bigmeech

Git Submodules basic explanation

Why submodules?

In Git you can add a submodule to a repository. This is basically a repository embedded in your main repository. This can be very useful. A couple of advantages of using submodules:

• You can separate the code into different repositories.

bigmeech

sudo certbot renew --dry-run

bigmeech

HTTP Streaming (or Chunked vs Store & Forward)

The standard way of understanding the HTTP protocol is via the request reply pattern. Each HTTP transaction consists of a finitely bounded HTTP request and a finitely bounded HTTP response.

However it's also possible for both parts of an HTTP 1.1 transaction to stream their possibly infinitely bounded data. The advantages is that the sender can send data that is beyond the sender's memory limit, and the receiver can act on

bigmeech

Docker - How to cleanup (unused) resources

Once in a while, you may need to cleanup resources (containers, volumes, images, networks) ...

delete volumes

// see: https://github.com/chadoe/docker-cleanup-volumes

$ docker volume rm $(docker volume ls -qf dangling=true)

$ docker volume ls -qf dangling=true | xargs -r docker volume rm

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# This is how you add a Jenkins slave

# On master:

  sudo -u jenkins -H ssh-keygen

# On slave

  adduser --system --group --home=/var/lib/jenkins-slave --no-create-home --disabled-password --quiet --shell /bin/bash jenkins-slave
  install -d -o jenkins-slave -g jenkins-slave /var/lib/jenkins-slave

bigmeech

Not all random values are created equal - for security-related code, you need a specific kind of random value.

A summary of this article, if you don't want to read the entire thing:

• Don't use Math.random(). There are extremely few cases where Math.random() is the right answer. Don't use it, unless you've read this entire article, and determined that it's necessary for your case.
• Don't use crypto.getRandomBytes directly. While it's a CSPRNG, it's easy to bias the result when 'transforming' it, such that the output becomes more predictable.
• If you want to generate random tokens or API keys: Use uuid, specifically the uuid.v4() method. Avoid node-uuid - it's not the same package, and doesn't produce reliably secure random values.
• If you want to generate random numbers in a range: Use random-number-csprng.

You should seriously consider reading the entire article, though - it's

bigmeech

import * as mongoose from 'mongoose';

export let Schema = mongoose.Schema;
export let ObjectId = mongoose.Schema.Types.ObjectId;
export let Mixed = mongoose.Schema.Types.Mixed;

export interface IHeroModel extends mongoose.Document {
  name: string;
  power: string;

bigmeech

App configuration in environment variables: for and against

For (some of these as per the 12 factor principles) 

1) they are are easy to change between deploys without changing any code

2) unlike config files, there is little chance of them being checked
into the code repo accidentally

3) unlike custom config files, or other config mechanisms such as Java

bigmeech

# install java
apt-get install -y software-properties-common
apt-add-repository -y ppa:webupd8team/java
apt-get update
apt-get install -y oracle-java8-installer

# download latest android sdk
# http://developer.android.com/sdk/index.html#Other
cd /opt
wget http://dl.google.com/android/android-sdk_r24.4.1-linux.tgz

bigmeech

Virtual Hosts on nginx (CSC309)

When hosting our web applications, we often have one public IP address (i.e., an IP address visible to the outside world) using which we want to host multiple web apps. For example, one may wants to host three different web apps respectively for example1.com, example2.com, and example1.com/images on the same machine using a single IP address.

How can we do that? Well, the good news is Internet browsers