THIS IS A TEST INSTANCE. ALL YOUR CHANGES WILL BE LOST!!!!
Data structures
Source location for common data structures module: https://github.com/apache/ambari/tree/trunk/ambari-metrics/ambari-metrics-common/
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Sending Metrics to AMS (POST)
Sending metrics to Ambari Metrics Service can be achieved through the following API call.
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Connecting (POST) to <ambari-metrics-collector>:6188/ws/v1/timeline/metrics/ Http response: 200 OK
Fetching Metrics from AMS (GET)
Sample callGET http://<ambari-metrics-collector>:6188/ws/v1/timeline/metrics?metricNames=AMBARI_METRICS.SmokeTest.FakeMetric&appId=amssmoketestfake&hostname=<hostname>&precision=seconds&startTime=1432075838000&endTime=1432075959000
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{"metrics": [ {"timestamp": 1432075898089, "metricname": "AMBARI_METRICS.SmokeTest.FakeMetric", "appid": "amssmoketestfake", "hostname": "ambari20-5.c.pramod-thangali.internal", "starttime": 1432075898000, "metrics": {"1432075898000": 0.963781711428, "1432075899000": 1432075898000 } } ] } |
The Metric Record Key data structure is described below:
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Property
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Type
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Comment
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Optional
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Metric Name
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String
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First key part, important consideration while querying from HFile storage
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N
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Hostname
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String
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Second key part
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N
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Server time
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Long
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Timestamp on server when first metric write request was received
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N
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Application Id
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String
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Uniquely identify service
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N
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Instance Id
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String
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Second key part to identify instance/ component
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Y
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Start time
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Long
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Start of the timeseries data
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Precision query parameter
&precision=[ seconds, minutes, hours, days ]
- This flag can override which table gets queried and hence influence the amount of data returned.
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Generic GET call format
http://<AMS_HOST>:6188/ws/v1/timeline/metrics?metricNames=<>&hostname=<>&appId=<>&startTime=<>&endTime=<>&precision=<>
Query Parameters Explanation
| Parameter | Optional/Mandatory | Explanation | Values it can take |
|---|---|---|---|
| metricNames | Mandatory | Comma separated list of metrics that are required. | disk_free,mem_free... etc |
| appId | Mandatory | The AppId that corresponds to the metricNames that were requested. Currently, only 1 AppId is required and allowed. | HOST/namenode/datanode/nimbus/hbase/kafka_broker/FLUME_HANDLER etc |
| hostname | Optional | Comma separated list of hostnames. When no specified, cluster aggregates are returned. | h1,h2..etc |
| startTime, endTime | Optional | Start and End time values. If not specified, the last data point of the metric is returned. | epoch times in seconds or milliseconds |
| precision | Optional | What precision the data needs to be returned. If not specified, the precision is calculated based on the time range requested (Table below) | SECONDS/MINUTES/DAYS/HOURS |
Precision query parameter (Default resolution)
Query Time range | Resolution of returned metrics | Comments |
|---|---|---|
Last 1 hour | 30-60 sec resolution | Precision data available on demand as well |
Last 10 hours | 30-60 sec resolution | Honor query result limit |
Last 24 hours | 1 min aggregates | min and seconds precision available if requested |
Last week | 1 hour aggregates | |
| Last month | 1 hour aggregates | |
Last year | Daily aggregates | If query limit is reached query weekly aggregates |
Upto 2 hours | SECONDS |
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2 hours - 1 day | MINUTES | 5 minute data |
1 day - 30 days | HOURS | 1 hour data |
> 30 days | DAYS | 1 day data |
Specifying Aggregate Functions
The metricName can have a specific aggregate function qualifier after the metricName (as shown below) to request specific aggregates. Valid values are ._avg, ._max, ._min, ._sum. When an aggregate query is requested without an aggregate function in the metricName, the default is AVG.
Examples
http://<AMS_HOST>:6188/ws/v1/timeline/metrics?metricNames=regionserver.Server.totalRequestCount._avg,regionserver.Server.writeRequestCount._max&appId=hbase&startTime=14000000&endTime=14200000
http://<AMS_HOST>:6188/ws/v1/timeline/metrics?metricNames=regionserver.Server.readRequestCount,regionserver.Server.writeRequestCount._max&appId=hbase&startTime=14000000&endTime=14200000
Specifying Post processing Functions
Similar to aggregate functions, post processing functions can also be specified. Currently, we have 2 post processing functions - rate (Rate per second) and diff (difference between consecutive values). Post processing functions can be also be applied after aggregate functions.
Examples
http://<AMS_HOST>:6188/ws/v1/timeline/metrics?metricNames=regionserver.Server.totalRequestCount._rate,regionserver.Server.writeRequestCount._diff&appId=hbase&startTime=14000000&endTime=14200000
http://<AMS_HOST>:6188/ws/v1/timeline/metrics?metricNames=regionserver.Server.readRequestCount._max._diff&appId=hbase&startTime=14000000&endTime=14200000
Specifying Wild Cards
Both metricNames and hostname take wildcard (%) values for a group of metric (or hosts). A query can have a combination of full metric names and names with wildcards also.
Examples
http://<AMS_HOST>:6188/ws/v1/timeline/metrics?metricNames=regionserver.Server.%&appId=hbase&startTime=14000000&endTime=14200000
http://<AMS_HOST>:6188/ws/v1/timeline/metrics?metricNames=regionserver.Server.%&hostname=abc.testdomain124.devlocal&appId=hbase&startTime=14000000&endTime=14200000
http://<AMS_HOST>:6188/ws/v1/timeline/metrics?metricNames=master.AssignmentManger.ritCount,regionserver.Server.%&hostname=abc.testdomain124.devlocal&appId=hbase&startTime=14000000&endTime=14200000
http://<AMS_HOST>:6188/ws/v1/timeline/metrics?metricNames=regionserver.Server.%&hostname=abc.testdomain12%.devlocal&appId=hbase&startTime=14000000&endTime=14200000
Downsampling
As discussed before, AMS downsamples data when higher time ranges are requested. The default "downsampled across time" data returned is AVG. Specific downsamples can be requested by adding the aggregate function qualifiers ( ._avg, ._max, ._min, ._sum ) to the metric names the same way like requesting aggregates across the cluster.
Example
http://<AMS_HOST>:6188/ws/v1/timeline/metrics?metricNames=regionserver.Server.totalRequestCount._max&hostname=abc.testdomain124.devlocal&appId=hbase&startTime=14000000&endTime=14200000&precision=MINUTES
The above query returns 5 minute data for the metric, where the data point value is the MAX of the values found in every 5 minute range.
Aggregation
- The granularity of aggregate data can be controlled by setting wake up interval for each of the aggregator threads.
- Presently we support 2 types of aggregators, HOST and APPLICATION with 3 time dimensions, per minute, per hour and per day.
- The HOST aggregates are just aggregates on precision data across the supported time dimensions.
- The APP aggregates are across appId. Note: We ignore instanceId for APP level aggregates. Same time dimensions apply for APP level aggregates.
- We also support HOST level metrics for APP, meaning you can expect a system metric example: "cpu_user" to be aggregated across datanodes, effectively calculating system metric for hosted apps.
- Each aggregator performs checkpointing by storing last successful time of completion in a file. If the checkpoint is too old, the aggregators will discard checkpoint and aggregate data for the configured interval, meaning data in between (now - interval) time.
- Refer to Phoenix table schema for details of tables and records.
Internal Data structures
Source location for common data structures module: https://github.com/apache/ambari/tree/trunk/ambari-metrics/ambari-metrics-common/
The Metric Record Key data structure is described below:
Property | Type | Comment | Optional |
|---|---|---|---|
Metric Name | String | First key part, important consideration while querying from HFile storage | N |
Hostname | String | Second key part | N |
Server time | Long | Timestamp on server when first metric write request was received | N |
Application Id | String | Uniquely identify service | N |
Instance Id | String | Second key part to identify instance/ component | Y |
Start time | Long | Start of the timeseries data |