parse - Amazon CloudWatch Logs
Examples of the parse command

parse

Use parse to extract data from a log field and create an extracted field that you can process in your query. parse supports both glob mode using wildcards, and regular expressions. For information about regular expression syntax, see Supported regular expressions (regex) syntax.

You can parse nested JSON fields with a regular expression.

Example: Parsing a nested JSON field

The code snippet shows how to parse a JSON log event that's been flattened during ingestion. 

{'fieldsA': 'logs', 'fieldsB': [{'fA': 'a1'}, {'fA': 'a2'}]}

The code snippet shows a query with a regular expression that extracts the values for fieldsA and fieldsB to create the extracted fields fld and array. 

parse @message "'fieldsA': '*', 'fieldsB': ['*']" as fld, array

Named capturing groups

When you use parse with a regular expression, you can use named capturing groups to capture a pattern into a field. The syntax is parse @message (?<Name>pattern)

The following example uses a capturing group on a VPC flow log to extract the ENI into a field named NetworkInterface.

parse @message /(?<NetworkInterface>eni-.*?) / | display NetworkInterface, @message
Note

JSON log events are flattened during ingestion. Currently, parsing nested JSON fields with a glob expression isn't supported. You can only parse JSON log events that include no more than 200 log event fields. When you parse nested JSON fields, you must format the regular expression in your query to match the format of your JSON log event.

Examples of the parse command

Use a glob expression to extract the fields @user, @method, and @latency from the log field @message and return the average latency for each unique combination of @method and @user. 

parse @message "user=*, method:*, latency := *" as @user,
    @method, @latency | stats avg(@latency) by @method,
    @user

Use a regular expression to extract the fields @user2, @method2, and @latency2 from the log field @message and return the average latency for each unique combination of @method2 and @user2.

parse @message /user=(?<user2>.*?), method:(?<method2>.*?),
    latency := (?<latency2>.*?)/ | stats avg(latency2) by @method2, 
    @user2

Extracts the fields loggingTime, loggingType and loggingMessage, filters down to log events that contain ERROR or INFO strings, and then displays only the loggingMessage and loggingType fields for events that contain an ERROR string.

FIELDS @message
    | PARSE @message "* [*] *" as loggingTime, loggingType, loggingMessage
    | FILTER loggingType IN ["ERROR", "INFO"]
    | DISPLAY loggingMessage, loggingType = "ERROR" as isError