502 Bad Gateway nginx, or 503 Backend fetch failed with varnish about magento-2-server-installation HOT 8 CLOSED

Remove .probe at varnish default.vcl

from magento-2-server-installation.

I'm experiencing the same issue as @karamucho - including certbot installation failure.

I've removed .probe from varnish default.vcl and restarted varnish - however this did not resolve the issue.

from magento-2-server-installation.

I'm experiencing the same issue as @karamucho - including certbot installation failure.

I've removed .probe from varnish default.vcl and restarted varnish - however this did not resolve the issue.

Almost certain that magento is trying to reach https version of the site, but since certbot failed you will have to modify nginx configuration file and listen 443 is commented.

There are several solutions: you can create a self signed certificate and modify nginx conf, or pass varnish or disable varnish proxy (in this case you must garantee that magento will allow http without redirecting to https).

A bit tricky in fact if something goes wrong.

from magento-2-server-installation.

Removing .probe from varnish default.vcl before installing letsencrypt allowed the certificate to be installed, but despite the fact that the installation passed flawlessly https does not work and http causes a redirect loop on every browser, the problem must be somewhere between ssl, nginx and varnish, but where to look for it ?

from magento-2-server-installation.

In my version, i always generate a self signed ssl and uncomment the port 443 and attach the crt and key to nginx config.
That way will always work because https will be available. After that you run certbot.
In my opinion is the most reliable way. Never fails

from magento-2-server-installation.

for now this part is a bit confusing,
so probably better:

• comment varnish probe
• get cert with webroot
• enable ssl in nginx
• reload nginx

from magento-2-server-installation.

Hello this is normal to Magento 2

You need to update the /etc/varnish/default.vlc
Note this is for magento 2 lastest 2.3.5.p1
for magento 2.3.1 ---> 2.3.3 you need to update file /pub/health_check.php (Please Just Google it as I forgot already the link) and also update the default.vlc

backend default {
.host = "localhost";
.port = "8080";
.first_byte_timeout = 600s;
.probe = {
.url = "/health_check.php";
.timeout = 2s;
.interval = 5s;
.window = 10;
.threshold = 5;
}
}

and your site is working

BTW

on nginx.conf
you need to have event{} just add this and restart your nginx to be able to start Nginx service

from magento-2-server-installation.

After about 10times installing a server with this script. For me worked now.

Give the machine a hostname before installation
hostnamectl set-hostname server.yourdomain.com --static

Disable selinux

Check if DNS / Connection are working (after that my DNS Servers was not working anymore)
ping google.com , Set new DNS Server with nmtui / cmcli (ex. 1.1.1.1 , 1.0.0.1)

There is also a little bug in the code, change the line before installation
from
redis-cli -p6380 flushall
to
redis-cli -p 6380 flushall

If lets encrypt error in installation , create a new certificate and run certbot again.
certbot-auto

Restart Services:
systemctl restart nginx varnish

Clear Magento Cache
php bin/magento cache:clean

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