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Hacking on influx-spout

Running influx-spout on a developer machine

The tools directory contains a set of configuration files for running a full influx-spout system on a single machine. These should work together and can be used as-is or tweaked as required.

Before running influx-spout, InfluxDB needs to be installed and set up:

  • Install InfluxDB as per the official documentation.
  • Start influxdb. How to do this is dependent on your Linux distribution. Starting InfluxDB may involve sudo systemctl start influxdb or sudo influxd.
  • Create a spout database: influx -execute "create database spout"

A NATS server is also required:

  • Install NATS as per the official documentation.
  • Start a NATS server with the default configuration by running: gnatsd

Now build and install influx-spout: go install github.com/jumptrading/influx-spout/.... Then start the various influx-spout components:

influx-spout tools/monitor.toml
influx-spout tools/listener.toml
influx-spout tools/listener_http.toml
influx-spout tools/filter.toml
influx-spout tools/writer.toml

You'll want to run each component in its own termnial session.

At this point influx-spout should be ready to accept measurements via UDP or HTTP.

Monitoring memory usage

The tools/watchmem script can be used to monitor the memory usage of a program. This is useful for checking influx-spout for memory leaks. For example, to monitor the memory used by a influx-spout writer over time, run:

tools/watchmem writer-mem.dat influx-spout tools/writer.toml

The elapsed time and current resident set size (RSS) of the writer processes will be emitted every 2s as well as being written out to writer-mem.dat. This file can be directly plotted by tools like gnuplot or imported into a spreadsheet for analysis.

Slow consumer testing

It can be useful to check the effect of a slow InfluxDB instance on influx-spout. Slow consumers have historically caused problems for influx-spout.

To run a slow consumer test, start influx-spout as described above but replace InfluxDB with the slowinfluxd utility provided with influx-spout.

  • Build slowinfluxd: go install github.com/jumptrading/influx-spout/cmd/slowinfluxd
  • Ensure influxd isn't running (sudo systemctl stop influxdb)
  • Run slowinfluxd
  • Ensure gnatsd is running (as above).
  • Run the various influx-spout components as described above. Run the writers using the watchmem tool above.

Any measurements fed into influx-spout will now end up being written to the slowinfluxd server which holds up the writer(s) by delaying responses to write requests. Even with a high rate of measurements into the listener, memory usage for all the influx-spout components should increase to some threshold and then plateau. If memory consumption increases without bound, there could be a configuration problem or a bug in influx-spout.

Releases

Public releases of influx-spout are automatically created when a tagged revision successfully builds in Travis CI. GoReleaser is used to create release tarbals and create a release on Github.

To publish a new release:

  • Add notes for the release at the top of release-notes.md. Important: Ensure the notes start with a level 1 header for the release (e.g. # v3.2.1). The git log --reverse <previous-tag>..HEAD command is useful for browsing the commits in the release.
  • Commit and merge the updates to release-notes.md to the master branch on Github.
  • Create an annotated tag for the release. For example: git tag -a v3.2.1 -m "3.2.1 release"
  • Push the tag to Github. For example: git push origin v3.2.1
  • If the tagged revision builds successfully under Travis CI a release should be automatically published to Github.