How to fix missing foreign keys and/or indexes – AWS DMS

AWS Database Migration Service (DMS) helps you migrate databases to AWS quickly and securely. The source database remains fully operational during the migration, minimizing downtime to applications that rely on the database. The AWS Database Migration Service can migrate your data to and from most widely used commercial and open-source databases.

The Database Migration Service is a data mover. It creates only the structures required to migrate your data, (this is for performance reasons mainly.) Additionally, it doesn’t migrate secondary indexes, default values, procedures, triggers, auto increment columns etc. These objects/modifications need to be made after migrating the data, (and typically prior to switching the app.)

But it can be fixed by importing schema manually.

Problem

missing foreign keys and/or indexes

Solution

To fix foreign keys & indexes missing issue, follow this

  1. Import Database schema manually to RDS.
  2. Set Target table preparation mode to Truncate

Using JSON:

dms

Using DMS GUI:

dms

Now run the task.

You will see all foreign keys and indexes in target (RDS).

How to install Ansible AWX on centos 7

Ansible Tower (formerly ‘AWX’) is a web-based solution that makes Ansible even more easy to use for IT teams of all kinds. It’s designed to be the hub for all of your automation tasks.

Tower allows you to control access to who can access what, even allowing sharing of SSH credentials without someone being able to transfer those credentials. Inventory can be graphically managed or synced with a wide variety of cloud sources. It logs all of your jobs, integrates well with LDAP, and has an amazing browsable REST API. Command line tools are available for easy integration with Jenkins as well. Provisioning callbacks provide great support for autoscaling topologies.

AWX provides a web-based user interface, REST API, and task engine built on top of Ansible. It is the upstream project for Tower, a commercial derivative of AWX.

Installation

1. Setup Requirements

yum install -y epel-release

yum remove python-docker-py
pip install cryptography
pip install jsonschema
pip install docker-compose~=1.23.0
pip install docker –upgrade

yum install -y yum-utils device-mapper-persistent-data lvm2 ansible git python-devel python-pip python-docker-py vim-enhanced

2. Install docker

Configure docker ce stable repository.

yum-config-manager --add-repo https://download.docker.com/linux/centos/docker-ce.repo

Installing docker.

yum install docker-ce -y

Start docker service.

systemctl start docker

Enable docker service.

systemctl enable docker

3. Deploy AWX

Clone AWX repo

git clone https://github.com/ansible/awx.git

Clone commercial logos

cd awx/

git clone https://github.com/ansible/awx-logos.git

Configure AWX

cd installer/

$ vim inventory

awx_official=true

Deploy AWX

ansible-playbook -i inventory install.yml -vv

Check the status

docker ps -a

AWX is ready and can be accessed from the browser.

http://ipaddress:80/

username is “admin” and the password is “password”.

 

How to setup SOCKS proxy in Linux

SOCKS server is a general purpose proxy server that establishes a TCP connection to another server on behalf of a client, then routes all the traffic back and forth between the client and the server. It works for any kind of network protocol on any port. SOCKS Version 5 adds additional support for security and UDP.

Use of SOCKS is as a circumvention tool, allowing traffic to bypass Internet filtering to access content otherwise blocked, e.g., by governments, workplaces, schools, and country-specific web services

Using SSH

SOCKS proxies can be created without any special SOCKS proxy software if you have Open SSH installed on your server and an SSH client with dynamic tunnelling support installed on your client computer.

Now, enter your password and make sure to leave the Terminal window open. You have now created a SOCKS proxy at localhost:1080. Only close this window if you wish to disable your local SOCKS proxy.

Using Microsocks program

MicroSocks is a multithreaded, small, efficient SOCKS5 server.

It’s very lightweight, and very light on resources too:

for every client, a thread with a stack size of 8KB is spawned. the main process basically doesn’t consume any resources at all.

the only limits are the amount of file descriptors and the RAM.

It’s also designed to be robust: it handles resource exhaustion gracefully by simply denying new connections, instead of calling abort() as most other programs do these days.

another plus is ease-of-use: no config file necessary, everything can be done from the command line and doesn’t even need any parameters for quick setup.

Installing microsocks

git clone git@github.com:rofl0r/microsocks.git

cd microsocks

make

Starting socks service

all arguments are optional. by default listenip is 0.0.0.0 and port 1080.

option -1 activates auth_once mode: once a specific ip address authed successfully with user/pass, it is added to a whitelist and may use the proxy without auth. this is handy for programs like firefox that don’t support user/pass auth. for it to work you’d basically make one connection with another program that supports it, and then you can use firefox too.

How to protect files from overwriting with noclobber in bash

This tip is for people who have ever hosed important files by using > when they meant to use >>. Add the following line to .bashrc:

set -o noclobber

The noclobber option prevents you from overwriting existing files with the > operator.

If the redirection operator is ‘>’, and the noclobber option to the set builtin has been enabled, the redirection will fail if the file whose name results from the expansion of word exists and is a regular file. If the redirection operator is ‘>|’, or the redirection operator is ‘>’ and the noclobber option is not enabled, the redirection is attempted even if the file named by word exists.

Example:

 

Run:

noclobber

 

Manhole service in Twisted Application.

What is Manhole?

Manhole is an in-process service, that will accept UNIX domain socket connections and present the stack traces for all threads and an interactive prompt.

Using it we can access and modify objects or definition in the running application, like change or add the method in any class, change the definition of any method of class or module.

This allows us to make modifications in running an application without restarting the application, it makes work easy like debugging the application, you are able to check the values of the object while the program is running.

How to configure it?

Once you run above snippet, the service will start on TCP port 2222.

You need to use SSH command to get login into the service.

See below how it looks like.

Here In the first login, we change the value in DATA dictionary in running application, as we can see we get the new value in the second login.

Simple port scanner in python

a port scanner is an application designed to probe a server or host for open ports. Such an application may be used by administrators to verify the security policies of their networks and by attackers to identify network services running on a host and exploit vulnerabilities.

port-scanner.py

Example

port-scannin

Howto use ssh as VPN tunnel

SSH is typically used to log into a remote machine and execute commands, but it also supports tunneling, forwarding TCP ports and X11 connections.

What is SSH Tunneling?

A tunneling protocol may, for example, allow a foreign protocol to run over a network that does not support that particular protocol, such as running IPv6 over IPv4.

SSH tunneling is a method of transporting arbitrary networking data over an encrypted SSH connection. It can be used to add encryption to legacy applications. … It also provides a way to secure the data traffic of any given application using port forwarding, basically tunneling any TCP/IP port over SSH.

sshuttle

sshuttle is not exactly a VPN, and not exactly port forwarding. It’s kind of both, and kind of neither.

It’s like a VPN, since it can forward every port on an entire network, not just ports you specify. Conveniently, it lets you use the “real” IP addresses of each host rather than faking port numbers on localhost.

On the other hand, the way it works is more like ssh port forwarding than a VPN. Normally, a VPN forwards your data one packet at a time, and doesn’t care about individual connections; ie. it’s “stateless” with respect to the traffic. sshuttle is the opposite of stateless; it tracks every single connection.

Installation

 sudo pip install sshuttle

Example

$ sshuttle --dns -v -r <remote-host> 0/0

ssh-tunnel

* This will forward all connections including DNS requests…

Usage

Working with Spinner in Android (Single Selector)

Spinner

Spinners provide a quick way to select one value from a set then we called it a single selector. A spinner shows its currently selected value from set. In the default state, it shows 0 index value from a set. Touching the spinner displays a dropdown menu or dialog with all other available values in the set, So we can be called it a dropdown.

Dropdown

 

 

 

 

 

 

Let’s check, how we can use it in an application.

Spinner integration has 3 key classes:-

1.  Spinner

2. Spinner Adapter

3. Spinner OnItemSelectedListener

So we will discuss above these classes also, with integration. You can add a spinner to your layout XML file. You can use the below sample code –

Spinner Adapter uses for bind between data set and spinner widget and it manages view for the spinner row item. We can use data as an array of string. See sample code –

Above string array, we will use for the display. So now we need to get reference Spinner which we defined in the XML file. We can use the below sample code –

So now we need to set values in ArrayAdapter. and We set this ArrayAdapter in Spinner. Use below code –

When the user selects an item from the drop-down, the Spinner object receives an on-item-selected event. for manage event, we can use OnItemSelectedListener in the Spinner. Sample code –

onItemSelected gives us a selected position of the spinner.

That’s it. Happy Coding 🙂

Reference:-

https://developer.android.com/guide/topics/ui/controls/spinner#java

Migrate an Existing Project to AndroidX

AndroidX is an open-source project by Google that provides a major improvement to the original Android Support Library. AndroidX is replaced the Support Library. Like support library, Google keeps AndroidX is independently from the Android OS and provides backward-compatibility across Android releases. AndroidX package structure is to encourage smaller and more focused libraries.

AndroidX replaces the original support library APIs with packages in the androidx namespace. Only the package and import names changed. Class, method, and field names did not change in migration.

Example:-

android.support.v7.widget.RecyclerView is changed to androidx.recyclerview.widget.RecyclerView

android.support.v7 is replced by androidx.

Migrating existing project:-

Before start migration, we need to make sure to follow the below things:-

1.  Android studio version should be higher than 3.2, You can check your android studio version from About Android Studio section. also use the latest Gradle version. Check project level Build.Gradle file to change the version.

2. Target SDK version and Compile SDK version should be 28 or greater. Check your app level Build.Gradle file to change target and compile SDK version.

3. Take a backup of your project. 

4. Add below properties to gradle.properties file. You can find this file on Project Level.

A.) android.useAndroidX: set to true, the Android plugin uses the AndroidX library instead of a Support Library. The value is false by default.

B.) android.enableJetifier: set to true, the Android plugin automatically migrates existing third-party libraries to use AndroidX. The value is false by default.

Let’s start migration:-

1.  Click Refactor from the menu in Android studio.

2. Then Click on Migrate to AndroidX from Refactor dropdown.

3. After that, It will ask you to take a backup of the whole project. If you have already taken the backup then ignore this step.

4. After the backup process clicks on Migrate, It will show list all support library where we are using in this project. Just click on Do Refactor and wait for some time.

5. After some time, you can see the project all support library replaced by the AndroidX library. Most of the support library will merge automatically and few we need to replaced manually. If you found any error,  Fix it manually. and test your app carefully. The application could crash due to incorrect auto-correction during migration.

That’s it. Enjoy Coding using AndroidX. 🙂

Reference:-

https://developer.android.com/jetpack/androidx/migrate

Shell script wrapper function for sending messages through Pushover

Pushover makes it easy to get real-time notifications on your Android, iPhone, iPad, and Desktop (Android Wear and Apple Watch, too!)

You can use this shell function anywhere in your script.

Example:

Note: you need to update API tokens and title above