Application service¶
Overview¶
Application service is a representation of a service in an application instance. Or it can be described as a configuration entity created per each service in a stack. It's similar to a stack service inside a stack but exists in the context of an app instance.
When you create a new app, app services created with the default configuration of corresponding stack services. You can further override configuration per specific app instance through app services.
You can also change your stack configuration and then upgrade an app instance's stack with override settings, in this case configurations from stack services will be transferred to app services.
Configuration¶
- Each app services can be enabled or disabled
- Service version can be changed
- For stateless services you can change the number of replicas
When an app service's configuration changed, the app instance will be marked as needs rebuild because configuration may affect the build process.
Build source¶
If a service is buildable, app service will have configuration for build source. You can specify a git repository and a reference: branch, tag or commit hash. Build source selected when you create a new app instance but can be also changed in the existing app instance.
Integrations¶
If a service provides certain integrations (e.g. backup storage for a database) you can attach integrations of the appropriate types to an app service.
Environment variables¶
Here you can add, remove and override environment variables that will apply to a selected container. Some of the environment variables cannot be removed but can be overridden. Environment variables that cannot be removed can come from the following sources:
- Service manifest. A service may define environment variables in its manifest
- Stack manifest. A stack manifest can override environment variables or add global environment variables that added to all services in the stack
- From linked service, for example, a database link usually adds environment variables with connection credentials
- From settings
Also, Wodby adds the following global variables to every container:
| Variable | Description |
|---|---|
WODBY_APP_NAME |
Machine name of the application |
WODBY_INSTANCE_NAME |
Machine name of the application instance |
WODBY_ENVIRONMENT_NAME |
Name of the environment |
WODBY_ENVIRONMENT_TYPE |
Type of the environment |
WODBY_HOSTS |
List of domains from enabled HTTP routes |
WODBY_PRIMARY_HOST |
Hostname from the enabled main app service with an HTTP route |
WODBY_PRIMARY_URL |
URL (https if certificate attached) of the enabled main app service with an HTTP route |
Resources¶
Here you can configure resources for a service. You can specify CPU and memory requests and limits. CPU request and limits specified in milicores where 1000 milicores equal to 1 CPU core. Memory requests and limits specified in mebibytes where 1024 mebibytes equal to 1 GB.
Please note that resources request affects the deployment of the app service. For example, if your kubernetes cluster does not have enough resources to deploy an app service's pod with a requested amount of CPU or memory, the pod will be in a pending state until the resources become available. If your cluster has horizontal autoscaling enabled, it will scale up number of nodes to meet the demand.
Replicas¶
App service replicas is the number of an app service's container instances. Serverless app services can be easily scaled with the number of replicas for high availability and redundancy. Also, can be increased automatically if autoscaling enabled. Some stateful services support scalability with extra replicas, e.g. database server's read replicas.
Links¶
Here you can change links between app services. Usually they are set up in a stack but can also be overridden per app instance.
Volumes¶
Currently, volumes resize not supported and cannot be changed in an existing app instance. You can only specify volume sizes when you create a new app instance.
Settings¶
You can change values of settings
Configs¶
You can view default configs and override them.
Tokens¶
You can add or remove tokens that can be used in environment variables.