VolSync Builders

VolSync Builders - ReplicationSource and ReplicationDestination

The volsync package provides strongly-typed constructor functions for VolSync (volsync.backube/v1alpha1) resources. It is the canonical entry point for building ReplicationSource and ReplicationDestination objects in kure.

Overview

VolSync replicates persistent volume data between Kubernetes clusters. Each replication direction (source and destination) selects exactly one mover — the data-transfer backend — from a sum of choices: Restic, Rsync (legacy SSH), RsyncTLS, Rclone, Syncthing (source-only), or an External passthrough.

This package encodes the mover one-of as a sealed-interface sum type: Mover on the parent Config holds exactly one variant. Setting two movers is a compile error; setting none is detected at construction. See docs/ARCHITECTURE.md § One-of Constraints for the rationale.

Constructors

Every kind this package registers has a generated Create<Kind> wrapper in zz_generated_create.go, produced from the scheme by pkg/kubernetes/internal/gen (make gen-builders, checked by make check-builders in CI). A wrapper delegates to kubernetes.Create[T] and emits TypeMeta and identity only: no default, no label, no spec value. Namespaced kinds take (name, namespace), cluster-scoped kinds take (name). The upstream struct is the construction API; set spec fields directly or through the admissible Set*/Add* sugar below.

obj := volsync.CreateReplicationSource("db-backup", "data")

The config-struct builders (volsync.ReplicationSource(&volsync.ReplicationSourceConfig{...})) are a separate, opinionated layer on top of the same upstream types; they are unchanged by the generated constructors. The hand-written Create* helpers for spec fragments that remain in this package are legacy and are removed by the prune work item of the builder-contract epic.

See the Kubernetes Builders page for the full builder contract: construction, sugar admission classes, purity and the release-1 migration ledger.

Supported Resources

ReplicationSource

import (
    volsyncv1alpha1 "github.com/backube/volsync/api/v1alpha1"

    "github.com/go-kure/kure/pkg/kubernetes/volsync"
)

schedule := "@hourly"
rs := volsync.ReplicationSource(&volsync.ReplicationSourceConfig{
    Name:      "db-backup",
    Namespace: "data",
    SourcePVC: "postgres-data",
    Trigger:   &volsync.TriggerConfig{Schedule: &schedule},
    Mover: &volsync.SourceResticConfig{
        Repository: "restic-creds",
        ReplicationSourceVolumeOptions: volsyncv1alpha1.ReplicationSourceVolumeOptions{
            CopyMethod: volsync.CopyMethodSnapshot,
        },
        Retain: &volsyncv1alpha1.ResticRetainPolicy{
            Daily:   ptr.Int32(7),
            Weekly:  ptr.Int32(4),
            Monthly: ptr.Int32(12),
        },
    },
})

ReplicationDestination

rd := volsync.ReplicationDestination(&volsync.ReplicationDestinationConfig{
    Name:      "db-restore",
    Namespace: "dr",
    Trigger:   &volsync.TriggerConfig{Manual: "restore-1"},
    Mover: &volsync.DestinationResticConfig{
        Repository: "restic-creds",
        ReplicationDestinationVolumeOptions: volsyncv1alpha1.ReplicationDestinationVolumeOptions{
            CopyMethod:  volsync.CopyMethodSnapshot,
            Capacity:    resource.MustParse("10Gi").DeepCopy(),
            AccessModes: []corev1.PersistentVolumeAccessMode{corev1.ReadWriteOnce},
        },
    },
})

Movers

Modifying a resource

The config struct is the only mutation surface this package offers. Trigger, paused, source PVC and the mover variant are all fields on ReplicationSourceConfig / ReplicationDestinationConfig, so build the resource the way you want it:

schedule := "@daily"
rs := volsync.ReplicationSource(&volsync.ReplicationSourceConfig{
    Name:      "data-backup",
    Namespace: "apps",
    SourcePVC: "data",
    Paused:    true,
    Trigger:   &volsync.TriggerConfig{Schedule: &schedule},
    Mover:     &volsync.SourceRcloneConfig{ /* ... */ },
})

To change a built resource, assign the field:

rs.Spec.Paused = false
rs.Spec.Trigger = &volsyncv1alpha1.ReplicationSourceTriggerSpec{Manual: "go"}

The per-field SetReplicationSource* / SetReplicationDestination* helpers are gone. They were bare field assignments, and the mover ones duplicated the constructor’s type switch — the constructor is the one place that knows a mover variant clears its siblings. Switching a mover on an existing resource means clearing the other five arms yourself, which is exactly the multi-field write the builder contract forbids a Set<Field> helper from hiding.

The one appender remains, because a peer list is a slice the contract admits sugar for:

volsync.AddSyncthingPeer(syncCfg, "tcp://peer:22000", "PEER-ID", false)

Related Packages

• kubernetes-builders — broader resource builder family
• stack — domain model that produces Kubernetes resources