docs: add tensorboard notes

docs/wiki/handy-gcp-commands.md

@@ -45,5 +45,33 @@ Copy from the host to the local machine (do this in a local terminal window).
 gcloud compute scp instance-3:~/model.tar ~/Downloads/model.tar
 ```
 
-
 Otherwise, could share state dir from host into docker and save a few steps...
+
+
+
+## Setting SSH key
+
+To fix `Remote Host changed` error, delete these files from your local machine.
+```shell
+~/.ssh/google_compute_engine
+~/.ssh/google_compute_engine.pub
+~/.ssh/google_compute_known_hosts
+```
+
+Then recreate them. Start the VM in the browser interface. Login and generate new SSH keys.
+```shell
+gcloud auth login
+gcloud compute ssh --zone "us-central1-c" "instance-3"  --tunnel-through-iap --project "elpis-workshop"
+``` 
+
+
+
+## Viewing Tensorboard on GCP
+
+Connect to the tensorboard that shows train loss (currently in the HFT branch).
+
+* Add a Firewall rule in `GCP > VPC networks > Firewall` for TCP port `6006` using a tagname `firewall`.
+* Create/edit a VM instance.
+* Include the `firewall` tagname in the list of VM Network tags.
+* Start the VM and connect to it. `gcloud compute ssh instance-3`
+* Run tensorbaord with host arg. `tensorboard --logdir=/state/models/MODEL-HASH/runs --port 6006 --host=0.0.0.0`