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MeshRetry
This policy uses new policy matching algorithm. Do not combine with Retry.
This policy enables Kong Mesh to know how to behave if there are failed requests which could be retried.
TargetRef support matrix
targetRef.kind |
top level | to | from |
|---|---|---|---|
Mesh |
✅ | ✅ | ❌ |
MeshSubset |
✅ | ❌ | ❌ |
MeshService |
✅ | ✅ | ❌ |
MeshServiceSubset |
✅ | ❌ | ❌ |
To learn more about the information in this table, see the matching docs.
Configuration
The policy let you configure retry behaviour for HTTP, GRPC and TCP protocols.
The protocol is selected by picking the most specific protocol.
Each protocol has a separate section under default in the policy yaml.
Some sections are common between protocols or have similar meaning.
Retry on
The field retryOn is a list of conditions which will cause a retry.
For HTTP these are related to the response status code or method (5xx, 429, HttpMethodGet).
For gRPC these are status codes in response headers (canceled, deadline-exceeded, etc.).
There is no equivalent for TCP.
One or more conditions can be specified, for example:
retryOn:
- "429"
- "503"
means that it the policy will retry on a status code 429 or 503.
Full list of available HTTP conditions:
retryOn:
- 5XX
- GatewayError
- Reset
- Retriable4xx
- ConnectFailure
- EnvoyRatelimited
- RefusedStream
- Http3PostConnectFailure
- HttpMethodConnect
- HttpMethodDelete
- HttpMethodGet
- HttpMethodHead
- HttpMethodOptions
- HttpMethodPatch
- HttpMethodPost
- HttpMethodPut
- HttpMethodTrace
- "429" # any HTTP status code
- "503"
Full list of available gRPC conditions:
retryOn:
- Canceled
- DeadlineExceeded
- Internal
- ResourceExhausted
- Unavailable
Back off
This parameter is applicable to both HTTP and GRPC.
It consists of BaseInterval (the amount of time between retries) and
MaxInterval (the maximal amount of time taken between retries).
We use an exponential back-off algorithm with jitter for retries. Given a base interval B and retry number N, the back-off for the retry is in the range [0, (2N - 1) × B).
For example, given a 25 ms interval, the first retry will be delayed randomly by 0-24 ms, the second by 0-74 ms, the third by 0-174 ms, and so on.
The interval is capped at a MaxInterval, which defaults to 10 times the BaseInterval.
Rate limited back off
This parameter is applicable to both HTTP and GRPC.
MeshRetry can be configured in such a way that
when the upstream server rate limits the request and responds with a header like retry-after or x-ratelimit-reset
it uses the value from the header to determine when to send the retry request instead of the back off algorithm.
Example
Given this configuration:
retryOn:
- "503"
rateLimitedBackOff:
resetHeaders:
- name: retry-after
format: Seconds
- name: x-ratelimit-reset
format: UnixTimestamp
and an HTTP response:
HTTP/1.1 503 Service Unavailable
retry-after: 15
The retry request will be issued after 15 seconds.
If the response is as follows:
HTTP/1.1 503 Service Unavailable
x-ratelimit-reset: 1706096119
The request will be retried at Wed Jan 24 2024 11:35:19 GMT+0000.
If the response does not contain retry-after or x-ratelimit-reset header (with valid integer value)
then the amount of time to wait before issuing a request is determined by back off algorithm.
Examples
HTTP frontend to backend on 5xx
apiVersion: kuma.io/v1alpha1
kind: MeshRetry
metadata:
name: web-to-backend-retry-http
namespace: kong-mesh-system
labels:
kuma.io/mesh: default
spec:
targetRef:
kind: MeshService
name: web
to:
- targetRef:
kind: MeshService
name: backend_kuma-demo_svc_8080
default:
http:
numRetries: 10
backOff:
baseInterval: 15s
maxInterval: 20m
retryOn:
- 5xx
gRPC frontend to backend on DeadlineExceeded
apiVersion: kuma.io/v1alpha1
kind: MeshRetry
metadata:
name: web-to-backend-retry-grpc
namespace: kong-mesh-system
labels:
kuma.io/mesh: default
spec:
targetRef:
kind: MeshService
name: web
to:
- targetRef:
kind: MeshService
name: backend_kuma-demo_svc_8080
default:
grpc:
numRetries: 5
backOff:
baseInterval: 5s
maxInterval: 1m
retryOn:
- DeadlineExceeded
TCP frontend to backend
apiVersion: kuma.io/v1alpha1
kind: MeshRetry
metadata:
name: web-to-backend-retry-tcp
namespace: kong-mesh-system
labels:
kuma.io/mesh: default
spec:
targetRef:
kind: MeshService
name: web
to:
- targetRef:
kind: MeshService
name: backend_kuma-demo_svc_8080
default:
tcp:
maxConnectAttempt: 5
All policy options
Spec is the specification of the Kuma MeshRetry resource.
Type: object
Properties
targetRef
required- TargetRef is a reference to the resource the policy takes an effect on. The resource could be either a real store object or virtual resource defined inplace.
- Type:
object - Properties
- kind
- Kind of the referenced resource
- Type:
string - The value is restricted to the following:
- "Mesh"
- "MeshSubset"
- "MeshService"
- "MeshServiceSubset"
- "MeshHTTPRoute"
- mesh
- Mesh is reserved for future use to identify cross mesh resources.
- Type:
string
- name
- Name of the referenced resource. Can only be used with kinds:
MeshService,MeshServiceSubsetandMeshGatewayRoute - Type:
string
- Name of the referenced resource. Can only be used with kinds:
- tags
- Tags used to select a subset of proxies by tags. Can only be used with kinds
MeshSubsetandMeshServiceSubset - Type:
object - This schema accepts additional properties.
- Properties
- Tags used to select a subset of proxies by tags. Can only be used with kinds
- kind
to
To list makes a match between the consumed services and corresponding configurations
Type:
arrayItems
Type:
objectProperties
default
Default is a configuration specific to the group of destinations referenced in 'targetRef'
Type:
objectProperties
grpc
GRPC defines a configuration of retries for GRPC traffic
Type:
objectProperties
backOff
- BackOff is a configuration of durations which will be used in exponential backoff strategy between retries.
- Type:
object - Properties
- baseInterval
- BaseInterval is an amount of time which should be taken between retries. Must be greater than zero. Values less than 1 ms are rounded up to 1 ms. Default is 25ms.
- Type:
string
- maxInterval
- MaxInterval is a maximal amount of time which will be taken between retries. Default is 10 times the "BaseInterval".
- Type:
string
- baseInterval
numRetries
- NumRetries is the number of attempts that will be made on failed (and retriable) requests.
- Type:
integer
perTryTimeout
- PerTryTimeout is the amount of time after which retry attempt should timeout. Setting this timeout to 0 will disable it. Default is 15s.
- Type:
string
rateLimitedBackOff
- RateLimitedBackOff is a configuration of backoff which will be used when the upstream returns one of the headers configured.
- Type:
object - Properties
- maxInterval
- MaxInterval is a maximal amount of time which will be taken between retries. Default is 300 seconds.
- Type:
string
- resetHeaders
- ResetHeaders specifies the list of headers (like Retry-After or X-RateLimit-Reset) to match against the response. Headers are tried in order, and matched case-insensitive. The first header to be parsed successfully is used. If no headers match the default exponential BackOff is used instead.
- Type:
array- Items
- Type:
object - Properties
- format
required- The format of the reset header, either Seconds or UnixTimestamp.
- Type:
string - The value is restricted to the following:
- "Seconds"
- "UnixTimestamp"
- name
required- The Name of the reset header.
- Type:
string - The value must match this pattern:
^[a-z0-9!#$%&'*+\-.^_\x60|~]+$ - Length: between 1 and 256
- format
- maxInterval
retryOn
- RetryOn is a list of conditions which will cause a retry. Available values are: [Canceled, DeadlineExceeded, Internal, ResourceExhausted, Unavailable].
- Type:
array- Items
- Type:
string
http
HTTP defines a configuration of retries for HTTP traffic
Type:
objectProperties
backOff
- BackOff is a configuration of durations which will be used in exponential backoff strategy between retries
- Type:
object - Properties
- baseInterval
- BaseInterval is an amount of time which should be taken between retries. Must be greater than zero. Values less than 1 ms are rounded up to 1 ms. Default is 25ms.
- Type:
string
- maxInterval
- MaxInterval is a maximal amount of time which will be taken between retries. Default is 10 times the "BaseInterval".
- Type:
string
- baseInterval
hostSelection
- HostSelection is a list of predicates that dictate how hosts should be selected when requests are retried.
- Type:
array- Items
- Type:
object - Properties
- predicate
required- Type is requested predicate mode. Available values are OmitPreviousHosts, OmitHostsWithTags, and OmitPreviousPriorities.
- Type:
string
- tags
- Tags is a map of metadata to match against for selecting the omitted hosts. Required if Type is OmitHostsWithTags
- Type:
object - This schema accepts additional properties.
- Properties
- updateFrequency
- UpdateFrequency is how often the priority load should be updated based on previously attempted priorities. Used for OmitPreviousPriorities. Default is 2 if not set.
- Type:
integer
- predicate
hostSelectionMaxAttempts
- HostSelectionMaxAttempts is the maximum number of times host selection will be reattempted before giving up, at which point the host that was last selected will be routed to. If unspecified, this will default to retrying once.
- Type:
integer
numRetries
- NumRetries is the number of attempts that will be made on failed (and retriable) requests
- Type:
integer
perTryTimeout
- PerTryTimeout is the amount of time after which retry attempt should timeout. Setting this timeout to 0 will disable it. Default is 15s.
- Type:
string
rateLimitedBackOff
- RateLimitedBackOff is a configuration of backoff which will be used when the upstream returns one of the headers configured.
- Type:
object - Properties
- maxInterval
- MaxInterval is a maximal amount of time which will be taken between retries. Default is 300 seconds.
- Type:
string
- resetHeaders
- ResetHeaders specifies the list of headers (like Retry-After or X-RateLimit-Reset) to match against the response. Headers are tried in order, and matched case-insensitive. The first header to be parsed successfully is used. If no headers match the default exponential BackOff is used instead.
- Type:
array- Items
- Type:
object - Properties
- format
required- The format of the reset header, either Seconds or UnixTimestamp.
- Type:
string - The value is restricted to the following:
- "Seconds"
- "UnixTimestamp"
- name
required- The Name of the reset header.
- Type:
string - The value must match this pattern:
^[a-z0-9!#$%&'*+\-.^_\x60|~]+$ - Length: between 1 and 256
- format
- maxInterval
retriableRequestHeaders
RetriableRequestHeaders is an HTTP headers which must be present in the request for retries to be attempted.
Type:
arrayItems
HeaderMatch describes how to select an HTTP route by matching HTTP request headers.
Type:
objectProperties
name
required- Name is the name of the HTTP Header to be matched. Name MUST be lower case as they will be handled with case insensitivity (See https://tools.ietf.org/html/rfc7230#section-3.2).
- Type:
string - The value must match this pattern:
^[a-z0-9!#$%&'*+\-.^_\x60|~]+$ - Length: between 1 and 256
type
- Type specifies how to match against the value of the header.
- Type:
string - The value is restricted to the following:
- "Exact"
- "Present"
- "RegularExpression"
- "Absent"
- "Prefix"
- Default: "Exact"
value
- Value is the value of HTTP Header to be matched.
- Type:
string
retriableResponseHeaders
RetriableResponseHeaders is an HTTP response headers that trigger a retry if present in the response. A retry will be triggered if any of the header matches match the upstream response headers.
Type:
arrayItems
HeaderMatch describes how to select an HTTP route by matching HTTP request headers.
Type:
objectProperties
name
required- Name is the name of the HTTP Header to be matched. Name MUST be lower case as they will be handled with case insensitivity (See https://tools.ietf.org/html/rfc7230#section-3.2).
- Type:
string - The value must match this pattern:
^[a-z0-9!#$%&'*+\-.^_\x60|~]+$ - Length: between 1 and 256
type
- Type specifies how to match against the value of the header.
- Type:
string - The value is restricted to the following:
- "Exact"
- "Present"
- "RegularExpression"
- "Absent"
- "Prefix"
- Default: "Exact"
value
- Value is the value of HTTP Header to be matched.
- Type:
string
retryOn
- RetryOn is a list of conditions which will cause a retry. Available values are: [5XX, GatewayError, Reset, Retriable4xx, ConnectFailure, EnvoyRatelimited, RefusedStream, Http3PostConnectFailure, HttpMethodConnect, HttpMethodDelete, HttpMethodGet, HttpMethodHead, HttpMethodOptions, HttpMethodPatch, HttpMethodPost, HttpMethodPut, HttpMethodTrace]. Also, any HTTP status code (500, 503, etc).
- Type:
array- Items
- Type:
string
tcp
- TCP defines a configuration of retries for TCP traffic
- Type:
object - Properties
- maxConnectAttempt
- MaxConnectAttempt is a maximal amount of TCP connection attempts which will be made before giving up
- Type:
integer
- maxConnectAttempt
targetRef
required- TargetRef is a reference to the resource that represents a group of destinations.
- Type:
object - Properties
- kind
- Kind of the referenced resource
- Type:
string - The value is restricted to the following:
- "Mesh"
- "MeshSubset"
- "MeshService"
- "MeshServiceSubset"
- "MeshHTTPRoute"
- mesh
- Mesh is reserved for future use to identify cross mesh resources.
- Type:
string
- name
- Name of the referenced resource. Can only be used with kinds:
MeshService,MeshServiceSubsetandMeshGatewayRoute - Type:
string
- Name of the referenced resource. Can only be used with kinds:
- tags
- Tags used to select a subset of proxies by tags. Can only be used with kinds
MeshSubsetandMeshServiceSubset - Type:
object - This schema accepts additional properties.
- Properties
- Tags used to select a subset of proxies by tags. Can only be used with kinds
- kind
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