dev-docs: Go package docs (#958)

* Remove unused package

* Add Go package docs to most packages

Signed-off-by: Daniel Weiße <dw@edgeless.systems>
Signed-off-by: Fabian Kammel <fk@edgeless.systems>
Signed-off-by: Paul Meyer <49727155+katexochen@users.noreply.github.com>
Co-authored-by: Paul Meyer <49727155+katexochen@users.noreply.github.com>
Co-authored-by: Fabian Kammel <fk@edgeless.systems>

internal/cloud/qemu/qemu.go

@@ -0,0 +1,103 @@
+/*
+Copyright (c) Edgeless Systems GmbH
+
+SPDX-License-Identifier: AGPL-3.0-only
+*/
+
+/*
+This package provides an interface to fake a CSP API for QEMU instances.
+*/
+package qemu
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"net/url"
+
+	"github.com/edgelesssys/constellation/v2/internal/cloud/metadata"
+)
+
+const qemuMetadataEndpoint = "10.42.0.1:8080"
+
+// Cloud provides an interface to fake a CSP API for QEMU instances.
+type Cloud struct{}
+
+// New returns a new Cloud instance.
+func New() *Cloud {
+	return &Cloud{}
+}
+
+// List retrieves all instances belonging to the current constellation.
+func (c *Cloud) List(ctx context.Context) ([]metadata.InstanceMetadata, error) {
+	instancesRaw, err := c.retrieveMetadata(ctx, "/peers")
+	if err != nil {
+		return nil, err
+	}
+
+	var instances []metadata.InstanceMetadata
+	err = json.Unmarshal(instancesRaw, &instances)
+	return instances, err
+}
+
+// Self retrieves the current instance.
+func (c *Cloud) Self(ctx context.Context) (metadata.InstanceMetadata, error) {
+	instanceRaw, err := c.retrieveMetadata(ctx, "/self")
+	if err != nil {
+		return metadata.InstanceMetadata{}, err
+	}
+
+	var instance metadata.InstanceMetadata
+	err = json.Unmarshal(instanceRaw, &instance)
+	return instance, err
+}
+
+// GetLoadBalancerEndpoint returns the endpoint of the load balancer.
+// For QEMU, the load balancer is the first control plane node returned by the metadata API.
+func (c *Cloud) GetLoadBalancerEndpoint(ctx context.Context) (string, error) {
+	endpointRaw, err := c.retrieveMetadata(ctx, "/endpoint")
+	if err != nil {
+		return "", err
+	}
+	var endpoint string
+	err = json.Unmarshal(endpointRaw, &endpoint)
+	return endpoint, err
+}
+
+// InitSecretHash returns the hash of the init secret.
+func (c *Cloud) InitSecretHash(ctx context.Context) ([]byte, error) {
+	initSecretHash, err := c.retrieveMetadata(ctx, "/initsecrethash")
+	if err != nil {
+		return nil, fmt.Errorf("could not retrieve init secret hash: %w", err)
+	}
+	return initSecretHash, nil
+}
+
+// UID returns the UID of the constellation.
+func (c *Cloud) UID(ctx context.Context) (string, error) {
+	// We expect only one constellation to be deployed in the same QEMU / libvirt environment.
+	// the UID can be an empty string.
+	return "", nil
+}
+
+func (c *Cloud) retrieveMetadata(ctx context.Context, uri string) ([]byte, error) {
+	url := &url.URL{
+		Scheme: "http",
+		Host:   qemuMetadataEndpoint,
+		Path:   uri,
+	}
+
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, url.String(), nil)
+	if err != nil {
+		return nil, err
+	}
+	res, err := (&http.Client{}).Do(req)
+	if err != nil {
+		return nil, err
+	}
+	defer res.Body.Close()
+
+	return io.ReadAll(res.Body)
+}