ajayk

If you're coming to this page in search of jq related AWS commands, but come from xpath or e4x (jsonpath) domains, then you may find this article helpful: https://github.com/stedolan/jq/wiki/For-JSONPath-users.

Another good learning site: https://shapeshed.com/jq-json/

The jq playground (live testing): https://jqplay.org

A lovely tutorial: https://programminghistorian.org/lessons/json-and-jq

Using aws-cli and jq

ajayk

Ansible playbook to setup HTTPS using Let's encrypt on nginx.

The Ansible playbook installs everything needed to serve static files from a nginx server over HTTPS.
The server pass A rating on [SSL Labs](https://www.ssllabs.com/).

To use:
 1. Install [Ansible](https://www.ansible.com/)
 2. Setup an Ubuntu 16.04 server accessible over ssh
 3. Create `/etc/ansible/hosts` according to template below and change example.com to your domain
 4. Copy the rest of the files to an empty directory (`playbook.yml` in the root of that folder and the rest in the `templates` subfolder)

ajayk

I've been playing with jq, and I've been having a hard time finding examples of how it works with output from a service like AWS (which I use a lot).

Here is one I use a lot with vagrant-ec2.

When we're launching and killing a lot of instances, the AWS API is the only way to track down which instances are live, ready, dead, etc.

To find instances that are tagged with e.g. {"Key" = "Name", "Value" = "Web-00'} in the middle of a vagrant dev cycle, or a prod launch/replace cycle, you can do something like this:

ajayk

I came across HikariCP and I was amazed by the benchmarks and I wanted to try it instead of my default choice C3P0 and to my surprise I struggled to get the configurations right probably because the configurations differ based on what combination of tech stack you are using.

I have setup Spring Boot project with JPA, Web, Security starters (Using [Spring Initializer][1]) to use PostgreSQL as a database with HikariCP as connection pooling.
I have used Gradle as build tool and I would like to share what worked for me for the following assumptions:

1. Spring Boot Starter JPA (Web & Security - optional)
2. Gradle build tool
3. PostgreSQL running and setup with a database (i.e. schema, user, db)

This gist is related to SO post https://stackoverflow.com/questions/26490967/how-do-i-configure-hikaricp-in-my-spring-boot-app-in-my-application-properties-f

ajayk

$  echo "secret" > secret.txt
$  key_material=$(aws kms generate-data-key --key-id <CMK_key_id> --key-spec AES_256)
$  echo ${key_material} | jq ".CiphertextBlob" | sed 's/"//g' | base64 -d > key.enc
$  export key=$(echo ${key_material} | jq ".Plaintext" | sed 's/"//g' | base64 -d)
$  openssl enc -aes-256-cbc -pass env:key -in secret.txt -out secret.txt.enc
$  rm secret.txt
$  ls
key.enc secret.txt.enc
$  key=$(aws-fd-full kms decrypt --ciphertext-blob fileb://key.enc --output text --query Plaintext  | base64 -d)
$  openssl enc -d -aes-256-cbc -pass env:key -in secret.txt.enc -out secret.txt

ajayk

# By default, Docker containers run as the root user. This is bad because:
#   1) You're more likely to modify up settings that you shouldn't be
#   2) If an attacker gets access to your container - well, that's bad if they're root.
# Here's how you can run change a Docker container to run as a non-root user

## CREATE APP USER ##

# Create the home directory for the new app user.
RUN mkdir -p /home/app

ajayk

What I Know About PKI

Abstract Syntax Notation One (ASN.1)

Much of the data in the PKI world is stored in ASN.1 so a basic understanding is necessary. ASN.1 is a way to describe data by starting from primitive types and building up to more complex types. Do you remember Backus-Naur Form? What about writing XML schemas in XSD? It's the same concept.

Let's say we have a Widget. Every Widget has a model name, a serial number, and some inspection information with the name of the inspector and the dates of the inspections. Our Widget then looks like this in ASN.1:

Widget ::= SEQUENCE {
    model IA5String, 

serialNumber INTEGER,

ajayk

The introduction to Reactive Programming you've been missing

(by @andrestaltz)

---

This tutorial as a series of videos

If you prefer to watch video tutorials with live-coding, then check out this series I recorded with the same contents as in this article: Egghead.io - Introduction to Reactive Programming.

---

ajayk

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <dependencies>
        <!-- https://mvnrepository.com/artifact/org.kohsuke.stapler/json-lib -->
        <dependency>
            <groupId>org.kohsuke.stapler</groupId>
            <artifactId>json-lib</artifactId>

ajayk

Classification

Regression and Classification works on labeled data Clustering

Regression real value quantity ( housing prices)

Yes/No -> Classification