Issue Plesk operations with cURL fail

[Chris Dempsey]

Plesk Backup Manager is configured to store backups on Amazon S3 and successfully ran daily since the server was created around 2 weeks ago.

Environment details

Plesk Obsidian v18.0.32_build20201221.13 os_Windows 2012/2016/2019
Microsoft Windows 10.0;build-14393;sp0.0;suite272;product3

On login Plesk showed error alerts

Unable to create remote backup, the local backup will be created. Error: Unable to export backup: Transport error: Extension transport: ext://s3-backup/server/: Error executing "PutObject" on "https://mybucket.s3.us-west-2.amazonaws.com/backups/plesk/system/"; AWS HTTP error: cURL error 6: Could not resolve host: mybucket.s3.us-west-2.amazonaws.com (see http://curl.haxx.se/libcurl/c/libcurl-errors.html)

On viewing Backup Manager the following error alerts are shown

Warning: Could not display the list of backups in the Amazon S3 Backup storage: Unable to get dumps list: Transport error: Extension transport: ext://s3-backup/server: Error executing "ListObjects" on "https://mybucket.s3.us-west-2.amazonaws.com/?prefix=backups%2Fplesk%2Fsystem%2F&delimiter=%2F&encoding-type=url"; AWS HTTP error: cURL error 6: Could not resolve host: mybucket.s3.us-west-2.amazonaws.com (see http://curl.haxx.se/libcurl/c/libcurl-errors.html). Please check the storage settings.

Warning: Unable to upload a file to the storage: Error executing "CreateMultipartUpload" on "https://mybucket.s3.us-west-2.amazonaws.com/backups/plesk/system/test-0f818b6a1aa414175c58e2e07d42db8f?uploads"; AWS HTTP error: cURL error 6: Could not resolve host: mybucket.s3.us-west-2.amazonaws.com (see http://curl.haxx.se/libcurl/c/libcurl-errors.html). Make sure you have granted the permission for multipart upload of files.

I notice the host Plesk looks for is: mybucket.s3.us-west-2.amazonaws.com however my bucket is stored in eu-west-2. I am not sure this matters though as I can connect to the bucket with the Key and Secret in FileZilla without specifying the region.

Updating the Remote Storage Settings with the same Key and Secret returns error

Error: Error executing "HeadObject" on "https://ds-skye.s3.us-west-2.amazonaws.com/backups/plesk/system/"; AWS HTTP error: cURL error 6: Could not resolve host: mybucket.s3.us-west-2.amazonaws.com (see http://curl.haxx.se/libcurl/c/libcurl-errors.html)

The Plesk Dashborard Home page reports another error

Error: Failed to update the ModSecurity rule set.

To further test cURL from Plesk I updated a Let's Encrypt Certificate, this returned error

Error: Could not issue a Let's Encrypt SSL/TLS certificate for mydomain.co.uk.


    Failed to connect to the Let's Encrypt server https://acme-v02.api.letsencrypt.org.
    Please try again later or report the issue to support.
    Details
    Could not obtain directory: cURL error 6: Could not resolve host: acme-v02.api.letsencrypt.org (see https://curl.haxx.se/libcurl/c/libcurl-errors.html)

So this looks very much like Plesk cURL is broken or misconfigured.

Next I created a simple php script to test cURL. It fails to fetch content from a text file on a remote server but successfully fetches content from a local domain (the hosts file maps the domain to the local server IP).

Can anyone suggest what the cause might be or how I can investigate further?

There is a similar error linked below but this doesn't help as it's related to Plesk Linux

Issue - cURL error

In the last two weeks I have been getting the following errors AWS HTTP error: cURL error 6: Could not resolve host - Unknown error (see libcurl - Error Codes) AWS HTTP error: cURL error 52: Empty reply from server (see libcurl - Error Codes) I use the Amazon S3 Backup Extension but it...

talk.plesk.com

Thanks,

Chris

 

[Bitpalast]

It looks like your server does not resolve external domain names correctly. Have you checked that the name servers entered in /etc/resolv.conf can be reached? Have you tried to do a manual name resolution like
# dig acme-v02.api.letsencrypt.org +short
# nslookup acme-v02.api.letsencrypt.org
# ping acme-v02.api.letsencrypt.org

 

[Chris Dempsey]

It's a Windows machine so I don't have DIG but you are correct.

I can reach

https://ds-skye.s3.us-west-2.amazonaws.com/backups/plesk/system/

from my local machine in the browser but not in a browser on the server over RDP.

It seems

Windows can't communicate with the device or resource (primary DNS server)

.

I have referred this back to Engineers at the data centre, I'm unsure how to resolve myself.

Thanks Peter

 

[Chris Dempsey]

Turns out it was a network configuration error.

Unsure what caused it as the machine was stable in that sense since it was built two weeks ago until today.