feat(installer): Add bash install script

install.sh

@@ -0,0 +1,102 @@
+#!/bin/bash
+# This is derived from https://github.com/jpillora/installer
+
+TMP_DIR="/tmp/install-fossa-cli"
+
+function cleanup {
+	echo rm -rf $TMP_DIR > /dev/null
+}
+
+function fail {
+	cleanup
+	msg=$1
+	echo "============"
+	echo "Error: $msg" 1>&2
+	exit 1
+}
+
+function install {
+	# Settings
+	USER="fossas"
+	REPO="fossa-cli"
+  BIN="fossa"
+  # TODO: automatically get latest version from GitHub Releases API
+  VERSION="0.4.1"
+	RELEASE="v$VERSION"
+	MOVE="true"
+	INSECURE="false"
+	OUT_DIR="/usr/local/bin"
+	GH="https://github.com"
+
+	# `bash` check
+	[ ! "$BASH_VERSION" ] && fail "Please use bash instead"
+	[ ! -d $OUT_DIR ] && fail "output directory missing: $OUT_DIR"
+
+  # Check for non-POSIX dependencies
+	GET=""
+	if which curl > /dev/null; then
+		GET="curl"
+		if [[ $INSECURE = "true" ]]; then GET="$GET --insecure"; fi
+		GET="$GET --fail -# -L"
+	elif which wget > /dev/null; then
+		GET="wget"
+		if [[ $INSECURE = "true" ]]; then GET="$GET --no-check-certificate"; fi
+		GET="$GET -qO-"
+	else
+		fail "neither wget nor curl are installed"
+	fi
+  which sha256sum > /dev/null || fail "sha256sum is not installed"
+  which tar > /dev/null || fail "tar is not installed"
+  which gzip > /dev/null || fail "gzip is not installed"
+
+	# Detect OS
+	case `uname -s` in
+    Darwin) OS="darwin";;
+    Linux) OS="linux";;
+    *) fail "unknown os: $(uname -s)";;
+	esac
+
+	# Detect architecture
+	if uname -m | grep 64 > /dev/null; then
+		ARCH="amd64"
+	elif uname -m | grep arm > /dev/null; then
+		ARCH="arm"
+	elif uname -m | grep 386 > /dev/null; then
+		ARCH="386"
+	else
+		fail "unknown arch: $(uname -m)"
+	fi
+
+	# Fail for unsupported OS/architecture combinations
+	case "${OS}_${ARCH}" in
+	"darwin_amd64") ;;
+	"linux_amd64") ;;
+	"windows_amd64") ;;
+	*) fail "No asset for platform ${OS}-${ARCH}";;
+	esac
+
+
+	# Enter temporary directory
+	echo "Installing $USER/$REPO $RELEASE..."
+	mkdir -p $TMP_DIR
+	cd $TMP_DIR
+
+  # Download and validate release
+  RELEASE_URL="$GH/$USER/$REPO/releases/download/$RELEASE"
+  bash -c "$GET $RELEASE_URL/${REPO}_${VERSION}_${OS}_${ARCH}.tar.gz" > release.tar.gz || fail "downloading release failed"
+  bash -c "$GET $RELEASE_URL/${REPO}_${VERSION}_checksums.txt" > checksums.txt || fail "downloading checksums failed"
+  [ "$(grep "${OS}_${ARCH}" checksums.txt | cut -f 1 -d " ")" == "$(sha256sum release.tar.gz | cut -f 1 -d " ")" ] || fail "invalid checksum"
+
+  # Extract release
+  tar zxf release.tar.gz || fail "tar failed"
+  rm release.tar.gz
+
+	# Move binary into output directory
+	chmod +x $BIN || fail "chmod +x failed"
+	mv $BIN $OUT_DIR/$BIN || fail "mv failed"
+	echo "Installed at $OUT_DIR/$BIN"
+
+	cleanup
+}
+
+install