Snapshots

Snapshots capture the disk state of a running VM at a point in time. You can use them to save checkpoints, duplicate environments, or roll back to a known-good state.

How It Works

When you take a snapshot, Iron.sh flushes pending writes and captures a crash-consistent disk image that captures the state of the VM. This is fine for most workloads, but if you are running something IO-sensitive like a database, you should take care to ensure your data is in a consistent state before snapshotting. The VM continues running throughout with no downtime.

You can take as many snapshots of a VM as you want. Each snapshot can be given an optional label to help you identify it later.

A snapshot is always linked to its source: either the base image the VM was originally created from, or the snapshot the VM was restored from. This forms a chain you can trace back to the original image.

Creating a Snapshot

irons snapshots create my-dev-env --label before-refactor

The command returns immediately after the API accepts the request. Use --wait to block until the snapshot reaches ready:

irons snapshots create my-dev-env --label before-refactor --wait

You can list snapshots for a specific VM or across all VMs:

irons snapshots list my-dev-env
irons snapshots list

Restoring from a Snapshot

Restoring a snapshot creates a new VM that boots from the captured state. The original VM is untouched.

# Find the snapshot you want
irons snapshots list my-dev-env
 
# Create a new VM from it
irons create my-restored-env --snapshot snap_x9f2km4p

The new VM starts with the same disk contents as the original had at the moment the snapshot was taken.

Forking

The fork command combines snapshotting and restoring into a single step. It takes a snapshot of the source VM, waits for it to be ready, then creates a new VM from it:

irons fork my-dev-env
irons fork my-dev-env --fork-name my-dev-env-copy

This is the fastest way to duplicate a running environment. See the fork CLI reference for all available flags.

Further Reading

• Snapshots API reference — create, list, get, and delete snapshots via the REST API.
• Snapshots CLI reference — manage snapshots from the command line.
• fork CLI reference — one-command VM duplication.