--- name: azion-add-a-backup-origin-to-a-connector description: >- Keep a standby origin out of daily traffic, and let it receive requests only when every primary address of the connector fails. --- # Add a backup origin to a connector You add a standby origin to a [connector](/en/documentation/platform/connectors/) as a *Backup* address of [Load Balancer](/en/documentation/platform/connectors/#load-balancer), from Azion Console, the API, or the Azion CLI. To spread live traffic across several origins with weights instead, refer to [Balance traffic across multiple origins](/en/documentation/guides/application-performance/availability/multiple-origins/). A *Backup* address stands by out of daily traffic, and it receives requests only when every *Primary* address fails. *Primary* addresses are always preferred, so the standby carries no traffic while the primary answers. Load Balancer has no health check: no probe and no interval, so nothing tests an address between requests. ```mermaid %%{init: {"layout": "dagre", "themeVariables": {"fontSize": "13px"}, "flowchart": {"nodeSpacing": 12, "rankSpacing": 12, "padding": 6, "wrappingWidth": 70, "minNodeWidth": 40, "useMaxWidth": true}}}%% flowchart TD Rule["A Set Connector rule names the connector"] --> Role{"Does a Primary address answer?"} Role -->|"yes"| Primary["The Primary address receives the request"] Role -->|"no: every Primary address fails"| Backup["The Backup address receives the request"] Primary --> Client["The client receives the response"] Backup --> Client ``` 1. A rule's *Set Connector* behavior sends the request to the connector, which has Load Balancer on. 2. While a *Primary* address answers, it receives every request, and the *Backup* address receives none. 3. When every *Primary* address fails, the *Backup* address receives the request. 4. The client receives the response from the address that served it, with no DNS change. --- ## Prerequisites - A connector of type `http` that reaches your primary origin, and a rule whose *Set Connector* behavior sends requests to it. To create both, refer to [Connectors quickstart](/en/documentation/platform/connectors/quickstart/). - A standby origin that holds the same content as the primary and is set up the same way for the application. - Access to Azion Console, for the Console procedure. Refer to [Access Azion Console](/en/documentation/guides/platform/account-and-billing/how-to-access-azion-console/). - A [personal token](/en/documentation/guides/platform/account-and-billing/personal-tokens/) and the ID of the connector, for the API procedure. - The [Azion CLI](/en/documentation/devtools/cli/) installed and authorized, and the ID of the connector, for the CLI procedure. The examples use `primary.example.com` for the primary origin, `standby.example.com` for the standby, and `www.example.com` for the domain. Replace them with yours. --- ## Add the standby as a backup address A connector holds one address until Load Balancer is on, and up to 15 addresses with it on. The method is *Round Robin* or *Least Connections*, because *IP Hash* refuses a *Backup* address with `28005`. Every address is *Primary* unless you set it otherwise. **Max Retries** sets the retry attempts when a connection to the origin fails, from 0 to 20. **Connection Timeout** limits the wait for that connection, from 1 to 300 seconds, and **Read/Write Timeout** limits the wait for data on an open connection, from 1 to 600 seconds. The client waits through every retry before it receives an answer. The Console fills in `3`, `30`, and `60`. The API and the CLI give a key the body leaves out `0`, `60`, and `120`, so a connector without `max_retries` does not retry a failed connection. The examples set the Console values in every interface. **Console** To add the backup address in Azion Console: 1. **Open the connector** Access [Azion Console](https://console.azion.com/) > **Connectors**, and select the connector of your primary origin. 2. **Turn on Load Balancer** In **Modules**, turn on **Load Balancer**. The form fills in **Max Retries**, **Connection Timeout**, and **Read/Write Timeout**. 3. **Select the method** In **Load Balancer Configuration**, set **Method** to *Round Robin*. 4. **Set the retries and timeouts** Enter `3` in **Max Retries**, `30` in **Connection Timeout**, and `60` in **Read/Write Timeout**. 5. **Keep the primary origin as primary** Under **Address Management**, on `primary.example.com`, set **Server Role** to *Primary*. 6. **Select Add Address** 7. **Enter the standby** In the new **Address**, enter `standby.example.com`, without a protocol or a port. 8. **Set the backup role** Set **Server Role** to *Backup*, and keep **Active** turned on. 9. **Select Save** The Console shows `Connector has been updated`. **API** To add the backup address with the API, send a `PATCH` request to the connector. `addresses` replaces the list of addresses, so the body carries both: ```bash curl --request PATCH \ --url https://api.azion.com/v4/workspace/connectors/ \ --header 'Accept: application/json' \ --header 'Authorization: Token ' \ --header 'Content-Type: application/json' \ --data '{ "attributes": { "addresses": [ { "address": "primary.example.com", "modules": { "load_balancer": { "server_role": "primary", "weight": 1 } } }, { "address": "standby.example.com", "modules": { "load_balancer": { "server_role": "backup", "weight": 1 } } } ], "modules": { "load_balancer": { "enabled": true, "config": { "method": "round_robin", "max_retries": 3, "connection_timeout": 30, "read_write_timeout": 60 } } } } }' ``` The API answers `202` with `"state": "pending"`. A `PATCH` keeps the connection options the body leaves out. **CLI** The update command takes the whole connector from a file, with every field the connector keeps. To read the current settings of the connector: ```bash azion describe connector --connector-id --format json ``` The command prints the full object. On a connector of type `http`, `attributes` holds `addresses`, `connection_options`, and `modules`. Save the connector as `connector.json`, with the standby added and Load Balancer on. Replace `name` and `connection_options` with the values the command printed: ```json { "name": "", "active": true, "type": "http", "attributes": { "addresses": [ { "address": "primary.example.com", "modules": { "load_balancer": { "server_role": "primary", "weight": 1 } } }, { "address": "standby.example.com", "modules": { "load_balancer": { "server_role": "backup", "weight": 1 } } } ], "connection_options": { "dns_resolution": "both", "transport_policy": "preserve", "host": "${host}" }, "modules": { "load_balancer": { "enabled": true, "config": { "method": "round_robin", "max_retries": 3, "connection_timeout": 30, "read_write_timeout": 60 } } } } } ``` Update the connector from the file. The command needs `--type` even though the file names the type: ```bash azion update connector --connector-id --type http --file connector.json ``` The output confirms the update: ```text Updated Connector with ID ``` The connector holds the primary origin and the standby, and the rule that names it needs no change. A connector change reaches Azion's distributed infrastructure over several minutes, and data centers apply it at different times. Both addresses receive the same `Host` header, path prefix, and protocol from the connector. When the standby answers under another name than the primary, set **Host** to `${host}`, which sends the host the client requested. For the connection options, refer to [Connector settings](/en/documentation/platform/connectors/settings/#connection-options). --- ## Confirm the standby takes over The check takes the primary out of service, so run it in a maintenance window. It reads **Upstream Addr** in the *HTTP Requests* data source of Real-Time Events, which holds the IP address and port of the server a request was sent to. To confirm the failover: 1. **Stop the primary origin** Stop the web server on `primary.example.com`, or block the connections from Azion at its firewall. 2. **Send requests through your domain** ```bash curl -s -o /dev/null -w '%{http_code}\n' https://www.example.com/ ``` The command prints the status code of each response. Send it several times. 3. **Open Real-Time Events** Access [Azion Console](https://console.azion.com/) > **Products menu** > **Observe** > **Real-Time Events**, and select *HTTP Requests* in **Data Sources**. 4. **Filter by your domain** In **Filter by**, enter `host='www.example.com'`, and select **Refresh**. 5. **Read the upstream address** The newest records carry the IP address of `standby.example.com` in **Upstream Addr**. 6. **Start the primary origin again** The standby serves the requests while the primary is down. Once the primary answers again, it takes the requests back, because *Primary* addresses are always preferred over *Backup* addresses. A data center that has not received a change yet can still answer as before, so repeat the search until the records agree. For the filter syntax, refer to [Filter events](/en/documentation/guides/platform/observability/add-filters-events/). --- ## Next steps - [Balancing methods](/en/documentation/platform/connectors/load-balancer/balancing-methods.md#server-role): How the server role, the retries, and the timeouts decide where a request goes. - [Show your own page when no origin answers](/en/documentation/guides/application-performance/availability/show-your-own-page-when-no-origin-answers.md): Replace Azion's error with your page when neither the primary nor the standby answers. - [Keep an application online when an origin fails](/en/documentation/use-cases/improve-performance-and-reliability/keep-an-application-online-when-an-origin-fails.md): A primary and a standby origin in one pool, with an error page when both fail. - [Route users to regional origins](/en/documentation/use-cases/improve-performance-and-reliability/route-users-to-regional-origins.md): A default region with a backup in another region, only where residency rules allow it.