add support of chunk responses for selectors and instrument in telemetry

.changesets/feat_bnjjj_feat_chunk_resp_selector.md

@@ -0,0 +1,45 @@
+### Add support of event responses and critical errors for selectors and instrument in telemetry ([Issue #5027](https://github.com/apollographql/router/issues/5027))
+
+Giving the ability to compute new attributes everytime we receive a new event in supergraph response. Would be really helpful to create observability for subscriptions and defer.
+
+I also added the support of `on_error` for selectors and especially `error` selector I added for every services. Which will let you create some metrics,events or span attributes containing error message. By adding this we will now have to ability to create a counter of request timed out for subgraphs for example:
+
+```yaml
+telemetry:
+  instrumentation:
+    instruments:
+      subgraph:
+        requests.timeout:
+          value: unit
+          type: counter
+          unit: request
+          description: "subgraph requests containing subgraph timeout"
+          attributes:
+            subgraph.name: true
+          condition:
+            eq:
+              - "request timed out"
+              - error: reason
+```
+
+And thanks to the event support for selectors you'll be able to fetch data directly from the supergraph response body:
+
+```yaml
+telemetry:
+  instrumentation:
+    instruments:
+      acme.request.on_graphql_error:
+        value: event_unit
+        type: counter
+        unit: error
+        description: my description
+        condition:
+          eq:
+          - MY_ERROR_CODE
+          - response_errors: "$.[0].extensions.code"
+        attributes:
+          response_errors:
+            response_errors: "$.*"
+```
+
+By [@bnjjj](https://github.com/bnjjj) in https://github.com/apollographql/router/pull/5022

apollo-router/src/configuration/snapshots/apollo_router__configuration__tests__schema_generation.snap

@@ -1873,6 +1873,17 @@ expression: "&schema"
         }
       ]
     },
+    "ErrorRepr": {
+      "oneOf": [
+        {
+          "description": "The error reason",
+          "enum": [
+            "reason"
+          ],
+          "type": "string"
+        }
+      ]
+    },
     "ErrorsConfiguration": {
       "additionalProperties": false,
       "properties": {
@@ -1928,6 +1939,13 @@ expression: "&schema"
           ],
           "type": "string"
         },
+        {
+          "description": "Log the event on every chunks in the response",
+          "enum": [
+            "event_response"
+          ],
+          "type": "string"
+        },
         {
           "description": "Log the event on error",
           "enum": [
@@ -1968,6 +1986,38 @@ expression: "&schema"
       ],
       "type": "object"
     },
+    "Event_for_RouterSelector": {
+      "oneOf": [
+        {
+          "description": "For every chunk sent through http multipart connection",
+          "enum": [
+            "event_duration"
+          ],
+          "type": "string"
+        },
+        {
+          "description": "For every chunk sent through http multipart connection",
+          "enum": [
+            "event_unit"
+          ],
+          "type": "string"
+        },
+        {
+          "additionalProperties": false,
+          "description": "For every chunk sent through http multipart connection",
+          "properties": {
+            "event_custom": {
+              "$ref": "#/definitions/RouterSelector",
+              "description": "#/definitions/RouterSelector"
+            }
+          },
+          "required": [
+            "event_custom"
+          ],
+          "type": "object"
+        }
+      ]
+    },
     "Event_for_SubgraphAttributes_and_SubgraphSelector": {
       "description": "An event that can be logged as part of a trace. The event has an implicit `type` attribute that matches the name of the event in the yaml and a message that can be used to provide additional information.",
       "properties": {
@@ -1999,6 +2049,38 @@ expression: "&schema"
       ],
       "type": "object"
     },
+    "Event_for_SubgraphSelector": {
+      "oneOf": [
+        {
+          "description": "For every chunk sent through http multipart connection",
+          "enum": [
+            "event_duration"
+          ],
+          "type": "string"
+        },
+        {
+          "description": "For every chunk sent through http multipart connection",
+          "enum": [
+            "event_unit"
+          ],
+          "type": "string"
+        },
+        {
+          "additionalProperties": false,
+          "description": "For every chunk sent through http multipart connection",
+          "properties": {
+            "event_custom": {
+              "$ref": "#/definitions/SubgraphSelector",
+              "description": "#/definitions/SubgraphSelector"
+            }
+          },
+          "required": [
+            "event_custom"
+          ],
+          "type": "object"
+        }
+      ]
+    },
     "Event_for_SupergraphAttributes_and_SupergraphSelector": {
       "description": "An event that can be logged as part of a trace. The event has an implicit `type` attribute that matches the name of the event in the yaml and a message that can be used to provide additional information.",
       "properties": {
@@ -2030,6 +2112,38 @@ expression: "&schema"
       ],
       "type": "object"
     },
+    "Event_for_SupergraphSelector": {
+      "oneOf": [
+        {
+          "description": "For every chunk sent through http multipart connection",
+          "enum": [
+            "event_duration"
+          ],
+          "type": "string"
+        },
+        {
+          "description": "For every chunk sent through http multipart connection",
+          "enum": [
+            "event_unit"
+          ],
+          "type": "string"
+        },
+        {
+          "additionalProperties": false,
+          "description": "For every chunk sent through http multipart connection",
+          "properties": {
+            "event_custom": {
+              "$ref": "#/definitions/SupergraphSelector",
+              "description": "#/definitions/SupergraphSelector"
+            }
+          },
+          "required": [
+            "event_custom"
+          ],
+          "type": "object"
+        }
+      ]
+    },
     "Events": {
       "additionalProperties": false,
       "description": "Events are",
@@ -2744,6 +2858,10 @@ expression: "&schema"
           "$ref": "#/definitions/Standard",
           "description": "#/definitions/Standard"
         },
+        {
+          "$ref": "#/definitions/Event_for_RouterSelector",
+          "description": "#/definitions/Event_for_RouterSelector"
+        },
         {
           "$ref": "#/definitions/RouterSelector",
           "description": "#/definitions/RouterSelector"
@@ -2756,6 +2874,10 @@ expression: "&schema"
           "$ref": "#/definitions/Standard",
           "description": "#/definitions/Standard"
         },
+        {
+          "$ref": "#/definitions/Event_for_SubgraphSelector",
+          "description": "#/definitions/Event_for_SubgraphSelector"
+        },
         {
           "$ref": "#/definitions/SubgraphSelector",
           "description": "#/definitions/SubgraphSelector"
@@ -2768,6 +2890,10 @@ expression: "&schema"
           "$ref": "#/definitions/Standard",
           "description": "#/definitions/Standard"
         },
+        {
+          "$ref": "#/definitions/Event_for_SupergraphSelector",
+          "description": "#/definitions/Event_for_SupergraphSelector"
+        },
         {
           "$ref": "#/definitions/SupergraphSelector",
           "description": "#/definitions/SupergraphSelector"
@@ -4393,6 +4519,19 @@ expression: "&schema"
             "on_graphql_error"
           ],
           "type": "object"
+        },
+        {
+          "additionalProperties": false,
+          "properties": {
+            "error": {
+              "$ref": "#/definitions/ErrorRepr",
+              "description": "#/definitions/ErrorRepr"
+            }
+          },
+          "required": [
+            "error"
+          ],
+          "type": "object"
         }
       ]
     },
@@ -5328,6 +5467,19 @@ expression: "&schema"
             "static"
           ],
           "type": "object"
+        },
+        {
+          "additionalProperties": false,
+          "properties": {
+            "error": {
+              "$ref": "#/definitions/ErrorRepr",
+              "description": "#/definitions/ErrorRepr"
+            }
+          },
+          "required": [
+            "error"
+          ],
+          "type": "object"
         }
       ]
     },
@@ -5801,6 +5953,42 @@ expression: "&schema"
           ],
           "type": "object"
         },
+        {
+          "additionalProperties": false,
+          "properties": {
+            "default": {
+              "$ref": "#/definitions/AttributeValue",
+              "description": "#/definitions/AttributeValue",
+              "nullable": true
+            },
+            "response_data": {
+              "description": "The supergraph response body json path of the chunks.",
+              "type": "string"
+            }
+          },
+          "required": [
+            "response_data"
+          ],
+          "type": "object"
+        },
+        {
+          "additionalProperties": false,
+          "properties": {
+            "default": {
+              "$ref": "#/definitions/AttributeValue",
+              "description": "#/definitions/AttributeValue",
+              "nullable": true
+            },
+            "response_errors": {
+              "description": "The supergraph response body json path of the chunks.",
+              "type": "string"
+            }
+          },
+          "required": [
+            "response_errors"
+          ],
+          "type": "object"
+        },
         {
           "additionalProperties": false,
           "properties": {
@@ -5853,6 +6041,19 @@ expression: "&schema"
           ],
           "type": "object"
         },
+        {
+          "additionalProperties": false,
+          "properties": {
+            "error": {
+              "$ref": "#/definitions/ErrorRepr",
+              "description": "#/definitions/ErrorRepr"
+            }
+          },
+          "required": [
+            "error"
+          ],
+          "type": "object"
+        },
         {
           "additionalProperties": false,
           "description": "Cost attributes",

apollo-router/src/plugins/demand_control/mod.rs

@@ -39,6 +39,7 @@ pub(crate) mod cost_calculator;
 pub(crate) mod strategy;
 
 /// The cost calculation information stored in context for use in telemetry and other plugins that need to know what cost was calculated.
+#[derive(Debug)]
 pub(crate) struct CostContext {
     pub(crate) estimated: f64,
     pub(crate) actual: f64,

apollo-router/src/plugins/telemetry/config.rs

@@ -379,6 +379,12 @@ pub(crate) enum AttributeValue {
     Array(AttributeArray),
 }
 
+impl From<String> for AttributeValue {
+    fn from(value: String) -> Self {
+        AttributeValue::String(value)
+    }
+}
+
 impl From<&'static str> for AttributeValue {
     fn from(value: &'static str) -> Self {
         AttributeValue::String(value.to_string())