kvm2: base image cache with a streamed upload and the pool-space precheck

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

internal/provider/kvm2/kvm2.go

@@ -7,13 +7,16 @@ package kvm2
 import (
 	"context"
 	"errors"
+	"net/http"
 	"os"
+	"sync"
 	"time"
 
 	"github.com/go-logr/logr"
 	logf "sigs.k8s.io/controller-runtime/pkg/log"
 
 	"gitea.home.hrajfrisbee.cz/kacerr/egress-proxies-operator/internal/provider"
+	"gitea.home.hrajfrisbee.cz/kacerr/egress-proxies-operator/internal/tracing"
 )
 
 const (
@@ -25,10 +28,33 @@ const (
 // Provider is one configured kvm2 entry: a set of hosts sharing one SSH key
 // and one image and machine-type catalogue.
 type Provider struct {
-	name  string
-	cfg   provider.KVMConfig
-	now   func() time.Time
-	hosts *hostTable
+	name    string
+	cfg     provider.KVMConfig
+	now     func() time.Time
+	hosts   *hostTable
+	http    *http.Client
+	budgets budgets
+	tracing []tracing.Option
+
+	// imageLocks serialises image fetches per (host, volume), spec entry 19.
+	imageMu    sync.Mutex
+	imageLocks map[string]chan struct{}
+}
+
+// providerOption adjusts what newProvider builds; tests inject an HTTP
+// client bound to a test server, a span recorder and shorter budgets.
+type providerOption func(*Provider)
+
+func withHTTPClient(c *http.Client) providerOption {
+	return func(p *Provider) { p.http = c }
+}
+
+func withBudgets(b budgets) providerOption {
+	return func(p *Provider) { p.budgets = b }
+}
+
+func withTracing(opts ...tracing.Option) providerOption {
+	return func(p *Provider) { p.tracing = opts }
 }
 
 var _ provider.Provider = (*Provider)(nil)
@@ -59,9 +85,26 @@ func New(ctx context.Context, pc provider.ProviderConfig) (provider.Provider, er
 }
 
 // newProvider is the constructor tests use: d hands out the backends, the
-// production one being newLibvirtDialer.
-func newProvider(name string, cfg provider.KVMConfig, d dialer) *Provider {
-	return &Provider{name: name, cfg: withDefaults(cfg), now: time.Now, hosts: newHostTable(d)}
+// production one being newLibvirtDialer. Without options the image
+// downloads use http.DefaultClient (system CA roots, no client timeout: the
+// per-request ctx carries the transfer budget) and the default budgets.
+func newProvider(name string, cfg provider.KVMConfig, d dialer, opts ...providerOption) *Provider {
+	p := &Provider{
+		name:       name,
+		cfg:        withDefaults(cfg),
+		now:        time.Now,
+		hosts:      newHostTable(d),
+		http:       http.DefaultClient,
+		budgets:    defaultBudgets,
+		imageLocks: make(map[string]chan struct{}),
+	}
+	for _, opt := range opts {
+		opt(p)
+	}
+	if p.http == nil {
+		p.http = http.DefaultClient
+	}
+	return p
 }
 
 // withDefaults returns cfg with every optional field filled in, so the rest