Command 'juju relate'

system · 20 April 2023 07:34

The information in this doc is based on Juju version 3.5.5, and may not accurately reflect other versions of Juju.

See also: consume, find-offers, set-firewall-rule, suspend-relation Alias: integrate

Summary

Integrate two applications.

Usage

juju relate [options] <application>[:<endpoint>] <application>[:<endpoint>]

Options

Flag	Default	Usage
`-m`, `--model`		Model to operate in. Accepts [<controller name>:]<model name>\|<model UUID>
`--via`		for cross model integrations, specify the egress subnets for outbound traffic

Examples

Integrate wordpress and percona-cluster, asking Juju to resolve the endpoint names. Expands to “wordpress:db” (with the requires role) and “percona-cluster:server” (with the provides role).

juju integrate wordpress percona-cluster

Integrate wordpress and postgresql, using an explicit endpoint name.

juju integrate wordpress postgresql:db

Integrate an etcd instance within the current model to centrally managed EasyRSA Certificate Authority hosted in the “secrets” model.

juju integrate etcd secrets.easyrsa

Integrate a wordpress application with a mysql application hosted within the “prod” model, using the “automation” user. Facilitate firewall management by specifying the routes used for integration data.

juju integrate wordpress automation/prod.mysql --via 192.168.0.0/16,10.0.0.0/8

Details

Integrate two applications. Integrated applications communicate over a common interface provided by the Juju controller that enables units to share information. This topology allows units to share data, without needing direct connectivity between units is restricted by firewall rules. Charms define the logic for transferring and interpreting integration data.

The most common use of ‘juju integrate’ specifies two applications that co-exist within the same model:

juju integrate <application> <application>

Occasionally, more explicit syntax is required. Juju is able to integrate units that span models, controllers and clouds, as described below.

Integrating applications in the same model

The most common case specifies two applications, adding specific endpoint name(s) when required.

juju integrate <application>[:<endpoint>] <application>[:<endpoint>]

The role and endpoint names are described by charms’ metadata.yaml file.

The order does not matter, however each side must implement complementary roles. One side implements the “provides” role and the other implements the “requires” role. Juju can always infer the role that each side is implementing, so specifying them is not necessary as command-line arguments.

<application> is the name of an application that has already been added to the model. The Applications section of ‘juju status’ provides a list of current applications.

<endpoint> is the name of an endpoint defined within the metadata.yaml of the charm for <application>. Valid endpoint names are defined within the “provides:” and “requires:” section of that file. Juju will request that you specify the <endpoint> if there is more than one possible integration between the two applications.

Subordinate applications

Subordinate applications are designed to be deployed alongside a primary application. They must define a container scoped endpoint. When that endpoint is related to a primary application, wherever a unit of the primary application is deployed, a corresponding unit of the subordinate application will also be deployed. Integration with the primary application has the same syntax as integration any two applications within the same model.

Peer integrations

Integrations within an application between units (known as “peer integrations”) do not need to be added manually. They are created when the ‘juju add-unit’ and ‘juju scale-application’ commands are executed.

Cross-model integrations

Applications can be integrated, even when they are deployed to different models. Those models may be managed by different controllers and/or be hosted on different clouds. This functionality is known as “cross-model integration” or CMI.

Cross-model integrations: different model on the same controller

Integrating applications in models managed by the same controller is very similar to adding an integration between applications in the same model:

juju integrate <application>[:<endpoint>] <model>.<application>[:<endpoint>]

<model> is the name of the model outside of the current context. This enables the Juju controller to bridge two models. You can list the currently available models with ‘juju models’.

To integrate models outside of the current context, add the ‘-m <model>’ option:

juju integrate -m <model> <application>[:<endpoint>] \
                 <model>.<application>[:<endpoint>]

Cross-model integrations: different controllers

Applications can be integrated with a remote application via an “offer URL” that has been generated by the ‘juju offer’ command. The syntax for adding a cross-model integration is similar to adding a local integration:

juju integrate <application>[:<endpoint>] <offer-endpoint>

<offer-endpoint> describes the remote application, from the point of view of the local one. An <offer-endpoint> takes one of two forms:

<offer-alias>
<offer-url>[:<endpoint>]

<offer-alias> is an alias that has been defined by the ‘juju consume’ command. Use the ‘juju find-offers’ command to list aliases.

<offer-url> is a path to enable Juju to resolve communication between controllers and the models they control.

[[<controller>:]<user>/]<model-name>.<application-name>

<controller> is the name of a controller. The ‘juju controllers’ command provides a list of controllers.

<user> is the user account of the model’s owner.

Cross-model integration: network management

When the consuming side (the local application) is behind a firewall and/or NAT is used for outbound traffic, it is possible to use the ‘–via’ option to inform the offering side (the remote application) the source of traffic to enable network ports to be opened.

... --via <cidr-subnet>[,<cidr-subnet>[, ...]]