By default, if we don't define any VirtualService, Istio will generate something like the following Envoy route/retry configuration:
{
"cluster": "outbound|9100||quote-svc-cip.quote.svc.cluster.local",
"timeout": "0s",
"retry_policy": {
"retry_on": "connect-failure,refused-stream,unavailable,cancelled,retriable-status-codes",
"num_retries": 2,
"retry_host_predicate": [
{
"name": "envoy.retry_host_predicates.previous_hosts"
}
],
"host_selection_retry_max_attempts": "5",
"retriable_status_codes": [
503
]
},
"max_grpc_timeout": "0s"
}
But if we specify our own VirtualService, e.g.:
apiVersion: networking.istio.io/v1beta1
kind: VirtualService
metadata:
name: book-svc-cip
namespace: book
spec:
hosts:
- book-svc-cip.book.svc.cluster.local
http:
- retries:
attempts: 3
retryOn: connect-failure,refused-stream,unavailable,retriable-status-codes
route:
- destination:
host: book-svc-cip.book.svc.cluster.local
The generated config will look like:
{
"cluster": "outbound|9281||book-svc-cip.book.svc.cluster.local",
"timeout": "0s",
"retry_policy": {
"retry_on": "connect-failure,refused-stream,unavailable,retriable-status-codes",
"num_retries": 3,
"retry_host_predicate": [
{
"name": "envoy.retry_host_predicates.previous_hosts"
}
],
"host_selection_retry_max_attempts": "5"
},
"max_grpc_timeout": "0s"
}
Notice that the retriable_status_codes is missing.
For the default, looks like it's defined in https://github.com/istio/istio/blob/1.9.0/pilot/pkg/networking/core/v1alpha3/route/retry/retry.go#L38-L39. But there is no option/field to configure retriable_status_codes via VirtualService.
How could we define the retriable_status_codes in Istio?
Update #1: My Istio version is 1.6.9. But if any newer version can support it, it's also appreciated.
The example in the documentation should work (according to the source code); I can verify it works on a later version.
https://istio.io/latest/docs/reference/config/networking/virtual-service/#HTTPRetry
retries:
attempts: 3
perTryTimeout: 2s
retryOn: connect-failure,refused-stream,503
The source code for 1.6.9 shows that the above example should work