IoC : Ulises Fasoli's blog: 2018

docker compose on multiple environments

docker-compose is a pretty cool tool that allows you to bootstrap and run multiple docker containers with 1 configuration file

Below is an example docker-compose file for staring a 3 node confluent kafka cluster

---
version: '2'
services:
  zookeeper:
    image: confluentinc/cp-zookeeper:latest
    network_mode: host
    environment:
      ZOOKEEPER_CLIENT_PORT: 32181
      ZOOKEEPER_TICK_TIME: 2000
    extra_hosts:
      - "moby:127.0.0.1"
    restart: always

  kafka-1:
    image: confluentinc/cp-kafka:latest
    network_mode: host
    depends_on:
      - zookeeper
    environment:
      KAFKA_BROKER_ID: 1
      KAFKA_ZOOKEEPER_CONNECT: localhost:32181
      KAFKA_ADVERTISED_LISTENERS: PLAINTEXT://myserver.com:29092
    restart: always
    extra_hosts:
      - "moby:127.0.0.1"

  kafka-2:
      image: confluentinc/cp-kafka:latest
      network_mode: host
      depends_on:
        - zookeeper
      environment:
        KAFKA_BROKER_ID: 2
        KAFKA_ZOOKEEPER_CONNECT: localhost:32181
        KAFKA_ADVERTISED_LISTENERS: PLAINTEXT://myserver.com:29093
      restart: always
      extra_hosts:
        - "moby:127.0.0.1"

  kafka-3:
        image: confluentinc/cp-kafka:latest
        network_mode: host
        depends_on:
          - zookeeper
        environment:
          KAFKA_BROKER_ID: 3
          KAFKA_ZOOKEEPER_CONNECT: localhost:32181
          KAFKA_ADVERTISED_LISTENERS: PLAINTEXT://myserver.com:29094
        restart: always
        extra_hosts:
          - "moby:127.0.0.1"

  kafka-rest:
    image: confluentinc/cp-kafka-rest:latest
    network_mode: host
    depends_on:
      - kafka-1
      - kafka-2
      - kafka-3
    restart: always
    environment:
      KAFKA_REST_ZOOKEEPER_CONNECT: localhost:32181
      KAFKA_REST_LISTENERS: http://0.0.0.0:8082
      KAFKA_REST_HOST_NAME: kafka-rest
    extra_hosts:
      - "moby:127.0.0.1"

---
version: '2'
services:
  zookeeper:
    image: confluentinc/cp-zookeeper:latest
    network_mode: host
    environment:
      ZOOKEEPER_CLIENT_PORT: 32181
      ZOOKEEPER_TICK_TIME: 2000
    extra_hosts:
      - "moby:127.0.0.1"
    restart: always

  kafka-1:
    image: confluentinc/cp-kafka:latest
    network_mode: host
    depends_on:
      - zookeeper
    environment:
      KAFKA_BROKER_ID: 1
      KAFKA_ZOOKEEPER_CONNECT: localhost:32181
      KAFKA_ADVERTISED_LISTENERS: PLAINTEXT://test.myserver.com:29092
    restart: always
    extra_hosts:
      - "moby:127.0.0.1"

  kafka-2:
      image: confluentinc/cp-kafka:latest
      network_mode: host
      depends_on:
        - zookeeper
      environment:
        KAFKA_BROKER_ID: 2
        KAFKA_ZOOKEEPER_CONNECT: localhost:32181
        KAFKA_ADVERTISED_LISTENERS: PLAINTEXT://test.myserver.com:29093
      restart: always
      extra_hosts:
        - "moby:127.0.0.1"

  kafka-3:
        image: confluentinc/cp-kafka:latest
        network_mode: host
        depends_on:
          - zookeeper
        environment:
          KAFKA_BROKER_ID: 3
          KAFKA_ZOOKEEPER_CONNECT: localhost:32181
          KAFKA_ADVERTISED_LISTENERS: PLAINTEXT://test.myserver.com:29094
        restart: always
        extra_hosts:
          - "moby:127.0.0.1"

  kafka-rest:
    image: confluentinc/cp-kafka-rest:latest
    network_mode: host
    depends_on:
      - kafka-1
      - kafka-2
      - kafka-3
    restart: always
    environment:
      KAFKA_REST_ZOOKEEPER_CONNECT: localhost:32181
      KAFKA_REST_LISTENERS: http://0.0.0.0:8082
      KAFKA_REST_HOST_NAME: kafka-rest
    extra_hosts:
      - "moby:127.0.0.1"

You can now run docker-compose by with a second -f and the redefined properties in the test file will ovewrite those in the base file

docker-compose -f docker-compose.yml -f docker-compose.test.yml up -d

More information regarding docker compose advanced configuration can be found here

Angular6 hiding component selector

It's sometimes useful to have angular's component selector not to be rendered in the page, as sometimes this can cause problems with CSS rendering (since we will have an intermediate tag in between 2 tags)

For example :


@Component({
    selector: 'my-component'
})
export class MyComponent{

@Input()
title:String;


}
...

Now you will use your component for example like so :


<html>
.....

<div class='container'>
<my-component [title]="'Test'" ></my-component>

</div>
.....

</html>

With this approach in the rendered HTML you will have the angular component tab generated inside the div but what if this causes problems with some CSS code ?

Well luckily enough there's a simple way to change this and that is changer your selector from a tag to an attribute


@Component({
    selector: '[my-component]'
})
export class MyComponent{

@Input()
title:String;


}
...

By changing the value of the selector property from my-component to [my-component] you should be able to "apply" your component directly to a standard HTML tag, so this will prevent the <my-component> tag to be rendered in the final HTML


<html>
.....
<div class='container' [title]="'Test'" my-component >


</div>
.....

</html>

OSX paste unformatted text / remove text formatting

So recently I found about what is for me one of the best keyboard shortcuts on OSX often I copy text from somewhere and whenever I paste it it comes with all the original formatting, which TBH mostly of the time is a pain (at least for me) even though a lot of applications have a "paste special" or something like that is a bit cumbersome to me

So the following keyboard shortcut allows you to paste unformatted text in almost any application :

This for me is a great productivity shortcut and one of the best ones I found for OSX

Angular 4/5 override class in body tag (Shadow Piercing combinators approach)

In angular component CSS styles are encapsulated into the component's view and don't affect the rest of the application; usually this is the behaviour that you want however sometimes it's useful to be able to affect tags outside the component, for example the body tag

This can be achieved in a few different ways, like for example tweaking view encapsulation parameters

In this post I will show you a CSS approach to this using The Shadow Piercing combinators, starting in Angular 4.3.0 you can use the custom shadow piercing combinator ::ng-deep to achieve this

For example if we had a component named "CustomComponent" we could have a set of files similar to :

custom.component.ts
custom.component.css
custom.component.html

In order for us to shadow and override the main body tag would be to put the following in the custom.component.css :

::ng-deep body {
  min-height: 75rem;
  padding-top: 4.5rem;
}

BigDecimal rounding to the nearest 5 cents with Java's BigDecimal

Recently I hat to implement a function that would round to the nearest 5 cents and after googling around a bit I found bits and pieces here and there but none just worked for me, so below you can find a function that should do just that

/**
     * Rounds a decimal number to the nearest 5 cents using the following rules
     * 
     * Rounding rules :
     * - 0.1299 = 0.10
     * - 0.1300 = 0.15
     * - 0.1799 = 0.15
     * - 0.1800 = 0.20
     *
     * @param value the BigDecimal value to round
     * @return the rounded value for the big decimal with a scale of 2
     */
    public static BigDecimal roundToNearest5Cents(final BigDecimal value) {
        return value.setScale(2, RoundingMode.FLOOR).multiply(new BigDecimal(20)).add(new BigDecimal("0.5"))
                .setScale(0, RoundingMode.FLOOR).divide(new BigDecimal(20)).setScale(2, RoundingMode.FLOOR);
    }