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Log to Metrics
Generate metrics from logs
The Log To Metrics Filter plugin allows you to generate log-derived metrics. It currently supports modes to count records, provide a gauge for field values or create a histogram. You can also match or exclude specific records based on regular expression patterns for values or nested values. This filter plugin does not actually act as a record filter and does not change or drop records. All records will pass this filter untouched and generated metrics will be emitted into a seperate metric pipeline.
Please note that this plugin is an experimental feature and is not recommended for production use. Configuration parameters and plugin functionality are subject to change without notice.
The plugin supports the following configuration parameters:
Key | Description | Mandatory | Value Format |
|---|---|---|---|
tag | Defines the tag for the generated metrics record | Yes | |
metric_mode | Defines the mode for the metric. Valid values are [ counter, gauge or histogram] | Yes | |
metric_name | Sets the name of the metric. | Yes | |
metric_description | Sets a help text for the metric. | Yes | |
bucket | Defines a bucket for histogram | Yes, for mode histogram | e.g. 0.75 |
add_label | Add a custom label NAME and set the value to the value of KEY | | |
label_field | Includes a record field as label dimension in the metric. | | |
value_field | Specify the record field that holds a numerical value | Yes, for modes [ gauge and histogram] | |
kubernetes_mode | If enabled, it will automatically put pod_id, pod_name, namespace_name, docker_id and container_name into the metric as labels. This option is intended to be used in combination with the kubernetes filter plugin, which fills those fields. | | |
Regex | Include records in which the content of KEY matches the regular expression. | | KEY REGEX |
Exclude | Exclude records in which the content of KEY matches the regular expression. | | KEY REGEX |
The following example takes records from two dummy inputs and counts all messages passing through the
log_to_metrics filter. It then generates metric records which are provided to the prometheus_exporter:[SERVICE]
flush 1
log_level info
[INPUT]
Name dummy
Dummy {"message":"dummy", "kubernetes":{"namespace_name": "default", "docker_id": "abc123", "pod_name": "pod1", "container_name": "mycontainer", "pod_id": "def456", "labels":{"app": "app1"}}, "duration": 20, "color": "red", "shape": "circle"}
Tag dummy.log
[INPUT]
Name dummy
Dummy {"message":"hello", "kubernetes":{"namespace_name": "default", "docker_id": "abc123", "pod_name": "pod1", "container_name": "mycontainer", "pod_id": "def456", "labels":{"app": "app1"}}, "duration": 60, "color": "blue", "shape": "square"}
Tag dummy.log2
[FILTER]
name log_to_metrics
match dummy.log*
tag test_metric
metric_mode counter
metric_name count_all_dummy_messages
metric_description This metric counts dummy messages
[OUTPUT]
name prometheus_exporter
match *
host 0.0.0.0
port 2021
You can then use e.g. curl command to retrieve the generated metric:
> curl -s http://127.0.0.1:2021/metrics
# HELP log_metric_counter_count_all_dummy_messages This metric counts dummy messages
# TYPE log_metric_counter_count_all_dummy_messages counter
log_metric_counter_count_all_dummy_messages 49
The
gauge mode needs a value_field specified, where the current metric values are generated from. In this example we also apply a regex filter and enable the kubernetes_mode option:[FILTER]
name log_to_metrics
match dummy.log*
tag test_metric
metric_mode gauge
metric_name current_duration
metric_description This metric shows the current duration
value_field duration
kubernetes_mode on
regex message .*el.*
add_label app $kubernetes['labels']['app']
label_field color
label_field shape
You can then use e.g. curl command to retrieve the generated metric:
> curl -s http://127.0.0.1:2021/metrics
# HELP log_metric_gauge_current_duration This metric shows the current duration
# TYPE log_metric_gauge_current_duration gauge
log_metric_gauge_current_duration{namespace_name="default",pod_name="pod1",container_name="mycontainer",docker_id="abc123",pod_id="def456",app="app1",color="blue",shape="square"} 60
As you can see in the output, only one line is printed, as the records from the first input plugin are ignored, as they do not match the regex.
The filter also allows to use multiple rules which are applied in order, you can have many Regex and Exclude entries as required (see grep filter plugin).
If you execute the above
curl command multiple times, you see, that in this example the metric value stays at 60, as the messages generated by the dummy plugin are not changing. In a real-world scenario the values would change and return the last processed value.As you can see, the label sets defined by
add_label and label_field are added to the metric. The lines in the metric represent every combination of labels. Only actually used combinations are displayed here. To see this, you can add a dummy dummy input to your configuration.The metric output would then look like:
> curl -s http://127.0.0.1:2021/metrics
# HELP log_metric_gauge_current_duration This metric shows the current duration
# TYPE log_metric_gauge_current_duration gauge
log_metric_gauge_current_duration{namespace_name="default",pod_name="pod1",container_name="mycontainer",docker_id="abc123",pod_id="def456",app="app1",color="blue",shape="square"} 60
log_metric_gauge_current_duration{namespace_name="default",pod_name="pod1",container_name="mycontainer",docker_id="abc123",pod_id="def456",app="app1",color="red",shape="circle"} 20
You can also see, that all the kubernetes labels have been attached to the metric, accordingly.
Similar to the
gauge mode, histogram needs a value_field specified, where the current metric values are generated from. In this example we also apply a regex filter and enable the kubernetes_mode option:[FILTER]
name log_to_metrics
match dummy.log*
tag test_metric
metric_mode histogram
metric_name current_duration
metric_description This metric shows the request duration
value_field duration
kubernetes_mode on
regex message .*el.*
add_label app $kubernetes['labels']['app']
label_field color
label_field shape
You can then use e.g. curl command to retrieve the generated metric:
> curl -s http://127.0.0.1:2021/metrics
# HELP log_metric_histogram_current_duration This metric shows the request duration
# TYPE log_metric_histogram_current_duration histogram
log_metric_histogram_current_duration_bucket{le="0.005",namespace_name="default",pod_name="pod1",container_name="mycontainer",docker_id="abc123",pod_id="def456",app="app1",color="red",shape="circle"} 0
log_metric_histogram_current_duration_bucket{le="0.01",namespace_name="default",pod_name="pod1",container_name="mycontainer",docker_id="abc123",pod_id="def456",app="app1",color="red",shape="circle"} 0
log_metric_histogram_current_duration_bucket{le="0.025",namespace_name="default",pod_name="pod1",container_name="mycontainer",docker_id="abc123",pod_id="def456",app="app1",color="red",shape="circle"} 0
log_metric_histogram_current_duration_bucket{le="0.05",namespace_name="default",pod_name="pod1",container_name="mycontainer",docker_id="abc123",pod_id="def456",app="app1",color="red",shape="circle"} 0
log_metric_histogram_current_duration_bucket{le="0.1",namespace_name="default",pod_name="pod1",container_name="mycontainer",docker_id="abc123",pod_id="def456",app="app1",color="red",shape="circle"} 0
log_metric_histogram_current_duration_bucket{le="0.25",namespace_name="default",pod_name="pod1",container_name="mycontainer",docker_id="abc123",pod_id="def456",app="app1",color="red",shape="circle"} 0
log_metric_histogram_current_duration_bucket{le="0.5",namespace_name="default",pod_name="pod1",container_name="mycontainer",docker_id="abc123",pod_id="def456",app="app1",color="red",shape="circle"} 0
log_metric_histogram_current_duration_bucket{le="1.0",namespace_name="default",pod_name="pod1",container_name="mycontainer",docker_id="abc123",pod_id="def456",app="app1",color="red",shape="circle"} 0
log_metric_histogram_current_duration_bucket{le="2.5",namespace_name="default",pod_name="pod1",container_name="mycontainer",docker_id="abc123",pod_id="def456",app="app1",color="red",shape="circle"} 0
log_metric_histogram_current_duration_bucket{le="5.0",namespace_name="default",pod_name="pod1",container_name="mycontainer",docker_id="abc123",pod_id="def456",app="app1",color="red",shape="circle"} 0
log_metric_histogram_current_duration_bucket{le="10.0",namespace_name="default",pod_name="pod1",container_name="mycontainer",docker_id="abc123",pod_id="def456",app="app1",color="red",shape="circle"} 0
log_metric_histogram_current_duration_bucket{le="+Inf",namespace_name="default",pod_name="pod1",container_name="mycontainer",docker_id="abc123",pod_id="def456",app="app1",color="red",shape="circle"} 28
log_metric_histogram_current_duration_sum{namespace_name="default",pod_name="pod1",container_name="mycontainer",docker_id="abc123",pod_id="def456",app="app1",color="red",shape="circle"} 560
log_metric_histogram_current_duration_count{namespace_name="default",pod_name="pod1",container_name="mycontainer",docker_id="abc123",pod_id="def456",app="app1",color="red",shape="circle"} 28
log_metric_histogram_current_duration_bucket{le="0.005",namespace_name="default",pod_name="pod1",container_name="mycontainer",docker_id="abc123",pod_id="def456",app="app1",color="blue",shape="circle"} 0
log_metric_histogram_current_duration_bucket{le="0.01",namespace_name="default",pod_name="pod1",container_name="mycontainer",docker_id="abc123",pod_id="def456",app="app1",color="blue",shape="circle"} 0
log_metric_histogram_current_duration_bucket{le="0.025",namespace_name="default",pod_name="pod1",container_name="mycontainer",docker_id="abc123",pod_id="def456",app="app1",color="blue",shape="circle"} 0
log_metric_histogram_current_duration_bucket{le="0.05",namespace_name="default",pod_name="pod1",container_name="mycontainer",docker_id="abc123",pod_id="def456",app="app1",color="blue",shape="circle"} 0
log_metric_histogram_current_duration_bucket{le="0.1",namespace_name="default",pod_name="pod1",container_name="mycontainer",docker_id="abc123",pod_id="def456",app="app1",color="blue",shape="circle"} 0
log_metric_histogram_current_duration_bucket{le="0.25",namespace_name="default",pod_name="pod1",container_name="mycontainer",docker_id="abc123",pod_id="def456",app="app1",color="blue",shape="circle"} 0
log_metric_histogram_current_duration_bucket{le="0.5",namespace_name="default",pod_name="pod1",container_name="mycontainer",docker_id="abc123",pod_id="def456",app="app1",color="blue",shape="circle"} 0
log_metric_histogram_current_duration_bucket{le="1.0",namespace_name="default",pod_name="pod1",container_name="mycontainer",docker_id="abc123",pod_id="def456",app="app1",color="blue",shape="circle"} 0
log_metric_histogram_current_duration_bucket{le="2.5",namespace_name="default",pod_name="pod1",container_name="mycontainer",docker_id="abc123",pod_id="def456",app="app1",color="blue",shape="circle"} 0
log_metric_histogram_current_duration_bucket{le="5.0",namespace_name="default",pod_name="pod1",container_name="mycontainer",docker_id="abc123",pod_id="def456",app="app1",color="blue",shape="circle"} 0
log_metric_histogram_current_duration_bucket{le="10.0",namespace_name="default",pod_name="pod1",container_name="mycontainer",docker_id="abc123",pod_id="def456",app="app1",color="blue",shape="circle"} 0
log_metric_histogram_current_duration_bucket{le="+Inf",namespace_name="default",pod_name="pod1",container_name="mycontainer",docker_id="abc123",pod_id="def456",app="app1",color="blue",shape="circle"} 27
log_metric_histogram_current_duration_sum{namespace_name="default",pod_name="pod1",container_name="mycontainer",docker_id="abc123",pod_id="def456",app="app1",color="blue",shape="circle"} 1620
log_metric_histogram_current_duration_count{namespace_name="default",pod_name="pod1",container_name="mycontainer",docker_id="abc123",pod_id="def456",app="app1",color="blue",shape="circle"} 27
As you can see in the output, there are per default the buckets
0.005, 0.01, 0.025, 0.05, 0.1, 0.25, 0.5, 1.0, 2.5, 5.0, 10.0 and +Inf, in which values are sorted into. A sum and a counter are also part of this metric. You can specify own buckets in the config, like in the following example:[FILTER]
name log_to_metrics
match dummy.log*
tag test_metric
metric_mode histogram
metric_name current_duration
metric_description This metric shows the HTTP request duration as histogram in milliseconds
value_field duration
kubernetes_mode on
bucket 1
bucket 5
bucket 10
bucket 50
bucket 100
bucket 250
bucket 500
bucket 1000
regex message .*el.*
label_field color
label_field shape
Please note, that the
+Inf bucket will always be included implicitly. The buckets in a histogram are cumulative, so a value added to one bucket will add to all larger buckets, too.You can also see, that all the kubernetes labels have been attached to the metric, idential to the behavior of
label_field described in the previous chapter. That results in two sets for the histogram.Last modified 1mo ago