[Bug][Change Proposal] `constant_keyword` cannot be a TSDB dimension

[AndersonQ]

The current spec/validation rules for TSDB fields allows setting a constant_keyword field as dimension. The package builds and the validation step succeeds. However, upon trying to install the package, it fails with:

Error: can't install the package: could not zip-install package; API status code = 500; response body = {"statusCode":500,"error":"Internal Server Error","message":"mapper_parsing_exception\n\tCaused by:\n\t\tmapper_parsing_exception: unknown parameter [time_series_dimension] on mapper [namespace] of type [constant_keyword]\n\tRoot causes:\n\t\tmapper_parsing_exception: unknown parameter [time_series_dimension] on mapper [namespace] of type [constant_keyword]"}

Similar to #1106, the list of supported types for dimension fields is validated in

package-spec/code/go/internal/validator/semantic/validate_dimensions.go

Line 36 in 3e48996

var allowedDimensionTypes = []string{

Which allows for constant_keyword.

Steps to reproduce:

With elastic-package

• set some constant keyword as TSDB dimension. For example in the linux integration:

diff --git a/packages/linux/data_stream/conntrack/fields/base-fields.yml b/packages/linux/data_stream/conntrack/fields/base-fields.yml
index 55fc16df87..a88e935670 100644                                                                 
--- a/packages/linux/data_stream/conntrack/fields/base-fields.yml                                   
+++ b/packages/linux/data_stream/conntrack/fields/base-fields.yml                                   
@@ -1,20 +1,25 @@                                                                                   
 - name: data_stream.type                                                                           
   type: constant_keyword                                                                           
   description: Data stream type.                                                                   
+  dimension: true                                                                                  
 - name: data_stream.dataset                                                                        
   type: constant_keyword                                                                           
   description: Data stream dataset.                                                                
+  dimension: true                                                                                  
 - name: data_stream.namespace                                                                      
   type: constant_keyword                                                                           
   description: Data stream namespace.                                                              
+  dimension: true                                                                                  
 - name: '@timestamp'                                                                               
   type: date                                                                                       
   description: Event timestamp.                                                                    
 - name: event.module                                                                               
   type: constant_keyword                                                                           
   description: Event module                                                                        
+  dimension: true                                                                                  
   value: linux                                                                                     
 - name: event.dataset                                                                              
   type: constant_keyword                                                                           
   description: Event dataset                                                                       
+  dimension: true                                                                                  
   value: linux.conntrack                                                                           
diff --git a/packages/linux/data_stream/conntrack/manifest.yml b/packages/linux/data_stream/conntrack/manifest.yml
index 254989e11e..78a64a2758 100644                                                                 
--- a/packages/linux/data_stream/conntrack/manifest.yml                                             
+++ b/packages/linux/data_stream/conntrack/manifest.yml                                             
@@ -1,5 +1,7 @@                                                                                     
 title: System conntrack metrics                                                                    
 type: metrics                                                                                      
+elasticsearch:                                                                                     
+  index_mode: "time_series"                                                                        
 streams:                                                                                           
   - input: linux/metrics                                                                           
     vars:                                                                                          

• build and install the package:

elastic-package build 

[...]
2026/03/10 17:27:29 DEBUG Validating built .zip package (path: /home/ainsoph/devel/github.com/elastic/integrations/build/packages/linux-1.1.0.zip)
Package built: /home/ainsoph/devel/github.com/elastic/integrations/build/packages/linux-1.1.0.zip
Done

• install it

Observe the build works, the

elastic-package install -v

[...]
2026/03/10 17:21:52 DEBUG Validating built .zip package (path: /home/ainsoph/devel/github.com/elastic/integrations/build/packages/linux-1.1.0.zip)
Error: can't install the package: could not zip-install package; API status code = 500; response body = {"statusCode":500,"error":"Internal Server Error","message":"mapper_parsing_exception\n\tCaused by:\n\t\tmapper_parsing_exception: unknown parameter [time_series_dimension] on mapper [namespace] of type [constant_keyword]\n\tRoot causes:\n\t\tmapper_parsing_exception: unknown parameter [time_series_dimension] on mapper [namespace] of type [constant_keyword]"}

With Kibana devtools

PUT _index_template/validate-constant-keyword-tsdb
{
  "index_patterns": [
    "test-const*"
  ],
  "data_stream": {},
  "template": {
    "settings": {
      "index.mode": "time_series",
      "index.routing_path": [
        "app_environment"
      ]
    },
    "mappings": {
      "properties": {
        "@timestamp": {
          "type": "date"
        },
        "app_environment": {
          "type": "constant_keyword",
          "value": "production",
          "time_series_dimension": true 
        },
        "memory_usage": {
          "type": "float",
          "time_series_metric": "gauge"
        }
      }
    }
  }
}

It fails with a similar error:

{
  "error": {
    "root_cause": [
      {
        "type": "illegal_argument_exception",
        "reason": "composable template [validate-constant-keyword-tsdb] template after composition is invalid"
      }
    ],
    "type": "illegal_argument_exception",
    "reason": "composable template [validate-constant-keyword-tsdb] template after composition is invalid",
    "caused_by": {
      "type": "illegal_argument_exception",
      "reason": "invalid composite mappings for [validate-constant-keyword-tsdb]",
      "caused_by": {
        "type": "mapper_parsing_exception",
        "reason": "Failed to parse mapping: unknown parameter [time_series_dimension] on mapper [app_environment] of type [constant_keyword]",
        "caused_by": {
          "type": "mapper_parsing_exception",
          "reason": "unknown parameter [time_series_dimension] on mapper [app_environment] of type [constant_keyword]"
        }
      }
    }
  },
  "status": 400
}

• a simple keyword works:

{
  "error": {
    "root_cause": [
      {
        "type": "illegal_argument_exception",
        "reason": "composable template [validate-constant-keyword-tsdb] template after composition is invalid"
      }
    ],
    "type": "illegal_argument_exception",
    "reason": "composable template [validate-constant-keyword-tsdb] template after composition is invalid",
    "caused_by": {
      "type": "illegal_argument_exception",
      "reason": "invalid composite mappings for [validate-constant-keyword-tsdb]",
      "caused_by": {
        "type": "mapper_parsing_exception",
        "reason": "Failed to parse mapping: unknown parameter [time_series_dimension] on mapper [app_environment] of type [constant_keyword]",
        "caused_by": {
          "type": "mapper_parsing_exception",
          "reason": "unknown parameter [time_series_dimension] on mapper [app_environment] of type [constant_keyword]"
        }
      }
    }
  },
  "status": 400
}