Add troubleshooting guide for Confidential

docs/computing/confidential/instance.md

@@ -2,6 +2,8 @@
 
 This section explain how to allocate your VM on the Aleph Network and start it on a chosen CRN.
 
+If you encounter any problem, check the [Confidential VM troubleshooting](./troubleshooting.md) guide
+
 ## Ensure you have uploaded your VM in the aleph network.
 See previous section: [Encrypted Virtual Machine image](./encrypted-disk.md)
 

docs/computing/confidential/troubleshooting.md

@@ -0,0 +1,43 @@
+# Troubleshooting a confidential VM 
+
+What to do in case your confidential VM is not working
+
+## Fetch the logs
+If the VM is supposed to be started but cannot be reached, try fetching the logs of your VM, use the commands:
+
+```shell
+aleph instance logs <vm_id>
+```
+
+If you don't know the id of your VM use `aleph instance list`
+
+You should see in the logs, the disk unlocking , the boot logs and the system invite.
+
+The last lines  should be something similar to this
+```
+cloud-init[502]: Cloud-init v. 24.1.3-0ubuntu1~22.04.5 finished at Thu, 05 Sep 2024 19:36:07 +0000. Datasource DataSourceNoCloud [seed=/dev/sr0][dsmode=net].  Up 23.63 seconds
+[  OK  ] Finished Execute cloud user/final scripts.
+[  OK  ] Reached target Cloud-init target.
+
+Ubuntu 22.04.4 LTS dbnszzoulvoea7crseir75egj4xbm5zzzaaut2nbpknjadidp3ua ttyS0
+```
+
+## Attempt launching the VM locally.
+
+If the VM fail to start, try launching your VM disk image locally in QEMU, this will allow to check if the disk image has been
+properly built.
+
+```shell
+sudo qemu-system-x86_64 \
+  -enable-kvm \
+  -m 2048 \
+  -nic user,model=virtio \
+  -nographic \
+  -serial mon:stdio \
+  -drive if=pflash,format=raw,unit=0,file=/usr/share/ovmf/OVMF.fd,readonly=on
+  -drive format=raw,file=</path/to/your/image.img> \
+```
+
+> Note: Once you have entered your password you might have to wait a minute or so for the disk to decrypt and boot.
+
+To exit qemu : press `Ctrl + a`, then `x` and then `[Enter]`

mkdocs.yml

@@ -123,6 +123,7 @@ nav:
           - 'Requirements': computing/confidential/requirements.md
           - 'Encrypted disk image': computing/confidential/encrypted-disk.md
           - 'Instance': computing/confidential/instance.md
+          - 'Troubleshooting': computing/confidential/troubleshooting.md
         - 'Tutorials':
           - 'Testing microVMs': guides/testing_microvms.md
           - 'Update a program': guides/update_a_program.md