From 76f89f40b37f0581b51033c16ec961a854e84e14 Mon Sep 17 00:00:00 2001
From: Matt McEuen <madgin@madgin.net>
Date: Mon, 31 Aug 2020 13:13:20 -0500
Subject: [PATCH] Dynamically determine disk for images & bindmounts

This removes an assumption in the ephemeral cloud-init that
vda should be used to hold ironic images and container bindmounts.
Cloud-init will now use the ram-backed FS if there's enough
memory, and otherwise will default to vda or sda as appropriate.

Change-Id: If2a05348df7fae99598ff76e171b0e88fc2e6f88
---
 manifests/function/ephemeral/secret.yaml | 39 ++++++++++++++++--------
 1 file changed, 27 insertions(+), 12 deletions(-)

diff --git a/manifests/function/ephemeral/secret.yaml b/manifests/function/ephemeral/secret.yaml
index 9edc08825..12a838d42 100644
--- a/manifests/function/ephemeral/secret.yaml
+++ b/manifests/function/ephemeral/secret.yaml
@@ -105,15 +105,30 @@ stringData:
       path: /tmp/kubeadm.yaml
       permissions: "0640"
     bootcmd:
-    - /usr/sbin/mkfs.ext4 /dev/vda
-    - mkdir /mnt/vda
-    - mount /dev/vda /mnt/vda
-    - mkdir -p /opt/metal3-dev-env/ironic/html/images
-    - mkdir -p /mnt/vda/opt/metal3-dev-env/ironic/html/images
-    - mount --bind /mnt/vda/opt/metal3-dev-env/ironic/html/images /opt/metal3-dev-env/ironic/html/images
-    - mkdir -p /var/lib/docker /mnt/vda/var/lib/docker
-    - mount --bind /mnt/vda/var/lib/docker /var/lib/docker
-    - mkdir -p /var/lib/docker-engine /mnt/vda/var/lib/docker-engine
-    - mount --bind /mnt/vda/var/lib/docker-engine /var/lib/docker-engine
-    - mkdir -p /mnt/vda/var/lib/kubelet/ /var/lib/kubelet/
-    - mount --bind /mnt/vda/var/lib/kubelet/ /var/lib/kubelet/
+    - NEED_MB=16384 # MB of storage needed for ironic images & bindmounts
+    - FREE_MB=$(df -m --output=avail /var/lib | tail -n 1)
+    # if there's not enough memory-backed storage, mount an available disk
+    - if [ ${FREE_MB} -lt ${NEED_MB} ]; then
+    -   mkdir /mnt/ephemeral
+        # Use vda if provided by a hypervisor
+    -   if [ -e /dev/vda ]; then
+    -     mkfs.ext4 /dev/vda
+    -     mount /dev/vda /mnt/ephemeral
+        # Fall back to sda
+    -   elif [ -e /dev/sda ]; then
+    -     mkfs.ext4 -F /dev/sda
+    -     mount /dev/sda /mnt/ephemeral
+    -   else
+    -     echo "Not enough RAM to host images, and no available disks found"
+    -     exit 1
+    -   fi
+    -   mkdir -p /opt/metal3-dev-env/ironic/html/images
+    -   mkdir -p /mnt/ephemeral/opt/metal3-dev-env/ironic/html/images
+    -   mount --bind /mnt/ephemeral/opt/metal3-dev-env/ironic/html/images /opt/metal3-dev-env/ironic/html/images
+    -   mkdir -p /var/lib/docker /mnt/ephemeral/var/lib/docker
+    -   mount --bind /mnt/ephemeral/var/lib/docker /var/lib/docker
+    -   mkdir -p /var/lib/docker-engine /mnt/ephemeral/var/lib/docker-engine
+    -   mount --bind /mnt/ephemeral/var/lib/docker-engine /var/lib/docker-engine
+    -   mkdir -p /mnt/ephemeral/var/lib/kubelet/ /var/lib/kubelet/
+    -   mount --bind /mnt/ephemeral/var/lib/kubelet/ /var/lib/kubelet/
+    - fi