Kevin Karwaski kevinkarwaski

Optimizing Rust container builds

I'm a Rust newbie, and one of the things that I've found frustrating is that the default docker build experience is extremely slow. As it downloads crates, then dependencies, then finally my app - I often get distracted, start doing something else, then come back several minutes later and forget what I was doing

Recently, I had the idea to make it a little better by combining multistage builds with some of the amazing features from BuildKit. Specifically, cache mounts, which let a build container cache directories for compilers & package managers. Here's a quick annotated before & after from a real app I encountered.

Before

This is a standard enough multistage Dockerfile. Nothing seemingly terrible or great here - just a normal build stage, and a smaller runtime stage.

Tar Usage / Cheat Sheet

Compress a file or directory

e.g: tar -czvf name-of-archive.tar.gz /path/to/directory-or-file

-c: Create an archive.
-z: Compress the archive with gzip.
-v: makes tar talk a lot. Verbose output shows you all the files being archived and much.
-f: Allows you to specify the filename of the archive.

Variable

Type

PSQL

Magic words:

psql -U postgres

Some interesting flags (to see all, use -h or --help depending on your psql version):

-E: will describe the underlaying queries of the \ commands (cool for learning!)
-l: psql will list all databases and then exit (useful if the user you connect with doesn't has a default database, like at AWS RDS)

	import boto3
	import certbot.main
	import datetime
	import os
	import raven
	import subprocess

	def read_and_delete_file(path):
	with open(path, 'r') as file:
	contents = file.read()

	"""
	Copies all keys from the source Redis host to the destination Redis host.
	Useful to migrate Redis instances where commands like SLAVEOF and MIGRATE are
	restricted (e.g. on Amazon ElastiCache).

	The script scans through the keyspace of the given database number and uses
	a pipeline of DUMP and RESTORE commands to migrate the keys.

	Requires Redis 2.8.0 or higher.

	#!/bin/bash

	#
	# This script will mount /Users in the boot2docker VM using NFS (instead of the
	# default vboxsf). It's probably not a good idea to run it while there are
	# Docker containers running in boot2docker.
	#
	# Usage: sudo ./boot2docker-use-nfs.sh
	#

	#!/bin/sh

	# Fix NTP/Time
	# https://github.com/boot2docker/boot2docker/issues/290
	boot2docker ssh -- sudo killall -9 ntpd
	boot2docker ssh -- sudo ntpclient -s -h pool.ntp.org
	boot2docker ssh -- sudo ntpd -p pool.ntp.org