Reference meta

`availability`

Declare the highest availability level a package or one of its workloads can provide.

meta.availability.max states the highest availability level the entire package can provide.

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# One writer: the program keeps its state in a local SQLite file.
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meta.availability.max = "none";

The value is one of these levels:

Ceiling	Meaning	Replicas
`none`	One pod at a time: a single writer, no coordination between pods.	0 or 1
`pod`	Survives a pod crash or a rolling update, not a node loss.	any
`node`	Survives a node loss, not a zone loss.	any

Any other value is an evaluation error. A zone ceiling limits nothing, so packages omit it.

When an instance requests a higher level, Kix passes the ceiling to the package and warns that the instance does not meet the requested level. Because the package never sees a level above its ceiling, kix.availability.atLeast refuses a threshold above the ceiling, which would always be false. The evaluation error names the instance.

max is the only key of meta.availability. Any other key, or a value that is not an attribute set, is an evaluation error.

Use a package ceiling for a limit of the program itself that holds for every workload and that no configuration lifts. Do not use it merely because one replica option has not been mapped from the availability argument.

Per-workload ceiling

Workload builders (mkDeployment, mkStatefulSet, mkJob, mkCronJob) also accept availability.max:

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worker = scope.mkDeployment {
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  name = "${scope.instanceName}-worker";
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  availability.max = "none";
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  spec.replicas = 1;
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  # ...
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};

This ceiling applies only to that workload’s derived placement, disruption budget, and replica checks. It does not change the package’s availability argument or the level used by sibling workloads. Kix warns when it caps the instance’s level, naming the workload and what it cannot survive.

max is the only key. mkDaemonSet refuses availability, because a DaemonSet runs one pod per node and the ceiling has no effect on it.

Put the ceiling on the builder call when the limit belongs to one workload, depends on the package’s configuration (the builder call can compute it from config), or comes from what the package wires rather than from the program.

Effective ceiling

A workload’s effective ceiling is the lower of its builder availability.max and the package’s meta.availability.max.

A Deployment or StatefulSet with more than one replica under an effective ceiling of none is an evaluation error. The message names the workload and says whether the ceiling comes from its builder call or from the package. Kix checks the final manifests, so the error also covers chart workloads under a package ceiling and replica counts that an instance or a partsOverlays entry sets.

A partsOverlays entry that rebuilds a workload without availability.max drops its builder ceiling, which lets a cluster operator run more pods once the workload can coordinate them. An overlay that keeps the builder ceiling and raises the replica count fails. A package ceiling has no such escape.