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Build

Builders

Builds run on their own Server, so they never slow your Apps

build 3 min read

Every Build runs on a Builder, its own Server with its own CPU and memory, so a heavy Build never slows your running Apps. You don’t need to set anything up: your first Build in a region creates that region’s Default Builder.

Setting Default Change it when
Size Auto, preferring 4 vCPU / 8 GB Can use 2 vCPU / 4 GB; explicit minimums support up to 8 vCPU / 16 GB
Idle time 1 hour after a Build You deploy all day: keep it 8 hours
Build timeout 30 minutes per Build Allow longer builds, up to 2 hours, or stop slow builds sooner
Persistent cache Off Builds still start cold or download a lot

Blossom BYOC Builder management is eligible for the Organization’s $20 monthly credit. Your provider bills the Server separately. See Builder pricing.

Default Builder

An Environment set to Auto builds on its region’s Default Builder. It starts when a Build needs it, so the first Build of the hour waits a few minutes while its Server starts. Builds within its idle time reuse it and its local cache. The idle timer restarts after each Build; one hour of idle retention does not mean a new Server or a separate hourly charge per Build.

See it under Apps → Builders, or from the CLI:

blossom builder:list

Change Its Settings

Deploying all day? Keep your Builder warm 8 hours and add a Persistent cache, so every Build starts warm. Open the Builder’s Settings, or from the CLI:

builder.yml:

builder:
  idle_retention_seconds: 28800 # stays warm for 8 hours after a Build
  volume_gib: 50 # Persistent cache, 10 to 1,000 GiB

blossom builder:update --id builder-100 --data builder.yml

Build timeout is the maximum duration of each Build, not its expected duration. Builds that exceed it fail. You can see it on the Builder overview and change it beside Idle time in Settings. Idle time starts after a Build finishes.

A new size applies the next time the Builder starts. The Persistent cache is a disk that keeps image layers and dependencies across days; 50 GiB is a good start for a few Apps. It’s available in Hetzner regions.

More Builders

A Builder runs one Build at a time. Create another for parallel Builds or for one heavy App:

blossom builder:init
blossom builder:create --data builder.yml

Choose it per Environment in Source and Build, or with builder_id in its build settings. Make default on a Builder’s page, or default: true, points Auto in its region at it instead:

builder_id Builds run on
auto The region’s Default Builder
builder-100 That Builder

What You Get

  • Builds on their own CPU and memory, never your Apps’
  • A Builder ready on your first deploy, with nothing to set up
  • A warm cache within its idle time, or across days with a Persistent cache
  • Self-healing: if a Builder’s Server is lost, Blossom replaces it and the next Build carries on

Delete a Builder with blossom builder:delete --id builder-100; Environments using it switch to Auto. Deleting the Default is fine: the next Build in its region creates a new one.

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