prologic

Learn Go in ~5mins

This is inspired by A half-hour to learn Rust and Zig in 30 minutes.

Basics

Your first Go program as a classical "Hello World" is pretty simple:

First we create a workspace for our project:

llllllllll

Comments on optimizations around string concatenation.

Note: The code links are to CPython 3.8.5, the most recent release when this was written.

I was recently asked about a performance optimization in CPython around using += and + for string objects. As some people may already know, if you use += or + a string, it can sometimes be just as fast as ''.join. The question was to explain when that optimization couldn't be performed.

We will be going through the following example scenarios:

BretFisher

Replace your Swarm Manager and Workers with updated versions of docker

• it's best to replace nodes, don't do apt/yum upgrades.
• both would work, but VM replacment forces me to think of it as immutable and prevents making pets
• if you don't want to update join scripts for manager IP's, then do something like Elastic IP's so manager IP's won't change.

Lets assume you have 3 managers and 3 workers on 17.06 and you want to update to 17.12

• managers: m1, m2, m3

barnybug

  # Docker-in-Docker Gitlab runners setup taken from:
  # https://medium.com/@tonywooster/docker-in-docker-in-gitlab-runners-220caeb708ca
  dind:
    restart: always
    privileged: true
    volumes:
    - /var/lib/docker
    image: docker:17.09.0-ce-dind
    command: 
    - --storage-driver=overlay2

cjbarker

# ########################################################## #
# Makefile for Golang Project
# Includes cross-compiling, installation, cleanup
# ########################################################## #

# Check for required command tools to build or stop immediately
EXECUTABLES = git go find pwd
K := $(foreach exec,$(EXECUTABLES),\
        $(if $(shell which $(exec)),some string,$(error "No $(exec) in PATH)))

jkullick

docker build -t $IMAGE_NAME - << EOF
FROM alpine:latest
...
EXPOSE 80
EOF

cherti

#!/bin/bash

name=$RANDOM
url='http://localhost:9093/api/v1/alerts'

echo "firing up alert $name" 

# change url o
curl -XPOST $url -d "[{ 
	\"status\": \"firing\",

timtadh

#!/usr/bin/env bash

rep() {
  i=$1
  data=$2
  ## run the replicate ....
}

# make the files
START=$(mktemp -t start-XXXX) ## signals the workers are starting

ursuad

Kafka Topics

List existing topics

bin/kafka-topics.sh --zookeeper localhost:2181 --list

Describe a topic

bin/kafka-topics.sh --zookeeper localhost:2181 --describe --topic mytopic

Purge a topic

bin/kafka-topics.sh --zookeeper localhost:2181 --alter --topic mytopic --config retention.ms=1000

... wait a minute ...

otobrglez

# Single line of Ruby <3.
ruby -rjson -ryaml -e "puts YAML.load_file('my_file.yml').to_json"

# You can also pipe it to Python to get pretty ouput
ruby -rjson -ryaml -e "puts YAML.load_file('my_file.yml').to_json" | \
  python -mjson.tool

# Thats all. :)