install

#!/bin/bash

# This script may help people in installing and configuring awsudo
# and awsrotate in the simplest way. It can also be done manually; see
# README.md.
#
# The install is done into a virtualenv because it's more robust. In
# particular, Mac OS X system Python installs six in such a way that it can't
# be overridden by user packages, and comes with an old version that doesn't
# have the "wraps" method. Using a virtualenv steps around all that.

default_path="$HOME/Documents/awsudo"

read_with_default() {
	prompt="$1"
	default="$2"

	read -p "$prompt [$default] " value || exit
	echo "${value:-$default}"
}


confirm() {
	prompt="$1"
	read -p "$prompt [y] " response || exit
	[[ "${response:-y}" = 'y' ]]
}


install_virtualenv() {
	if ! hash virtualenv &>/dev/null; then
		echo "I'll need to install virtualenv to proceed."

		if ! hash pip &>/dev/null; then
			echo "But first I'll need to install pip to install virtualenv."
			confirm "Shall I install pip?" || exit 1
			sudo easy_install pip || exit
		fi

		confirm "Shall I install virtualenv?" || exit 1
		sudo pip install virtualenv || exit
	fi
}


# check that a program is installed; create a symlink if not.
check_symlink() {
	local prog="$1"

	if hash "$prog" &>/dev/null; then
		cat <<-EOF
		$prog is already installed at $(hash -t "$prog").
		Maybe you have a preexisting installation? Things could be confusing.

		EOF
		confirm "Proceed anyway?" || exit
	else
		echo "Looks like $prog is not in your \$PATH."
		confirm "Should I make a symlink?" || return 0

		local bin=$(read_with_default \
			"Where?" \
			"/usr/local/bin")

		if [[ -w "$bin" ]]; then
			local ln="ln"
		else
			local ln="sudo ln"
		fi

		$ln -s "$path/bin/$prog" "$bin" || exit

		if ! hash $prog &>/dev/null; then
			cat >&2 <<-EOF
			Something is wrong: I can't find $prog even though I just
			created a symlink in in $bin. Maybe $bin isn't in your
			\$PATH?

			EOF
			confirm "Proceed anyway?" || exit 1
		else
			local actual_location=$(hash -t "$prog")
			if [[ "$actual_location" != "$bin/$prog" ]]; then
				cat >&2 <<-EOF
				This is odd: even though I just made a symlink for $prog in
				$bin, bash thinks $prog is at $actual_location.
				Maybe you need to adjust the order of your \$PATH?

				EOF
				confirm "Proceed anyway?" || exit 1
			fi
		fi
	fi
}


rotate_key() {
	confirm "Do you want to rotate your key now?" || return 0
	echo "Running 'awsrotate'. It takes about 10 seconds..."

	if ! awsrotate; then
		cat >&2 <<-EOF
		Looks like it didn't work :(

		Things to check:
		- the correct credentials are in ~/.aws/credentials
		- AWS account permissions allow you to modify your own API access keys
		- "awsrotate" and "awsudo" and "aws" are executable and in \$PATH

		To try again, later you can just run "awsrotate".

		Would you like to proceed? I can still help you set up cron to run
		awsrotate automatically, and you can troubleshoot this failure later.

		EOF
		confirm "Proceed on to configuring cron?" || exit 1
	fi

	echo "Success!"
	echo
}


create_cron_entry() {
	if ! crontab -l &>/dev/null; then
		cat <<-EOF
		I can't run 'crontab -l', so I can't configure cron for you."
		For great security, consider configuring something to run 'awsrotate'
		periodically (daily, perhaps) so your API key is automatically rotated.
		EOF
		return 0
	fi

	cat <<-EOF
	I can add an entry to your crontab to automatically rotate your key daily at
	noon. Cron works pretty well as long as your machine is usually on at the
	scheduled time. There are other tools (anacron, upstart, systemd, launchd)
	which might work better, but I don't know how to configure those.

	If you want to edit the cron entry later, you can do that by running:
	
	    crontab -e

	EOF
	confirm "Should I add a crontab entry now?" || return 0
	(crontab -l; echo "00 12 * * * $path/bin/awsrotate") | crontab - || exit
}


install_in_virtualenv() {
	path=$(read_with_default \
		"Where would you like awsudo installed?" \
		"$HOME/Documents/awsudo")

	# expand ~ to the home directory like Bash does
	path="${path/#\~/$HOME}"

	if [[ -e "$path" ]] && [[ ! -d "$path" ]]; then
		echo "$path already exists but is not a directory! Aborting." >&2
		exit 1
	fi

	mkdir -p "$path" || exit

	if [[ ! -e "$path/bin/python" ]]; then
		echo "Creating a virtualenv at $path"
		virtualenv -q "$path" || exit
	fi

	echo "Updating pip and setuptools to the latest version"
	"$path/bin/pip" -q install --upgrade pip setuptools || exit

	echo "Installing awsudo and awsrotate"
	"$path/bin/pip" -q install --upgrade git+https://github.com/makethunder/awsudo.git || exit

	echo
}


configure_aws() {
	if [[ ! -e ~/.aws/credentials ]]; then
		echo "Looks like the AWS CLI isn't configured."
		if confirm "Configure it now?"; then
			"$path/bin/aws" configure || exit
		fi
	fi
}


cat <<-EOF
This interactive script will help you to:

	- install awsudo and awsrotate,
	- perform a minimal configuration, and
	- (optionally) configure cron to automatically rotate your AWS API keys.
	
It will install in a Python virtualenv, an isolated Python environment. This
helps to make the installation more robust against environmental variations.

If you want to abort installation, press CTRL-C now. Otherwise answer the
questions that follow, or press enter to accept the defaults in square
brackets.

EOF

install_virtualenv

install_in_virtualenv

for prog in awsudo awsrotate; do
	check_symlink "$prog"
done

configure_aws

rotate_key

create_cron_entry