The Observe Data Generator tool is a Scala based tool that can be used to generate synthetic log events in a varierty of formats and send those events to Observe's HTTP end point (https://docs.observeinc.com/en/latest/content/data-ingestion/endpoints/http.html) for testing purposes. Out of the box the tool has templates for generating events in the following formats:
- Accesslog
- VPC Flow Logs
- Corelight DNS Logs
Additional log types can be added by creating new templates as described futher down in this readme.
Important Note: The Observe Data Generator tool is derived from the humio-ingest-load-test tool that is available at: https://github.com/humio/humio-ingest-load-test. The code in this project has been modified to remove Humio specific functionality and features not required for the Observe use case.
The easiest way to run the Observe Data Generator tool is to download the latest release of the tool from: https://github.com/obs-gh-craigvitter/observe-data-generator/releases and unzip it.
From the commandline you can execute the tool using the following command:
java \
-Dbaseurl=https://[tenantid].collect.observe.com \
-Dendpoint=/v1/http \
-Dtoken=[observetoken] \
-Dtemplate=templates/accesslog.ssp \
-jar ./observedg.jar \
-s com.observe.datageneration.TemplateSimulation
Within the command you will need to replace values in the following arguments:
- Dbaseurl: The collection endpoint URL (typically: https://[tenantid].collect.observe.com). Replacing the [tenantid] with the correct ID you are sending data to.
- Dendpoint: The tool only sends data to the HTTP end point which is at '/v1/http' however you can append values to that endpoint address to provide additional path information to Observe, for example: '/v1/http/accesslog' or '/v1/http/vpcflow'
- Dtoken: This is the Datastream Token that you wish to use for ingesting into Observe.
- Dtemplate: The template to run during the execution. Currently the following templates are available: accesslog.ssp, corelight-dns.ssp, and vpcflow.ssp. See the templates README for more information.
By default the application is configured to execute for one (1) minute and generate 55 to 65 events during the execution. The following parameters can be adjusted to increase run time and the volume of events sent to Observe.
- Dtime: Default = 1, number of minutes that the application should execute.
- Dusers: Default = 1, increase the number of users to send from multiple origins and increase the number of events sent in a given time frame.
- Dbatchsize: Default = 1, increase the number of events sent per post to the HTTP end point.
For most use cases you do not need to build your own version of the executable. For example, you can add templates and data files to the application (see the section on Templates) without building the executable. You will only need to build the executable if you make changes to the core code.
If you decide to build the executable you will need to have the following on your environment:
- Java
- sbt
- make
Note: The latest release used OpenJDK Version 20.0.1, SBT Version 1.9.0, GNU Make 3.81 and was built on a MacBook Pro running Ventura 13.4.
Clone the project to your environment and run make from the project's root. That's really all there is too it...
The goal of TemplateSimulation is to make dynamic content generation easier, as well as generate data that is realistically compressible and, ideally, quasi-meaningfully queryable for demonstration purposes.
Toward this end, TemplateSimulation provides the ability to use a specified .ssp file, interpreted by the
Scalate engine; in this specific instance, the
SSP implementation is used, which is similar to
Velocity, JSP, Erb, etc.
Along with the ability to template, TemplateSimulation adds the ability to generate different types of data according to a
specified distribution (examples below).
SSP (so-called "Scala Server Pages") directives are documented in full here.
Below I will walk you through the different sections, and mechanics, of template handling. See the file templates/test.ssp for a full working example.
Templates require a number of imports to function correctly. More may be required if you implement custom functionality beyond that supported by these typical libraries:
import com.humio.perftest._
import play.api.libs.json._
import org.fusesource.scalate._
import org.fusesource.scalate.RenderContext._
Templates typically use an init block to create and register data generators and one-time values. This block of the template is only run once upon initialization. It is implemented very simply, switched on a context variable init:
if (init) {
data.register("httpMethod",
new ArraySampler(
data.distributions.exponential,
Array("GET", "POST", "PUT", "DELETE", "OPTION")
)
)
// ....
}
All code outside the init block between <% and %> (see the SSP & Scalate reference docs for more information on this and other template directives) is executed on every data generation request. This is the section where the actual data generation from the template takes place. For example, with the templates/test.ssp example, this section is outside the init block and is executed on every generation call:
val sourceType = "applog"
val logTs = data.timestamp
val tag = "tag" + data.sample("tagNum")
val source = "file" + data.sample("sourceNum")
val viewId = data.sha1(data.sample("viewAndQueryId")).substring(0,10)
val queryId = "IQ-" + viewId.substring(0,5).reverse + viewId.substring(5).reverse
var logLine: String = capture {
%>
${logTs} requests 11 - route=humio method=<%= data.sample("httpMethod") %>, remote=10.0.<%= data.sample("host1") %>.<%= data.sample("host2") %>:<%= data.sample("port") %> uri=http://newcloud<%= data.sample("cloudHost") %>:8080/api/v1/internal/views/${viewId}/queryjob/${queryId}, status=<%= data.sample("status") %>, time=<%= data.sample("time") %>, internal=<%= data.sample("internal") %>, contentLength=<%= data.sample("contentLength") %>
<%
}.trim // capture
val jsonObj = Json.obj(
"source" -> source,
"sourcetype" -> sourceType,
"event" -> logLine,
"time" -> logTs,
"fields" -> Json.obj(
"host" -> "perftesthost",
"source2" -> source
)
)
val output = Json.toJson(jsonObj)
%>${output.toString.trim}
Simple data generation methods provide things like timestamps, etc. Sampled data generators must be created and registered. Their function is to select from sets of elements with specified probabilities.
There are a handful of functions available to generate simple types of data:
| Name | Implementation |
|---|---|
data.timestamp |
Current timestamp, via "%.6f".format(ZonedDateTime.now().toInstant.toEpochMilli.toDouble / 1000d) |
data.iso8601Timestamp |
Current timestamp, via SimpleDateFormat format yyyy-MM-dd'T'HH:mm'Z' |
data.sha1(String) |
SHA1 hash of given string. Useful for generating identifiers from other data types. |
For example, let's say you have a log line you would like to generate similar log lines of:
2021-01-01T0:0:0.0Z requests 11 - route=humio method=GET, remote=10.0.1.10, ...
We want to replace the values for the method and remote key-value pairs with data that is plausible. The first step is to think about how the log line works: "What is the distribution of HTTP request methods for this endpoint?". For this example, let's say it's predominantly GET, with POST a distant second, and the rest typically representative of error or malformed calls. For the purposes of this example, let's say it's best represented by an exponential distribution. Highly accurate distribution estimation is not generally necessary to achieve the aims of this project and its methods are beyond the scope of this document.
So, for method, to sample from an array of values with exponentially decreasing probability (more later on his this mapping is achieved), you can create an ArraySampler and register it with the name httpMethod:
data.register("httpMethod",
new ArraySampler(
data.distributions.exponential,
Array("GET", "POST", "PUT", "DELETE", "OPTION")
)
)
The above code creates an ArraySampler that maps exponentially decreasing probabilities to successive elements in the provided array.
Now, the remote element. To make this more interesting to query when combined with other generated elements, let's break the field into 10.0.host1.host2, where the distributions of host1 and host2, while different, combine to form a useful structure of IP addresses in the aggregate. For example:
data.register("host1", new IntSampler(data.distributions.exponential, 0, 10))
data.register("host2", new IntSampler(data.distributions.uniform, 0, 20))
The first generator, host1, is defined as a sampler over the integer range 0 to 10 with decreasing exponential probability (i.e., 0 is most likely, 10 least). The second generator, host2, is defined as a sampler over the integer range 0 to 20, with uniform probability.
The available samplers and distributions are described in complete below.
Once a sampler (e.g., ArraySampler) has been created and registered, it can be sampled from to produce a value. Following along with the templates/test.ssp example, the example log line we're trying to create a generator for becomes the following:
${logTs} requests 11 - route=humio method=<%= data.sample("httpMethod") %>, remote=10.0.<%= data.sample("host1") %>.<%= data.sample("host2") %>, ...
The relevant part in this context is this: <$= data.sample("httpMethod") %>. The <%= and %> tags say "execute the code within this block and output the value. The data.sample("httpMethod") code requests a sample from the sampler registered under the name httpMethod, which we created and registered above. The same concept applies to the host1 and host2 samplers.
Note: CSVSampler is a sampler that exposes a sampleRow function as well as a sample function. sampleRow samples a row of values from the provided CSV file that can then be access by index, e.g., someVar(1). Using sample with a CSVSampler simply returns the value in the first column of the sampled row.
| Name | Description | Signature |
|---|---|---|
| ArraySampler | Samples from an array of Strings. | new ArraySampler(<distribution>, Array("value", ...)) |
| IntSampler | Samples from an increasing range of integers. | new IntSampler(<distribution>, <lower>, <upper>) |
| RealSampler | Samples from an increasing range of doubles. | new RealSampler(<distribution>, <lower>, <upper>) |
| CSVSampler | Samples rows from a CSV file. | new CSVSampler(<distribution>, "<csv filename>") |
Distributions are implemented with the Apache Commons Math Library. Since they are distributions over the reals, the following method was used to map probabilities (see SimUtils for further information):
abstract class Sampleable(distribution: RealDistribution) {
val minProbability = 0.0001
val maxProbability = 0.999999
val icp0 = distribution.inverseCumulativeProbability(minProbability)
val icp1 = distribution.inverseCumulativeProbability(maxProbability)
val icpDif = icp1 - icp0
def sampleDistribution = {
val sample = distribution.sample()
if (sample < icp0) 0
else if (sample > icp1) 1
else (sample - icp0) / icpDif
}
def sample: String
}
With the mapping following the pattern similar to:
class ArraySampler(distribution: RealDistribution, values:Array[String]) extends Sampleable(distribution = distribution) {
override def sample: String = values(((values.length-1).toDouble * sampleDistribution).round.toInt)
}
The actual distribution sampling, distribution.sample(), is implemented by Inverse transform sampling.
Distribution specification has been simplified with default values, which are described below. If you require a specific configuration, see TemplateHelper.distributions in SimUtils.
| Name | Description |
|---|---|
| data.distributions.exponential | Exponential distribution, default mean=1 |
| data.distributions.normal | Normal distribution, default mean=0, scale=1 |
| data.distributions.uniform | Uniform distribution |
| data.distributions.logNormal | Log-normal distribution, default scale=0, shape=1 |
In a pinch, you can import import org.apache.commons.math3.distribution._ in your template and construct a distribution directly if you don't want to add the specific distribution and associated default parameters to the default options, e.g.,
data.register("contentLength",
new IntSampler(
new BetaDistribution(0.5, 0.5),
0, 256000))
All available distributions are subclasses of AbstractRealDistribution.
All distribution sampling uses the Well19937c generator.
Let's say you have a pair of fields being generated that must be correlated, e.g., a pair of fields named rcode_name and rcode, where they both hold a value that relates to the other. A good way to do this is to use a CSVSampler that references a CSV file that maps one to the other, e.g.,
NOERROR,0
SERVFAIL,2
NXDOMAIN,3
REFUSED,5
With this input to the CSVSampler, along with an appropriate distribution, you can use sampleRow, e.g.,
// init:
data.register("rcode", new CSVSampler(data.distributions.exponential, "templates/data/dns_rcode.samples.csv"))
// sample:
val rcodeRow = data.sampleRow("rcode")
val rcodeName = rcodeRow(0)
val rcode = rcodeRow(1)
For a real-world example of this, see the corelight-dns.ssp template.
Let's say you have a variable that you're unsure how to model, but you do have many observations of that variable (the "sample frame"). One method of sampling this variable is to load a CSV file with all the observations -- do not process this list of values in any way! -- into a CSVSampler with a uniform distribution, e.g.,
// init:
data.register("TTL", new CSVSampler(data.distributions.uniform, "templates/data/dns_ttls0.csv"))
// sample:
val ttl = data.sample("TTL")
The bigger the sample frame, the more the sampled data will be representative of the underlying distribution.
Notes:
- All
CSVSamplerdata is stored in memory: be mindful and plan accordingly when using large sets of observations. - While there are many opportunities for significant error when using this method, for simple data generation tasks it can still be useful.
This project includes sample templates that can be found in the templates directory: templates.
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