Miscellaneous Oracle Cloud Infrastructure (OCI) scripts

`ssh-oci-bastion.sh`

Configure and ssh or create a tunnel to an Oracle Cloud Infrastructure host via the bastion.

Bash shell, perl, sleep, etc.
- (macOS, Linux) Out-of-the-box
- (Windows) Install WSL or Cygwin
ssh CLI client.
- Generate an SSH key pair if you don't have any. One of the following SSH public keys in `~/.ssh/` is required: `id_rsa.pub`, `id_dsa.pub`, `id_ecdsa.pub`, `id_ed25519.pub`, or `id_xmss.pub`. If there are multiple keys the first one found in this order will be used. The corresponding private key is usually also present there, but it can be moved to a credential vault and SSH agent, e.g. 1Password.
Install and configure OCI CLI.
Install jq.
Install PCRE.
Define the following environment variables. OCI menus below are as of October 2022.
1. OCI_INSTANCE_OCID. See Compute > Instances > {host} > General information > OCID
2. OCI_BASTION_OCID. See Identity & Security > Bastion > {bastion} > Bastion information > OCID
3. For host_user SSH sessions only: OCI_INSTANCE: OCI host Internal FQDN or Private IP. See Compute > Instances > {host} > Primary VNIC.
- If you're working with the single OCI host, setting them globally in your environment will work well.
- If you're working with multiple hosts, you can pass these vars on-the-fly: see the Usage Examples section.

Create a bastion session and ssh as taras server user using the system environment vars: ssh-oci-bastion.sh taras
Create a bastion session and ssh: OCI_INSTANCE_OCID=ocid1.instance.xx OCI_BASTION_OCID=ocid1.bastion.xx OCI_INSTANCE=10.xx ssh-oci-bastion.sh taras
Create a bastion port-forwarding session and launch the tunnel for the port 1234: OCI_INSTANCE_OCID=ocid1.instance.xx OCI_BASTION_OCID=ocid1.bastion.xx ssh-oci-bastion.sh -p 1234
Create a bastion session and ssh using the ADMIN OCI client profile: ssh-oci-bastion.sh -o ADMIN taras