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feat: support resource limits on the build container

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Adds a `docker-args-process-build` trigger to the resource plugin so
limits set via `dokku resource:limit --process-type build APP` are
applied during the build phase. Only `build.limit.*` properties are
read - defaults do not inherit, since builds typically need more memory
than runtime and a leaked tiny default would cause confusing OOM
failures. Reservations are never applied at build time. Allowed flags
are filtered per builder: herokuish gets cpu, memory, memory-swap, and
nvidia-gpu; dockerfile gets memory and memory-swap; pack, nixpacks,
railpack, lambda, and null emit nothing because their underlying CLIs
do not accept docker run resource flags. The dockerfile builder
whitelists the new memory flags and corrects pre-existing typos where
`--ssh` mapped to `--platform` and `--ulimit` mapped to `--tag`.
This commit is contained in:
Jose Diaz-Gonzalez
2026-04-29 03:42:10 -04:00
parent d51726b7cb
commit 132f724841
7 changed files with 285 additions and 6 deletions
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36
docs/advanced-usage/resource-management.md
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@@ -32,7 +32,7 @@ Valid resource options include:
See the [Supported Resource Management Properties](/docs/deployment/schedulers/docker-local.md#supported-resource-management-properties) section of the docker local scheduler documentation for more information on how each resource limit maps to Docker.
Resource limits and reservations are applied only during the `run` and `deploy` phases of an application, and will not impact the `build` phase of an application.
Resource reservations are applied only during the `run` and `deploy` phases of an application. Resource limits also apply during the `build` phase when explicitly configured against the `build` process type - see [Build-time Resource Limits](#build-time-resource-limits) below.
### Resource Limits
@@ -120,6 +120,40 @@ dokku resource:limit --process-type web node-js-app
nvidia-gpu:
```
#### Build-time Resource Limits
> [!IMPORTANT]
> New as of 0.38.0
Resource limits may be applied to the build container by using the special `build` process type. This allows constraining memory and CPU usage during the `build` phase, which is otherwise unconstrained.
```shell
dokku resource:limit --memory 4g --process-type build node-js-app
```
```
=====> Setting resource limits for node-js-app (build)
memory: 4g
```
Build-time limits are applied via the `docker-args-process-build` plugin trigger. They do not inherit from default (`_default_`) limits - only limits explicitly set against the `build` process type are applied at build time. This is intentional: build phases often require more memory than the runtime process, and silently inheriting a small runtime limit would cause confusing OOM failures.
> [!WARNING]
> Do not use `build` as a runtime process type in your `Procfile`. The `build` name is reserved by the resource plugin to scope limits to the build container, and using it as a Procfile entry will cause those limits to be applied to that runtime container as well.
Supported limits per builder:
| Builder | `--cpu` | `--memory` | `--memory-swap` | `--nvidia-gpu` |
|------------|---------|------------|-----------------|----------------|
| herokuish | yes | yes | yes | yes |
| dockerfile | no | yes | yes | no |
| pack | no | no | no | no |
| nixpacks | no | no | no | no |
| railpack | no | no | no | no |
| lambda | no | no | no | no |
Resource keys outside the supported set for a builder are silently ignored. Reservations (`resource:reserve`) are never applied at build time - only limits.
#### Clearing Resource Limits
In cases where the values are incorrect - or there is no desire to limit resources - resource limits may be cleared using the `resource:limit-clear` command.