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/
/var/lib/cloud
The main directory containing the cloud-init specific subdirectories. It is typically located at
/var/lib
but there are certain configuration scenarios where this can be altered.TBD, describe this overriding more.
data/
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).
handlers/
Custompart-handlers
code is written out here. Files that end up here are written out with in the scheme ofpart-handler-XYZ
whereXYZ
is the handler number (the first handler found starts at 0).
instance
A symlink to the current instances/
subdirectory that points to the
currently active instance (which is active is dependent on the datasource
loaded).
instances/
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 instance
symlink file
defined previously.
scripts/
Scripts that are downloaded/created by the corresponding part-handler
will end up in one of these subdirectories.
seed/
TBD
sem/
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).