Easier and More Powerful Observability with the OpenCensus Agent and Collector

The OpenCensus project has grown considerably over the past year, and we’ve had several significant announcements in the first half of 2019, including the project’s merger into OpenTelemetry. The features discussed in this post will move into OpenTelemetry over the coming months.

For those who aren’t already familiar with the project, OpenCensus provides a set of libraries that collect distributed traces and application metrics from your applications and send them to your backend of choice. Google announced OpenCensus one year ago, and the community has since grown to include large companies, major cloud providers, and APM vendors. OpenCensus includes integrations with popular web, RPC, and storage clients out of the box, along with exporters that allow it to send captured telemetry to your backend of choice.

We’ve recently enhanced OpenCensus with two new components: an optional agent that can manage exporters and collect system telemetry from VMs and containers, and an optional collector service that offers improved trace sampling and metrics aggregation. While we’ve already demonstrated these components on stage at Kubecon and Next, we’re now ready to show them more broadly and encourage their use.

The OpenCensus Agent

The OpenCensus agent is an optional component that can be deployed to each of your virtual machines or kubernetes pods. The agent receives traces and metrics from OpenCensus libraries, collects system telemetry, and can even capture data from a variety of different sources including Zipkin, Jaeger, and Prometheus. The agent has several benefits over exporting telemetry directly from the OpenCensus libraries:

• The OpenCensus libraries export data to the OpenCensus agent by default, meaning that backend exporters can be reconfigured on the agent without having to rebuild or redeploy your application. This provides value for applications with high deployment costs and for PaaS-like platforms that have OpenCensus already integrated.
• While the OpenCensus libraries collect application-level telemetry, the agent also captures system metrics like CPU and memory consumption and exports these to your backend of choice.
• You can configure stats aggregations without redeploying your application.
• The OpenCensus agent will host z-pages. While we originally made these a part of the libraries, we’ll be moving this functionality to the agent. This should result in a higher quality diagnostic page experience, as we’ll no longer have to reimplement the pages in each language.
• The OpenCensus agent uses the same exporters already written for the Go OpenCensus library.

While directly exporting to a backend will remain a common use case for developers, we expect most larger deployments to start using the OpenCensus agent. The agent is currently in beta and we expect it to reach production ready quality and feature completeness later this year.

The OpenCensus Collector

The OpenCensus collector and agent share the same source code and are both optional – the key difference is how they’re deployed. While the agent runs on each host, the collector is deployed as a service and receives data from OpenCensus libraries and agents running across multiple hosts. The collector has several benefits over exporting telemetry directly from the OpenCensus libraries or agent:

• Intelligent (tail based) trace sampling is one of the biggest benefits of the collector. By configuring your OpenCensus libraries to sample all traces and send all spans to the collector, you can have the collector perform sampling decisions after the fact! For example, you can configure the collector to sample the slowest one percent of traces at 30%, traces with errors at 100%, and all other traces at 1%!
• The collector performs well and can be sharded across multiple instances. Current performance scales linearly across cores, allowing 10,000 spans to be collected per 1.2 cores.
• The collector can be used as a proxy for other telemetry sources. In addition to receiving data from OpenCensus libraries and agents, Zipkin clients, Jaeger clients, and Prometheus clients, the service can be used to receive telemetry from client applications running on the web or on mobile devices.
• The collector will soon host z-pages for your entire cluster. This is simply an expansion of the z-page functionality that we’ve added to the OpenCensus agent.
• The collector can be used to apply telemetry policies across your entire application including adding span attributes such as region to all spans received, stripping personally identifiable information by removing or overwriting span attributes, or mapping span attributes to different names.

When to Use Each

As mentioned above, both the agent and collector are optional, and we expect that some developers will continue to export traces and metrics directly from the OpenCensus libraries. However, we expect both to become quite popular in the following scenarios:

• Many organizations don’t want to have to rebuild and redeploy their apps when they change exporters. The agent provides the flexibility to change exporters without having to modify and redeploy your code.
• With the OpenCensus agent you can capture system metrics via the same pipeline used to extract application metrics and distributed traces from your application.
• If you want to make trace sampling decisions more intelligently, you’ll need to start using the collector.
• With the OpenCensus collector you can minimize egress points and support features including batching, queuing and retry. These features are important when sending tracing and metric data to SaaS-based backends.
• Platform providers can include the OpenCensus agent and collector into their services, making them available out of the box to customers.

Status

Both the agent and collector are currently in beta, though we know that several companies are already using them in their production services. We’re working towards the 1.0 release of each of these, and we expect this to occur by the end of Q2.

In the meantime, please join us on GitHub, Gitter, and in our monthly community meetings!

OpenTelemetry: The Merger of OpenCensus and OpenTracing

We’ve talked about OpenCensus a lot over the past few years, from the project’s initial announcement, roots at Google and partners (Microsoft, Dynatrace) joining the project, to new functionality that we’re continually adding. The project has grown beyond our expectations and now sports a mature ecosystem with Google, Microsoft, Omnition, Postmates, and Dynatrace making major investments, and a broad base of community contributors.

We recently announced that OpenCensus and OpenTracing are merging into a single project, now called OpenTelemetry, which brings together the best of both projects and has a frictionless migration experience. We’ve made a lot of progress so far: we’ve established a governance committee, a Java prototype API + implementation, workgroups for each language, and an aggressive implementation schedule.

Today we’re highlighting the combined project at the keynote of Kubecon and announcing that OpenTelemetry is now officially part of the Cloud Native Computing Foundation! Full details are available in the CNCF’s official blog post, which we’ve copied below:

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A Brief History of OpenTelemetry (So Far)

After many months of planning, discussion, prototyping, more discussion, and more planning, OpenTracing and OpenCensus are merging to form OpenTelemetry, which is now a CNCF sandbox project. The seed governance committee is composed of representatives from Google, Lightstep, Microsoft, and Uber, and more organizations are getting involved every day.

And we couldn't be happier about it – here’s why.

Observability, Outputs, and High-Quality Telemetry

Observability is a fashionable word with some admirably nerdy and academic origins. In control theory, “observability” measures how well we can understand the internals of a given system using only its external outputs. If you’ve ever deployed or operated a modern, microservice-based software application, you have no doubt struggled to understand its performance and behavior, and that’s because those “outputs” are usually meager at best. We can’t understand a complex system if it’s a black box. And the only way to light up those black boxes is with high-quality telemetry: distributed traces, metrics, logs, and more.

So how can we get our hands – and our tools – on precise, low-overhead telemetry from the entirety of a modern software stack? One way would be to carefully instrument every microservice, piece by piece, and layer by layer. This would literally work, it’s also a complete non-starter – we’d spend as much time on the measurement as we would on the software itself! We need telemetry as a built-in feature of our services.

The OpenTelemetry project is designed to make this vision a reality for our industry, but before we describe it in more detail, we should first cover the history and context around OpenTracing and OpenCensus.

OpenTracing and OpenCensus

In practice, there are several flavors (or “verticals” in the diagram) of telemetry data, and then several integration points (or “layers” in the diagram) available for each. Broadly, the cloud-native telemetry landscape is dominated by distributed traces, timeseries metrics, and logs; and end-users typically integrate with a thin instrumentation API or via straightforward structured data formats that describe those traces, metrics, or logs.



For several years now, there has been a well-recognized need for industry-wide collaboration in order to amortize the shared cost of software instrumentation. OpenTracing and OpenCensus have led the way in that effort, and while each project made different architectural choices, the biggest problem with either project has been the fact that there were two of them. And, further, that the two projects weren’t working together and striving for mutual compatibility.

Having two similar-yet-not-identical projects out in the world created confusion and uncertainty for developers, and that made it harder for both efforts to realize their shared mission: built-in, high-quality telemetry for all.

Getting to One Project

If there’s a single thing to understand about OpenTelemetry, it’s that the leadership from OpenTracing and OpenCensus are co-committed to migrating their respective communities to this single and unified initiative. Although all of us have numerous ideas about how we could boil the ocean and start from scratch, we are resisting those impulses and focusing instead on preparing our communities for a successful transition; our priorities for the merger are clear:

• Straightforward backwards compatibility with both OpenTracing and OpenCensus (via software bridges)
• Minimizing the time where OpenTelemetry, OpenTracing, and OpenCensus are being co-developed: we plan to put OpenTracing and OpenCensus into “readonly mode” before the end of 2019.
• And, again, to simplify and standardize the telemetry solutions available to developers.

In many ways, it’s most accurate to think of OpenTelemetry as the next major version of both OpenTracing and OpenCensus. Like any version upgrade, we will try to make it easy for both new and existing end-users, but we recognize that the main benefit to the ecosystem is the consolidation itself – not some specific and shiny new feature – and we are prioritizing our own efforts accordingly.

How you can help

OpenTelemetry’s timeline is an aggressive one. While we have many open-source and vendor-licensed observability solutions providing guidance, we will always want as many end-users involved as possible. The single most valuable thing any end-user can do is also one of the easiest: check out the actual work we’re doing and provide feedback. Via GitHub, Gitter, email, or whatever feels easiest.

Of course we also welcome code contributions to OpenTelemetry itself, code contributions that add OpenTelemetry support to existing software projects, documentation, blog posts, and the rest of it. If you’re interested, you can sign up to join the integration effort by filling in this form.

By Ben Sigelman, co-creator of OpenTracing and member of the OpenTelemetry governing committee, and Morgan McLean, Product Manager for OpenCensus at Google since the project’s inception