Graylog: Handling the error "failed to parse field [XXXX] of type [YYYY]"

This documentation is part of the Getting started guide. You can view the complete guide here: How to get started with Graylog.

👋 Welcome to the Stackhero documentation!

Stackhero offers a ready-to-use Graylog cloud solution that provides a host of benefits, including:

• Unlimited and dedicated SMTP email server included.
• Effortless updates with just a click.
• Customizable domain name secured with HTTPS (for example, https://logs.your-company.com).
• Optimal performance and robust security powered by a private and dedicated VM.

Save time and simplify your life: it only takes 5 minutes to try Stackhero's Graylog cloud hosting solution!

You may encounter an error such as:

org.opensearch.index.mapper.MapperParsingException: failed to parse field [time] of type [long] in document with id 'xxxx'

You can view this error in the logs available in the Stackhero dashboard or in the Graylog admin panel under System > Overview > Indexer failures.

This error means that a log was sent with a value for the time field that does not match the expected type (in this case, a numeric value of type "long"). Graylog relies on the dynamic mapping feature of OpenSearch. When a log is sent for the first time, OpenSearch tries to guess the field types. For example, if a log contains the field time with the numeric value 1234, OpenSearch defines it as a numeric field. If another log is sent with the field time set to "abcd", a string, OpenSearch will reject it because it expects a numeric value.

Keep in mind that the field name time is just an example. This can apply to any field name and type.

To resolve this issue, you need to redefine the type that OpenSearch expects. For more information, please refer to the official Graylog documentation.

Update the OpenSearch mapping

Before proceeding, enable OpenSearch access in the Stackhero dashboard. Go to your Graylog service and click the "Configure" button to activate OpenSearch access.

Be careful with these changes, as incorrect configurations can block your OpenSearch cluster and lead to data loss. If you are unsure, do not proceed.

1. Define your new mapping. In this example, we redefine the time field as a string type. You can find the available types in the OpenSearch field datatypes documentation.

2. Save the following content to a file named graylog-custom-mapping.json:

   {
     "template": "graylog_*",
     "mappings": {
       "message": {
         "properties": {
           "time": {
             "type": "string",
             "index": "not_analyzed"
           }
         }
       }
     }
   }
   

3. Upload this file using the following curl command (replace <XXXXXX>.stackhero-network.com with your instance domain name):

   curl -u 'admin' -X PUT -d @'graylog-custom-mapping.json' -H 'Content-Type: application/json' 'https://<XXXXXX>.stackhero-network.com/opensearch/_template/graylog-custom-mapping?pretty'
   

   You should receive a response like:

   {
     "acknowledged": true
   }
   

4. Finally, verify that the mapping has been updated with this command (replace the domain as needed):

   curl -u 'admin' -X GET 'https://<XXXXXX>.stackhero-network.com/opensearch/graylog_deflector/_mapping?pretty'