I installed the s3 snapshot plugin on my ES 5.6 cluster. Those nodes are CentOS 7.4. I installed ES using yum. I needed to upgrade to v6, so I wanted to make a backup.
I installed the repository-s3. I read the documentation for it (inadvertently, I read v6's docs).
I installed the keystore (elasticsearch-keystore create) and added the s3.client.default.access_key and s3.client.default.secret_key values to it.
I know now that on 5.x, those values should have been on the .yml config, but I made that mistake by not paying attention to the docs version.
Anyway. I left that there, didn't make the backup and tried to do a rolling upgrade to 6.x.
When I restarted the node, it failed to start giving out an error reading like: "could not create /etc/elasticsearch/elasticsearch.keystore.tmp. Check permissions". I do not have the exact text for the error, but that was the gist of it.
I had to rollback to a snapshot of that VM, to get everything to the safe side and forgot to copy the error message. I panicked. Sorry.
Is there a way I can delete the keystore from that install (after removing repository-s3, of course), so I can retry the upgrade to 6?