--- title: 'Linux deployment tools: MAAS 3.1 for hot metal' description: Using Linux deployment tools like MAAS often means a fresh install. MAAS 3.1 will provision hot metal (running machines) without disturbing them. See how! url: https://canonical.com/blog/linux-deployment-tool-for-hot-metal?format=md --- 1. [Blog](https://canonical.com/blog) 2. Article --- [Bill Wear](https://canonical.com/blog/author/billwear "More about Bill Wear") 13 December 2021 # Linux deployment tools: MAAS 3.1 for hot metal [bare-metal cloud](https://canonical.com/blog/tag/bare-metal-cloud) [bare-metal provisioning](https://canonical.com/blog/tag/bare-metal-provisioning) [cloud](https://canonical.com/blog/tag/cloud) [linux deployment tools](https://canonical.com/blog/tag/linux-deployment-tools) [MAAS](https://canonical.com/blog/tag/maas) [sc:snap:maas](https://canonical.com/blog/tag/scsnapmaas) [Server](https://canonical.com/blog/tag/server) [server provisioning](https://canonical.com/blog/tag/server-provisioning) --- Share the article Back a few months ago, we did a [feature poll](https://discourse.maas.io/t/maas-feature-poll/4865) on our [MAAS forum](https://discourse.maas.io/), and the most-requested new feature turned out to be “[Recommission/rescan a machine after it has been deployed](https://discourse.maas.io/t/recommission-rescan-a-machine-after-it-has-been-deployed/1035)“. With the release of MAAS 3.1, we’ve added that feature, making [MAAS](https://maas.io) an even better choice for linux deployment tools. Here’s a sample of how it works. ## Start with any old machine In the [Developer Advocate](https://ubuntu.com/blog/author/billwear)‘s lab, we have a stack of NUCs and a bunch of different laptops. For this exercise, we chose a gaming laptop because: 1. it’s fully loaded: Ryzen 7, 16GB RAM, a couple TB of space, etc., hooked up via Ethernet to a 1GB+ internet connection. 2. it’s likely to be something a lot of developers would probably have nearby, making it easier to duplicate this experiment in odd moments. We freshly installed and initialized [MAAS 3.1](https://maas.io/docs/snap/3.1/ui/maas-installation) and [LXD](https://maas.io/docs/snap/3.1/ui/how-to-use-lxd#heading--lxd-setup), just following the instructions — *except* that we *didn’t* disable DHCP/DNS on LXD, and we *didn’t* enable DHCP on MAAS. This configuration shows that MAAS doesn’t *have* to have DHCP enabled to manage machines that are already running — especially since it’s likely that a running machine already has a DHCP-assigned IP address, that it got from somewhere else. ## Create and verify a LXD container Using the command below we can deploy Ubuntu Linux: ``` lxc launch ubuntu:20.04 u1 ``` When the container is running, we can check it with: A connected, running, independent LXD container To demonstrate that the workload doesn’t get disturbed, we’ll do this: A “top” session started just before enlisting this running machine ## Capturing the hot metal with the best of linux provisioning tools Using the “deployed=true” flag, we’ll enlist this machine into MAAS with the following command sequence: ``` stormrider@cloudburst:~$ maas admin machines create deployed=true hostname=u1 architecture=amd64 mac_addresses=00:16:3e:fc:71:98 power_type=manual Success. Machine-readable output follows: { "pool": { "name": "default", "description": "Default pool", "id": 0, "resource_uri": "/MAAS/api/2.0/resourcepool/0/" }, "node_type": 0, "cache_sets": [], "volume_groups": [], "description": "", "status_action": null, "disable_ipv4": false, "other_test_status_name": "Unknown", "fqdn": "u1.maas", "boot_disk": null, "numanode_set": [ { "index": 0, "memory": 0, "cores": [], "hugepages_set": [] .... ``` Part of the (rather long) JSON response is shown to highlight the fact MAAS has accepted the machine as deployed, but currently knows nothing about it. We can confirm this by looking at the machine list: The LXD container has been enlisted by MAAS as a deployed machine We can further confirm the lack of commissioning data by zooming in on the newly-enlisted machine: Note the number of “Unknown” values for the newly-enlisted machine ## Did we disturb the machine? We can check the running “top” command on the newly-enlisted machine to make sure nothing’s been disturbed: The “top” command is still running, completely oblivious to machine enlistment by MAAS Indeed, the machine doesn’t even seem to notice that it’s been enlisted by MAAS — at least, not in terms of impact on the workload. ## Updating hardware information Of course, just knowing the machine is connected to MAAS doesn’t do much for us. What we *really* need is to update the hardware information — but we want to do that without disturbing the workload significantly. To accomplish this, we’ll log onto the machine with in a different window and download the “maas-run-scripts” to the machine: Downloading and setting run permissions for the maas-run-scripts Here, we’ve not only downloaded the scripts, we’ve actually set permissions so the scripts can run. To run the script to gather hardware information, though, we’ll need some authentication information, from MAAS, about the machine. Back on the MAAS host, we’ll run this command: MAAS authenication information for the newly-enlisted MAAS machine We’ll create a credentials file called “u1-creds.yaml” that looks like this: ``` root@u1:~# cat u1-creds.yaml reporting: maas: consumer_key: UUy9RkZt5gLcC7db6S endpoint: http://192.168.1.107:5240/MAAS/metadata/status/8gf6sb token_key: 44mZe589X3kzew4qrr token_secret: 5yKB33R99NYpQ2ZZEJrXZQGFjhe4aPQz ``` Before we run the command to collect hardware information, let’s check our “top” process to make sure it’s still running properly: The “top” session is still running undisturbed With these creds in place, we can run the following (just-downloaded) command to update MAAS about this machine’s hardware info: Using maas-run-scripts to gather hardware info and send it to MAAS Let’s check on that “top” process one more time: The load average rose from 0.53 to 0.62 during the scan, which is miniscule Good. The machine hasn’t been disturbed much, if at all. Now, let’s see if MAAS knows more about this machine: A perfect result for the ultimate linux deployment tool: MAAS You can see from this that MAAS has learned, as of MAAS 3.1, to enlist running machines, that is, to deploy hot metal, without disturbing its workload. MAAS is always evolving and is one of the best linux deployment tools. ## Further reading for linux deployment tools: MAAS Canonical has released an **[extensive whitepaper](https://ubuntu.com/engage/bare-metal-kubernetes)** [for](https://ubuntu.com/engage/bare-metal-kubernetes) **[bare metal Kubernetes](https://ubuntu.com/engage/bare-metal-kubernetes)** – going in depth into many of the different aspects involved and heavily featuring the usage of MAAS. Also, don’t forget to check out our previous blogs about MAAS, for example the 3.1 [release blog](https://ubuntu.com/blog/announcing-maas-3-1). Learn more about MAAS at our Metal As A Service [webpage](https://maas.io). If you like the nuts and bolts (more puns for the people), you can get into more detail at our [About MAAS](https://maas.io/docs/snap/3.0/ui/About-MAAS) page, and we’ve also published an [ebook](https://pages.ubuntu.com/eBook-MAAS.html). There are also plenty of great resources about linux deployment tools and MAAS on the new [MAAS resources](https://maas.io/resources) page, and don’t forget to visit our [tutorials](https://maas.io/tutorials) page. [Get in touch Interested in running Ubuntu in your organization?](https://ubuntu.com/about/contact-us/form) ## Sign up for our newsletter Get the latest Canonical news and updates in your inbox. Work email: \*I agree to receive information about Canonical's products and services. By submitting this form, I confirm that I have read and agree to [Canonical's Privacy Policy](https://canonical.com/legal/dataprivacy). 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