Per comment discussion, the OP leveraged this repository: https://github.com/jraps20/Solr-AzureAppService/tree/Sitecore
Note: This repo intentionally comes in two flavors: Solr (master branch) and Sitecore Solr (Sitecore branch).
The Sitecore branch is designed to install the necessary Solr cores for a new Sitecore installation. It was intentionally designed to work with the Azure Marketplace Sitecore Cloud resource.
After Solr is installed, the script
Deploy-SolrAzureAppService.ps1 is executed. This script is responsible for creating the Solr cores:
- Downloads requested Solr version set in one-click deployment properties to the web app root
- Copies native Solr config set (either
basic_configs based on Solr version) as
sitecore config set, to be referenced by each Sitecore Solr core config properties.
- Modifies the
conf\managed-schema of the
sitecore config set with required Sitecore updates
<field name="_uniqueid"... /> to schema
- Creates all Sitecore cores referencing
sitecore config set
- Creates xDB cores referencing native config set (
Once completed, you should see all cores in Solr. You can verify this prior to installing Sitecore from Azure.
When creating Sitecore from Azure, when it asks for the Solr URL, the format is like this:
https://myappservice.dev.azure.net/solr (i.e. the same URL you use to view the Solr instance)
The question mentions that Solr is already up and running, and while you could upload the cores via FTP or leverage the Kudu tool, it would be much quicker to remove the existing app service and then redo the installation with the same app service name. My hunch is that you used the non-Sitecore version originally and that is why no cores are present.