[Hawkular-dev] Hawkular Metrics 0.3.4 - Release & Beyond

[Stefan Negrea]

Hello Everybody,

I am happy to announce release 0.3.4 of Hawkular Metrics. The release is anchored by stability improvements and Docker + Kubernetes work.

Here are the release highlights:

1) InfluxDB Compatibility Layer
 - pretty printing of query results with the 'pretty' query parameter
 - absolute moment operands in queries (ex: select * from test where time > 1501560s and time < 4560546h)
 - various fixes which allow to integrate nicely with Grafana (declaring Hawkular Metrics as an InfluxDB 0.8 datasource)

2) RxJavaMigration 
 - big refactoring to use RxJava instead of Guava's ListenableFuture
 - RxJava provides a much richer API for building asynchronous programs

3) Server Start-up
 - the server no longer requires Cassandra to be started first
 - any client requests will get back a 503 response code if the server has not fully initialized due to Cassandra being down at start up time

4) Docker and Kubernetes
 - all project docker images are now available in Docker Hub! Get them here:
    https://registry.hub.docker.com/u/hawkular/hawkular-metrics/
    https://registry.hub.docker.com/u/hawkular/hawkular-cassandra/
 - improved replication controller support now means that both the Hawkular-Metrics and Cassandra images can be scaled up or down
 - various other smaller improvements, including better support for when containers startup

5) REST API (IMPORTANT!)
 - tenantId header was renamed to Hawkular-Tenant
 - tenantId header fallback was removed
 - GET {id}/tags only returns the tags, not the whole definition anymore
 - GET {id} returns the metric definition (see HWKMETRICS-110 [1] for known issue)

6) UI Explorer 
 - was removed from the project
 - discussions are underway to find a new home for the functionality and code (probably hawkular-ui-components)
 - npm is no longer required to compile the project

7) Task Queue
 - a generic task queue was designed and developed as part of this release 
 - provides functionality for scheduling and executing background tasks or jobs
 - task execution is
    scalable - automatically distributed among Hawkular Metrics servers
    durable - Tasks are persisted
    fault tolerant - Tasks are rescheduled for future execution when there is a failure
 - it will serve as the foundation for 
    computing/storing aggregated metrics (i.e., rollups)
    deleting metrics
    changing data retention
 - this functionality will be basis for any background task based design for the project


Github Release:
https://github.com/hawkular/hawkular-metrics/releases/tag/0.3.4

JBoss Nexus Maven artifacts:
http://origin-repository.jboss.org/nexus/content/repositories/public/org/hawkular/metrics/

Jira release tracker:
https://issues.jboss.org/browse/HWKMETRICS/fixforversion/12327259/


Hawkular Metrics 0.3.5 and Beyond
1) Gauge Aggregates - Long-term storage of numeric metrics at the expense of losing some fidelity. With task queue released in 0.3.4, the expectation is to start the actual implementation 0.3.5.
2) Update REST testing - while the current set of tests is a good gauge for regressions, the overall coverage is still low. The plan for 0.3.5 is to increase coverage.
3) Improved Docker and Kubernetes support - this is a long term goal for the project
4) RXJava - the initial transition from Guava was done in 0.3.4. Future releases will build upon this foundation.
 

A big "Thank  you" goes to John Sanda, Thomas Segismont, Mike Thompson, Matt Wringe, Michael Burman, and Heiko Rupp for their project contributions. Special mentions go to Jeeva Kandasamy and Jirka  Kremser for their project  help.


[1] https://issues.jboss.org/browse/HWKMETRICS-110

Thank you,
Stefan Negrea

Software Engineer