Container Placement Groups
Through the topology modeler tab of the Add Application Profile form, Workload Manager lets you create a single container tier with multiple containers in the same pod. The graphical tool that lets you do this is called a container placement group.
A placement group represents a container pod and a tier in the application profile. A placement group is represented by a rectangle that you add to the topology modeler canvas by clicking the Create A Group button as indicated in the following screenshot. This support is available for some services like Apache, Nginx, MongoDB, and MySQL.
You can only drag and drop supported containers into the Create a Group rectangle.
Click and drag container-based services from the services palate on the left side of the topology modeler tab to the placement group rectangle, similar to the Apache2 profile and MongoDB profile that are visible in the canvas displayed in the following screenshot.
The properties panel on the right displays the properties for the currently selected object, which in this case is the last container dragged into the placement group, MongoDB. Notice that the minimum and maximum replicas fields in the General Settings section are not available, and the Network Services and Firewall Rules sections are also not available for this container. This is because these parameters are properties of the tier/pod. To see these parameters, click on the border of the placement group to select the placement group as a whole.
After selecting the placement group, notice the following in the Properties panel:
The name of the placement group contains the name of the first container dragged to the group (but you can edit this field).
Expanding the sections for Network Services and then Firewall Rules reveals that these sections automatically contain the union of the corresponding network services and firewall rules of the constituent containers.
The sections for Volumes, Deployment Parameters, and Minimum Resource Specifications are gone as these are specific to each container in the pod.
When deploying an application with a container tier that contains multiple containers, each container is listed within the corresponding per tier section on Page 1 of the deploy form.
If the container has visible parameters (defined in the application profile), an expand triangular icon appears to the left of the container name. Click on the expand icon to expand that section and display the deployment parameters.
On Page 2 of the deploy form you have the option to specify the instance type for each container separately.
After the application successfully deploys, the individual containers within each replica of the pod are shown in the deployment Details page as described in the Deployment Details section.
See Container Service for details on the Generate unique service name toggle switch.
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