How to resolve "No Entry" sign at Mac startup page?

Software Required

- macOS High Sierra


Problem

• Update my Mac OS (High Sierra) recently, no symptom after the OS update
• Restart my Macbook recently, encounter Macbook unable to boot up issue
• "No Entry" sign always show after the Apple logo
• The system will reboot and it will keep repeating couple of times and remain shut down afterwards

Steps

• Make sure your Mac machine is shutting down. 
• Press "Command" + "R" key
• Press the "Power" button to start the Mac machine
• "Mac OS X Utilities" window will be displayed
• Select "Reinstall Mac OS X" option, click on "Continue" button
• Follow the steps in the wizard, you will get the your Mac machine start up to work like a charm.

Note: Reinstall Mac OS X will not cause data lost.

How to resolve "Unknown version of Tomcat was specified." error message when add Tomcat server to Spring Tool Suite IDE?

Software Required

- macOS High Sierra
- Spring Tool Suite Version: 3.9.6.RELEASE

Problem

• Error message "Unknown version of Tomcat was specified." is displayed when adding new Tomcat server to Spring Tool IDE

• Obviously, Tomcat installation directory cannot be found. The Tomcat server haven't install on the machine yet

Steps

• Run command below to install Tomcat on the machine

brew install tomcat

• Run command below to find the tomcat home directory

brew ls tomcat

• Add Tomcat home directory into "Tomcat Installation directory" field, for example "/usr/local/Cellar/tomcat/9.0.13/libexec"

• Click on "Finish" button, the new Tomcat server will be added into the Spring Tool IDE instance.

How to resolve "The certificates path does not contain ca.pem" issue when NetBean connect to Docker?

Software Required
- macOS High Sierra
- NetBean IDE 8.2

- docker version 18.06.1-ce

• Try to configure Docker connection from Netbean 8.2, encounter error message "The certificates path does not contain ca.pem" as shown in the screenshot below

Steps

• Run the command below to install socat

brew install socat

• Run the command below to start a bridge instance to listen to port 9090 and connect to Docker socket.

socat tcp-listen:9090,fork UNIX:///var/run/docker.sock

• Configure the URL to point to "http://localhost:9090" and leave the "Certificates Path" field empty.

• Click on "Finish" button. Voila, all the Docker images and containers will be displayed.

How to resolve Netbean unable to create new project issue?

Software Required

- macOS High Sierra
- NetBean IDE 8.2

Problem

• Click File-> New Project menu, no response and unable to create a new project.

Steps

• Browse to Oracle website to download JDK1.8 and install the JDK1.8
• Open the terminal window, browse to 
  "/Applications/NetBeans/NetBeans 8.2.app/Contents/Resources/NetBeans/etc", edit the netbeans.conf file to point to the jdk1.8 library that located at "/Library/Java/JavaVirtualMachines/jdk1.8.0_191.jdk/Contents/Home".

  
  netbeans_jdkhome="/Library/Java/JavaVirtualMachines/jdk1.8.0_191.jdk/Contents/Home"
  
  

•  Restart NetBean and repeat the same steps to create a new project. "New Project" window is popup.

How to start Moodle on docker?

Software Required

- docker-compose version 1.22.0
- macOS High Sierra
- docker version 18.06.1-ce

Steps

• Construct the docker-compose.xml as shown below

version: '2'

services:
  mariadb:
    image: 'bitnami/mariadb:latest'
    environment:
      - MARIADB_USER=bn_moodle
      - MARIADB_DATABASE=bitnami_moodle
      - ALLOW_EMPTY_PASSWORD=yes
    volumes:
      - 'mariadb_data:/bitnami'
  moodle:
    image: 'bitnami/moodle:latest'
    environment:
      - MARIADB_HOST=mariadb
      - MARIADB_PORT_NUMBER=3306
      - MOODLE_DATABASE_USER=bn_moodle
      - MOODLE_DATABASE_NAME=bitnami_moodle
      - ALLOW_EMPTY_PASSWORD=yes
    ports:
      - '80:80'
      - '443:443'
    volumes:
      - 'moodle_data:/bitnami'
    depends_on:
      - mariadb

volumes:
  mariadb_data:
    driver: local
  moodle_data:
    driver: local

• Run command below to pull the Moodle image 

docker-compose up -d

• Browse to http://localhost

• Login as user id: user and password: bitnami, Moodle console page is displayed

How to resolve minikube hang issue after the start?

Software Required

- MiniKube version 0.30.0
- macOS High Sierra

• Install MiniKube on my Mac machine, encounter a hang issue after I triggered the command below

minukube start

• The application always stop at "Starting cluster components" 

Starting local Kubernetes v1.10.0 cluster...

Starting VM...

Getting VM IP address...

Moving files into cluster...

Setting up certs...

Connecting to cluster...

Setting up kubeconfig...

Starting cluster components...

• In order to resolve this problem, run the command below to delete the machine, it will work like a charm

minikube delete && minikube start

How to setup Facebook ChatBot (2) ?

Note: Facebook has provided a very details step by step guide. This is for my own note taking and reference

Based on the previous tutorial, we know the steps and configuration that we need to perform to create Facebook Chatbot. However, it still lack of human intelligent to interact with human being.

In order to enable the Facebook chatbot to understand your question and respond intelligently, a backend system with machine learning and natural language processing (NLP) is required. We have selected DialogFlow as the platform which powered by Google, as the platform to allow us to explore the Chatbot and AI technology.

Prerequisite
- Register an account at DialogFlow

Create the DialogFlow Agent

- Click on the dropdown menu at the left menu, select create new agent menu. Fill in the information

- Fill in the information as listed below:

• Agent Name - A name to identified the agent
• Default Language - I used English
• Default time zone - Depends on your location

- Click on "Create" button, agent will be created.  A google project will be created as well.

- Select "Small Talk" at the menu, check enable checkbox. 

- Click on "Integrations" at the left menu to launch the "Integration" listing

- Click on "Facebook Messenger", enter the token from Facebook messenger into the "Verify Token" and "Page Access Token" fields. Copy the "Callback URL" and paste it into Facebook messenger.

- Login to Facebook developer console, click on "Webhooks" at the left menu, click on "Edit Subscription" button. Paste the url from "Dialog flow" and paste into "Callback URL" field.

- Now, the Facebook messenger able to answer the simple question. Please refer to the screenshot below.