Cloud-init’s directory structure is somewhat different from a regular application:
/var/lib/cloud/ - data/ - instance-id - previous-instance-id - datasource - previous-datasource - previous-hostname - handlers/ - instance - instances/ i-00000XYZ/ - boot-finished - cloud-config.txt - datasource - handlers/ - obj.pkl - scripts/ - sem/ - user-data.txt - user-data.txt.i - scripts/ - per-boot/ - per-instance/ - per-once/ - seed/ - sem/
The main directory containing the cloud-init specific subdirectories. It is typically located at
/var/libbut there are certain configuration scenarios where this can be altered.
Contains information related to instance ids, datasources and hostnames of the previous and current instance if they are different. These can be examined as needed to determine any information related to a previous boot (if applicable).
part-handlerscode is written out here. Files that end up here are written out with in the scheme of
XYZis the handler number (the first handler found starts at 0).
A symlink to the current
instances/subdirectory that points to the currently active instance (which is active is dependent on the datasource loaded).
All instances that were created using this image end up with instance identifier subdirectories (and corresponding data for each instance). The currently active instance will be symlinked the
instancesymlink file defined previously.
Scripts that are downloaded/created by the corresponding
part-handlerwill end up in one of these subdirectories.
Contains seeded data files: meta-data, network-config, user-data, vendor-data
Cloud-init has a concept of a module semaphore, which basically consists of the module name and its frequency. These files are used to ensure a module is only ran per-once, per-instance, per-always. This folder contains semaphore files which are only supposed to run per-once (not tied to the instance id).