file to be installed
  # $2 is the absolute name of the file to be installed
  # $3 is the absolute name of its destination
  #
  # Installs (links) a single file, debugging as appropriate

  if [ -n "$DEBUG" ]; then
      echo "[DBG] $1 -> $3"
  fi
  ln -s "$2" "$3"
}

export -f arrdem_installf

function arrdem_installd () {
  # $1 is an un-normalized path which should be created (or cleared!)

  dir="$(echo $1 | sed 's/\.\///g')"
  if [ ! -d "$dir" ]; then
      if [ -n "$FORCE" ]; then
          rm -rf "$dir"
      fi

      mkdir -p "$dir"
  fi
}

export -f arrdem_installd

function arrdem_stowf () {
  # $1 is the stow target dir
  # $2 is the name of the file to stow

  f="$(echo $2 | sed 's/\.\///g')" # Strip leading ./
  TGT="$1/$f"
  ABS="$(realpath $f)"

  if [ -h "$TGT" ] || [ -e "$TGT" ]; then
      if [ "$(realpath $TGT)" != "$ABS" ]; then
          if [ -n "$FORCE" ]; then
              if [ -n "$DEBUG" ]; then
                  echo "[DBG] Clobbering existing $ABS"
              fi
              rm "$TGT"
              arrdem_installf "$f" "$ABS" "$TGT"
          else
            echo "[WARNING] $TGT already exists! Not replacing!"
            echo "          Would have been replaced with $ABS"
          fi
      else
        if [ -n "$DEBUG" ]; then
            echo "[DEBUG] $TGT ($f) already installed, skipping"
        fi
      fi
  else
    arrdem_installf "$f" "$ABS" "$TGT"
  fi
}

export -f arrdem_stowf

function arrdem_stow () {
  # $1 is the install target dir
  # $2 is the source package dir
  #
  # Makes all required directories and links all required files to install a given package.

  # If a target directory doesn't exist, create it as a directory.
  # For each file in the source, create symlinks into the target directory.
  #
  # This has the effect of creating merge mounts between multiple packages, which gnu stow doesn't
  # support.
  ( cd "$2"

    # Make all required directories if they don't exist
    #
    # If force is set and something is already there blow it the fsck away
    find . -mindepth 1 \
         -type d \
         -exec bash -c 'arrdem_installd "$0/$1"' "$1" {} \;

    # Link in all files.
    #
    # If the file already exists AND is a link to the thing we want to install, don't bother.
    # Else if the file already exists and isn't the thing we want to install and force is set, clobber
    # Else if the file already exists emit a warning
    # Else link the file in as appropriate
    #
    # Note that this skips install, build and README files
    find . -type f \
         -not -name "INSTALL" \
         -not -name "BUILD" \
         -not -name "README.*" \
         -exec bash -c 'arrdem_stowf "$0" "$1"' "$1" {} \;
  )
}

export -f arrdem_stow

function install_package() {
  # $1 is the path of the package to install
  #
  # Executes the package build script if present.
  #
  # Then executes the install script if present, otherwise using arrdem_stow to install the built
  # package.

    echo "[INFO - install_package] installing $1"

    if [ -x "$1/BUILD" ]; then
        ( cd "$1";
          ./BUILD)
    fi

    if [ -e "$1/INSTALL" ]; then
        ( cd "$1";
          ./INSTALL)
    else
        arrdem_stow ~ "$1"
    fi
}

export -f install_package

function install_profile() {
  # $1 is the path of the profile to install
  #
  # Reads the requires file from the profile, installing all required profiles and packages, then
  # installs any packages in the profile itself.

  if [ -d "$1" ]; then
      echo "[INFO] installing $1"

      # Install requires
      REQUIRES="$1/requires"

      if [ -e "$REQUIRES" ]; then
          cat $REQUIRES | while read -r require; do
              echo "[INFO] $require"
              case "$require" in
                  profiles.d/*)
                      echo "[INFO - install_profile($1)] recursively installing profile $require"
                      install_profile "$require"
                      ;;

                  packages.d/*)
                      echo "[INFO - install_profile($1)] installing package $require"
                      install_package "$require"
                      ;;
              esac
          done
      fi

      # Install the package(s)
      find "$1" \
           -maxdepth 1 \
           -mindepth 1 \
           -type d \
           -exec bash -c 'install_package "$0"' {} \;
  else
    echo "[WARN] No such package $1!"
  fi
}

function main() {
  # Normalize hostname

  HOSTNAME="$(hostname | tr '[:upper:]' '[:lower:]')"
  HOST_DIR="hosts.d/$HOSTNAME"

  if [ -d "$HOST_DIR" ]; then
      # Install the host profile itself
      #
      # It is expected that the host requires default explicitly (or transitively) rather than getting
      # it "for free".
      echo "[INFO - main] installing profile $HOST_DIR"
      install_profile "$HOST_DIR"
  else
    # Otherwise just install the default profile
    echo "[INFO - main] installing fallback profile profile profiles.d/default"
    install_profile "profiles.d/default"
  fi
}

main