07 - Revisions and Traffic Splitting¶

Azure Container Apps revisions provide immutable deployment snapshots of your .NET application. Use them for safe releases, canary traffic, and quick rollback to a known-good state.

flowchart TD
    INET[Internet] -->|HTTPS| CA["Container App\nConsumption\nLinux .NET 8"]

    subgraph VNET["VNet 10.0.0.0/16"]
        subgraph ENV_SUB["Environment Subnet 10.0.0.0/23\nDelegation: Microsoft.App/environments"]
            CAE[Container Apps Environment]
            CA
        end
        subgraph PE_SUB["Private Endpoint Subnet 10.0.2.0/24"]
            PE_ACR[PE: ACR]
            PE_KV[PE: Key Vault]
            PE_ST[PE: Storage]
        end
    end

    PE_ACR --> ACR[Azure Container Registry]
    PE_KV --> KV[Key Vault]
    PE_ST --> ST[Storage Account]

    subgraph DNS[Private DNS Zones]
        DNS_ACR[privatelink.azurecr.io]
        DNS_KV[privatelink.vaultcore.azure.net]
        DNS_ST[privatelink.blob.core.windows.net]
    end

    PE_ACR -.-> DNS_ACR
    PE_KV -.-> DNS_KV
    PE_ST -.-> DNS_ST

    CA -.->|System-Assigned MI| ENTRA[Microsoft Entra ID]
    CAE --> LOG[Log Analytics]
    CA --> AI[Application Insights]

    style CA fill:#107c10,color:#fff
    style VNET fill:#E8F5E9,stroke:#4CAF50
    style DNS fill:#E3F2FD

Revision Traffic Splitting¶

graph LR
    INGRESS[Ingress] -->|90%| V1[Revision v1]
    INGRESS -->|10%| V2[Revision v2]

Prerequisites¶

• Completed 06 - CI/CD with GitHub Actions
• At least two deployed images/tags in your ACR
• Container App currently running in multiple revision mode or ready to switch

Step-by-step¶

1. Set standard variables

RG="rg-dotnet-guide"
DEPLOYMENT_NAME="main"
BASE_NAME="dotnet-guide"

APP_NAME=$(az deployment group show \
  --name "$DEPLOYMENT_NAME" \
  --resource-group "$RG" \
  --query "properties.outputs.containerAppName.value" \
  --output tsv)

ACR_NAME=$(az deployment group show \
  --name "$DEPLOYMENT_NAME" \
  --resource-group "$RG" \
  --query "properties.outputs.containerRegistryName.value" \
  --output tsv)

ACR_LOGIN_SERVER=$(az deployment group show \
  --name "$DEPLOYMENT_NAME" \
  --resource-group "$RG" \
  --query "properties.outputs.containerRegistryLoginServer.value" \
  --output tsv)

1. Switch to multiple revision mode

By default, Container Apps operate in single revision mode (100% traffic to the latest). To split traffic, you must enable multiple mode.

az containerapp revision set-mode \
  --name "$APP_NAME" \
  --resource-group "$RG" \
  --mode multiple

???+ example "Expected output"

"Multiple"

1. Deploy a new version to create a new revision

az acr build --registry "$ACR_NAME" --image "$BASE_NAME:v3" ./apps/dotnet-aspnetcore

az containerapp update \
  --name "$APP_NAME" \
  --resource-group "$RG" \
  --image "$ACR_LOGIN_SERVER/$BASE_NAME:v3"

???+ example "Expected output"

{
  "latestRevision": "<your-app-name>--xxxxxxx",
  "name": "<your-app-name>",
  "provisioningState": "Succeeded"
}

1. List revisions and identify target names

az containerapp revision list \
  --name "$APP_NAME" \
  --resource-group "$RG" \
  --query "[].{name:name,active:properties.active,createdTime:properties.createdTime}" \
  --output table

???+ example "Expected output"

Name                               Active    CreatedTime
---------------------------------  --------  -------------------------
<your-app-name>--0000001           True      2026-04-04T16:00:00+00:00
<your-app-name>--0000002           True      2026-04-04T16:30:00+00:00

1. Apply canary traffic split (90/10)

Capture the revision names from the list above, then apply traffic weights:

# Replace with your actual revision names from Step 4
OLD_REV="${APP_NAME}--0000001"
NEW_REV="${APP_NAME}--0000002"

az containerapp ingress traffic set \
  --name "$APP_NAME" \
  --resource-group "$RG" \
  --revision-weight "$OLD_REV=90" "$NEW_REV=10"

???+ example "Expected output"

[
  {
    "revisionName": "<your-app-name>--0000001",
    "weight": 90
  },
  {
    "revisionName": "<your-app-name>--0000002",
    "weight": 10
  }
]

1. Verify applied traffic routing

az containerapp ingress show \
  --name "$APP_NAME" \
  --resource-group "$RG"

???+ example "Expected output"

{
  "fqdn": "<your-app-name>.<env-suffix>.koreacentral.azurecontainerapps.io",
  "traffic": [
    { "revisionName": "<your-app-name>--0000001", "weight": 90 },
    { "revisionName": "<your-app-name>--0000002", "weight": 10 }
  ]
}

1. Rollback instantly if .NET exceptions increase

If the canary revision shows high error rates in Log Analytics, move all traffic back to the stable revision.

az containerapp ingress traffic set \
  --name "$APP_NAME" \
  --resource-group "$RG" \
  --revision-weight "$OLD_REV=100"

1. Deactivate the bad revision

az containerapp revision deactivate \
  --name "$APP_NAME" \
  --resource-group "$RG" \
  --revision "$NEW_REV"

Operational Guidance for .NET¶

• Health Probes: Ensure your liveness and readiness probes (/health) are correctly configured so Container Apps doesn't route traffic to a revision that hasn't finished its .NET runtime startup.
• Graceful Shutdown: ASP.NET Core handles SIGTERM signals. When you shift traffic away from a revision, the platform waits for active connections to finish (up to the termination grace period) before stopping the container.
• Sticky Sessions: If your .NET app uses in-memory sessions (not recommended), traffic splitting will break session state unless you use an external provider like Redis.

Advanced Topics¶

• Blue/Green Deployment: Use labels to route traffic to specific revisions without modifying weights until the "Green" revision is fully verified.
• Dapr service invocation: Dapr can be configured to respect traffic splitting or route to specific revisions using headers.
• Automated Promotion: Use GitHub Actions to increase traffic weight automatically if health checks and telemetry thresholds are met.

See Also¶

• 04 - Logging, Monitoring, and Observability
• 06 - CI/CD with GitHub Actions
• Revision Management Operations

Sources¶

• Revisions in Azure Container Apps (Microsoft Learn)
• Traffic splitting (Microsoft Learn)