OTel isn’t going well
matduggan.com
matduggan.com
It can do distributed tracing of otherwise traditional long running microservices, but breaks down when your functions are distributed like in durable execution engines, Cloudflare Workflows, “functions” that span hours/days/weeks and steps that retry many times.
I had to reverse engineer how SDKs work and how tracing UIs display data so I could make simpler functions that fit wider variety of runtimes and more freely parent spans, start spans and end them from different function instances.
I think most of the API and terminology complexity is self inflicted. Would love to see a rebooted developer experience that is less Kubernates-brained.
1. A spec 2. A ref implementation
Similar to other projects (e.g. python), if there's complaints about (2), that should trigger an ecosystem of alternative implementations that are guaranteed to be compatible because of (1).
I suspect there's actually quite a few private, separate otel implementations. Maybe these just aren't being contributed as oss?
As it stands, due to the tower of abstractions that could've just been "init with an implementation of this interface", you need to learn several pieces and how they work together (hint: convoluted and horrifically inefficiently) to modify any piece, and inevitably you learn that to get what you want, you need to swap out a major portion of it... but doing that while maintaining the auto-registry nonsense is a gigantic effort. If it's even possible.
It is the new poster-child for "design by committee". It's horrific. Unfortunately it's also usually the best option in large setups. I greatly approve of the high level goal, but omfg
Trying to make all the supported languages feel similar (beyond sharing concepts which almost directly match the protocol) is foolish in the extreme, and it's why it's such a monstrosity. And worse, they seem to treat that as more important than the bottom-most clients that speak the protocol, so you might be waiting years for any support for a third of the system!
[1]: https://opentelemetry.io/docs/languages/go/getting-started/#...
For example, if I look at a graph in monitoring dashboard and see something suspicious, I’d like to say: “The next time something like this occurs again, please save me a trace.” I should be able to just do that with a single mouse click.
I remember them releasing the tracing spec/SDKs and saying “now let’s move on to metrics/logs.” That never sat right with me.
What I’m suggesting is that your apps by default only send metrics to your monitoring system, but that the monitoring system can specifically ask to “upgrade” metrics to traces. Or to log entries.
The same thing with metric cardinality: by default, only report metrics in a fully aggregated manner. But do tell the monitoring system how they can potentially be broken up if needed (i.e., which labels to add).
How does the monitoring system have any of the context to add labels? That would only exist in application memory.
Grafana went the other way - your app exports all labels, and then you selectively aggregate on ingest: https://grafana.com/docs/grafana-cloud/observe-and-act/adapt...
> That may be prohibitively expensive in terms of CPU/network load.
In practice I've not experienced this even on quite high request rates. While it isn't free, exporting everything has been cheap enough that the real cost in dollars spent is basically marginal (it's _storing_ the data that's expensive)
Indeed. If you have a protocol that doesn’t allow exposing that kind of information, then that only lives in application memory. But my suggestion is that it’s exposed.
For your feature to work you need bi-directional communication between the otel receiver and your application - that's still doable in general, but now you want a synchronous "upgrade" to traces.
Now we're talking about a massive performance impact - and you need to somehow cache all otel data locally so they're available for the upgrade and only then submit then.
It is a architecture that's not very smart, honestly. And precisely the reason why you'd simply submit everything and let the receiver figure out which samples it wants to keep - as thorian pointed out earlier.
Yes, because otherwise what you propose requires modifying the binary in-place and that's too big of a security hole for lots of (production) environments. Some variants of that could work with an out-of-process method like Dtrace or eBPF, but that means mutating the kernel, even more of a no-no.
Trace spans are time-delimited units of "stuff that happened", with a tree relationship among the spans, and each span can have arbitrary tags (key/value pairs) and events (time/value).
From that, if you chose, you could derive metrics and logs. The trick is to start with tracing and to actually put it in your program, rather than trying to mostly-automatically tack it on later.
There is no magic bullet. Observability isn’t something you can just slap on and call it a day. While traces and logs might share superficial similarities, they are not the same. And metrics are something else altogether. Trying to somehow unify them would be a prime example of "wrong abstraction".
> “The next time something like this occurs again, please save me a trace.”
The building blocks for this exist. The observability platform must simply (haha) implement the pattern detectors and use them for sampling decisions.
https://docs.micrometer.io/micrometer/reference/observation....
A metric is a point in time. A metric is very small but you have a lot of them.
A log is when something is happening but you need to log it out. A logline is heavy and has a lot of context. User id, message, etc.
A trace needs to start at the request level and tracing until the response. This is the slowest and heaviest operation.
How do you decide when to suddenly do the trace and send it? IF you always do the trace, you have to pay for the overhead of that tracing constantly.
Then separately you can have log levels or verbosity levels that control to which level you actually emit traces/logs and/or roll up metrics.
All the log ingestion systems i have seen were bigger elastic search clusters.
A trace is a period of execution between two events. You could record a trace as a pair of log entries, or one log entry at the end. You can then reconstruct a trace from those log entries. If you want to associate multiple spans, and separate log entries, within a trace, you use a shared ID, which is just the same as a context entry for logging.
All three of these pillars are just ways of looking at events. They are not fundamentally different at all. This is a mistaken idea in "Observability 1.0" whose correction is the basis of "Observability 2.0".
The pillars still have their uses, but the choice between them is really a non-functional one - storing a log entry for every event might be too expensive, so just store metrics instead, and index every log entry so it can be correlated with nearby ones might be too expensive, so just store specific traces instead.
You don't have a metric 'person logged in' because you would need to scrape the metric at the moment a person logged in.
You have a metric called 'overall people have logged in so far' and you do math on it.
The 'person logged in' is an event you log out.
No, metric is just value. Some are derived from events (like histogram/rate of given event duration) but others are wholly independent (like returning app's CPU/memory usage)
If you sample the CPU usage at 1Hz, the metric is attached to the tick event.
Logs, metrics, and traces are all derived from raw events but none of them are intrinsically discrete events in a systems engineering sense. They are all different data models with different patterns of traversal over raw events. As data model, you need to build secondary indexes over the raw metrics to reflect the orthogonal data access patterns depending on if you are evaluating them as logs, metrics, or traces. This famously has poor scalability and performance.
In analytical processing we largely manage the inherent performance and scalability issues using denormalization, which allows processing pipelines with very different requirements to be optimized independently. Or in this context, treating logs, metrics, and traces as unrelated things with independent infrastructure.
"Observability 2.0" deeply embeds an architectural assumption that all systems are small. It is not a tractable architecture in high-scale or high-performance systems.
Real silicon has a long history of destroying beautiful conceptual abstractions in software engineering.
It is only "easy" if performance and scalability don't matter.
Search keyword: "Adaptive sampling"
Tracing traces a particular event.
I'm quite aware of the difference between sampling, tracing and profiling.
It can be applied to tracing, metrics, logging ("sampling") and profiling.
Just instrument your meter implementation so each observation produces a span. Boom, free metric-derived traces.
In the code define everything as a span with a name, scope (start-end), description and tags... and then you can easily dynamically produce traces, spans, logs or metrics based on what you need.
While it may intuitively may look like there is a large overlap in the three areas there is suprisingly little, and for the few parts there are (e.g. trace <-> log correlation), OTEL does offer a standard.
Historically, logging and metrics have been different problem domains with different implementations for ages.
Now to your point: Note that tracing does get the most of love, and that it does include constructs to add logging and metrics into these traces (spans actually). So you could argue that they are trying to develop a single interface.
> “The next time something like this occurs again, please save me a trace.”
Well, if you want this you either need to propagate this predicate to all points that might be involved, or always emit all traces and have the predicate included in the filter. And then you need to be able to dynamically propagate this predicate from the system/ui where you click to where you filter.
This is one of the reasons why we always propagate and emit traces and just post filter it in processing before it lands in the persistence layer.
It's missing a few things that I'd like, but I was able to implement them myself. I guess the major design issue is that the sampling decision is made at the _start_ of the segment. So I hacked up a few improvements:
1. Ability to mark segments as "boring", so they are dropped before the export. For things like healthchecks, empty "get the pending jobs" queries, etc.
2. Ability to downgrade errors for segments that are expected to return an error (e.g. HEAD on a non-existing object in S3 to check if there's a cached blob).
I understand the author's perspective in the linked article, but none of that data shows a project in trouble? Some languages have more resources than others, but those all look like healthy open source projects
Every time I share your blog (and I share it a lot) I tell people:
"This guy started a blog in 2024. Wrote three posts and all three of them would still make my top ten list of 'greatest posts on observability' today".
'A practitioner's guide to wide events' especially is still my number 1.
The net of this is, otel is a very flexible system you can use and adapt in all kinds of ways and while the spec is important, using the toolkit to FAFO yourself, ahead of any beaten path, should really be encouraged. That's the message I'd want to see being radiated out about otel.
My life of working with it got easier when I started just looking at the actual code, using network level tools like nc/tcpdump, making extensive use of the debug exporter, and almost ignoring the docs entirely except as a basic summary of what a thing does.
I think the actual APIs kinda smell at the language level, and when Honeycomb decided to lean into otel and deprecate its Python libs I was super sad, cuz HC's libs were _way_ more usable IMO. Docs are also... painful. Real painful.
I wish that I could get a Python lib which is like "here this is Otel but the config phase isn't weird, and the API just looks a bit better". One of these days.
The biggest trouble I have with Otel recently is getting fixes patched upstream in contrib. Using contribs is super dangeerous, and I would basically recommend people write their own instrumentation and treat the contrib packages as just examples of how to do it
1. Every major vendor is still in some weird alpha/beta support for OTel even after all this time.
2. The performance hit is substantial and makes you question what the point of performance instrumentation is if you need twice as much compute/RAM to run the same workload now.
3. Serverless runtimes pay a heavy penalty for cold starts with OTel.
4. You're basically forced to run both gateway collectors and edge collectors for any realistic usage.
5. You still need to configure destination exporters in unique ways. This leaves you questioning what the value of OTel was.
6. Vendors that go beyond the scope of what OTel covers still need their own bespoke instrumentation. What was the point of any of this then?
You most certainly don't. You can run your app (especially if it's "serverless") without the collector agent.
App-to-agent and agent-to-sink use the same protocol, so all you need to do is set up the tracing/logging/metrics exporters to directly speak with the sink. These days, it typically means specifying the URL and the DSN header.
Gateway collectors are unavoidable because various SaaS platforms require you to be running publicly reachable endpoints to send telemetry to.
In a runtime like Lambda, how would you avoid the need to run an edge collector? The only thing that comes to mind is to write to logs and then have a log stream processor that then writes to your gateway collector. Other than that, it seems unavoidable, no? Sure, in something like Fargate you could go app to sink. But even that has its own tradeoffs.
I follow the [gateway deployment pattern](https://opentelemetry.io/docs/collector/deploy/gateway/). Everything sends telemetry to our gateway, which exports to ClickHouse (formerly Datadog).
We use Node.js, so all we need to do is run a script initializing Otel before running the app. We set this up following the docs a few years ago, and haven’t had to change it much since then.
The collector process then sends the metrics/traces/logs to the observability sink. But there's nothing at all preventing you from sending telemetry directly to the observability sink.
It's just outbound HTTP or GRPC, and it doesn't have to go over public Internet.
> In a runtime like Lambda, how would you avoid the need to run an edge collector?
Here's my setup (in Go, very simplified):
> // Instantiate a new slog logger > logger := otelslog.NewLogger("root", otelslog.WithLoggerProvider(otelLogger)) > // Use the logger as needed
My code uses proper Go loggers exclusively. I also redirected the stdout and stderr to a goroutine (via the usual close(2)+open() trick) to serve as a catch-all sink for anything that slips the net.
It doesn't block, but it does consume compute/memory resources and takes forever to startup[0][1]. To be fair, Rotel is promising in this regard[2].
[0]: https://github.com/open-telemetry/opentelemetry-lambda/issue...
[1]: https://github.com/aws-observability/aws-otel-lambda/issues/...
The X-Ray daemon and SDKs are all deprecated now in favor of OTel. Things like enchrichment of resource level traces for things like the DynamoDB client in v3 of the AWS JS SDK don't work with the X-Ray SDK. And they never will now. You're now recommended to use the AWS Distro for OpenTelemetry setup and OTel SDKs. The performance overhead of this is heavy, with big cold-start penalties.
Compare this with how the Datadog layer does adaptive flushing and performs relatively much better. Rotel is also promising in this space. But right now, OTel feels immature and things are being deprecated without the replacement being fully baked.
That's really all there is to it. You can just submit it directly, without involving any layers.
I don't mean to disparage anyone working on OTel. I can appreciate that it has ambitious goals and it's not an easy problem to get alignment and interop here. Especially with all the stakeholders involved. But as a user, it feels simultaeneously over-engineered and under-engineered.
- Using and configuring a suite of tools (Jaeger for tracing, Vector or Fluentd for logs, Prometeheus for metrics)
I wish the observability vendors would move to using it under the covers so it's easier to mix and match.
I wish the otel support wasn't super buggy in most of the frameworks and backends.
If you get rid of that, and just pass dependencies around, create some appropriate local abstraction around them.. the tooling, be it datadog or honeycomb does a great job making it useful. Can't really say the same for grafana, but ymmv - depending on budget
At least with Open Telemetry, anyone can write an OTLP "source" using free, open specifications, and it'll "just work" with dozens of third-party "sinks". That's huge!
Sure, there's a lot of experimental tags on semantic conventions, but at the end of the day, that's not that critical. It's just data: most sinks don't "interpret" these tags, they just display them as-is, so changes aren't breaking changes.
Neither Prometheus metrics nor Jaeger traces are magic bullets. Neither of them are complicated, either, and in fact the fact that they're not complicated is their greatest strength. You can and should understand every facet of what they entail. You should build the (very small) shims that they need for your company's framework every time. It's not hard. It's not hard because it's not complicated. The fact that it's not complicated seems to break people's brains. They are accurate because they're simple and they're easy to work with because they're simple, and OTel is neither.
Node exporter runs on my Prometheus server next to Blackbox Exporter. Blackbox Exporter handles TLS expiry metrics.
Jaeger uses the OTLP protocol nowadays. So it _is_ OTEL.
Kinda like people hating Obamacare but loving the ACA.
Jaeger does not implement all the OTEL features, though. It's specifically focused on traces rather than metrics.
While I usually think that at least having some standard that people agree on I think OpenTelemtry should be dropped.
A lot of the less popular alternatives (just going with Prometheus, Victoriametrics, etc) are de-facto competing smaller standards and a lot better both in terms of less added complexity and the results you get.
I think OpenTelemetry turned metrics into a farce. In many situations even self-rolled telemetry works better even with the added stuff. The annoying thing is that OpenTelemtry is that big standard now one kind of has to to add compatibility. So please, if you write software, make sure you don't lock yourself into OTel.
> A lot of the less popular alternatives (just going with Prometheus, Victoriametrics, etc) are de-facto competing smaller standards
By all metrics (hah), Prometheus is the more popular solution and is the de-facto standard, as far as I know.
Grafana is fine to get to a selfhosted basic install. But once you try to actually connect logs, metrics, traces in selfhosted context and perhaps sprinkle some otel in...that sht gets out of hand very fast. It's modular in a way that seems like a win but once you start connecting stuff it starts adding complexity not ease.
Signoz...still pretty early in exploring this and so far it's acceptable, but it too relies on a mix of query languages incl the competitors promql so some panels support it other seem to not to?
The entire thing just seems bewildering to me. Not gonna say "why is this so hard" because I genuinely thing smart people are genuinely trying here...but there result just isn't great.
Maybe because some open-source software has limitations? That seems reasonable to me.
Our team tried to set up open telemetry to replace Datadog and got totally crushed in complexity. The model of having Open Telemetry just be for standardizing & exporting to other backends, needing glue for each part of the setup was nuts.
But yes it seemed like OTel was more interested in being a spec than a tool.
The biggest challenge I have is that each data source needs it's own query language, which DD and the like don't. That's why at my day job they went with DD despite the costs. Still OTEL but the querying is the same. We are also looking at Dash0 but for all of my personal and consulting jobs, OSS LGTM/P works good for me.
Datadog isn't just a collector, but the whole querying UI as well, right?
The lead dev is super passionate about straightforward software that just works, and it shows.
Later my coworker deployed VictoriaLogs in about 15 minutes, added it to our syslog targets. Night and day compared to Elastic. Use both of them probably every day through Grafana.
is the closest i've seen to the datadog experience
OTel looks like something designed by a committee of committees, funded by someone who is in the business of selling cloud storage/data warehousing services.
OTel is a fine system for learning observability; it does an okay job of exposing capabilities given how diverse the vendor ecosystem is.
The core of logs and spans are just wide events with some inter-connections, those SDKs and OTel docs make them less obvious.
(I maintain o11ylite https://github.com/o11ylite/o11ylite)
1. The worst thing you can do is try to stuff too many things into one specification. So you want an API? That's great. What's that? You want a rigid set of types so that any tiny changes over time aren't compatible? You want to try to define every conceivable use case as a new call? You want to combine multiple elements from different domains into one flat set of functions? You don't have any hierarchy or inheritance? You don't support extensions?
2. The second-worst thing you can do is to force a whole lot of different people to go through a single standards body. So you want to support a thousand different 3rd party components. What's that? You want to require everyone get their adapter approved by one group? And there's only one supported adapter per 3rd party component?
If you're trying to feed an entire city, it's logistically incredibly difficult to try to do it all yourself. If instead you just define where food can be dropped off or picked up, and ask volunteers to bring their own food there whenever they can/want, now you don't have a logistical nightmare on your hands anymore. The tech alternative? Add support for "plugins", make the plugin interface incredibly loose/backwards-compatible/layered, and invite people to publish their own plugins. If you under-engineer it, it actually works better.
Using is hard, vendors are hostile, it seems like no-one want it to be a first class citizen...
The only choices you get is full auto instrumentation, which breaks most non-trivial apps, or zero assistance/documentation.
There is no in-between where I can inject the functionality required in a way that is compatible with the application.
If I recall the primary issue was the forced loading of the django settings file by otel.
I get that fully automated instrumentation should be turn-key and the current approach kinda works on basic applications.
But most production django applications are monoliths and generally larger apps. They have non-trivial configuration processes which are often multi step and source settings from multiple places.
Otel should not assume it can just randomly load a the django settings at an arbitrary time point in the startup process.
In one of our apps the MIDDLEWARE setting specifically is dynamically generated and re-ordered based on enabled features. That application's startup process also has multiple stages and the initialisation of django occurs much later, after dependant config loaders etc have been initialised.
What would allow us to integrate with opentelemetry-instrumentation-django much more easily is a set of smaller primitives that we can configure and call at the appropriate time.
opentelemetry-instrumentation-django has (had?) a lot of logic hidden inside a large "inject" function which could not easily be extracted into the constituent parts and applied in a compatible manner.
https://github.com/open-telemetry/opentelemetry-python-contr...
- Running an old version of Golang (older than 1.18 if memory serves), or
- has libraries that the eBPF probes don't like.
And while I like OTel, I agree with the OP that you are absolutely going deep-sea diving if you're going to do anything beyond the examples provided (which is very easy to do!)
20 years ago, we were doing (what I think) OTel is doing: with “hit IDs” (half way between a session and a request) that were consistently applied when logging the cause a request being fired; along centralised logging and really good timekeeping. Essentially a unique identifier as a tag that followed the request as it passed through the system.
This was enough to debug basically any problem.
We could even measure the distance between requests of the same “hit” and the total wall-time before it managed to return through the load balancer, so we could track our p99 easily.
Though truthfully we didn't make pretty graphs.
I sometimes wonder what OTel gives me more than this, but I work in games now and lots of these things that work well in webdev do not apply at all to our problems.
You are right that what you were doing is very similar! However standardization helps a lot here.
This is just plain wrong, binaries of the collector are shipped which are available to use straight away. You can use the builder if you want to create your own version with a selected set of components but it is no way a hard requirement.
The perf is meh, but tbh if you look at the kind of code we, regular developers write for work, it's probably still vastly better.
It’s modular, but the author is appraising the Ruby shortcomings as a problem while also saying they unfortunately don’t have time to contribute because, you know, they can’t “join the calls” lol
We just got a CTO who loves Ruby and guess what I’m about to do: use AI to fill in the Ruby gaps and open a PR and work a weekend or two and see if they like it and then you won’t write any more articles disparaging a project that I personally love.
It saves our company AT LEAST 10k a month vs having datadog / splunk / enterprise-y bullcrap. You seem so educated, why not roll up your sleeves instead of patronizing the hard working people that make the project work with your “if it were me” just go ahead and say it in their forums.
And, if you work for your paycheck, you’re using an agent. A mature project like Otel? Shit. That’s easy-peasy to feed into an agent, so what’s what is actually the problem? Take the time to learn and help them out if it bothers you so much you want to share it with the world!
Isn’t every single “problem” found in every large and successful open sourced framework?
Throwing out a baity framing like it’s some kind of project going wrong and then kind of just ending the article without making any sort of judgement on where this all leads, proceeding to post on hackernews.. bait!
It’s a cloud native project that is not owned by any company. That’s so rare and worth an article to celebrate open source! What a privilege to stand on the shoulders of giants!
> So OpenTelemetry currently is attempting to support a dizzying number of languages and frameworks.
“dizzying” — so I’m lost, did the author remmeber the scope of the project before they started making judgements about it?
And calling the attention of hackernews here: what’s the alternative? Oh that’s right, there isn’t one. Because this is a wag my finger article for attention and aggregating the author on a developer channel to boost their presence. Lame.
(Thumbs down)