This is a big release that includes support for Kubernetes workloads, LXD remote clustering, managed OS series upgrades, support for charms with LXD profiles, Oracle OCI cloud support, and bundle enhancements.
For highlights of this release, please see the What’s new in 2.5 page in the documentation. Further details are below.
New and improved
Kubernetes workloads support
Juju has been able to install a Kubernetes cluster for a while now. However, only until
v.2.5 is Juju able to take a pre-existing cluster and add it to its list of backing clouds. This renders the cluster available for charm deployment. Kubernetes-specific charms are naturally required.
LXD clustering support
Juju now supports managing models on a remote LXD cluster. Leveraging the density of a LXD cluster of remote machines means you can test full HA scenarios in complex workloads easily. With three bare metal machines you can create a HA Juju control plane along with deploying HA enabled workloads. This is a great setup for development, testing, and validating failover scenarios or just providing a great dense “micro cloud” for a team to work against.
- Documentation: https://docs.jujucharms.com/2.5/clouds-lxd-advanced
- Tips on setting up the LXD cluster networking: https://discourse.jujucharms.com/t/manual-network-setup-for-lxd-clustering/261
Upgrading of underlying OS support
Juju supports a new
upgrade-series command that allows you to upgrade a machine running Ubuntu Trusty to Xenial or Xenial to Bionic. Charms now have the ability to provide new hooks that can script the work required for applications to handle the big OS upgrade scenario. With this you can now migrate your infrastructure without redeploying and keep up with the latest LTS releases available.
The OpenStack charms are updated to support this in their latest release. You can see a charm that uses this feature here.
Bundle export feature
This feature provides a CLI command which exports the configuration of the current model in bundle format which can then be used for subsequent (re-)deployment.
The command added to support this functionality is
juju export-bundle --filename <outputfile> juju export-bundle
--filename option is not specified the output is printed to STDOUT.
Bundle diff feature
This feature provides a command to compare a bundle with a model and report any differences. This is really useful when you’re trying to see what changes might have been made in production over time that are different than the original bundle you started out with. You might also use this to snapshot updates to the bundle over time.
The bundle to compare can be a local bundle file or the name of a bundle in the Charm Store. The bundle can also be combined with overlays (in the same way as the deploy command) before comparing with the model.
The map-machines option works similarly as for the deploy command, but existing is always assumed, so it doesn’t need to be specified.
Here are some examples to demonstrate the flexibility available:
juju diff-bundle localbundle.yaml juju diff-bundle canonical-kubernetes juju diff-bundle -m othermodel hadoop-spark juju diff-bundle mongodb-cluster --channel beta juju diff-bundle canonical-kubernetes --overlay local-config.yaml --overlay extra.yaml juju diff-bundle localbundle.yaml --map-machines 3=4
Support for charms with LXD profiles
Sometimes an application needs to have a LXD profile with some tweaks in order to work properly in a LXD container. Some examples of this include things like allowing nested containers, so that workload creating Docker containers is able to create those containers, or perhaps an application needs a kernel module added into the LXD container it runs in. In Juju 2.5 charms can now provide a
lxd-profile.yaml file that helps tell Juju what it needs. Juju will then make sure that the LXD containers the application runs it is provided the tweaks it needs.
A charm in development that uses this feature can be seen here (see the
lxd-profile.yaml in the file listing).
Oracle Cloud Infrastructure support
The Oracle cloud has been updated and now supports Oracle Cloud Infrastructure (OCI) as a cloud.
If you wish to use the older legacy cloud you can find it listed as “OCI Classic”.
Credential Management and Validation
Juju uses a cloud credential to bootstrap a controller or to add a model. This credential is then used in cloud communications on the model’s behalf. The credentials however can expire, be revoked and deleted or simply need to be changed during the life of the model. From 2.5, Juju gains the ability to react to these changes.
Whenever the underlying cloud rejects Juju’s call because of an invalid credential, all communications between this model and the cloud are stopped until the credential is either updated or changed. If more than one model uses the same credential, these models will react the same way. This ability has been rolled out to most supported cloud providers.
In order to re-enable cloud communications on the models that have invalid credentials, users can use the existing
update-credential command. If the model requires a completely different credential, a new command can be used to upload a new credential and use it on the model, see
Juju users can examine what credential models have via
OpenStack cloud config supports CA_CERT
Juju now supports OpenStack clouds requiring CA Certificates. Simply run
juju add-cloud with your novarc file sourced, Juju will pick up the value of OS_CACERT, or provide the location of the certificate and Juju will take it from there.
Adding zones as a valid constraint
You can now select one or more zones to be a constraint on the deployment. If you wish to use a subset of the available zones you can list them at deploy time and all units will respect that selection over time.
New config-changed hook behaviour
The config-changed hook is now only run when needed. This solves a problem on deployments with a large number of units whereby the system thrashed after any upgrade (or other agent restart) due to each and every unit agent running config-changed for all charms. Instead of speculatively running the hook whenever the agent restarts, or when an update is made that doesn’t really change anything, we now track the hash of 3 artefacts - config settings, machine/container addresses, trust config. If any of these change, the hook is run. The agent still checks on start up but will no longer run the hook if nothing has changed since the last invocation. Note that the first agent restart after upgrade to Juju 2.5 will run the hook as there are no hashes recorded yet.
Some important fixes include:
LP #1791715 - juju does not support --to placement directive in bundles
LP #1806442 - primary charm with a customized lxd profile fails
LP #1804669 - Charm channel isn’t used on upgrade-charm
LP #1787986 - Run action on leader
LP #1799365 - Juju HA controllers need to distribute client connections
LP #1796378 - Subordinate charm deployment ignores global series settings
LP #1776995 - subordinate can’t relate to applications with different series
LP #1804701 - (2.5-beta1) juju upgrade-series from Trusty to Xenial hangs up
LP #1787753 - Add europe-north1 region to google clouds
LP #1778033 - juju stuck attaching storage to OSD
LP #1751858 - support vsphere disk.enableUUID model config
For a detailed breakdown of fixed bugs:
LP #1808515 - updating a charm with a LXD profile, directly after deploying a charm can prevent any new upgrades of the same charm
LP #1808551 - model migration fails when using a previous client and breaks current client
If you were affected by any of the bugs fixed in this release, your feedback is appreciated. Please contact the Juju team using the communication channels specified in the feedback section.
The recommended install method is by snaps:
sudo snap install juju --classic
Those already using the ‘stable’ snap channel (the default as per the above command) should be upgraded automatically. Other packages are available for a variety of platforms (see the install documentation).
Let us know how you’re using Juju or of any questions you may have. You can join us on Discourse, send us a message on Twitter (hashtag
#jujucharms), or talk to us in the
#juju IRC channel on freenode.
To learn more about Juju visit our home page at https://jujucharms.com.