Monitor infrastructure and applications with New Relic


New Relic is a SaaS that monitors infrastructure and applications, and there is Datadog as a similar service. It seems that the pricing plans were changed drastically in 2020, and it charges according to the transfer volume and the number of admin users. Therefore compared to Datadog, which charges for hosts and additional features, there is an advantage when managing a large number of instances with a small number of people. And Datadog pricing plans are relatively complex and hard to estimate how much the bill will be in an environment where the number of instances increases and decreases frequently, while New Relic’s plans are easy. Even if you try to new features, the unit price will not increase, so you can easily try it.

On the other hand, if there are a lot of admin users or the number of requests is huge so the transfer volume about APM is increased, it may be more expensive than Datadog. In many cases, user charges are the majority, so if you replaces some Full platform users with half priced Core user or free Basic user, the charges will be reduced but while Dashboard and Alert are available to all users, APM screens are available to only full platform users. The transfer volume charges can be reduced by Drop data. It cannot be set from the screen for now, so it is necessary to use NerdGraph. The following is an example of setting with Terraform.

Query resources with NerdGraph, New Relic’s GraphQL API - sambaiz-net

resource "newrelic_nrql_drop_rule" "heavy_path" {
  account_id  = *****
  description = "Drop transactions data"
  action      = "drop_data"
  nrql        = "SELECT * FROM Transaction WHERE `request.uri` = '/heavy_path'"

I feel troubleshooting is relatively difficult. I faced some troubles such as sending no metrics or referencing old documents but the libraries and documents are OSS so I think they can be almost resolved by reading the code or sending a PR. However, there are informations which are not written clearly in docs, or even if they are written, it may be difficult to find them, so esecially if you use New Relic for the first time, although the user unit price will increase, pro or higher plan which have support may be better. New features, including CodeStream, which was acquired last year, are being actively developed, so I hope that the troubleshooting will be improved as well.

Make asking about codes and debugging efficient with New Relic CodeStream - sambaiz-net

AWS integration

Create a Role with ReadOnlyAccess and budgets:ViewBudget to AssumeRole from New Relic.

AWSのAssumeRole - sambaiz-net

  "Statement": [
      "Action": [
      "Effect": "Allow",
      "Resource": "*"
  "Version": "2012-10-17"

For metric acquisition, the conventional method of calling the API regularly for polling, and the method of using CloudWatch Metric Steams streaming to Firehose are supported, and the latter is recommended. Required resources can be created by passing the License Key to the provided CloudFormation template. The following resources are created and the metrics are displayed on the New Relic dashboard.

Looking at the created Metric Streams settings, it can find all namespace metrics are sent.

If the metrics are not sent, make sure you have not copied the wrong Key or Key ID.

Install an infrastructure monitoring agent

Install an agent to collect the CPU usage rate and network I/O etc. of the instance. The following commands are for Amazon Linux 2 (arm64).

$ echo "license_key: ****-" | sudo tee -a /etc/newrelic-infra.yml
$ sudo curl -o /etc/yum.repos.d/newrelic-infra.repo
$ sudo yum -q makecache -y --disablerepo='*' --enablerepo='newrelic-infra'
$ sudo yum install newrelic-infra -y
$ sudo systemctl start newrelic-infra

New Relic Flex

If following yaml file is put under /etc/newrelic-infra/integrations.d, command outputs, HTTP responses or file contents can be send on a regular basis.

For monitoring Fluentd, the value of monitor_agent can be sent with Telemetry SDK, but if use this feature instead, an application to send it is not needed to run on log aggregator.

fluentdのmonitor_agentのデータをGoでGoogle Stackdriverに送って監視する - sambaiz-net

$ cat /etc/newrelic-infra/integrations.d/fluentd.yml
- name: nri-flex
    name: fluentd
    - event_type: fluentd
      url: http://localhost:24220/api/[email protected]=forward

Check the data with following NRQL.

FROM fluentd SELECT rate(average(buffer_total_queued_size), 1 minute) FACET `config.@id` TIMESERIES 


APM is a feature to collect runtime information such as the number of Goroutines and GC execution time, as well as X-Ray-like request traces and show their summaries. The agent libraries are provided in C, Go, Java, .NET, Node.js, PHP, Python ans Ruby.

$ go get

Integrations are provided for major WAFs such as echo and gin in Go, and this middleware writes Transaction associated with the request to the context and make it retrievable with nrecho.FromContext(c). Transaction that are not associated with a request are treated as Background jobs.

import ""
app, err := newrelic.NewApplication(

http.HandleFunc(newrelic.WrapHandleFunc(app, "/users", usersHandler))

// in middleware
c.Response().Writer = txn.SetWebResponse(rw)
c.SetRequest(c.Request().WithContext(newrelic.NewContext(c.Request().Context(), txn)))

func handler(c echo.Context) error {
	txn := nrecho.FromContext(c)
	return c.String(http.StatusOK, "ok")

NewApplication() spawns a goroutine which hervests data and send it so if you new a Application each time without calling Shutdown(), the goroutine leaks.

If create a segment, the execution time of that section is displayed on the timeline.

func do(ctx context.Context) {
  defer newrelic.FromContext(ctx).StartSegment("do").End()

If wrap a HTTP request, a segment for the external request is created and average latency etc. are displayed on the Service Map.

client := &http.Client{}
client.Transport = newrelic.NewRoundTripper(client.Transport)

request, _ := http.NewRequest("GET", "", nil)
request = newrelic.RequestWithTransactionContext(request, txn)

response, err := client.Do(request)

Custom metrics

When app.RecordCustomMetric(key,value) is called, metrics of Custom/ prefix are sent.

app.RecordCustomMetric("CustomMetricName", 132)

The metrics are not shown on Data explorer and you can see it on Metrics explorer of APM.

In NRQL, refer to newrelic.timeslice.value as follows.

FROM Metric SELECT count(newrelic.timeslice.value) 
  WHERE appName = 'MY APP' 
  WITH METRIC_FORMAT 'Custom/{name}' 

Characteristics of Metrics and Events in New Relic and queries in NRQL - sambaiz-net

Log forwarding

Logs can be forwarded with Fluentd, Fluent Bit and Log stash plugin.

$ td-agent-gem install fluent-plugin-newrelic
<filter foo>
  @type record_transformer
    service_name ${tag}
    hostname "#{Socket.gethostname}"

<match foo>
  @type newrelic
  api_key ****

Logrus, a logger in Go, integration is provided, which adds following fields to the log and associate the request trace with the log. Any loggers are available if add these yourself.

func AddLinkingMetadata(m map[string]interface{}, md newrelic.LinkingMetadata) {
	metadataMapField(m, KeyTraceID, md.TraceID)
	metadataMapField(m, KeySpanID, md.SpanID)
	metadataMapField(m, KeyEntityName, md.EntityName)
	metadataMapField(m, KeyEntityType, md.EntityType)
	metadataMapField(m, KeyEntityGUID, md.EntityGUID)
	metadataMapField(m, KeyHostname, md.Hostname)

If log is linked, it can be jumped from Errors Event, which is helpful to troubleshoot.

About newrelic-lambda-extension and how it works telemetry without CloudWatch Logs - sambaiz-net


NewRelic でtd-agent(fluentd) にメトリクスを監視する - y-ohgi’s blog