nexus copy assets from instance to instance

go.mod

module nexus_copy

go 1.14

require (
	github.com/cavaliercoder/grab v2.0.0+incompatible
	gopkg.in/yaml.v2 v2.4.0
)

main.go

package main

import (
	"bytes"
	"encoding/json"
	"flag"
	"fmt"
	"github.com/cavaliercoder/grab"
	"gopkg.in/yaml.v2"
	"io"
	"io/ioutil"
	"log"
	"mime/multipart"
	"net/http"
	"os"
	"strings"
)

var (
	conf   = flag.String("conf", "config.yaml", "The path to the config file.")
)

type NexusAssetsCollection struct {
	Items []NexusAsset `json:"items"`
	Token string `json:"continuationToken"`

}

type NexusAsset struct {
	DownloadURL string `json:"downloadUrl"`
	Path        string `json:"path"`
	ID          string `json:"id"`
	Repository  string `json:"repository"`
	Format      string `json:"format"`
	Name      string `json:"name"`
	Checksum    struct {
		Sha1   string `json:"sha1"`
		Sha512 string `json:"sha512"`
		Sha256 string `json:"sha256"`
		Md5    string `json:"md5"`
	} `json:"checksum"`
}

type Conf struct {
	WorkDir       string          `yaml:"work_dir"`
	Repo1 		  string          `yaml:"repo1"`
	Url1          string          `yaml:"url1"`
	User1         string          `yaml:"user1"`
	Pass1         string          `yaml:"pass1"`
	Repo2 		  string          `yaml:"repo2"`
	Url2          string          `yaml:"url2"`
	User2         string          `yaml:"user2"`
	Pass2         string          `yaml:"pass2"`
}

func (c *Conf) GetConf(configFile string) *Conf {

	yamlFile, err := ioutil.ReadFile(configFile)
	if err != nil {
		log.Printf("yamlFile.Get err   #%v ", err)
	}
	err = yaml.Unmarshal(yamlFile, c)
	if err != nil {
		log.Println("Unmarshal: %v", err)
	}

	return c
}

func downloadAssets(c Conf, assets *NexusAssetsCollection) {



	for  index, a :=range assets.Items {
		resp, err := grab.Get(c.WorkDir, a.DownloadURL)
		if err != nil {
			log.Println(err.Error())
		}

		//assets.Items[index].Name = resp.Filename
		assets.Items[index].Name = strings.TrimPrefix(resp.Filename, "assets\\")
	}

}

func GetAssets(c Conf, token string)  NexusAssetsCollection {
	url := c.Url1 + "/service/rest/v1/assets?repository=" + c.Repo1
	if token != "" {
		url += "&continuationToken=" + token
	}
	spaceClient := http.Client{}

	req, err := http.NewRequest(http.MethodGet, url, nil)
	if err != nil {
		log.Println(err)
	}
	req.Header.Set("Content-Type", "application/json; charset=UTF-8")
	req.SetBasicAuth(c.User1, c.Pass1)

	res, getErr := spaceClient.Do(req)
	if getErr != nil {
		log.Println(getErr)
	}

	if res.Body != nil {
		defer res.Body.Close()
	}


	body, readErr := ioutil.ReadAll(res.Body)
	if readErr != nil {
		log.Fatal(readErr)
	}
	//Convert the body to type string
	//sb := string(body)
	//log.Printf(sb)
	assets := NexusAssetsCollection{}
	jsonErr := json.Unmarshal(body, &assets)
	if jsonErr != nil {
		log.Fatal(jsonErr)
	}
	if assets.Token != "" {
		a2 :=  GetAssets(c, assets.Token)
		assets.Items = append(assets.Items, a2.Items...)
	}
	return assets

}
func uploadAssets(c Conf, assets *NexusAssetsCollection) {
	for _, a :=range assets.Items {
		uploadRawToNexus(c, a)
	}
}

func main() {
	var c Conf
	c.GetConf(*conf)
	if c.Url1 == "" {
		c.Url1 = "http://localhost:9090/nexus"
	}
	if c.Url2 == "" {
		c.Url2 = "http://localhost:8081/nexus"
	}
	if c.Repo1 == "" {
		c.Repo1 = "packages"
	}
	if c.Repo2 == "" {
		c.Repo2 = c.Repo1
	}
	if c.User1 == "" {
		c.User1 = "admin"
	}
	if c.User2 == "" {
		c.User2 = c.User1
	}

	c.WorkDir = "./assets"
	os.Mkdir("assets/", 0755)
	assets := GetAssets(c, "")
	downloadAssets(c, &assets)
	uploadAssets(c, &assets)

}



func uploadRawToNexus(c Conf, a NexusAsset) {
	// https://stackoverflow.com/questions/20205796/post-data-using-the-content-type-multipart-form-data

	var client http.Client
	u := fmt.Sprintf("%s/service/rest/v1/components?repository=%s", c.Url2, c.Repo2)
	remoteURL := u
	//prepare the reader instances to encode
	dir := strings.TrimSuffix(a.Path, a.Name)
	values := map[string]io.Reader{
		a.Format + ".asset":          mustOpen(c.WorkDir + "/" + a.Name), // lets assume its this file
		a.Format + ".asset.filename": strings.NewReader(a.Name),
	}
	if dir != "" {
		values = map[string]io.Reader{
			a.Format + ".asset":          mustOpen(c.WorkDir + "/" + a.Name), // lets assume its this file
			a.Format + ".asset.filename": strings.NewReader(a.Name),
			a.Format + ".directory": strings.NewReader(dir),
		}
	}
	if a.Format == "nuget" {
		values = map[string]io.Reader{
			a.Format + ".asset":          mustOpen(c.WorkDir + "/" + a.Name), // lets assume its this file
		}
	}

	err := Upload(&client, remoteURL, values, c)
	if err != nil {
		log.Println(err.Error())
	}
}


func Upload(client *http.Client, url string, values map[string]io.Reader, c Conf) (err error) {
	// Prepare a form that you will submit to that URL.
	var b bytes.Buffer
	w := multipart.NewWriter(&b)
	for key, r := range values {
		var fw io.Writer
		if x, ok := r.(io.Closer); ok {
			defer x.Close()
		}
		// Add an image file
		if x, ok := r.(*os.File); ok {
			if fw, err = w.CreateFormFile(key, x.Name()); err != nil {
				return
			}
		} else {
			// Add other fields
			if fw, err = w.CreateFormField(key); err != nil {
				return
			}
		}
		if _, err = io.Copy(fw, r); err != nil {
			return err
		}

	}
	// Don't forget to close the multipart writer.
	// If you don't close it, your request will be missing the terminating boundary.
	w.Close()

	// Now that you have a form, you can submit it to your handler.
	req, err := http.NewRequest("POST", url, &b)
	if err != nil {
		return
	}
	// Don't forget to set the content type, this will contain the boundary.
	req.Header.Set("Content-Type", w.FormDataContentType())
	req.SetBasicAuth(c.User2, c.Pass2)

	// Submit the request
	res, err := client.Do(req)
	if err != nil {
		return
	}

	// Check the response
	if res.StatusCode != http.StatusOK && res.StatusCode != http.StatusNoContent {
		body, _ := ioutil.ReadAll(res.Body)
		err = fmt.Errorf("bad status: %s", res.Status)
		log.Println(string(body))
	}
	return
}


func mustOpen(f string) *os.File {
	r, err := os.Open(f)
	if err != nil {
		log.Fatal(err)
	}
	return r
}

I ran this from my IDEA the config file looks something like this for me:

---
pass1: 'pass1'
pass2: 'pass2'

You can see in the code on line 138 to ... that it sets some default config that was ok for me. The same is repeated on line 44-54
if c.Url1 == "" {
c.Url1 = "http://localhost:9090/nexus"
}
if c.Url2 == "" {
c.Url2 = "http://localhost:8081/nexus"
}
if c.Repo1 == "" {
c.Repo1 = "packages"
}
if c.Repo2 == "" {
c.Repo2 = c.Repo1
}
if c.User1 == "" {
c.User1 = "admin"
}
if c.User2 == "" {
c.User2 = c.User1
}

this would translate in config.yaml to

---
url1: 'value'
url2: 'value'
user1: 'value'
user2: 'value'
repo1:  'value'
repo2: 'value'
pass1: 'pass1'
pass2: 'pass2'
work_dir: 'assets'

In theory I guess you run go build to build this script as well. And then just run it from the local directory. The config.yaml should be in the local dir. I adjusted on line of code my IDEA was giving trouble on.

I only tested this for raw assets though as uploading rpm's/etc might be different upload forms. I do also have a script somewhere to recreate my yum repos etc from instances. But I don't reupload my local ones.