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Background

Some notes on where and how you can use burry and what the design considerations were.

Use cases

UC1: Debugging

You can use burry to debug an infra service:

UC1 Debugging

A concrete example: screen dump of local ZooKeeper content.

UC2: Simple standby

You can use burry to back up and restore an on-premises infra service to/from the public cloud:

UC2 Simple standby

A concrete example: Restore Consul from Minio.

UC3: Cross-cluster failover

You can use burry to perform cross-cluster failover:

UC3 Cross-cluster failover schema

  • Let's assume the cluster in datacenter US is the primary, active one.
  • [B1] You perform regular backups of ZK to Minio running in datacenter EU
  • [R1] If ZK in datacenter US fails, you failover to datacenter EU and restore the state from Minio there.
  • [B2/R2] Same in the other direction.

Design considerations

Design goals

  • The tool must be safe to use: only non-existing nodes or keys will shall be restored, that is, no existing data in ZK or etcd will be overwritten when attempting to carry out a restore operation. This extends also to security consideration, such as leaking sensitive data or enabling protection of the data backed up.
  • The tool must be usable: simple things should be simple (sane defaults) and complex workflow must be possible to support.
  • The tool's operation must be transparent: at any point in time the actions must be deterministic and explained (logs, documentation, etc.).

Assumptions

burry assumes that the infra service it operates on is tree-like.

Backup algorithm

The essence of burry's backup algorithm is:

  • Walk the tree from the root of the infra service.
  • For every non-leaf node in infra service: create a sub-directory in the local filesystem and process its children.
  • For every leaf node in infra service, store the content (that is, the node value) in a corresponding file.
  • Depending on the storage target selected, create archive incl. metadata (possibly to remote).

Restore algorithm

The essence of burry's restore algorithm is:

  • Depending on the storage target selected, download the archive (possibly from remote).
  • Unarchive and walk the directory tree.
  • For every directory create a non-leaf node in infra service and process its children.
  • For every file create a leaf node in infra service.