ECONNREFUSED when using node with nano and couchdb - node.js

I was using nodejs + nano + couchdb for my application successfully up until today. For some reason all of a sudden I'm getting ECONNREFUSED when I try to run my application. If I try to query the database using the web browser or using a different application (java application) it works fine. I'm uncertain why just in this scenario it stopped working. I've been researching for the past 2 days and can't find any help. I believe this might have something to do with too many open connections, but that's a little bit out of my realm of knowledge. Can anyone provide me with any insight on debugging this issue or any direction I could go in? I should mention this couchdb lives on iriscouch

Add more information about stack that you're using. But basically it's server machine doesn't want to allow connecting. Also try run your app with DEBUG=*, nano will log via console.log almost everything.
E.g. change in package.json start command to node changetoyourapp.js DEBUG=*
I faced yesterday same issue with nodejitsu/iriscouch. Issue disappeared after some restarts.

Check the version of your node vs the expected node version of nano. It is possible that nano does not work with node > 16.

This is down to Node v18 now preferring an IPv6 address over and IPv4 address if two exist for the same hostname.
i.e. if your /etc/hosts contains entries like this:
127.0.0.1 localhost
::1 localhost
Node v16 will say that "localhost" resolves to 127.0.0.1 where Node v18 will say "localhost" resolves to ::1, the IPv6 equivalent. As CouchDB doesn't listen on an IPv6 port by default, then a connection to ::1 will be refused.
Solutions:
Use 127.0.0.1 instead of localhost in your URLs.
Use a domain name that resolves unambiguously to an IPv4 address e.g. 127.0.0.1 my.pretend.host in your /etc/hosts file.
Revert to Nodev16 which preferred IPv4 addresses in its dns lookup.
Make CouchDB bind to an IPv6 address by changing bind_address = ::1 in couchdb.ini. You can then do curl 'http://USER:PASS#[::1]:5984/.
See
https://github.com/apache/couchdb-nano/issues/313#issuecomment-1321760360

Related

DNS resolve timeout/delay for domains mapped to localhost in hosts file

I'm actually facing an issue which came up when using the proxy in Angular CLI.
But it's not related directly to Angular nor to node.js... it seems to have it's roots some levels deeper (namely on operating system level)
##Short version:
When I have a domain to IP mapping in my hosts file /etc/hosts and proxy it using node-http-proxy which is the underlying layer of the angular-cli proxy feature there's a delay of 5000ms before the request gets resolved and the response is provided.
Proxying is mandatory for backend communication to avoid cross origin errors in development because angular apps are served via port 4200.
##Longer version:
Operating System: OSX Catalina 10.15.4
Based on a deeper analysis it's not caused by Angular CLI and even not node.js.
It seems there's something going "wrong" with the system as I can reproduce the behavior in my terminal as well using the arp command
There's a mapping in the /etc/hosts file which looks like below:
127.0.0.1 service.company.local
When running then the command: arp service.company.local it won't resolve of course as this domain isn't known for DNS servers.
It finishes with the output: arp: service.company.local: Unknown host
Also when the computer is disconnected from internet/network (wifi of) the arp still takes 5000ms before it finishes with the Unknown host message, whereas it directly returns Unknown host for existing domains (then without delay).
The problem is pretty frustrating as it heavily slows down local development of an Angular app which is doing some cascading requests take so extremely long that a fluent work isn't possible.
Screenshot from Chrome Dev Tools:
Is there some known solution to get around this issue without moving away from the domain to ip mapping within the hosts file?
Addition (content of the hosts file)
##
# Host Database
#
# localhost is used to configure the loopback interface
# when the system is booting. Do not change this entry.
##
127.0.0.1 localhost
255.255.255.255 broadcasthost
::1 localhost
127.0.0.1 service.company.local
# Added by Docker Desktop
# To allow the same kube context to work on the host and the container:
127.0.0.1 kubernetes.docker.internal
# End of section
I'm very thankful for any hints.

MongoDB server not accessible in local Network despite binding ip

I am using MongoDB v3.6.3 on macOS, installed via home-brew. I have used almost every possible way to make my MongoDB server accessible on local network, but to no avail. I have:
Turned off firewall on both machines
Edited \etc\mongod.conf file to add bindIP.
used options-> bind_ip, bind_ip_all (127.0.0.1, 0.0.0.0, other machine's address)
As a matter of fact, also, my redis-server is not accessible on network.
I believe there is a common issue in between this.
I have tried the above mentioned solutions on macOS High Sierra, Ubuntu 16, Windows 10.
I have been facing the same error.
You could allow external access using the following parameters when starting your server:
mongod --bind_ip_all // Allow any ip
or
mongod --bind_ip <your_ip_here>
Open MongoDB config file.
Add the below command in that file(mongod.conf) and save it.
Mac config file location is : /usr/local/etc/mongod.conf
net:
bindIp: 0.0.0.0
Important Note: Once saved please restart the MongoDB services then only it will work.

Elasticsearch connecting to some random IP

Whenever I am executing curl command to query my Elasticsearch Instance, I am seeing it is trying to connect to random IP 208.73.211.70
curl -4 -u admin:root123 localhost:9200/amas/tasks/_search?pretty -v
* About to connect() to localhost port 9200 (#0)
* Trying 208.73.211.70...
I have not configured this IP anywhere in my configuration. Does anyone have idea what might be happening ?
That's something cURL is doing. If there is no Elasticsearch instance running on 208.73.211.70 it's not even reaching Elasticsearch.
Maybe you have a weird settings in hosts or some broken DNS entries?
Entry for localhost was missing in my /etc/hosts file. Because of which localhost was getting resolved to my domain address instead of 127.0.0.1. Adding localhost entry in /etc/hosts file resolved it.

Rename localhost 127.0.0.1, in LAMP stack

I am using a LAMP stack. Will there be problems if I update the /etc/host file to reflect 127.0.0.1 as somename from localhost?
Thanks!
Edit:
I sometimes work in remote sites with no network. I have the same setup on different machines and I need the server name to know dynamically where to do changes, etc.
I edited /etc/hosts to show
127.0.0.1 localhost somename
Now, with my Wifi off I am trying http://somename and it is not connecting. If I turn my wifi on, it works. But I need it to work with no connection. How can I resolve this?
No. Just add somename after localhost separated by space in /etc/hosts. You can add as many aliases as you like, as long as you don't delete localhost.

How can I find where node.js is running?

I have a VPS with node.js installed, I already uploaded a basic example to test it on the server, so I tried doing this:
I access by SSH, navigate to my project folder and run
node app.js
I get this message
Express server listening on port 8080
I thought i could see my app here
example.com:8080 or server.example:8080... but nothing. Then I tried with the info from os.networkInterfaces(); and os.host(); and still nothing happen
could you help me out? as you can see I am a total noob on node.js. What I'm doing wrong? or what should I do before running my app? Something related to DNS's? i have no idea
How do you ssh to your host? with ip or name? Is it something like:
ssh root#example.com
if so then at least you know your DNS is ok.
Once on the server do a
netstat -a
if you find *:8080 then your server is listening in the default ip. If you see something like 12.23.45.67:8080 then this number is the ip your server is listening.
ifconfig
will give you the servers ip. This should be the same as the ip of example.com. If not then maybe there is some router/firewall in front of your server and you have to configure that to allow port 8080 to reach your server.
if someone ever has the same problem this is how i solved on CentOS:
Open this file
/ Etc / csf / csf.conf
Add the required port
Allow incoming TCP ports
TCP_IN = "20,21,22,25,53,80,110,143,443,465,587,993,995,26"
Allow outgoing TCP ports
TCP_OUT = "20,21,22,25,37,43,53,80,110,113,443,587,873"
Restart
# # Csf-r

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