The remap processor can add, drop, or rename fields within your individual log data. Use this processor to enrich your logs with additional context, remove low-value fields to reduce volume, and standardize naming across important attributes. Select add field, drop field, or rename field in the dropdown menu to get started.

Add field

Use add field to append a new key-value field to your log.

To set up the add field processor:

1. Define a filter query. Only logs that match the specified filter query are processed. All logs, regardless of whether they do or do not match the filter query, are sent to the next step in the pipeline.
2. Enter the field and value you want to add. To specify a nested field for your key, use the path notation: <OUTER_FIELD>.<INNER_FIELD>. All values are stored as strings. Note: If the field you want to add already exists, the Worker throws an error and the existing field remains unchanged.

Drop field

Use drop field to drop a field from logging data that matches the filter you specify below.

To set up the drop field processor:

1. Define a filter query. Only logs that match the specified filter query are processed. All logs, regardless of whether they do or do not match the filter query, are sent to the next step in the pipeline.
2. Enter the key of the field you want to drop. To specify a nested field for your specified key, use the path notation: <OUTER_FIELD>.<INNER_FIELD>. Note: If your specified key does not exist, your log will be unimpacted.

Rename field

Use rename field to rename a field within your log.

To set up the rename field processor:

1. Define a filter query. Only logs that match the specified filter query are processed. All logs, regardless of whether they do or do not match the filter query, are sent to the next step in the pipeline.
2. Enter the name of the field you want to rename in the Source field. To specify a nested field for your key, use the path notation: <OUTER_FIELD>.<INNER_FIELD>. Once renamed, your original field is deleted unless you enable the Preserve source tag checkbox described below.
   Note: If the source key you specify doesn’t exist, a default null value is applied to your target.
3. In the Target field, enter the name you want the source field to be renamed to. To specify a nested field for your specified key, use the path notation: <OUTER_FIELD>.<INNER_FIELD>.
   Note: If the target field you specify already exists, the Worker throws an error and does not overwrite the existing target field.
4. Optionally, check the Preserve source tag box if you want to retain the original source field and duplicate the information from your source key to your specified target key. If this box is not checked, the source key is dropped after it is renamed.

Path notation example

For the following message structure, use outer_key.inner_key.double_inner_key to refer to the key with the value double_inner_value.

{
    "outer_key": {
        "inner_key": "inner_value",
            "a": {
                    "double_inner_key": "double_inner_value",
                    "b": "b value"
                },
            "c": "c value"
        },
        "d": "d value"
    }

Filter query syntax

Each processor has a corresponding filter query in their fields. Processors only process logs that match their filter query. And for all processors except the filter processor, logs that do not match the query are sent to the next step of the pipeline. For the filter processor, logs that do not match the query are dropped.

For any attribute, tag, or key:value pair that is not a reserved attribute, your query must start with @. Conversely, to filter reserved attributes, you do not need to append @ in front of your filter query.

For example, to filter out and drop status:info logs, your filter can be set as NOT (status:info). To filter out and drop system-status:info, your filter must be set as NOT (@system-status:info).

Filter query examples:

• NOT (status:debug): This filters for only logs that do not have the status DEBUG.
• status:ok service:flask-web-app: This filters for all logs with the status OK from your flask-web-app service.
  • This query can also be written as: status:ok AND service:flask-web-app.
• host:COMP-A9JNGYK OR host:COMP-J58KAS: This filter query only matches logs from the labeled hosts.
• @user.status:inactive: This filters for logs with the status inactive nested under the user attribute.

Learn more about writing filter queries in Datadog’s Log Search Syntax.