Refine binary archive.

This streamlines the resulting archive in three ways:

1. It only includes mcrouter and mcpiper from /bin (no thrift, zfmt,
etc)
2. It only includes the libraries that mcrouter and mcpiper actually
link against.  This removes a bunch of boost libraries from the archive.
3. It includes the dynamic libraries not only from INSTALL_DIR, but
also from the host system (e.g. libssl and libz).

This archive is *NOT PORTABLE* in any meaningful way, it is only
meant to run on essentially the same target system, amazon linux 2.

mcrouter/scripts/INSTALL.md

@@ -8,6 +8,6 @@ N.B These scripts *only* support Amazon Linux 2
 
         MY_INSTALL_DIR=path/to/install/dir
         TARGET=mcrouter
-        ./get_and_build_by_make $MY_INSTALL_DIR mcrouter
+        ./get_and_build_by_make.sh $MY_INSTALL_DIR mcrouter
 
 You can substitute individual dependencies as the value of TARGET in order to debug. 

mcrouter/scripts/Makefile_amazon-linux-2

@@ -67,6 +67,9 @@ mcrouter: .fbthrift-done .folly-done .fizz-done .wangle-done .fmt-done .zstd-don
 	${RECIPES_DIR}/mcrouter.sh $(PKG_DIR) $(INSTALL_DIR) $(INSTALL_AUX_DIR)
 	touch $@
 
-archive: mcrouter
-	touch $@
-	tar czfv "mcrouter.$$(git rev-parse --short=12 HEAD).$$(uname -m).tar.gz" -C $(INSTALL_DIR) aux bin lib lib64 share
+MCROUTER_ARCHIVE := mcrouter.$(shell git rev-parse --short=12 HEAD).$(shell uname -m).tar.gz
+
+$(MCROUTER_ARCHIVE): mcrouter
+	./slim-archive.sh $(INSTALL_DIR) $@
+
+archive: $(MCROUTER_ARCHIVE)

mcrouter/scripts/slim-archive.sh

@@ -0,0 +1,32 @@
+#!/usr/bin/env bash
+
+# This creates an archive suitable for distribution to other hosts with the same system.
+
+set -euo pipefail
+
+INSTALL_DIR="$1"
+ARCHIVE="$2"
+
+function die() {
+    printf "%s: %s\n" "$0" "$@"
+    exit 1
+}
+
+[ -n "$1" ] || die "INSTALL_DIR missing"
+[ -n "$2" ] || die "ARCHIVE missing"
+
+ARCHIVE_INSTALL_DIR=$(mktemp -d)
+mkdir "${ARCHIVE_INSTALL_DIR}"/lib
+mkdir "${ARCHIVE_INSTALL_DIR}"/bin
+
+# This expression uses "ldd" to locate all dynamically linked library dependencies.
+# We then copy them to a tempdir so we can simply create an archive of only the needed dependencies.
+# This will suck in libraries both from the "compiled from source" libraries (e.g. folly, thrift) as libraries
+# from the host system.
+
+LD_LIBRARY_PATH="${INSTALL_DIR}"/lib ldd "${INSTALL_DIR}"/bin/mcrouter "${INSTALL_DIR}"/bin/mcpiper \
+    | grep "=>" | tr -s "[:blank:]" " " | cut -d " " -f 4 | sort -u \
+    | xargs -I '%' cp '%' "${ARCHIVE_INSTALL_DIR}"/lib
+cp "${INSTALL_DIR}"/bin/mcrouter "${INSTALL_DIR}"/bin/mcpiper "${ARCHIVE_INSTALL_DIR}"/bin/
+
+tar czfv "${ARCHIVE}" -C "${ARCHIVE_INSTALL_DIR}" .