I have set up an Ethereum network an a couple of nodes using Kaleido. For each node an account is created by default. Is there a way to get the private key of that account?
The account private keys are stored in the wallet on the Go-ethereum node. JSON/RPC and web3 do not provide an API to retrieve that private key, only to perform signing using it.
Kaleido is in the process of introducing a secure backup store, which can be configured at node creation time to point at an AWS S3 storage bucket. When a node has this configured, it will be possible to backup the filesystem of the node to the S3 Bucket (which can be encrypted using standard AWS features), including the wallet and access passwords for that wallet. If you have a KMS configured on the node, those passwords will be further protected by the master key in KMS.
This secure backup facility is coming very soon (the APIs are actually already live, but it's a dark feature as the docs/UI are not published). However, this won't allow you to perform a backup of an existing node. The configurations for Backup, Log streaming and KMS needs to be set at node creation time at the moment. It is on the Kaleido roadmap to allow Backup & Log streaming to be reconfigured on an existing node, but we aren't able to commit to a timeline on that.
I hope that helps explain the situation. Regards, Peter