How to use standard images
MAAS is only useful once it has images available to provision its nodes. Therefore, one key post-install task is to select and import images from the boot source. Once MAAS imports images, it will update them on an hourly basis, via a default sync mechanism. This page explains how to select and import the images that MAAS requires to provision its nodes.
This article will help you learn:
- How to use image streams
- How to import standard images from maas.io
- How to use other image mirrors to download images
- How to import and provision non-Ubuntu images
Note that it is possible to build your own images in a limited sense: see MAAS Image Builder.
Canonical provides two SimpleStreams for MAAS images: candidate and stable. Both streams contain Ubuntu images, CentOS images, bootloaders extracted from the Ubuntu archive, and release notifications. Either stream can be used in any version of MAAS greater than 2.1 – but not all images are supported in older versions.
This subsection will help you learn:
- About the candidate stream
- About the stable stream
- About the retired daily stream
- How to change the stream with the UI
- How to change the stream with the CLI
The candidate stream contains images and bootloaders which have not been explicitly tested with MAAS. Canonical’s automated build process dumps all images and bootloaders here before they are tested with MAAS. This stream is useful when testing a bug fix before an image or bootloader has been promoted to stable. Think of the candidate stream as a preview: it should never be used in a production environment; and users are encouraged to provide feedback on any issues they find with this stream.
This stream is available here↗.
The stable stream contains images and bootloaders which have been tested with the latest version of MAAS. This is the default stream which should be used in production environments. This stream is available here↗.
About the retired daily stream
Previously there was only one MAAS stream available, daily. This stream has been replaced by the stable stream. Any client using this stream will be automatically redirected to the stable stream.
How to change the stream with the UI
To switch to the candidate stream simply select “custom” on the images page, set the URL to http://images.maas.io/ephemeral-v3/candidate, and click “Connect”
MAAS uses the stable stream by default. To switch back to it simply select maas.io on the images page
How to change the stream with the CLI
To switch to a stream with the CLI, enter the following commands:
BOOT_SOURCE_ID=$(maas $PROFILE boot-sources read | jq '.[] | select(.url | contains("images.maas.io/ephemeral-v3")) | .id')
maas $PROFILE boot-source update $BOOT_SOURCE_ID url=$STREAM_URL
How to import standard images from maas.io
The ‘Images’ page shows what images and architectures have been selected and downloaded. By default, MAAS will automatically grab the most recent Ubuntu LTS releases (and amd64 architecture). Below, we have selected two additional releases:
You can tell MAAS to sync images hourly, at the region level, using a toggle switch in the top-right corner of the screen. See Boot image sources) for more details. We highly recommended syncing images hourly. Syncing at the rack controller level (from regiond) occurs every 5 min and cannot be disabled.
Click the ‘Save selection’ button to initiate the import. MAAS will present existing images along with the newly-selected ones. The latter will have their status updated as the import is processed:
To remove an image, un-select it and click ‘Save selection’.
How to use other image mirrors to download images
You can also host Ubuntu images on a mirror. Configure this mirror by selecting ‘Custom’ beneath ‘Choose source’. Enter the mirror URL and click ‘Connect’.
Advanced options, such as using a GPG key or keyring to validate the mirror path (snap installation location: /snap/maas/current/usr/share/keyrings/ubuntu-cloudimage-keyring.gpg), are revealed by clicking ‘Show advanced options’:
Optionally, a local mirror can be set up as the boot source. MAAS will then use it instead of the standard internet-based server. Local mirroring significantly reduces the time required import images. See Local image mirror for instructions.
How to import and provision non-Ubuntu images
It is also possible to import and provision images other than Ubuntu. Images supported and provided by MAAS will appear beneath the ‘Other Images’ section. Currently, images for CentOS 6.6, CentOS 7.0, and CentOS 8.0 are available. These images can be imported and used just like the Ubuntu images above.
