helm/pkg/plugin/installer/http_installer.go

/*
Copyright 2016 The Kubernetes Authors All rights reserved.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package installer // import "k8s.io/helm/pkg/plugin/installer"

import (
    "k8s.io/helm/pkg/helm/helmpath"
    "path/filepath"
    "k8s.io/helm/pkg/getter"
    "k8s.io/helm/pkg/helm/environment"
    "k8s.io/helm/pkg/plugin/cache"
    "compress/gzip"
    "archive/tar"
    "io"
    "os"
    "fmt"
    "strings"
    "bytes"
    "regexp"
)

type HttpInstaller struct {
    CacheDir string
    PluginName string
    base
    extractor Extractor
    getter getter.Getter
}

type TarGzExtractor struct {}

type Extractor interface {
    Extract(buffer *bytes.Buffer, targetDir string) error
}

var Extractors = map[string]Extractor {
    ".tar.gz": &TarGzExtractor{},
    ".tgz": &TarGzExtractor{},
}

// NewExtractor creates a new extractor matching the source file name
func NewExtractor(source string) (Extractor, error) {
    for suffix, extractor := range Extractors {
        if strings.HasSuffix(source, suffix) {
            return extractor, nil
        }
    }
    return nil, fmt.Errorf("no extractor implemented yet for %s", source)
}

// NewHttpInstaller creates a new HttpInstaller.
func NewHttpInstaller(source string, home helmpath.Home) (*HttpInstaller, error) {

    key, err := cache.Key(source)
    if err != nil {
        return nil, err
    }

    extractor, err := NewExtractor(source)
    if err != nil {
        return nil, err
    }

    getConstructor, err := getter.ByScheme("http", environment.EnvSettings{})
    if err != nil {
        return nil, err
    }

    get, err := getConstructor.New(source,"", "", "")
    if err != nil {
        return nil, err
    }

    i := &HttpInstaller{
        CacheDir: home.Path("cache", "plugins", key),
        PluginName: stripPluginName(filepath.Base(source)),
        base: newBase(source, home),
        extractor: extractor,
        getter: get,
    }
    return i, nil
}

// helper that relies on some sort of convention for plugin name (plugin-name-<version>)
func stripPluginName(name string) string {
    var strippedName string
    for suffix := range Extractors {
        if strings.HasSuffix(name, suffix) {
            strippedName = strings.TrimSuffix(name, suffix)
            break
        }
    }
    re := regexp.MustCompile(`(.*)-[0-9]+\..*`)
    return re.ReplaceAllString(strippedName, `$1`)
}

// Install() downloads and extracts the tarball into the cache directory and creates a symlink to the plugin directory in $HELM_HOME.
//
// Implements Installer.
func (i *HttpInstaller) Install() error {

    pluginData, err := i.getter.Get(i.Source)
    if err != nil {
        return err
    }

    err = i.extractor.Extract(pluginData, i.CacheDir)
    if err != nil {
        return err
    }

    if !isPlugin(i.CacheDir) {
        return ErrMissingMetadata
    }

    src, err := filepath.Abs(i.CacheDir)
    if err != nil {
        return err
    }

    return i.link(src)
}

// Update updates a local repository
// Not implemented for now since tarball most likely will be packaged by version
func (i *HttpInstaller) Update() error {
    return fmt.Errorf("method Update() not implemented for HttpInstaller")
}

// Override link because we want to use HttpInstaller.Path() not base.Path()
func (i *HttpInstaller) link(from string) error {
    debug("symlinking %s to %s", from, i.Path())
    return os.Symlink(from, i.Path())
}

// Override Path() because we want to join on the plugin name not the file name
func (i HttpInstaller) Path() string {
    if i.base.Source == "" {
        return ""
    }
    return filepath.Join(i.base.HelmHome.Plugins(), i.PluginName)
}

// Extracts tar.gz archive
//
// Implements Extractor.
func (g *TarGzExtractor) Extract(buffer *bytes.Buffer, targetDir string) error {
    uncompressedStream, err := gzip.NewReader(buffer)
    if err != nil {
        return err
    }

    tarReader := tar.NewReader(uncompressedStream)

    os.MkdirAll(targetDir, 0755)

    for true {
        header, err := tarReader.Next()

        if err == io.EOF {
            break
        }

        if err != nil {
            return err
        }

        path := filepath.Join(targetDir, header.Name)

        switch header.Typeflag {
        case tar.TypeDir:
            if err := os.Mkdir(path, 0755); err != nil {
                return err
            }
        case tar.TypeReg:
            outFile, err := os.Create(path)
            if err != nil {
                return err
            }
            defer outFile.Close()
            if _, err := io.Copy(outFile, tarReader); err != nil {
                return err
            }
        default:
            return fmt.Errorf("unknown type: %s in %s", header.Typeflag, header.Name)
        }
    }

    return nil

}