add troubleshooting for cloud-init

README.md

@@ -75,3 +75,29 @@ one.
 Start `packer` with `-parallel=false`:
 
 `packer build -parallel=false vagrant.json`
+
+### Checking cloud-init support in our qcow2 images:
+
+```bash
+$ packer build cloud.json
+$ cp release/Arch-Linux-cloudimg-amd64-2020-02-24.img disk.img
+
+# Copied from (with minor changes): https://cloudinit.readthedocs.io/en/latest/topics/datasources/nocloud.html
+$ { echo instance-id: iid-local01; echo local-hostname: cloudimg; } > meta-data
+
+$ printf "#cloud-config\npassword: passw0rd\nchpasswd: { expire: False }\nssh_pwauth: True\n" > user-data
+
+## create a disk to attach with some user-data and meta-data (require cdrkit)
+$ genisoimage  -output seed.iso -volid cidata -joliet -rock user-data meta-data
+
+## create a new qcow image to boot, backed by your original image
+$ qemu-img create -f qcow2 -b disk.img boot-disk.img
+
+## boot the image and login as 'arch' with password 'passw0rd'
+## note, passw0rd was set as password through the user-data above,
+## there is no password set on these images.
+$ qemu-system-x86_64 -m 256 \
+   -net nic -net user,hostfwd=tcp::2222-:22 \
+   -drive file=boot-disk.img,if=virtio \
+   -drive file=seed.iso,if=virtio
+```