Userdata for Slicer VMs

Userdata can be used to customise VMs on first boot. Another option is to build a custom image.

This can include anything from installing packages, configuring services, or setting up user accounts.

If you wanted to run AI agents within Slicer, you could use userdata to install a custom AI framework, library, or agent for Remote Procedure Control (RPC).

Userdata in the config file

config:
  host_groups:
  - name: agent
+   userdata: |
+     # Install Ollama
+     curl -fsSL https://ollama.com/install.sh | sh
+
+     # Install a hard-coded SSH key for remote administration
+
+     echo "ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQC3... user@host" | tee -a /home/ubuntu/.ssh/authorized_keys
+     chmod 600 /home/ubuntu/.ssh/authorized_keys
+     chown ubuntu:ubuntu /home/ubuntu/.ssh/authorized_keys

You could also install something like Docker like this:

config:
  host_groups:
  - name: agent
+   userdata: |
+     # Install Docker
+     curl -fsSL https://get.docker.com | sh

Userdata via the CLI

You can add and remove VMs via Slicer's API directly using HTTP, or using the Slicer CLI itself as a client.

If you had a hostgroup named agents, you could run:

USERDATA=$(echo '# Install Ollama\ncurl -fsSL https://ollama.com/install.sh | sh' | jq -Rs .)

curl -sLSf http://127.0.0.1:8080/hostgroup/agents/nodes \
    -H "Content-Type: application/json" \
    -d "{
      \"userdata\": $USERDATA
    }"

For longer userdata scripts, you can save them to a file and reference it:

# Create userdata.sh
cat > userdata.sh << EOF
#!/bin/bash

# Install Docker
curl -fsSL https://get.docker.com | sh

# Add user to docker group
usermod -aG docker ubuntu
EOF

# Use the file in your API call
curl -sLSf http://127.0.0.1:8080/hostgroup/agents/nodes \
    -H "Content-Type: application/json" \
    -d "{
      \"userdata\": $(cat userdata.sh | jq -Rs .)
    }"

Or you can use the CLI for more convenience:

sudo -E slicer vm add \
    --userdata ./userdata.sh