Merge pull request dapr#3908 from elena-kolevska/error-codes

Error codes

daprdocs/content/en/reference/errors/_index.md

@@ -0,0 +1,99 @@
+---
+type: docs
+title: Dapr errors
+linkTitle: "Dapr errors"
+weight: 700
+description: "Information on Dapr errors and how to handle them"
+---
+
+## Error handling: Understanding errors model and reporting
+
+Initially, errors followed the [Standard gRPC error model](https://grpc.io/docs/guides/error/#standard-error-model). However, to provide more detailed and informative error messages, an enhanced error model has been defined which aligns with the gRPC [Richer error model](https://grpc.io/docs/guides/error/#richer-error-model). 
+
+{{% alert title="Note" color="primary" %}}
+Not all Dapr errors have been converted to the richer gRPC error model.
+{{% /alert %}}
+
+### Standard gRPC Error Model
+
+The [Standard gRPC error model](https://grpc.io/docs/guides/error/#standard-error-model) is an approach to error reporting in gRPC. Each error response includes an error code and an error message. The error codes are standardized and reflect common error conditions. 
+
+**Example of a Standard gRPC Error Response:**
+```
+ERROR:
+  Code: InvalidArgument
+  Message: input key/keyPrefix 'bad||keyname' can't contain '||'
+```
+
+### Richer gRPC Error Model
+
+The [Richer gRPC error model](https://grpc.io/docs/guides/error/#richer-error-model) extends the standard error model by providing additional context and details about the error. This model includes the standard error `code` and `message`, along with a `details` section that can contain various types of information, such as `ErrorInfo`, `ResourceInfo`, and `BadRequest` details.
+
+
+**Example of a Richer gRPC Error Response:**
+```
+ERROR:
+  Code: InvalidArgument
+  Message: input key/keyPrefix 'bad||keyname' can't contain '||'
+  Details:
+  1)	{
+    	  "@type": "type.googleapis.com/google.rpc.ErrorInfo",
+    	  "domain": "dapr.io",
+    	  "reason": "DAPR_STATE_ILLEGAL_KEY"
+    	}
+  2)	{
+    	  "@type": "type.googleapis.com/google.rpc.ResourceInfo",
+    	  "resourceName": "statestore",
+    	  "resourceType": "state"
+    	}
+  3)	{
+    	  "@type": "type.googleapis.com/google.rpc.BadRequest",
+    	  "fieldViolations": [
+    	    {
+    	      "field": "bad||keyname",
+    	      "description": "input key/keyPrefix 'bad||keyname' can't contain '||'"
+    	    }
+    	  ]
+    	}
+```
+
+For HTTP clients, Dapr translates the gRPC error model to a similar structure in JSON format. The response includes an `errorCode`, a `message`, and a `details` array that mirrors the structure found in the richer gRPC model.
+
+**Example of an HTTP error response:**
+```json
+{
+    "errorCode": "ERR_MALFORMED_REQUEST",
+    "message": "api error: code = InvalidArgument desc = input key/keyPrefix 'bad||keyname' can't contain '||'",
+    "details": [
+        {
+            "@type": "type.googleapis.com/google.rpc.ErrorInfo",
+            "domain": "dapr.io",
+            "metadata": null,
+            "reason": "DAPR_STATE_ILLEGAL_KEY"
+        },
+        {
+            "@type": "type.googleapis.com/google.rpc.ResourceInfo",
+            "description": "",
+            "owner": "",
+            "resource_name": "statestore",
+            "resource_type": "state"
+        },
+        {
+            "@type": "type.googleapis.com/google.rpc.BadRequest",
+            "field_violations": [
+                {
+                    "field": "bad||keyname",
+                    "description": "api error: code = InvalidArgument desc = input key/keyPrefix 'bad||keyname' can't contain '||'"
+                }
+            ]
+        }
+    ]
+}
+```
+
+You can find the specification of all the possible status details [here](https://github.com/googleapis/googleapis/blob/master/google/rpc/error_details.proto).
+
+## Related Links
+
+- [Authoring error codes](https://github.com/dapr/dapr/tree/master/pkg/api/errors)
+- [Using error codes in the Go SDK](https://docs.dapr.io/developing-applications/sdks/go/go-client/#error-handling)