The operating dials

A dial has an environment variable and a setting on Admin → Settings:

• The environment value is the install’s floor.
• The setting overrides it, live, with no restart.
• A cleared or zero setting means “use the environment value”, never “off”.

Dial	Environment	Setting	Takes effect
Memory ceiling per app	APP_MEMORY_LIMIT_MB / _GB	app_memory_limit_mb / _gb	Each app start
CPU reserved per app	APP_CPU_REQUEST_MILLICORES / _CORES	app_cpu_request_millicores / _cores	Each app start
CPU ceiling per app	APP_CPU_LIMIT_MILLICORES / _CORES	app_cpu_limit_millicores / _cores	Each app start
Builds at once	MAX_CONCURRENT_BUILDS	max_concurrent_builds	Each dequeue
Auto-deploy interval	AUTO_DEPLOY_POLL_INTERVAL	auto_deploy_poll_seconds	Each tick
R package repository	TOFT_R_REPOS	r_package_repository	Each build
Platform log level	LOG_LEVEL	log_level	Immediately

Resource dials reach a running app only when it next starts.

Two units, one at a time. _MB/_GB and _MILLICORES/_CORES are alternatives; setting both is refused.

Details that matter

Dial	Behavior
Builds at once	Limits how many builds may start; lowering it interrupts nothing. A value above the worker pool is refused, naming MAX_CONCURRENT_BUILDS.
Auto-deploy interval	AUTO_DEPLOY_POLL_INTERVAL=0 in the environment turns auto-deploy off entirely, and the setting field is disabled. A stored 0 setting means the environment value.
Log level	The only dial that applies immediately. A restart re-applies the stored level. LOG_FORMAT is configuration only, shown read-only beside it.
CPU ceiling	Off by default on purpose: over a CPU limit a workload is throttled, not killed, so a burst becomes a slow app.

Scope

• Memory applies in both modes; CPU in isolated mode only.
• Per-app override: an administrator can raise one app’s memory ceiling. There is no per-app CPU.
• A job on the platform’s own machine has its memory limit enforced by sampling, not the kernel — see where a job runs.

Admin → System info shows the resolved envelope: the environment value, any override, and what an app actually gets.