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 libcurl - Error Codes)

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.amazo...s/plesk/system/&delimiter=/&encoding-type=url"; AWS HTTP error: cURL error 6: Could not resolve host: mybucket.s3.us-west-2.amazonaws.com (see libcurl - Error Codes). Please check the storage settings.

Warning: Unable to upload a file to the storage: Error executing "CreateMultipartUpload" on "https://mybucket.s3.us-west-2.amazo...test-0f818b6a1aa414175c58e2e07d42db8f?uploads"; AWS HTTP error: cURL error 6: Could not resolve host: mybucket.s3.us-west-2.amazonaws.com (see libcurl - Error Codes). 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 libcurl - Error Codes)

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 Boulder: The Let's Encrypt CA.
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 libcurl - Error Codes)

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).

I tried repairing the cURL certificates with

"%plesk_cli%\repair" --update-php-curl-certificates

but this returned error

Error in cURL request: Could not resolve host: curl.haxx.se

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

 

[Nik G]

hello @Chris Dempsey ,

I suppose you have checked this first, but.. are you sure that your server uses DNS settings that allow to resolve remote hosts?
if you run something like

nslookup mybucket.s3.us-west-2.amazonaws.com

will it work ?
If you update your server recently it is recommended to reboot it (unfortunately in most cases reboot still useful at windows platform).

did you try to update to the latest 18.0.35.1 ?
in the 18.0.33 there was libcurl security update. so this also can be a reason.

In general I'd recommend you update your system to the latest available Obsidian and
submit request to the Plesk Technical Support for more deep investigation if this did not help.