Authentication failed for user ubuntu@{serve ip aws or other}.

cap production deploy …

If you facing this error while deployment

Steps to solve :

1 Check ssh to server ( ssh user@ip }

2 Check the you public key added in server ssh authorized keys

3. then If login is working ssh then do ,, ssh-add solved my problem

What is interpolation in angular ?

Templates always need text or string to be dynamic at runtime. So angular given us

Interpolation technique to title, username, error messages etc

We put inside {{text }} double curly braces

Class file

userName = “Anil”


Welcome, {{userName}}

Some time we need maths expression


Real Count Wins {{ total + 56 == 200 ? “Winner”: “Loser”}}

Can’t use javascript expression

+= , new , instanceof , typeof , ;

Angular runs template expressions after every change detection cycle runs.

A Rest api is accessible by any server path that communicates to the server from any client browser in case of angular. Angular provides us http service of Http module. Service have feature to request, error handling, interceptor, Rxjs observables and operators.

We need to Inject http module in the main module.

import { NgModule } from ‘@angular/core’;

import { BrowserModule } from ‘@angular/platform-browser’;

import { HttpClientModule } from ‘@angular/common/http’;


imports: [




declarations: [



bootstrap: [ AppComponent ]


export class AppModule {}

Then make common communication service using http service

import { Injectable } from ‘@angular/core’;

import { HttpClient } from ‘@angular/common/http’;


export class ConfigService {

constructor(private http: HttpClient) { }


Then make any kind of request get , post , put, delete

GET Request

getResponse(): Observable<HttpResponse<T>> {

return this.http.get<T>(



Component is an element of the Angular app. They are the main building blocks. Each component is a type of directive. Component is made of class with Component metadata, html template, css selector and optionally css style apply to html template. Component have lifecycle hooks.

Cli command

ng g c app-component-overview

Syntax :-


selector: ‘app-component-overview’,

templateUrl: ‘./component-overview.component.html’,

styleUrls: [‘./component-overview.component.css’]


export class ComponentOverviewComponent {


Performance and optimization

  1. How to support accessibility ?
  2. How to check version of angular app?
  3. How to update old angular third party libraries?
  4. What is a lightweight injection token?
  5. Step to deploy angular app?
  6. How to configure differential loading?
  7. What is AOT ?
  8. What are the phases included in compilation ?
  9. What is…


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