After a redeploy, you'll have to delete and reindex from:
Home > Administration > Configuration > Search and metadata > Search API
Default Solr content index
Clear all indexed data followed by Index now
To resolve this, the cache directory should probably be a mounted fs rather than in-container
To update the solr config download the config.zip from Islandora, then replace islandora8/conf/ with the contents of the zip file.