ENH: Add direnv, asdf helper

dot_config/asdf/asdfrc

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+# https://asdf-vm.com/manage/configuration.html
+legacy_version_file = yes
+always_keep_download = no

dot_config/direnv/direnvrc

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+########
+# ASDF #
+########
+
+# Usage (lines other than the first are optional):
+## use asdf
+#
+# This loads asdf and uses a cached setup which circumvents one reshim
+#
+# https://github.com/asdf-community/asdf-direnv
+#
+
+source "$(asdf direnv hook asdf)"
+
+########
+# Ruby #
+########
+
+# Usage (lines other than the first are optional):
+## layout ruby
+## use asdf
+## PATH_add .direnv/bundler-bin
+#
+# This watches some files. Uses asdf for managing versions.
+#
+# https://github.com/direnv/direnv/wiki/Ruby
+#
+
+layout_ruby() {
+      # Direnv specials
+      watch_file Gemfile
+      watch_file .ruby_version
+}
+
+######
+# Go #
+######
+
+# Usage: layout golang
+#
+# Sets up environment for a Go project using the alternative gb build tool. Also
+# works with the official dep package.In addition to project executables on
+# PATH, this includes an exclusive, project- local GOPATH which enables many
+# tools like gocode and oracle to "just work".
+#
+# http://getgb.io/
+# https://golang.github.io/dep/
+#
+
+layout_golang() {
+  export GOPATH="$PWD/vendor:$PWD"
+  PATH_add "$PWD/vendor/bin"
+  PATH_add bin
+}
+
+#######
+# Nix #
+#######
+
+# From https://github.com/direnv/direnv/wiki/Nix and https://github.com/kalbasit/nur-packages/blob/master/pkgs/nixify/envrc
+
+# Usage: use_nix [...]
+#
+# Load environment variables from `nix-shell`.
+# If you have a `default.nix` or `shell.nix` one of these will be used and
+# the derived environment will be stored at ./.direnv/env-<hash>
+# and symlink to it will be created at ./.direnv/default.
+# Dependencies are added to the GC roots, such that the environment remains persistent.
+#
+# The resulting environment is cached for better performance.
+#
+# To trigger switch to a different environment:
+# `rm -f .direnv/default`
+#
+# To derive a new environment:
+# `rm -rf .direnv/env-$(md5sum {shell,default}.nix 2> /dev/null | cut -c -32)`
+#
+# To remove cache:
+# `rm -f .direnv/dump-*`
+#
+# To remove all environments:
+# `rm -rf .direnv/env-*`
+#
+# To remove only old environments:
+# `find .direnv -name 'env-*' -and -not -name `readlink .direnv/default` -exec rm -rf {} +`
+#
+
+set -eo pipefail
+
+use_nix() {
+	# define all local variables
+	local shell f env_hash dir default wd drv dump path_backup
+	local files_to_watch=()
+
+	while getopts ":s:w:" opt; do
+		case "${opt}" in
+			s)
+				shell="${OPTARG}"
+				files_to_watch=("${files_to_watch[@]}" "${shell}")
+				;;
+			w)
+				files_to_watch=("${files_to_watch[@]}" "${OPTARG}")
+				;;
+			:)
+				>&2 echo "Invalid option: $OPTARG requires an argument"
+				;;
+			\?)
+				>&2 echo "Invalid option: $OPTARG"
+				exit 1
+				;;
+		esac
+	done
+	shift $((OPTIND -1))
+
+	if [[ -z "${shell}" ]]; then
+		>&2 echo "ERR: no shell was given"
+		exit 1
+	fi
+
+	for f in "${files_to_watch[@]}"; do
+		if ! [[ -f "${f}" ]]; then
+			>&2 echo "cannot watch file ${f} because it does not exist"
+			exit 1
+		fi
+	done
+
+	# compute the hash of all the files that makes up the development environment
+	env_hash="$(hashContents "${files_to_watch[@]}")"
+
+	dir="$(direnv_layout_dir)"
+	default="${dir}/default"
+	if [[ ! -L "${default}" ]] || [[ ! -d $(readlink "${default}") ]]; then
+		wd="${dir}/env-${env_hash}"
+		mkdir -p "${wd}"
+
+		drv="${wd}/env.drv"
+		if [[ ! -f "${drv}" ]]; then
+			log_status "use nix: deriving new environment"
+			IN_NIX_SHELL=1 nix-instantiate --add-root "${drv}" --indirect "${shell}" > /dev/null
+			nix-store -r $(nix-store --query --references "${drv}") --add-root "${wd}/dep" --indirect > /dev/null
+		fi
+
+		rm -f "${default}"
+		ln -s $(basename "${wd}") "${default}"
+	fi
+
+	drv=$(readlink "${default}/env.drv")
+	dump="${dir}/dump-$(hashFile ".envrc")-$(hashFile ${drv})"
+
+	if [[ ! -f "${dump}" ]] || [[ "${XDG_CONFIG_DIR}/direnv/direnvrc" -nt "${dump}" ]]; then
+		log_status "use nix: updating cache"
+
+		old=$(find "${dir}" -name 'dump-*')
+		nix-shell --pure "${drv}" --show-trace --run "$(join_args "$direnv" dump bash)" > "${dump}"
+		rm -f ${old}
+	fi
+
+	# evaluate the dump created by nix-shell earlier, but have to merge the PATH
+	# with the current PATH
+	# NOTE: we eval the dump here as opposed to direnv_load it because we don't
+	# want to persist environment variables coming from the shell at the time of
+	# the dump. See https://github.com/direnv/direnv/issues/405 for context.
+	path_backup="${PATH}"
+	eval $(cat "${dump}")
+	export PATH="${PATH}:${path_backup}"
+
+	for f in "${files_to_watch[@]}"; do
+		watch_file "${f}"
+	done
+}
+
+hashContents() {
+	if has md5sum; then
+		cat "${@}" | md5sum | cut -c -32
+	elif has md5; then
+		cat "${@}" | md5 -q
+	fi
+}
+
+hashFile() {
+	if has md5sum; then
+		md5sum "${@}" | cut -c -32
+	elif has md5; then
+		md5 -q "${@}"
+	fi
+}
+
+fail() {
+	log_error "${@}"
+	exit 1
+}
+
+validateVersion() {
+	local version="$("${direnv}" version)"
+	local major="$(echo "${version}" | cut -d. -f1)"
+	local minor="$(echo "${version}" | cut -d. -f2)"
+	local patch="$(echo "${version}" | cut -d. -f3)"
+
+	if [[ "${major}" -gt 2 ]]; then return 0; fi
+	if [[ "${major}" -eq 2 ]] && [[ "${minor}" -gt 18 ]]; then return 0; fi
+	if [[ "${major}" -eq 2 ]] && [[ "${minor}" -eq 18 ]] && [[ "${patch}" -ge 2 ]]; then return 0; fi
+	return 1
+}
+
+if ! validateVersion; then
+	echo "This .envrc requires direnv version 2.18.2 or above."
+	exit 1
+fi
+
+# Local Variables:
+# mode: sh
+# End:

runnable/run_once_asdf_direnv.sh

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+#!/usr/bin/env bash
+# Although I no longer recommend asdf, (shims are awful)
+# This is the fastest way to get direnv up and running
+
+if [[ ! -d ~/.asdf ]]; then
+    mkdir ~/.asdf
+    git clone https://github.com/asdf-vm/asdf.git ~/.asdf
+fi
+
+export ASDF_CONFIG_FILE="~/.config/asdf/asdfrc"
+
+asdf plugin-add direnv
+asdf install direnv latest
+asdf global direnv latest