feat(libhelm) import libhelm into CE pkg directory [EE-4650] (#8138)

* import libhelm and update some paths

* remove file

* update readme

pkg/libhelm/binary/search_repo.go

@@ -0,0 +1,84 @@
+package binary
+
+// Package common implements common functionality for the helm.
+// The functionality does not rely on the implementation of `HelmPackageManager`
+
+import (
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"net/url"
+	"path"
+	"time"
+
+	"github.com/pkg/errors"
+	"github.com/portainer/portainer/pkg/libhelm/options"
+	"gopkg.in/yaml.v3"
+)
+
+var errRequiredSearchOptions = errors.New("repo is required")
+
+type File struct {
+	APIVersion string             `yaml:"apiVersion" json:"apiVersion"`
+	Entries    map[string][]Entry `yaml:"entries" json:"entries"`
+	Generated  string             `yaml:"generated" json:"generated"`
+}
+
+type Annotations struct {
+	Category string `yaml:"category" json:"category"`
+}
+
+type Entry struct {
+	Annotations *Annotations `yaml:"annotations" json:"annotations,omitempty"`
+	Created     string       `yaml:"created" json:"created"`
+	Deprecated  bool         `yaml:"deprecated" json:"deprecated"`
+	Description string       `yaml:"description" json:"description"`
+	Digest      string       `yaml:"digest" json:"digest"`
+	Home        string       `yaml:"home" json:"home"`
+	Name        string       `yaml:"name" json:"name"`
+	Sources     []string     `yaml:"sources" json:"sources"`
+	Urls        []string     `yaml:"urls" json:"urls"`
+	Version     string       `yaml:"version" json:"version"`
+	Icon        string       `yaml:"icon" json:"icon,omitempty"`
+}
+
+// SearchRepo downloads the `index.yaml` file for specified repo, parses it and returns JSON to caller.
+// The functionality is similar to that of what `helm search repo [chart] --repo <repo>` CLI runs;
+// this approach is used instead since the `helm search repo` requires a repo to be added to the global helm cache
+func (hbpm *helmBinaryPackageManager) SearchRepo(searchRepoOpts options.SearchRepoOptions) ([]byte, error) {
+	if searchRepoOpts.Repo == "" {
+		return nil, errRequiredSearchOptions
+	}
+
+	// The current index.yaml is ~9MB on bitnami.
+	// At a slow @2mbit download = 40s. @100bit = ~1s.
+	// I'm seeing 3 - 4s over wifi.
+	// Give ample time but timeout for now.  Can be improved in the future
+	client := http.Client{
+		Timeout: 60 * time.Second,
+	}
+
+	url, err := url.ParseRequestURI(searchRepoOpts.Repo)
+	if err != nil {
+		return nil, errors.Wrap(err, fmt.Sprintf("invalid helm chart URL: %s", searchRepoOpts.Repo))
+	}
+
+	url.Path = path.Join(url.Path, "index.yaml")
+	resp, err := client.Get(url.String())
+	if err != nil {
+		return nil, errors.Wrap(err, "failed to get index file")
+	}
+
+	var file File
+	err = yaml.NewDecoder(resp.Body).Decode(&file)
+	if err != nil {
+		return nil, errors.Wrap(err, "failed to decode index file")
+	}
+
+	result, err := json.Marshal(file)
+	if err != nil {
+		return nil, errors.Wrap(err, "failed to marshal index file")
+	}
+
+	return result, nil
+}