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Resiliency Policy Error Code Retries
Signed-off-by: Anton Troshin <[email protected]>
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‎20240917-BR-resiliency-error-code-retries.md‎

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# Resiliency Policy Error Code Retries
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* Author(s): Anton Troshin (@antontroshin), Taction (@taction)
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* Updated: 2024-09-18
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## Overview
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This is a design proposal to provide additional functionality for Dapr Resiliency Policy Retries to be able to enforce policy only on specific response error codes.
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It only focuses on the `retries` (https://docs.dapr.io/operations/resiliency/policies/#retries) part of the policy.
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## Background
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In some applications, error codes may be used to indicate the business error, and retrying the operation might not be necessary or otherwise desirable.
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Customizing retry behavior will allow a more granular way to handle error codes that suit each use case.
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Currently, all errors are retried when the policy is applied.
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Some errors are not retryable, and subsequent calls will result in the same error, avoiding these retry calls will reduce the overall amount of requests, traffic, and errors.
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## Related Items
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https://github.com/dapr/dapr/issues/6683
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https://github.com/dapr/dapr/issues/6428
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https://github.com/dapr/dapr/issues/7697
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PR:
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https://github.com/dapr/dapr/pull/7132
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Docs:
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https://github.com/dapr/docs/issues/4254
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https://github.com/dapr/docs/issues/3859
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## Expectations and alternatives
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* What is in scope for this proposal?
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- HTTP and gRPC Service Invocation, direct and proxied
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- Bindings
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- Pub/Sub
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## Implementation Details
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### Design
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Add a new object field to the `retries` policy Spec to allow the user to specify the error codes that should be retried.
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Separate fields for HTTP and gRPC. The new fields should be optional and will default to the existing behavior, which is to retry on all errors.
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### Example 1:
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In this example, the retry policy will retry **_only_** on HTTP 500 and HTTP error range 502-504 (inclusive) and gRPC error range 2-4 (inclusive).
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The rest of the errors will not be retried.
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```yaml
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apiVersion: dapr.io/v1alpha1
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kind: Resiliency
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metadata:
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name: myresiliency
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scopes:
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- app1
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spec:
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policies:
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retries:
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pubsubRetry:
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policy: constant
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duration: 5s
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maxRetries: 10
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matching:
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httpStatusCodes: "500,502-504"
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gRPCStatusCodes: "2-4"
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```
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### Example 2:
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In this example, the retry policy will retry **_only_** on gRPC error range 1-15 (inclusive).
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However, this policy will not apply to the HTTP errors, and they will be retried according to the default behavior, which is to retry on all errors.
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```yaml
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apiVersion: dapr.io/v1alpha1
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kind: Resiliency
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metadata:
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name: myresiliency
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scopes:
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- app1
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spec:
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policies:
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retries:
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pubsubRetry:
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policy: constant
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duration: 5s
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maxRetries: 10
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matching:
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gRPCStatusCodes: "1-15"
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```
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### Acceptable Values
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The acceptable values are the same as the ones defined in the [HTTP Status Codes](https://developer.mozilla.org/en-US/docs/Web/HTTP/Status) and [gRPC Status Codes](https://grpc.io/docs/guides/status-codes/) documentation.
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- HTTP: from 100 to 599
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- gRPC: from 1 to 16
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### Setting Format
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Both the `httpStatusCodes` and `gRPCStatusCodes` fields are of type string and optional and can be set to a comma-separated list of error codes and/or ranges of error codes.
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The range must be in the format `<start>-<end>` (inclusive). Having more than one dash in the range is not allowed.
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### Parsing the configuration
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The configuration values will be first parsed as comma-separated lists.
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Each entry in the list will be then parsed as a single error code or a range of error codes.
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For invalid entries, the error will be logged when the policy is first loaded and the entry will be ignored, this will not fail the entire policy or the application start.
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Example:
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```yaml
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apiVersion: dapr.io/v1alpha1
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kind: Resiliency
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metadata:
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name: myresiliency
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scopes:
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- app1
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spec:
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policies:
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retries:
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pubsubRetry:
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policy: constant
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duration: 5s
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maxRetries: 10
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matching:
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httpStatusCodes: "500,502-504,15,404-405-500,-1,0,"
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```
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The steps to parse the configuration are:
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1. Split the `httpStatusCodes` configuration string `"500,502-504,15,404-405-500,-1,0,"` by the comma character resulting in the following list: `["500", "502-504", "15", "404-405-500", "-1", "0"]` ignoring the empty strings.
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2. For each entry in the list, parse it as a single error code or a range of error codes.
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3. If the entry is a single error code, add it to the list of error codes to retry.
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4. If the entry is a range of error codes (each field for the relevant HTTP or gRPC error codes), add all the error codes in the range to the list of error codes to retry.
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- 500 is **valid** code for HTTP
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- 502-504 **valid** range of codes for HTTP
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- 15 is **invalid** code for HTTP, error logged and entry ignored
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- 404-405-500 is **invalid** range contains more than one dash, error logged and entry ignored
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- -1 is ignored is **invalid** code for HTTP, error logged and entry ignored
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- 0 is ignored is **invalid** code for HTTP, error logged and entry ignored
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### Acceptance Criteria
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Integration and unit tests will be added to verify the new functionality.
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## Completion Checklist
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* Code changes
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* Tests added (e2e, unit)
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* Documentation

‎templates/proposal.md‎

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## Background
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This section is intented to provide the community with the reasoning behind this proposal -- why is this proposal being made? What problem is it solving for users / developers / operators and how does it solve that for them?
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This section is intended to provide the community with the reasoning behind this proposal -- why is this proposal being made? What problem is it solving for users / developers / operators and how does it solve that for them?
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## Related Items
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How will success be measured?
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* Performance targets
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* Compabitility requirements
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* Compatibility requirements
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* Metrics
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## Completion Checklist

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