Add a flag to make lighthouse portable across machines (#1423)

## Issue Addressed

Closes #1395

## Proposed Changes

* Add a feature to `lighthouse` and `lcli` called `portable` which enables the `portable` feature on our fork of BLST. This feature turns off the `-march=native` C compiler flag that produces binaries highly targeted to the host CPU's instruction set.
* Tweak the `Makefile` so that when the `PORTABLE` environment variable is set to `true`, it compiles with this feature.
* Temporarily enable `PORTABLE=true` in the Docker build so that the image on Docker Hub is portable. Eventually I think we should enable `PORTABLE=true` _only on Docker Hub_, so that users building locally can take advantage of the tasty compiler magic. This seems to be possible by setting a Docker Hub environment variable: https://docs.docker.com/docker-hub/builds/#environment-variables-for-builds

## Additional Info

Tested by compiling on a very new CPU (Intel Core i7-8550U) and copying the binary to a very old CPU (Intel Core i3 530). Before the portability fix, this produced the SIGILL crash described in #1395, and after the fix, it worked smoothly.

I'm in the process of testing the Docker build and running some benches to confirm that the performance penalty isn't too severe.

Dockerfile

@@ -1,8 +1,10 @@
-FROM rust:1.44.1 AS builder
+FROM rust:1.45.1 AS builder
 RUN apt-get update && apt-get install -y cmake
 COPY . lighthouse
+ARG PORTABLE
+ENV PORTABLE $PORTABLE
 RUN cd lighthouse && make
-RUN cd lighthouse && cargo install --path lcli --locked
+RUN cd lighthouse && make install-lcli
 
 FROM debian:buster-slim
 RUN apt-get update && apt-get install -y --no-install-recommends \

Makefile

@@ -7,11 +7,19 @@ STATE_TRANSITION_VECTORS = "testing/state_transition_vectors"
 #
 # Binaries will most likely be found in `./target/release`
 install:
+ifeq ($(PORTABLE), true)
+	cargo install --path lighthouse --force --locked --features portable
+else
 	cargo install --path lighthouse --force --locked
+endif
 
 # Builds the lcli binary in release (optimized).
 install-lcli:
+ifeq ($(PORTABLE), true)
+	cargo install --path lcli --force --locked --features portable
+else
 	cargo install --path lcli --force --locked
+endif
 
 # Runs the full workspace tests in **release**, without downloading any additional
 # test vectors.

book/src/docker.md

@@ -29,6 +29,10 @@ $ docker run sigp/lighthouse lighthouse --help
 > Note: when you're running the Docker Hub image you're relying upon a
 > pre-built binary instead of building from source.
 
+> Note: due to the Docker Hub image being compiled to work on arbitrary machines, it isn't as highly
+> optimized as an image built from source. We're working to improve this, but for now if you want
+> the absolute best performance, please build the image yourself.
+
 ### Building the Docker Image
 
 To build the image from source, navigate to

crypto/bls/Cargo.toml

@@ -17,10 +17,11 @@ eth2_hashing = "0.1.0"
 ethereum-types = "0.9.1"
 arbitrary = { version = "0.4.4", features = ["derive"], optional = true }
 zeroize = { version = "1.0.0", features = ["zeroize_derive"] }
-blst = { git = "https://github.com/sigp/blst.git", rev = "968c846a2dc46e836e407bbdbac1a38a597ebc46" }
+blst = { git = "https://github.com/sigp/blst.git", rev = "dad1ad0cd22861e5773bee177bee4e1684792605" }
 
 [features]
 default = ["supranational"]
 fake_crypto = []
 milagro = []
 supranational = []
+supranational-portable = ["supranational", "blst/portable"]

hooks/build

@@ -0,0 +1,4 @@
+#!/bin/bash
+
+# Build hook to run on Docker Hub to ensure that the image is built with `PORTABLE=true`.
+docker build --build-arg PORTABLE=true -f $DOCKERFILE_PATH -t $IMAGE_NAME .

lcli/Cargo.toml

@@ -5,9 +5,11 @@ version = "0.2.0"
 authors = ["Paul Hauner <[email protected]>"]
 edition = "2018"
 
-# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+[features]
+portable = ["bls/supranational-portable"]
 
 [dependencies]
+bls = { path = "../crypto/bls" }
 clap = "2.33.0"
 hex = "0.4.2"
 log = "0.4.8"

lighthouse/Cargo.toml

@@ -5,14 +5,18 @@ authors = ["Sigma Prime <[email protected]>"]
 edition = "2018"
 
 [features]
-write_ssz_files = ["beacon_node/write_ssz_files"]  # Writes debugging .ssz files to /tmp during block processing.
+# Writes debugging .ssz files to /tmp during block processing.
+write_ssz_files = ["beacon_node/write_ssz_files"]
+# Compiles the BLS crypto code so that the binary is portable across machines.
+portable = ["bls/supranational-portable"]
 
 [dependencies]
 beacon_node = { "path" = "../beacon_node" }
 tokio = "0.2.21"
 slog = { version = "2.5.2", features = ["max_level_trace"] }
 sloggers = "1.0.0"
 types = { "path" = "../consensus/types" }
+bls = { path = "../crypto/bls" }
 clap = "2.33.0"
 env_logger = "0.7.1"
 logging = { path = "../common/logging" }