The requirement for the Contoso Fiber CAMS application is that the combined service level agreement for all components in the hot path is greater than 99.9%. The components in the hot path comprise of any service that is used in fulfilling a web request from a user.
With a development environment, network isolation is not used. The following services are considered:
| Service | Azure SLA |
|---|---|
| Azure Front Door | 99.990% |
| Entra ID | 99.990% |
| Azure App Service | 99.950% |
| Azure Container Apps | 99.950% |
| Azure Container Registry | 99.900% |
| Azure Cache for Redis | 99.900% |
| Azure Postgres Flexible Server | 99.990% |
| Azure Storage | 99.900% |
| Azure Key Vault | 99.990% |
| App Configuration | 99.900% |
| Azure Service Bus | 99.900% |
| Combined SLA | 99.362% |
When operating in production, network isolation is used. We do not consider the availability of the hub resources or VNET peering.
| Service | Azure SLA |
|---|---|
| Azure Front Door | 99.9900% |
| Front Door Private Link | 99.9900% |
| Entra ID | 99.9900% |
| Private DNS Zone | 100.000% |
| Azure Key Vault | 99.9900% |
| Key Vault Private Link | 99.9900% |
| Azure Container Registry* | 99.9999% |
| Combined global SLO | 99.9499% |
- Note that the Azure Container Registry is deployed in two regions which allows its usual 99.9% SLA to increase to 99.9999% in total. For more information, see Azure Container Registry Geo-replication.
| Service | Azure SLA |
|---|---|
| Azure App Service | 99.950% |
| - Private Link | 99.990% |
| Azure Container App | 99.950% |
| - Private Link | 99.990% |
| Azure Cache for Redis | 99.900% |
| - Private Link | 99.990% |
| Azure Postgres Flexible Server | 99.990% |
| - Private Link | 99.990% |
| Azure Storage | 99.900% |
| - Private Link | 99.990% |
| App Configuration | 99.900% |
| - Private Link | 99.990% |
| Azure Service Bus | 99.900% |
| Combined regional SLO | 99.4215% |
Because there are two redundant regions, the total regional SLO for the two regions combined is calculated as 1 - (1 - SLO)^2 where SLO is the SLO for a single regional spoke deployment. This gives us a total combined regional service SLO of 99.9967%.
This total regional SLO is combined with the global SLO to give the total SLO for the production environment: 99.9467%.
By having redundant resources in two regions, the total SLO for the production environment (99.9467%) exceeds the requirement of 99.9%.
For more information on how to calculate effective SLO, please refer to the Well Architected Framework.