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Make service discoveries removable through build tags#17736

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ArthurSens merged 7 commits intomainfrom
removesds-buildtags
Jan 8, 2026
Merged

Make service discoveries removable through build tags#17736
ArthurSens merged 7 commits intomainfrom
removesds-buildtags

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@ArthurSens ArthurSens commented Dec 24, 2025 •
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Prometheus ships with quite a few service discovery mechanisms, each bringing its own dependencies (AWS SDK, Azure SDK, Kubernetes client-go, etc.). This results in a ~170MB binary even for users who only need a subset of these SDs.
This PR introduces build tags that allow users to exclude specific service discoveries at compile time, reducing binary size for deployments that don't require all SD mechanisms.

This is useful for:

  • Edge/IoT deployments with limited storage
  • Single-cloud deployments that only need one cloud provider's SD
  • Other systems that import the Prometheus service discovery codebase, like the OTel-Collector, that want to reduce their binary size as well.

What I'm doing here is splitting the codebase that imports service discoveries into several files, each with its own build tag for exclusion, so that all service discoveries continue to be enabled by default.

Results

Build Configuration Binary Size Reduction
All SDs 170 MB —
No k8s/aws/azure/gce 66 MB -61%
file+http only 49 MB -71%

Does this PR introduce a user-facing change?

[ENHANCEMENT] Service Discovery: Service discoveries are now removable from the Prometheus binary through the Go build tag `remove_all_sd` and individual service discoveries can be re-added with the build tags `enable_<sd name>_sd`. Users can build a custom Prometheus with only the necessary SDs for a smaller binary size.

@ArthurSens ArthurSens mentioned this pull request Dec 24, 2025
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@krajorama krajorama self-assigned this Dec 30, 2025
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roidelapluie commented Dec 31, 2025

I fail to understand the logic behind this.

Why do you import service discoveries you do not need?

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approved but see @roidelapluie question

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ArthurSens commented Jan 3, 2026 •
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I fail to understand the logic behind this.

Why do you import service discoveries you do not need?

Could you elaborate? I'm struggling to understand the question... The change I'm doing is to enable not importing SDs you don't need 🤔

Before this change, all SD's imports are in the same file and they are all registered together by their init() function, like here for example. With the change in this PR I'm splitting the imports into separate files and each file have their respective tags for exclusion

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ArthurSens commented Jan 3, 2026

One thing that I think might be missing here is documentation, I'm not sure where's the right place for that though

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SuperQ commented Jan 3, 2026

I think @roidelapluie is asking about why the existing plugins.yml / generator is not sufficient to configure the discovery inclusion.

This is what we've used so far to build customized binaries.

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ArthurSens commented Jan 3, 2026

I think @roidelapluie is asking about why the existing plugins.yml / generator is not sufficient to configure the discovery inclusion.

This is what we've used so far to build customized binaries.

Oh gotcha! To be honest, I didn't notice that plugins.yml was already one way of doing this 😮. It doesn't work for downstream projects that use Prometheus Scrape manager as a library, though.

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SuperQ commented Jan 3, 2026

I think build tags are probably a better Go-native way to do the configuration. If we do this, we should remove the plugins.yml setup so we keep things consistent.

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roidelapluie commented Jan 5, 2026

I think build tags are probably a better Go-native way to do the configuration. If we do this, we should remove the plugins.yml setup so we keep things consistent.

Yes, I think keeping both would be a distraction.

Oh gotcha! To be honest, I didn't notice that plugins.yml was already one way of doing this 😮. It doesn't work for downstream projects that use Prometheus Scrape manager as a library, though.

In the initial design, those projects should simply not import the libraries then and have their own "plugins" package which imports the SD they want.

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ArthurSens commented Jan 5, 2026

Oh gotcha! To be honest, I didn't notice that plugins.yml was already one way of doing this 😮. It doesn't work for downstream projects that use Prometheus Scrape manager as a library, though.

In the initial design, those projects should simply not import the libraries then and have their own "plugins" package which imports the SD they want.

Got it, I guess that works for most use cases with exception for the OTel Collector 🙈. The collector was designed to be as customizable as possible during build time, our goal there is to let users build their own collectors and not decide things for them

@ArthurSens
Make service discoveries removable through build tags
e6cd1ac 
Signed-off-by: Arthur Silva Sens <arthursens2005@gmail.com>
@ArthurSens
Fix cross-platform build issues
e0c68a9 
Signed-off-by: Arthur Silva Sens <arthursens2005@gmail.com>
@ArthurSens
Change build tags used
826e046 
Signed-off-by: Arthur Silva Sens <arthursens2005@gmail.com>
@ArthurSens
Remove year from License header
c558a1b 
Signed-off-by: Arthur Silva Sens <arthursens2005@gmail.com>
@ArthurSens
Remove plugins automation
0a91216 
Signed-off-by: Arthur Silva Sens <arthursens2005@gmail.com>
@ArthurSens
Update README
f198b86 
Signed-off-by: Arthur Silva Sens <arthursens2005@gmail.com>
@ArthurSens ArthurSens force-pushed the removesds-buildtags branch from bec9083 to f198b86 Compare January 5, 2026 14:01
roidelapluie
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Update README.md
421e30e 
Co-authored-by: Julien <291750+roidelapluie@users.noreply.github.com>
Signed-off-by: Arthur Silva Sens <arthursens2005@gmail.com>
@ArthurSens ArthurSens merged commit 14de1eb into main Jan 8, 2026
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@ArthurSens ArthurSens deleted the removesds-buildtags branch January 8, 2026 13:06
@ArthurSens ArthurSens mentioned this pull request Jan 8, 2026
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atoulme pushed a commit to open-telemetry/opentelemetry-collector-contrib that referenced this pull request Jan 21, 2026
@ArthurSens
Make service discoveries removable through Go build tags (#45148)
6f1d79c 
<!--Ex. Fixing a bug - Describe the bug and how this fixes the issue.
Ex. Adding a feature - Explain what this achieves.-->
#### Description
This PR is built on top of
prometheus/prometheus#17736. There are a lot of
go mod changes, and that also inherits fixes to interface changes that
were made since Prometheus 3.8

The only change that is really about making SDs removable is this change
in imports in `factory.go`:
```diff
-	_ "github.com/prometheus/prometheus/discovery/install" // init() of this package registers service discovery impl.
+	_ "github.com/prometheus/prometheus/plugins" // init() of this package registers service discovery impl.
```

<!-- Issue number (e.g. #1234) or full URL to issue, if applicable. -->
#### Link to tracking issue
Fixes #44406

<!--Describe what testing was performed and which tests were added.-->
#### Testing

Used two builder configs and measured the binary size difference:

Without build tags(120MB):
```yaml
dist:
  module: github.com/open-telemetry/otelcontribcol
  name: otelcontribcol
  version: 0.143.0
  output_path: ./cmd/otelcontribcol/sd-test/full

receivers:
  - gomod: github.com/open-telemetry/opentelemetry-collector-contrib/receiver/prometheusreceiver v0.143.0
    path: ./receiver/prometheusreceiver

exporters:
  - gomod: go.opentelemetry.io/collector/exporter/debugexporter v0.143.0
```

With build tags(63MG):
```yaml
dist:
  module: github.com/open-telemetry/otelcontribcol
  name: otelcontribcol
  version: 0.143.0
  output_path: ./cmd/otelcontribcol/sd-test/no-sd
  build_tags: "remove_all_sd"

receivers:
  - gomod: github.com/open-telemetry/opentelemetry-collector-contrib/receiver/prometheusreceiver v0.143.0
    path: ./receiver/prometheusreceiver

exporters:
  - gomod: go.opentelemetry.io/collector/exporter/debugexporter v0.143.0
```

---------

Signed-off-by: Arthur Silva Sens <arthursens2005@gmail.com>
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@roidelapluie roidelapluie roidelapluie approved these changes

@krajorama krajorama krajorama approved these changes

@simonpasquier simonpasquier Awaiting requested review from simonpasquier simonpasquier is a code owner

@SuperQ SuperQ Awaiting requested review from SuperQ SuperQ is a code owner

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