A model influences all the machines that Juju creates within it and, in turn, the applications that get deployed onto those machines. It is therefore a very powerful feature to be able to configure at the model level. Model configuration consists of a collection of keys and their respective values. An explanation of how to both view and set these key:value pairs is provided below. Notable examples are provided at the end.
You can display the current model settings by running the command:
This will include all the currently set key values - whether they were set by you, inherited as a default value or dynamically set by Juju.
A key's value may be set for the current model using the same command:
juju model-config no-proxy=jujucharms.com
It is also possible to specify a list of key-value pairs:
juju model-config test-mode=true enable-os-upgrade=false
Note: Juju does not currently check that the provided key is a valid setting, so make sure you spell it correctly.
To set a null value:
juju model-config apt-mirror=""
To return a value to the default setting the
--reset flag is used, along
with the key name:
juju model-config --reset test-mode
After deployment, the
model-defaults command allows a user to display the
configuration values for a model as well as set default values that all new
models will use. These values can even be specified for each cloud region
instead of just the controller.
To set a default value for 'ftp-proxy', for instance, you would enter the following:
juju model-defaults ftp-proxy=10.0.0.1:8000
To see both the default values and what they've been changed to, you would use:
To set default values for all new models in a specific controller region, state
the region in the command, shown here using the same example settings as our
model-config key-value pairs example above:
juju model-defaults us-east-1 test-mode=true enable-os-upgrade=false
Model settings can also be made when creating a new controller via either the
--model-default options. The difference being that
affects just the 'controller' and 'default' models while
affects all models, including any future ones. Below we use the
juju bootstrap --config image-stream=daily lxd lxd-daily
See Creating a controller for in-depth coverage on how to create a controller.
Note that these defaults can be overridden, on a per-model basis, during the
invocation of the
add-model command (option
--config) as well as by
resetting specific options to their original defaults through the use of the
model-config command (option
model-defaults commands can read key value pairs
from a YAML-formatted file. For example:
juju model-config no-proxy=jujucharms.com more-config-values.yaml
The table below lists all the model keys which may be assigned a value. Some of these keys deserve further explanation. These are explored in the sections below the table.
|agent-metadata-url||string||The URL of the private stream.|
|The version of Juju to use for deploy/upgrades. See [additional info|
|The desired Juju agent version to use. See additional info below.|
|apt-ftp-proxy||string||The APT FTP proxy for the model.|
|apt-http-proxy||string||The APT HTTP proxy for the model.|
|apt-https-proxy||string||The APT HTTPS proxy for the model.|
|apt-mirror||string||The APT mirror for the model. See additional info below.|
|automatically-retry-hooks||bool||true||Set the policy on retying failed hooks. See additional info below.|
|default-series||string||valid series name, e.g. 'xenial'||The default series of Ubuntu to use for deploying charms.|
|development||bool||false||Set whether the model is in development mode.|
|disable-network-management||bool||false||Set whether to give network control to the provider instead of Juju controlling configuration. See additional info below.|
|enable-os-refresh-update||bool||true||Set whether newly provisioned instances should run their respective OS's update capability. See additional info below.|
|enable-os-upgrade||bool||true||Set whether newly provisioned instances should run their respective OS's upgrade capability. See additional info below.|
|extra-info||string||This is a string to store any user-desired additional metadata.|
|firewall-mode||string||instance||instance/global/none||The mode to use for network firewalling. See additional info below.|
|ftp-proxy||string||url||The FTP proxy value to configure on instances, in the FTP_PROXY environment variable.|
|http-proxy||string||url||The HTTP proxy value to configure on instances, in the HTTP_PROXY environment variable.|
|https-proxy||string||url||The HTTPS proxy value to configure on instances, in the HTTPS_PROXY environment variable.|
|ignore-machine-addresses||bool||false||When true, the machine worker will not look up or discover any machine addresses.|
|image-metadata-url||string||url||The URL at which the metadata used to locate OS image ids is located.|
|image-stream||string||The simplestreams stream used to identify which image ids to search when starting an instance.|
|logforward-enabled||bool||false||Set whether the log forward function is enabled.|
|logging-config||string||The configuration string to use when configuring Juju agent logging (see this link for details).|
|max-status-history-age||string||72h, etc.||The maximum age for status history entries before they are pruned, in a human-readable time format.|
|max-status-history-size||string||400M, 5G, etc.||The maximum size for the status history collection, in human-readable memory format.|
|no-proxy||string||List of domain addresses not to be proxied (comma-separated).|
|provisioner-harvest-mode||string||destroyed||all/none/unknown/destroyed||Set what to do with unknown machines. See additional info below.|
|proxy-ssh||bool||false||Set whether SSH commands should be proxied through the API server.|
|resource-tags||string||none||A space-separated list of key=value pairs used to apply as tags on supported cloud models.|
|ssl-hostname-verification||bool||true||Set whether SSL hostname verification is enabled.|
|test-mode||bool||false||Set whether the model is intended for testing. If true, accessing the charm store does not affect statistical data of the store.|
|transmit-vendor-metrics||bool||true||Set whether the controller will send metrics collected from this model for use in anonymized aggregate analytics.|
|update-status-hook-interval||string||5m||30s, 6m, 1hr, etc.||The run frequency of the update-status hook. The value has a random +/- 20% offset applied to avoid hooks for all units firing art once. Value change only honoured during controller and model creation (
|vpc-id||string||The virtual private cloud (VPC) ID for use when configuring a new model to be deployed to a specific VPC during
The APT packaging system is used to install and upgrade software on machines provisioned in the model, and many charms also use APT to install software for the applications they deploy. It is possible to set a specific mirror for the APT packages to use, by setting 'apt-mirror':
juju model-config apt-mirror=http://archive.ubuntu.com/ubuntu/
To restore the default behaviour you would run:
juju model-config --reset apt-mirror
apt-mirror option is often used to point to a local mirror. The
Working offline page covers mirrors, proxies, and other
aspects related to network-restricted environments.
When Juju provisions a machine, its default behaviour is to upgrade existing packages to their latest version. If your OS images are fresh and/or your deployed applications do not require the latest package versions, you can disable upgrades in order to provision machines faster.
Two Boolean configuration options are available to disable APT updates and
enable-os-refresh-update (apt-get update) and
(apt-get upgrade), respectively.
enable-os-refresh-update: false enable-os-upgrade: false
You may also want to just update the package list to ensure a charm has the latest software available to it by disabling upgrades but enabling updates.
This can only be used with MAAS models and should otherwise be set to 'false' (default) unless you want to take over network control from Juju because you have unique and well-defined needs. Setting this to 'true' with MAAS gives you the same behaviour with containers as you already have with other providers: one machine-local address on a single network interface, bridged to the default bridge.
Modes available include:
- instance: Requests the use of an individual firewall per instance.
- global: Uses a single firewall for all instances (access for a network port is enabled to one instance if any instance requires that port).
- none: Requests that no firewalling should be performed inside the model, which is useful for clouds without support for either global or per instance security groups.
Juju keeps state on the running model and it can harvest (remove) machines which it deems are no longer required. This can help reduce running costs and keep the model tidy. Harvesting is guided by what "harvesting mode" has been set.
A Juju machine can be in one of four states:
- Alive: The machine is running and being used.
- Dying: The machine is in the process of being terminated by Juju, but hasn't yet finished.
- Dead: The machine has been successfully brought down by Juju, but is still being tracked for removal.
- Unknown: The machine exists, but Juju knows nothing about it.
Juju can be in one of several harvesting modes, in order of most conservative to most aggressive:
- none: Machines will never be harvested. This is a good choice if machines are managed via a process outside of Juju.
- destroyed: Machines will be harvested if i) Juju "knows" about them and ii) they are 'Dead'.
- unknown: Machines will be harvested if Juju does not "know" about them ('Unknown' state). Use with caution in a mixed environment or one which may contain multiple instances of Juju.
- all: Machines will be harvested if Juju considers them to be 'destroyed' or 'unknown'.
The default mode is destroyed.
Below, the harvest mode key for the current model is set to 'none':
juju model-config provisioner-harvest-mode=none
Prior to version 2.0, hooks returning an error would block until the user ran a command to retry them manually:
juju resolved unit-name/#
From version 2.0, Juju will automatically retry hooks periodically - there is an exponential backoff, so hooks will be retried after 5, 10, 20, 40 seconds up to a period of 5 minutes, and then every 5 minutes. The logic behind this is that some hook errors are caused by timing issues or the temporary unavailability of other applications - automatic retry enables the Juju model to heal itself without troubling the user.
However, in some circumstances, such as debugging charms, this behaviour can be
distracting and unwelcome. For this reason, it is possible to set the
automatically-retry-hooks option to 'false' to disable this behaviour. In this
case, users will have to manually retry any hook which fails, using the command
above, as with earlier versions of Juju.
Note: Even with the automatic retry enabled, it is still possible to use the
juju resolved unit-name/# command to retry manually.
Juju, by default, uses the slow-changing 'released' images when provisioning
machines. However, the
image-stream option can be set to 'daily' to use more
up-to-date images, thus shortening the time it takes to perform APT package
A full definition of an agent is provided on the Concepts and terms page.
agent-stream option specifies the "stream" to use when a Juju agent is to
be installed or upgraded. This setting reflects the general stability of the
software and defaults to 'released', indicating that only the latest stable
version is to be used.
To run the upcoming stable release (before it has passed the normal QA process) you can set:
For testing purposes, you can use the latest unstable version by setting:
agent-version option specifies a "patch version" for the agent that is to
be installed on a new controller relative to the Juju client's current
major.minor version (Juju uses a major.minor.patch numbering scheme).
For example, Juju 2.3.2 means major version 2, minor version 3, and patch version 2. On a client system with this release of Juju installed, the machine agent's version for a newly-created controller would be the same. To specify a patch version of 1 (instead of 2), the following would be run:
juju bootstrap aws --agent-version='2.3.1'