Sherlock is an anomaly detection service built on top of Druid. It leverages EGADS (Extensible Generic Anomaly Detection System) to detect anomalies in time-series data. Users can schedule jobs on an hourly, daily, weekly, or monthly basis, view anomaly reports from Sherlock's interface, or receive them via email.
Timeseries generation is the first phase of Sherlock's anomaly detection. The user inputs a full Druid JSON query with a metric name and group-by dimensions. Sherlock validates the query, adjusts the time interaval and granularity based on the EGADS config, and makes a call to Druid. Druid responds with an array of time-series, which are parsed into EGADS time-series.
{
"metric": "metric(metric1/metric2)",
"aggregations": [
{
"filter": {
"fields": [
{
"type": "selector",
"dimension": "dim1",
"value": "value1"
}
],
"type": "or"
},
"aggregator": {
"fieldName": "metric2",
"type": "longSum",
"name": "metric2"
},
"type": "filtered"
}
],
"dimension": "groupByDimension",
"intervals": "2017-09-10T00:00:01+00:00/2017-10-12T00:00:01+00:00",
"dataSource": "source1",
"granularity": {
"timeZone": "UTC",
"type": "period",
"period": "P1D"
},
"threshold": 50,
"postAggregations": [
{
"fields": [
{
"fieldName": "metric1",
"type": "fieldAccess",
"name": "metric1"
}
],
"type": "arithmetic",
"name": "metric(metric1/metric2)",
"fn": "/"
}
],
"queryType": "topN"
}[ {
"timestamp" : "2017-10-11T00:00:00.000Z",
"result" : [ {
"groupByDimension" : "dim1",
"metric(metric1/metric2)" : 8,
"metric1" : 128,
"metric2" : 16
}, {
"groupByDimension" : "dim2",
"metric(metric1/metric2)" : 4.5,
"metric1" : 42,
"metric2" : 9.33
} ]
}, {
"timestamp" : "2017-10-12T00:00:00.000Z",
"result" : [ {
"groupByDimension" : "dim1",
"metric(metric1/metric2)" : 9,
"metric1" : 180,
"metric2" : 20
}, {
"groupByDimension" : "dim2",
"metric(metric1/metric2)" : 5.5,
"metric1" : 95,
"metric2" : 17.27
} ]
} ]Sherlock calls the user-configured EGADS API for each generated time-series, generates anomaly reports from the response, and stores these reports in a database. Users may also elect to receive anomaly reports by email.
Sherlock uses a Redis backend Redis to store job metadata, generated anomaly reports, among other information, and as a persistent job queue. Keys related to Reports have retention policy. Hourly job reports have retention of 14 days and daily/weekly/monthly job reports have 1 year of retention.
Sherlock's user interface is built with Spark. The UI enables users to submit instant anomaly analyses, create and launch detection jobs, view anomalies on a heatmap, and on a graph.
A Makefile is provided with all build targets.
make jarThis creates sherlock.jar in the target/ directory.
Sherlock is run through the commandline with config arguments.
java -Dlog4j.configuration=file:${path_to_log4j}/log4j.properties \
-jar ${path_to_jar}/sherlock.jar \
--version $(VERSION) \
--project-name $(PROJECT_NAME) \
--port $(PORT) \
--enable-email \
--failure-email $(FAILURE_EMAIL) \
--from-mail $(FROM_MAIL) \
--reply-to $(REPLY_TO) \
--smtp-host $(SMTP_HOST) \
--interval-minutes $(INTERVAL_MINUTES) \
--interval-hours $(INTERVAL_HOURS) \
--interval-days $(INTERVAL_DAYS) \
--interval-weeks $(INTERVAL_WEEKS) \
--interval-months $(INTERVAL_MONTHS) \
--egads-config-filename $(EGADS_CONFIG_FILENAME) \
--redis-host $(REDIS_HOSTNAME) \
--redis-port $(REDIS_PORT) \
--execution-delay $(EXECUTION_DELAY) \
--timeseries-completeness $(TIMESERIES_COMPLETENESS)| args | required | default | description |
|---|---|---|---|
| --help | - | false |
help |
| --config | - | null |
config |
| --version | - | v0.0.0 |
version |
| --egads-config-filename | - | provided |
egads-config-filename |
| --port | - | 4080 |
port |
| --interval-minutes | - | 180 |
interval-minutes |
| --interval-hours | - | 672 |
interval-hours |
| --interval-days | - | 28 |
interval-days |
| --interval-weeks | - | 12 |
interval-weeks |
| --interval-months | - | 6 |
interval-months |
| --enable-email | - | false |
enable-email |
| --from-mail | if email enabled |
from-mail | |
| --reply-to | if email enabled |
reply-to | |
| --smtp-host | if email enabled |
smtp-host | |
| --smtp-port | - | 25 |
smtp-port |
| --smtp-user | - | smtp-user | |
| --smtp-password | - | smtp-password | |
| --failure-email | if email enabled |
failure-email | |
| --execution-delay | - | 30 |
execution-delay |
| --valid-domains | - | null |
valid-domains |
| --redis-host | - | 127.0.0.1 |
redis-host |
| --redis-port | - | 6379 |
redis-port |
| --redis-ssl | - | false |
redis-ssl |
| --redis-timeout | - | 5000 |
redis-timeout |
| --redis-password | - | - | redis-password |
| --redis-clustered | - | false |
redis-clustered |
| --project-name | - | - | project-name |
| --external-file-path | - | - | external-file-path |
| --debug-mode | - | false |
debug-mode |
| --timeseries-completeness | - | 60 |
timeseries-completeness |
| --http-client-timeout | - | 20000 |
http-client-timeout |
| --backup-redis-db-path | - | null |
backup-redis-db-path |
| --druid-brokers-list-file | - | null |
druid-brokers-list-file |
| --truststore-path | - | null |
truststore-path |
| --truststore-type | - | jks |
truststore-type |
| --truststore-password | - | null |
truststore-password |
| --keystore-path | - | null |
keystore-path |
| --keystore-type | - | jks |
keystore-type |
| --keystore-password | - | null |
keystore-password |
| --key-dir | - | null |
key-dir |
| --cert-dir | - | null |
cert-dir |
| --https-hostname-verification | - | true |
https-hostname-verification |
| --custom-ssl-context-provider-class | - | DefaultSslContextProvider |
custom-ssl-context-provider-class |
| --custom-secret-provider-class | - | DefaultSecretProvider |
custom-secret-provider-class |
| --prophet-url | - | 127.0.0.1:4080 |
prophet-url |
| --prophet-timeout | - | 120000 |
prophet-timeout |
| --prophet-principal | - | prophet-principal |
prophet-principal |
Prints commandline argument help message.
Path to a Sherlock configuration file, where the above configuration may be specified. Config arguments in the file override commandline arguments.
Version of sherlock.jar to display on the UI
Path to a custom EGADS configuration file. If none is specified, the default configuration is used.
Port on which to host the Spark application.
Number of historic data points to use for detection on time-series every minute.
Number of historic data points to use for detection on hourly time-series.
Number of historic data points to use for detection on daily time-series.
Number of historic data points to use for detection on weekly time-series.
Number of historic data points to use for detection on monthly time-series.
Enable the email service. This enables users to receive email anomaly report notifications.
The handle's FROM email displayed to email recipients.
The handle's REPLY TO email where replies will be sent.
The email service's SMTP HOST.
The email service's SMTP PORT. The default value is 25.
The email service's SMTP USER.
The email service's SMTP PASSWORD.
A dedicated email which may be set to receive job failure notifications.
Sherlock periodically pings Redis to check scheduled jobs. This sets the ping delay in seconds. Jobs are scheduled with a precision of one minute.
A comma-separated list of valid domains to receive emails, e.g. 'yahoo,gmail,hotmail'. If specified, Sherlock will restrict who may receive emails.
The Redis backend hostname.
The Redis backend port.
Whether Sherlock should connect to Redis via SSL.
The Redis connection timeout.
The password to use when authenticating to Redis.
Whether the Redis backend is a cluster.
Name of the project to display on UI.
Specify the path to external files for Spark framework via this argument.
Debug mode enables debug routes. Ex. '/DatabaseJson' (shows redis data as json dump). Look at com.yahoo.sherlock.App for more details.
This defines minimum fraction of datapoints needed in the timeseries to consider it as a valid timeseries o/w sherlock ignores such timeseries. (default value 60 i.e. 0.6 in fraction)
HttpClient timeout can be configured using this(in millis). (default value 20000)
Backup redis DB at given file path as json dump of indices and objects. Backup is done per day at midnight. Default this parameter is null i.e. no buckup. However, BGSAVE command is run at midnight to save redis local dump.
Specify the path to an access control list file of permitted druid broker hosts for querying. Format: <host1>:<port>,<host2>:<port>... (default null i.e any host is allowed)
Path to specify truststore location for mTLS connections. (default null)
Param to specify truststore type for mTLS connections. (default jks)
Param to specify truststore password for mTLS connections. (default null)
Path to specify keystore location for mTLS connections. (default null)
Param to specify keystore type for mTLS connections. (default jks)
Param to specify keystore password for mTLS connections. (default null)
Param to specify key directory containing multiple keys(for different clusters) for mTLS connections (default null).
This is used when Principal Name is given in druid cluster form.
It looks for filename containing Principal Name under this dir.
If --key-dir and --cert-dir values are same then the filename should also contain the identifier key for private key file and cert for public key file.
Param to specify cert directory containing multiple certs(for different clusters) for mTLS connections (default null)."
This is used when Principal Name is given in druid cluster form.
It looks for file name containing Principal Name under this dir.
If --key-dir and --cert-dir values are same then the filename should also contain the identifier key for private key file and cert for public key file.
Param to enable/disable https hostname verification for mTLS connections. (default true i.e. hostname verification enabled)
Param to specify custom ssl context provider class for mTLS connections. (default com.yahoo.sherlock.utils.DefaultSslContextProvider which returns SSLContext with validation)
Param to specify custom secret provider class for passwords. (default com.yahoo.sherlock.utils.DefaultSecretProvider which returns secrets specified from CLISettings)
API endpoint of a running Prophet Service. (default 127.0.0.1:4080 which include both url and port)
Timeout for querying the Prophet Service. (default 120000 milliseconds)
The Kubernetes principal that the Prophet Service is located. (default prophet-principal)
It is suggested to use Java8 and Maven 3.3 to develop Sherlock.
Currently, Sherlock supports two detector pipelines (Egads/Prophet). Both pipelines use Egads' anomaly detection module for anomaly detection.
The Egads pipeline conducts both time series forecasting and anomaly detection via Egads anomaly detection library.
On the other hand, the Prophet pipeline allows Sherlock to query forecasted time series from a Prophet web service.
After that, the Prophet pipeline performs anomaly detection via Egads' anomaly detection module.
If the developer wants to add a new anomaly detector to Sherlock, the developer should look at the abstract class service/DetectorAPIService.java, and implement a new detector class that extends DetectorAPIService.
More specifically, developers should implement abstract methods detectAnomaliesAndForecast and detectAnomalies. The two abstract methods are elaborated in sections below.
Sherlock allows the user to perform an instant anomaly detection, which is accessible via the /Flash-Query endpoint. The endpoint is linked to method processInstantAnomalyJob under Routes.java,
which calls method detectWithResults under DetectorService.java.
Method detectWithResults checks which detector the user wants to use, assign the corresponding DetectorAPIService instance, and calls the instance's detectAnomaliesAndForecast method.
Method detectAnomaliesAndForecast does anomaly detection and returns the original time series, expected time series, and the anomaly points. The combined results are displayed via the /Flash-Query/ProcessAnomalyReport endpoint.
Sherlock allows the user to schedule anomaly detection jobs that run routinely.
Regarding the job scheduling, Sherlock uses JobScheduler.java to maintain a Priority Queue stored in Redis. Every time the user adds a job,
Sherlock puts the job into via method scheduleJob with the job's next run time as the priority.
Sherlock keeps checking the current system time, and pops the Priority Queue as required via method consumeAndExecuteTasks.
For the actual detection, method consumeAndExecuteTasks executes a job that is due, which eventually goes to method runDetection under DetectorService.java.
Method runDetection checks which detector the user wants to use, assign the corresponding DetectorAPIService instance, and calls the instance's detectAnomalies method.
Method detectAnomalies does anomaly detection and returns anomaly points because job reports display only detected anomaly points.
All current pipelines use TimeSeries and Anomaly classes defined in Egads heavily. To gain a better understanding of those formats, developers should read TimeSeries.java/Anomaly.java defined in the Egads repository.
Jigar Patel, jigsdevbox@gmail.com
Jeff Niu, jeffniu22@gmail.com
Josh Walters, josh@joshwalters.com
Stephan Stiefel, Stephan3555
Han Xu, hanxu12
Code licensed under the GPL v3 License. See LICENSE file for terms.