The Docker image exposes four volumes in total, where cache, logs, plugins and persistent data are stored:
Resides under /data/storage and is used to store persistent data, such as Data Policies. For this data to survive between Docker runs and/or Lenses upgrades, the volume must be managed externally (persistent volume).
Resides under /data/plugins it’s where classes that extend Lenses may be added —such as custom serde, LDAP filters, UDFs for the Lenses SQL table engine and custom_http implementations. Learn more about plugins.
Resides under /data/logs, logs are stored here. The application also logs to stdout, so for most cases, the log files aren’t needed. Learn more about logs.
Resides under /data/kafka-streams-state, used when Lenses SQL is in IN_PROC configuration. In such a case, Lenses takes advantage of this scratch directory to cache Lenses SQL internal state. Whilst this directory can safely be removed, it can be beneficial to keep it around, so the Processors won’t have to rebuild their state during a restart.