Heroku Datadog Drain

Golang version of NodeJS

Funnel metrics from multiple Heroku apps into DataDog using statsd.

Supported Heroku metrics:

• Heroku Router response times, status codes, etc.
• Application errors
• Custom metrics
• Heroku Dyno runtime metrics
• (beta) Heroku Runtime Language Metrics - we add support for golang used in Heroku, next step add this to send to Datadog too for self monitoring app.

Get Started

Clone the Github repository

git clone git@github.com:busbud/heroku-datadog-drain-golang.git
cd heroku-datadog-drain-golang

Setup Heroku, add your statsd url and basic auth creds

heroku create
heroku config:set BASIC_AUTH_USERNAME=user BASIC_AUTH_PASSWORD=pass STATSD_URL=somewhere.com

OPTIONAL: Setup Heroku build packs, including the Datadog DogStatsD client. If you already have a StatsD client running, see the STATSD_URL configuration option below.

heroku buildpacks:add heroku/go

Don't forget set right golang version.

heroku config:add GOVERSION=go1.10

Deploy to Heroku.

git push heroku master
heroku ps:scale web=1

Add the Heroku log drain using the app slug and password created above.

heroku drains:add https://<username>:<password>@<this-log-drain-app-slug>.herokuapp.com?app=<your-app-slug> --app <your-app-slug>

Configuration

STATSD_URL=..             # Required. Set to: localhost:8125
DATADOG_API_KEY=...       # Required if STATSD_URL is not set. Datadog API Key - https://app.datadoghq.com/account/settings#api
BASIC_AUTH_USERNAME=...   # Required. Basic auth username to access drain.
BASIC_AUTH_USERNAME=...   # Required. Basic auth password to access drain.
DATADOG_DRAIN_DEBUG=..    # Optional. If DEBUG is set, a lot of stuff will be logged :)
EXCLUDED_TAGS: path,host  # Optional. Recommended to solve problem with tags limit (1000)

The rationale for EXCLUDED_TAGS is that the path= tag in Heroku logs includes the full HTTP path - including, for instance, query parameters. This makes very easy to swarm Datadog with numerous distinct tag/value pairs; and Datadog has a hard limit of 1000 such distinct pairs. When the limit is breached, they blacklist the entire metric.

Heroku settings

You need use Standard dynos and better and enable log-runtime-metrics in heroku labs for every application.

heroku labs:enable log-runtime-metrics -a APP_NAME

This adds basic metrics (cpu, memory etc.) into logs.

Custom Metrics

If you want to log some custom metrics just format the log line like following:

app web.1 - info: responseLogger: metric#tag#route=/parser metric#request_id=11747467-f4ce-4b06-8c99-92be968a02e3 metric#request_length=541 metric#response_length=5163 metric#parser_time=5ms metric#eventLoop.count=606 metric#eventLoop.avg_ms=515.503300330033 metric#eventLoop.p50_ms=0.8805309734513275 metric#eventLoop.p95_ms=3457.206896551724 metric#eventLoop.p99_ms=3457.206896551724 metric#eventLoop.max_ms=5008

We support:

• metric# and sample# for gauges
• metric#tag for tags.
• count# for counter increments
• measure# for histograms

more info here

Overriding prefix and tags with drain query params

To change the prefix use the drain of form: https://<your-app-slug>:<password>@<this-log-drain-app-slug>.herokuapp.com?prefix=abcd.

To change tags use the drain of form: https://<your-app-slug>:<password>@<this-log-drain-app-slug>.herokuapp.com?tags=xyz,abcd