Automatic Retries

Sometimes requests fail. When these requests fail for transient issues, Ambassador Edge Stack can automatically retry the request.

Retry policy can be set for all Ambassador Edge Stack mappings in the ambassador Module, or set per Mapping. Generally speaking, you should set retry policy on a per mapping basis. Global retries can easily result in unexpected cascade failures.

Configuring Retries

The retry_policy attribute configures automatic retries. The following fields are supported:

retry_policy:
retry_on: <string>
num_retries: <integer>
per_try_timeout: <string>

retry_on

(Required) Specifies the condition under which Ambassador Edge Stack retries a failed request.

ValueDescription
5xxRetries if the upstream service responds with any 5xx code or does not respond at all
gateway-errorSimilar to a 5xx but only applies to a 502, 503, or 504 response
connect-failureRetries on a connection failure to the upstream service (included in 5xx)
retriable-4xxRetries on a retriable 4xx response (currently only 409)
refused-streamRetires if the upstream service sends a REFUSED_STREAM error (included in 5xx)
retriable-status-codesRetries based on status codes set in the x-envoy-retriable-status-codes header. If that header isn't set, Ambassador will not retry the request.

For more details on each of these values, see the Envoy documentation.

num_retries

(Default: 1) Specifies the number of retries to execute for a failed request.

per_try_timeout

(Default: global request timeout) Specify the timeout for each retry, e.g., 1s, 1500ms.

Examples

A per mapping retry policy:

---
apiVersion: getambassador.io/v2
kind: Mapping
metadata:
name: quote-backend
spec:
prefix: /backend/
service: quote
retry_policy:
retry_on: "5xx"
num_retries: 10

A global retry policy (not recommended):

---
apiVersion: getambassador.io/v2
kind: Module
metadata:
name: ambassador
spec:
config:
retry_policy:
retry_on: "retriable-4xx"
num_retries: 4
---
apiVersion: getambassador.io/v2
kind: Mapping
metadata:
name: quote-backend
spec:
prefix: /backend/
service: quote

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