Express app not accessible sometimes only for some users - mysql

The app is not accessible sometimes but only for some users. In the same LAN also, some users can access but some cannot.
The web app was designed with following technologies
Node
Angular
Express
MySql.
It's hosted in AWS EC2, MySql is also installed on the same EC2 instance.
I have no idea how this is happening. The server was running all the time.

This eror is not related your application - it's just that domain can not be resolved. You should check your DNS setting on server and on clients. See also instruction here, for example.

Related

Deploy my Flask app to Heroku using my own MySQL server

I have a project with a Flask backend and Vue frontend. I want to deploy it to Heroku but using my own MySQL database from my own MySQL server, without using Heroku's dynos.
Is this possible?
That depends what you mean by
my own MySQL database from my own MySQL server, without using Heroku's dynos
If your MySQL server is accessible from the Internet, sure. Just point your application at it.
(Note that using one of Heroku's database addons does not mean using dynos. These services run as hosted services on the cloud, not on your dynos. JawsDB and ClearDB are both options and both have free tiers.)
If you're talking about something running inside a firewall, e.g. on your laptop, then this won't be possible without doing a bunch of network stuff. It's possible but I strongly urge you not to do this. It's easy to create security issues.

Express/NodeJS application on Cpanel

Ok so I have an app with a Node/Express API and everything works fine on localhost. I'm trying to figure out how to make everything work on CPanel that's running on Apache. The client side stuff but I am unable to fetch any data from the backed. I've searched and looked, yes, but I'm still quite unsure on how to approach this. Do I have to use a Virtual Host and if so what are the specific steps I need to do?
NodeJS doesn't run on Apache or Nginx. Most you can do in these web servers is to set a reverse proxy.
NodeJS has its own web-server. cPanel won't help you in that regard, since you only need to install NodeJS on your server (you must have SSH access-root), and run it from there. You can daemonize your Node process to keep running installing PM2 or Forever (NPM Packages).
Here's a good answer (search before asking, the issue might be solved by then).
Run node.js on cpanel hosting server
cPanel typically runs Apache or another web server that is shared among all the cPanel/unix accounts. The web server listens on port 80. Depending on the domain name in the requested URL, the web server uses "Virtual Hosting" to figure out which cPanel/unix account should process the request, i.e. in which home directory to find the files to serve and scripts to run. If the URL only contains an IP address, cPanel has to default to one of cPanel accounts.
Ordinarily, without root access, a job run by a cPanel account cannot listen on port 80. Indeed, the available ports might be quite restrictive. If 8080 doesn't work, you might try 60000. To access a running node.js server, you'll need to have the port number it's listening on. Since that is the only job listening on that port on that server, you should be able to point your browser to the domain name of any of the cPanel accounts or even the IP address of the server, adding the port number to the URL. But, it's typical to use the domain name for the cPanel account running the node.js job, e.g. http://cPanelDomainName.com:60000/ .
Of course port 80 is the default for web services, and relatively few users are familiar with optional port numbers in URLs. To make things easier for users, you can use Apache to "reverse proxy" requests on port 80 to the port that the node.js process is listening on. This can be done using Apache's RewriteRule directive in a configuration or .htaccess file. This reverse proxying of requests arguably has other benefits as well, e.g. Apache may be a more secure, reliable and manageable front-end for facing the public Internet.
Unfortunately, this setup for node.js is not endorsed by all web hosting companies. One hosting company that supports it, even on its inexpensive shared hosting offerings, is A2Hosting.com. They also have a clearly written description of the setup process in their Knowledge Base.
Finally, it's worth noting that the developers of cPanel are working on built-in node.js support. "If all of the stars align we might see this land as soon as version 68," i.e. perhaps early 2018.
References
Apache Virtual Hosting -
http://httpd.apache.org/docs/2.4/vhosts/
Apache RewriteRule Directive - http://httpd.apache.org/docs/2.4/mod/mod_rewrite.html
A2Hosting.com Knowledge Base Article on Configuring Node.js - https://www.a2hosting.com/kb/installable-applications/manual-installations/installing-node-js-on-managed-hosting-accounts
cPanel Feature Request Thread for node.js Support - https://features.cpanel.net/topic/nodejs-hosting
Related StackOverflow Questions
How to host a Node.Js application in shared hosting
Why node.js can't run on shared hosting?
Is worth to point out that the NodeJS support hasn't yet come to cPanel (as early 2019)

Implementing SSL in Java Based Web Applications

I have a java based web application developed in Amazon EC2. It is doing transactions of confidential information. I have a MySQL server installed all by my self in the same amazon instance. The web application access the database via localhost. In Security Groups, I have created a custom security where the port 8080 (the Tomcat) can be accessed only via localhost.
Considering these, do I still need SSL to make sure the transactions are secured?
It depends. Are you comfortable with plain text inside the datacenter? Don't bother with SSL.
Are you worried about that traffic being sniffed locally (tcpdump) or from a malicious source (for instance, if data was being rerouted from the switch between EC2 instances)? Use SSL.
There's a trend of large companies making sure to encrypt local traffic.

Connect localhost Codeigniter app to remote database on Dreamhost

I have a number of apps running on Dreamhost and am creating a small app I will use locally to present reports on information stored in various databases. I do not want to host this reporting tool online so I need the app to connect to the remote MySQL server from my machine.
Codeigniter has been giving me an error all afternoon that it can't connect to the remote server, I'm guessing this is down to Dreamhosts security on remote access. I don't have a dedicated IP address so it's not ideal to set on the user account to allow external access. I've tried exploring an IP tracking solution such as No-IP, however I'm not sure if I've configured it properly, or if it'll even the service is capable of allowing my app to access the remote MySQL server when ever it needs.
Does anyone know how to get these working correctly, or am I on the right track??

Database application and remote MySql

I would like to create a desktop application that should work with data on a mySql server running on a remote machine.
So each user has a copy of the desktop app and edits data on the remote mySql server.
Now my problem is that the mySql server will not allow connections from other hosts.
Question, is this just the wrong way of creating the app. If not how do I give any host access to the MYsql server.
(I know I can open up for a specific IP but that won't work as the app could be running anywhere)
You should front your database on the server with a thin service layer, where you could do some validation / processing on the data, perform authentication, etc. Your client apps would then expose those methods in your service layer as web services, to which your client apps would communicate using either SOAP/XML, REST/JSON, etc. In general, it is a bad idea to expose your database directly if your application is within a LAN, and a terrible one to expose it on the internet.