add doc about redesigned /var/lib/cloud

1 files changed, 46 insertions, 0 deletions

diff --git a/doc/var-lib-cloud.txt b/doc/var-lib-cloud.txt
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+/var/lib/cloud has the following structure:
+  - scripts/
+      per-instance/
+      per-boot/
+      per-once/
+
+    files in these directories will be run by 'run-parts' once per
+    instance, once per boot, and once per *ever*.
+
+  - seed/
+     <datasource>/
+        sys-user-data
+        user-data
+        meta-data
+
+     The 'seed/' directory allows you to seed a specific datasource
+     For example, to seed the 'nocloud' datasource you would need to
+     populate 
+       seed/nocloud/user-data
+       seed/nocloud/meta-data
+
+  - instance -> instances/i-abcde
+    This is a symlink to the current instance/<instance-id> directory
+    created/updated on boot
+  - instances/
+      i-abcdefgh/
+         scripts/ # all scripts in scripts are per-instance
+         sem/
+            config-puppet
+            config-ssh
+            set-hostname
+         cloud-config.txt
+         user-data.txt
+         user-data.txt.i
+         obj.pkl
+  - sem/
+      scripts.once
+    These are the cloud-specific semaphores.  The only thing that
+    would go here are files to mark that a "per-once" script
+    has run.
+    
+
+to clear out the current instance's data as if to force a "new run" on reboot
+do:
+  ( cd /var/lib/cloud/instance && sudo rm -Rf * )
+