Quelle est la signification du préfixe @ dans les noms de champ de journal de connexion?

La configuration logstash suivante est utilisée pour accepter les journaux d'événements Windows en tant que json sur une connexion TCP, puis après un certain filtrage, transmettre le résultat à la recherche élastique (source: https://gist.github.com/robinsmidsrod/4215337 ):

input {
    tcp {
        type => "syslog"
        host => "127.0.0.1"
        port => 3514
    }
    tcp {
        type   => "eventlog"
        host   => "10.1.1.2"
        port   => 3515
        format => 'json'
    }
}

# Details at http://cookbook.logstash.net/recipes/syslog-pri/
filter {

# Incoming data from rsyslog
    grok {
        type      => "syslog"
        pattern   => [ "<%{POSINT:syslog_pri}>(?:%{SYSLOGTIMESTAMP:syslog_timestamp}|%{TIMESTAMP_ISO8601:syslog_timestamp8601}) %{SYSLOGHOST:syslog_hostname} %{PROG:syslog_program}(?:\[%{POSINT:syslog_pid}\])?: %{GREEDYDATA:syslog_message}" ]
        add_field => [ "received_at", "%{@timestamp}" ]
        add_field => [ "received_from", "%{@source_host}" ]
    }
    syslog_pri {
        type => "syslog"
    }
    date {
        type                 => "syslog"
        syslog_timestamp8601 => "ISO8601" # RSYSLOG_ForwardFormat
        syslog_timestamp     => [ "MMM  d HH:mm:ss", "MMM dd HH:mm:ss" ]
    }
    mutate {
        type         => "syslog"
        exclude_tags => "_grokparsefailure"
        replace      => [ "@source_host", "%{syslog_hostname}" ]
        replace      => [ "@message", "%{syslog_message}" ]
    }
    mutate {
        type   => "syslog"
        remove => [ "syslog_hostname", "syslog_message", "syslog_timestamp", "syslog_timestamp8601" ]
    }

# Incoming Windows Event logs from nxlog
    # The EventReceivedTime field must contain only digits, or it is an invalid message
    grep {
        type              => "eventlog"
        EventReceivedTime => "\d+"
    }
    mutate {
        # Lowercase some values that are always in uppercase
        type      => "eventlog"
        lowercase => [ "EventType", "FileName", "Hostname", "Severity" ]
    }
    mutate {
        # Set source to what the message says
        type   => "eventlog"
        rename => [ "Hostname", "@source_host" ]
    }
    date {
        # Convert timestamp from integer in UTC
        type              => "eventlog"
        EventReceivedTime => "UNIX"
    }
    mutate {
        # Rename some fields into something more useful
        type   => "eventlog"
        rename => [ "Message", "@message" ]
        rename => [ "Severity", "eventlog_severity" ]
        rename => [ "SeverityValue", "eventlog_severity_code" ]
        rename => [ "Channel", "eventlog_channel" ]
        rename => [ "SourceName", "eventlog_program" ]
        rename => [ "SourceModuleName", "nxlog_input" ]
        rename => [ "Category", "eventlog_category" ]
        rename => [ "EventID", "eventlog_id" ]
        rename => [ "RecordNumber", "eventlog_record_number" ]
        rename => [ "ProcessID", "eventlog_pid" ]
    }
    mutate {
        # Remove redundant fields
        type   => "eventlog"
        remove => [ "SourceModuleType", "EventTimeWritten", "EventTime", "EventReceivedTime", "EventType" ]
    }
}

output {
    elasticsearch {
        embedded => true
    }
    graphite {
        # Ping the graphite server every time a syslog message is received
        type => "syslog"
        port => 2023     # carbon-aggregator
        metrics => [ "syslog.received.%{@source_host}.count", "1" ]
    }
    graphite {
        # Ping the graphite server every time an eventlog message is received
        type => "eventlog"
        port => 2023     # carbon-aggregator
        metrics => [ "eventlog.received.%{@source_host}.count", "1" ]
    }
}

Quelle est la signification du @préfixe sur certains noms de champ aux lignes 58 et 68? c'est à dire @source_hostet @messagesur ces mutatefiltres:

mutate {
    # Set source to what the message says
    type   => "eventlog"
    rename => [ "Hostname", "@source_host" ]
}

et

mutate {
    # Rename some fields into something more useful
    type   => "eventlog"
    rename => [ "Message", "@message" ]
    rename => [ "Severity", "eventlog_severity" ]
    rename => [ "SeverityValue", "eventlog_severity_code" ]
    rename => [ "Channel", "eventlog_channel" ]
    rename => [ "SourceName", "eventlog_program" ]
    rename => [ "SourceModuleName", "nxlog_input" ]
    rename => [ "Category", "eventlog_category" ]
    rename => [ "EventID", "eventlog_id" ]
    rename => [ "RecordNumber", "eventlog_record_number" ]
    rename => [ "ProcessID", "eventlog_pid" ]
}

Je crois que c'était simplement une décision d'espace de noms pour éviter les collisions.

Il a été principalement purgé des nouvelles versions de logstash. Seuls @timestamp et @version restent. Vous devriez envisager de mettre à niveau logstash et vos expéditeurs.