Application
An application is composed of a single or multiple Docker containers in CaaStle.
CaaStle offers ‘cld container create’ command to build your application container/s from your Docker files and push them to your registry of choice. The container is appropriately tagged for AWS ECR or Google GCR to make it ready to run on COE target of your choice.
Note that for GCR currently all the images are stored in the us.gcr.io region. We have an issue open to support different regions.
Application definition is done using our yaml format for single container applications or respective COE yaml format such as Kubernetes yaml format for multi-container applications. Note that for Kubernetes yaml format, currently only Pod definitions are supported. Support for ECS task yaml is planned.
Application definition includes URIs of the built containers from container registry, container inter-dependencies and any other run-time parameters to run each container. Here is a sample app yaml definition for a single container wordpress application.
app:
image: <image_uri>
container_port: 5000
env:
PASSWORD: $CLOUDARK_RDS_MasterUserPassword
DB: $CLOUDARK_RDS_DBName
HOST: $CLOUDARK_RDS_Address
USER: $CLOUDARK_RDS_MasterUsername
Our yaml format for single container applications supports following attributes: image, container_port, host_port, env. Default value for host_port is 80.
Application is deployed in an environment. The application deployment action takes the name of the environment as input (‘cld app deploy <app-name> <env-name> <app yaml>’). app.yaml contains definition of the application container image, the container port and any environment variables. As part of the deployment steps CaaStle binds the application container(s) to cloud resources defined in the environment.
For single container applications currently a single instance of the application container is deployed on the cluster in the environment.
We have an issue open to support scaling of application containers.