dgierejkiewicz

Golang — Understanding channel, buffer, blocking, deadlock and happy groutines.

I was so confused to understand behaviior of Golang channels, buffer, blocking, deadlocking and groutines.

I read Go by Example topics.

dgierejkiewicz

Updating a feature branch

First we'll update your local master branch. Go to your local project and check out the branch you want to merge into (your local master branch)

$ git checkout master

Fetch the remote, bringing the branches and their commits from the remote repository. You can use the -p, --prune option to delete any remote-tracking references that no longer exist in the remote. Commits to master will be stored in a local branch, remotes/origin/master

dgierejkiewicz

# go test -bench=.
goos: linux
goarch: amd64
pkg: tmp/eh4
BenchmarkSelect-8   	200000000	         7.65 ns/op
BenchmarkLen-8      	2000000000	         1.07 ns/op
PASS
ok  	tmp/eh4	4.580s

dgierejkiewicz

Project Title

One Paragraph of project description goes here

Getting Started

These instructions will get you a copy of the project up and running on your local machine for development and testing purposes. See deployment for notes on how to deploy the project on a live system.

Prerequisites

dgierejkiewicz

Currently, there is an explosion of tools that aim to manage secrets for automated, cloud native infrastructure management. Daniel Somerfield did some work classifying the various approaches, but (as far as I know) no one has made a recent effort to summarize the various tools.

This is an attempt to give a quick overview of what can be found out there. The list is alphabetical. There will be tools that are missing, and some of the facts might be wrong--I welcome your corrections. For the purpose, I can be reached via @maxvt on Twitter, or just leave me a comment here.

There is a companion feature matrix of various tools. Comments are welcome in the same manner.

dgierejkiewicz

Databases are a crazy topic and it seems everyone has an opinion. The trouble is that opinions are like belly buttons. Just because everyone has one it doesn’t mean they are useful for anything.

Time series databases (TSDB’s) in particular always provoke the usual “have you tried X”, where X is some obscure project with 50 commits back in 2009. Invariably, if X is something a bit more mainstream then yes, it probably has been played with. It’s probably good at certain things and bad at others like all software.

With all of the above in mind I decided to pen a magnum opus of my own opinions. Something I can point the HaveYouTriedX’ers at next time they make an appearance. So here it is..

My Top10 TSDB’s:

1. DalmatinerDB (no surprise here)
2. InfluxDB

dgierejkiewicz

-- show running queries (pre 9.2)
SELECT procpid, age(clock_timestamp(), query_start), usename, current_query 
FROM pg_stat_activity 
WHERE current_query != '<IDLE>' AND current_query NOT ILIKE '%pg_stat_activity%' 
ORDER BY query_start desc;

-- show running queries (9.2)
SELECT pid, age(clock_timestamp(), query_start), usename, query 
FROM pg_stat_activity 
WHERE query != '<IDLE>' AND query NOT ILIKE '%pg_stat_activity%' 

dgierejkiewicz

Running Docker behind the ufw firewall

Ubuntu ships with a very nice and simple frontend for iptables called ufw (uncomplicated firewall). Ufw makes it possible to setup a firewall without having to fully understand iptables itself. When you however are using Docker and you want to combine Docker with the ufw service. Things do get complicated.

The docker service talks directly to iptables for networking, basically bypassing everything that’s getting setup in the ufw utility and therefore ignoring the firewall. Additional configuration is required to prevent this behavior. The official Docker documentation however, seems to be incomplete.

Configure DEFAULT_FORWARD_POLICY and port 2375

Connections from docker containers get routed into the (iptables) FORWARD chain, this needs to be configured to allow connections through it. The default is to DROP the connections so a change is required:

dgierejkiewicz

PostgreSQL Configuration Optimization

Memory

Only four values really matter:

• shared-buffers: below 2GB: set it to 20% of full memory; below 32GB: 25% of your full memory.

dgierejkiewicz

Moved to git repository: https://github.com/denji/golang-tls

Generate private key (.key)

# Key considerations for algorithm "RSA" ≥ 2048-bit
openssl genrsa -out server.key 2048

# Key considerations for algorithm "ECDSA" ≥ secp384r1
# List ECDSA the supported curves (openssl ecparam -list_curves)