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refactor(server): Extract build logic into separate module

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This module is going to get more complex as the implementation of #32
progresses.
This commit is contained in:
Vincent Ambo 2019-08-14 17:20:01 +01:00 committed by Vincent Ambo
parent d9168e3e4d
commit 58380e3313
3 changed files with 365 additions and 304 deletions
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208
tools/nixery/server/builder/builder.go Normal file
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@ -0,0 +1,208 @@
// Copyright 2019 Google LLC
//
// 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
//
// https://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 builder implements the code required to build images via Nix. Image
// build data is cached for up to 24 hours to avoid duplicated calls to Nix
// (which are costly even if no building is performed).
package builder
import (
"bytes"
"context"
"encoding/json"
"fmt"
"io"
"io/ioutil"
"log"
"os"
"os/exec"
"strings"
"cloud.google.com/go/storage"
"github.com/google/nixery/config"
)
// Image represents the information necessary for building a container image.
// This can be either a list of package names (corresponding to keys in the
// nixpkgs set) or a Nix expression that results in a *list* of derivations.
type Image struct {
Name string
Tag string
// Names of packages to include in the image. These must correspond
// directly to top-level names of Nix packages in the nixpkgs tree.
Packages []string
}
// ImageFromName parses an image name into the corresponding structure which can
// be used to invoke Nix.
//
// It will expand convenience names under the hood (see the `convenienceNames`
// function below).
func ImageFromName(name string, tag string) Image {
packages := strings.Split(name, "/")
return Image{
Name: name,
Tag: tag,
Packages: convenienceNames(packages),
}
}
// BuildResult represents the output of calling the Nix derivation responsible
// for building registry images.
//
// The `layerLocations` field contains the local filesystem paths to each
// individual image layer that will need to be served, while the `manifest`
// field contains the JSON-representation of the manifest that needs to be
// served to the client.
//
// The later field is simply treated as opaque JSON and passed through.
type BuildResult struct {
Error string `json:"error"`
Pkgs []string `json:"pkgs"`
Manifest json.RawMessage `json:"manifest"`
LayerLocations map[string]struct {
Path string `json:"path"`
Md5 []byte `json:"md5"`
} `json:"layerLocations"`
}
// convenienceNames expands convenience package names defined by Nixery which
// let users include commonly required sets of tools in a container quickly.
//
// Convenience names must be specified as the first package in an image.
//
// Currently defined convenience names are:
//
// * `shell`: Includes bash, coreutils and other common command-line tools
func convenienceNames(packages []string) []string {
shellPackages := []string{"bashInteractive", "coreutils", "moreutils", "nano"}
if packages[0] == "shell" {
return append(packages[1:], shellPackages...)
}
return packages
}
// Call out to Nix and request that an image be built. Nix will, upon success,
// return a manifest for the container image.
func BuildImage(ctx *context.Context, cfg *config.Config, image *Image, bucket *storage.BucketHandle) (*BuildResult, error) {
packages, err := json.Marshal(image.Packages)
if err != nil {
return nil, err
}
args := []string{
"--argstr", "name", image.Name,
"--argstr", "packages", string(packages),
}
if cfg.Pkgs != nil {
args = append(args, "--argstr", "pkgSource", cfg.Pkgs.Render(image.Tag))
}
cmd := exec.Command("nixery-build-image", args...)
outpipe, err := cmd.StdoutPipe()
if err != nil {
return nil, err
}
errpipe, err := cmd.StderrPipe()
if err != nil {
return nil, err
}
if err = cmd.Start(); err != nil {
log.Println("Error starting nix-build:", err)
return nil, err
}
log.Printf("Started Nix image build for '%s'", image.Name)
stdout, _ := ioutil.ReadAll(outpipe)
stderr, _ := ioutil.ReadAll(errpipe)
if err = cmd.Wait(); err != nil {
// TODO(tazjin): Propagate errors upwards in a usable format.
log.Printf("nix-build execution error: %s\nstdout: %s\nstderr: %s\n", err, stdout, stderr)
return nil, err
}
log.Println("Finished Nix image build")
buildOutput, err := ioutil.ReadFile(strings.TrimSpace(string(stdout)))
if err != nil {
return nil, err
}
// The build output returned by Nix is deserialised to add all
// contained layers to the bucket. Only the manifest itself is
// re-serialised to JSON and returned.
var result BuildResult
err = json.Unmarshal(buildOutput, &result)
if err != nil {
return nil, err
}
for layer, meta := range result.LayerLocations {
err = uploadLayer(ctx, bucket, layer, meta.Path, meta.Md5)
if err != nil {
return nil, err
}
}
return &result, nil
}
// uploadLayer uploads a single layer to Cloud Storage bucket. Before writing
// any data the bucket is probed to see if the file already exists.
//
// If the file does exist, its MD5 hash is verified to ensure that the stored
// file is not - for example - a fragment of a previous, incomplete upload.
func uploadLayer(ctx *context.Context, bucket *storage.BucketHandle, layer string, path string, md5 []byte) error {
layerKey := fmt.Sprintf("layers/%s", layer)
obj := bucket.Object(layerKey)
// Before uploading a layer to the bucket, probe whether it already
// exists.
//
// If it does and the MD5 checksum matches the expected one, the layer
// upload can be skipped.
attrs, err := obj.Attrs(*ctx)
if err == nil && bytes.Equal(attrs.MD5, md5) {
log.Printf("Layer sha256:%s already exists in bucket, skipping upload", layer)
} else {
writer := obj.NewWriter(*ctx)
file, err := os.Open(path)
if err != nil {
return fmt.Errorf("failed to open layer %s from path %s: %v", layer, path, err)
}
size, err := io.Copy(writer, file)
if err != nil {
return fmt.Errorf("failed to write layer %s to Cloud Storage: %v", layer, err)
}
if err = writer.Close(); err != nil {
return fmt.Errorf("failed to write layer %s to Cloud Storage: %v", layer, err)
}
log.Printf("Uploaded layer sha256:%s (%v bytes written)\n", layer, size)
}
return nil
}

131
tools/nixery/server/config/config.go Normal file
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@ -0,0 +1,131 @@
// Copyright 2019 Google LLC
//
// 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
//
// https://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 config implements structures to store Nixery's configuration at
// runtime as well as the logic for instantiating this configuration from the
// environment.
package config
import (
"fmt"
"io/ioutil"
"log"
"os"
"cloud.google.com/go/storage"
)
// pkgSource represents the source from which the Nix package set used
// by Nixery is imported. Users configure the source by setting one of
// the supported environment variables.
type PkgSource struct {
srcType string
args string
}
// Convert the package source into the representation required by Nix.
func (p *PkgSource) Render(tag string) string {
// The 'git' source requires a tag to be present.
if p.srcType == "git" {
if tag == "latest" || tag == "" {
tag = "master"
}
return fmt.Sprintf("git!%s!%s", p.args, tag)
}
return fmt.Sprintf("%s!%s", p.srcType, p.args)
}
// Retrieve a package source from the environment. If no source is
// specified, the Nix code will default to a recent NixOS channel.
func pkgSourceFromEnv() *PkgSource {
if channel := os.Getenv("NIXERY_CHANNEL"); channel != "" {
log.Printf("Using Nix package set from Nix channel %q\n", channel)
return &PkgSource{
srcType: "nixpkgs",
args: channel,
}
}
if git := os.Getenv("NIXERY_PKGS_REPO"); git != "" {
log.Printf("Using Nix package set from git repository at %q\n", git)
return &PkgSource{
srcType: "git",
args: git,
}
}
if path := os.Getenv("NIXERY_PKGS_PATH"); path != "" {
log.Printf("Using Nix package set from path %q\n", path)
return &PkgSource{
srcType: "path",
args: path,
}
}
return nil
}
// Load (optional) GCS bucket signing data from the GCS_SIGNING_KEY and
// GCS_SIGNING_ACCOUNT envvars.
func signingOptsFromEnv() *storage.SignedURLOptions {
path := os.Getenv("GCS_SIGNING_KEY")
id := os.Getenv("GCS_SIGNING_ACCOUNT")
if path == "" || id == "" {
log.Println("GCS URL signing disabled")
return nil
}
log.Printf("GCS URL signing enabled with account %q\n", id)
k, err := ioutil.ReadFile(path)
if err != nil {
log.Fatalf("Failed to read GCS signing key: %s\n", err)
}
return &storage.SignedURLOptions{
GoogleAccessID: id,
PrivateKey: k,
Method: "GET",
}
}
func getConfig(key, desc string) string {
value := os.Getenv(key)
if value == "" {
log.Fatalln(desc + " must be specified")
}
return value
}
// config holds the Nixery configuration options.
type Config struct {
Bucket string // GCS bucket to cache & serve layers
Signing *storage.SignedURLOptions // Signing options to use for GCS URLs
Port string // Port on which to launch HTTP server
Pkgs *PkgSource // Source for Nix package set
WebDir string
}
func FromEnv() *Config {
return &Config{
Bucket: getConfig("BUCKET", "GCS bucket for layer storage"),
Port: getConfig("PORT", "HTTP port"),
Pkgs: pkgSourceFromEnv(),
Signing: signingOptsFromEnv(),
WebDir: getConfig("WEB_DIR", "Static web file dir"),
}
}

330
tools/nixery/server/main.go
View file

@ -12,8 +12,8 @@
// License for the specific language governing permissions and limitations under
// the License.
// Package main provides the implementation of a container registry that
// transparently builds container images based on Nix derivations.
// The nixery server implements a container registry that transparently builds
// container images based on Nix derivations.
//
// The Nix derivation used for image creation is responsible for creating
// objects that are compatible with the registry API. The targeted registry
@ -26,287 +26,32 @@
package main
import (
"bytes"
"context"
"encoding/json"
"fmt"
"io"
"io/ioutil"
"log"
"net/http"
"os"
"os/exec"
"regexp"
"strings"
"time"
"cloud.google.com/go/storage"
"github.com/google/nixery/builder"
"github.com/google/nixery/config"
)
// pkgSource represents the source from which the Nix package set used
// by Nixery is imported. Users configure the source by setting one of
// the supported environment variables.
type pkgSource struct {
srcType string
args string
}
// Convert the package source into the representation required by Nix.
func (p *pkgSource) renderSource(tag string) string {
// The 'git' source requires a tag to be present.
if p.srcType == "git" {
if tag == "latest" || tag == "" {
tag = "master"
}
return fmt.Sprintf("git!%s!%s", p.args, tag)
}
return fmt.Sprintf("%s!%s", p.srcType, p.args)
}
// Retrieve a package source from the environment. If no source is
// specified, the Nix code will default to a recent NixOS channel.
func pkgSourceFromEnv() *pkgSource {
if channel := os.Getenv("NIXERY_CHANNEL"); channel != "" {
log.Printf("Using Nix package set from Nix channel %q\n", channel)
return &pkgSource{
srcType: "nixpkgs",
args: channel,
}
}
if git := os.Getenv("NIXERY_PKGS_REPO"); git != "" {
log.Printf("Using Nix package set from git repository at %q\n", git)
return &pkgSource{
srcType: "git",
args: git,
}
}
if path := os.Getenv("NIXERY_PKGS_PATH"); path != "" {
log.Printf("Using Nix package set from path %q\n", path)
return &pkgSource{
srcType: "path",
args: path,
}
}
return nil
}
// Load (optional) GCS bucket signing data from the GCS_SIGNING_KEY and
// GCS_SIGNING_ACCOUNT envvars.
func signingOptsFromEnv() *storage.SignedURLOptions {
path := os.Getenv("GCS_SIGNING_KEY")
id := os.Getenv("GCS_SIGNING_ACCOUNT")
if path == "" || id == "" {
log.Println("GCS URL signing disabled")
return nil
}
log.Printf("GCS URL signing enabled with account %q\n", id)
k, err := ioutil.ReadFile(path)
if err != nil {
log.Fatalf("Failed to read GCS signing key: %s\n", err)
}
return &storage.SignedURLOptions{
GoogleAccessID: id,
PrivateKey: k,
Method: "GET",
}
}
// config holds the Nixery configuration options.
type config struct {
bucket string // GCS bucket to cache & serve layers
signing *storage.SignedURLOptions // Signing options to use for GCS URLs
port string // Port on which to launch HTTP server
pkgs *pkgSource // Source for Nix package set
}
// ManifestMediaType is the Content-Type used for the manifest itself. This
// corresponds to the "Image Manifest V2, Schema 2" described on this page:
//
// https://docs.docker.com/registry/spec/manifest-v2-2/
const manifestMediaType string = "application/vnd.docker.distribution.manifest.v2+json"
// Image represents the information necessary for building a container image.
// This can be either a list of package names (corresponding to keys in the
// nixpkgs set) or a Nix expression that results in a *list* of derivations.
type image struct {
name string
tag string
// Names of packages to include in the image. These must correspond
// directly to top-level names of Nix packages in the nixpkgs tree.
packages []string
}
// BuildResult represents the output of calling the Nix derivation responsible
// for building registry images.
//
// The `layerLocations` field contains the local filesystem paths to each
// individual image layer that will need to be served, while the `manifest`
// field contains the JSON-representation of the manifest that needs to be
// served to the client.
//
// The later field is simply treated as opaque JSON and passed through.
type BuildResult struct {
Error string `json:"error"`
Pkgs []string `json:"pkgs"`
Manifest json.RawMessage `json:"manifest"`
LayerLocations map[string]struct {
Path string `json:"path"`
Md5 []byte `json:"md5"`
} `json:"layerLocations"`
}
// imageFromName parses an image name into the corresponding structure which can
// be used to invoke Nix.
//
// It will expand convenience names under the hood (see the `convenienceNames`
// function below).
func imageFromName(name string, tag string) image {
packages := strings.Split(name, "/")
return image{
name: name,
tag: tag,
packages: convenienceNames(packages),
}
}
// convenienceNames expands convenience package names defined by Nixery which
// let users include commonly required sets of tools in a container quickly.
//
// Convenience names must be specified as the first package in an image.
//
// Currently defined convenience names are:
//
// * `shell`: Includes bash, coreutils and other common command-line tools
// * `builder`: All of the above and the standard build environment
func convenienceNames(packages []string) []string {
shellPackages := []string{"bashInteractive", "coreutils", "moreutils", "nano"}
if packages[0] == "shell" {
return append(packages[1:], shellPackages...)
}
return packages
}
// Call out to Nix and request that an image be built. Nix will, upon success,
// return a manifest for the container image.
func buildImage(ctx *context.Context, cfg *config, image *image, bucket *storage.BucketHandle) (*BuildResult, error) {
packages, err := json.Marshal(image.packages)
if err != nil {
return nil, err
}
args := []string{
"--argstr", "name", image.name,
"--argstr", "packages", string(packages),
}
if cfg.pkgs != nil {
args = append(args, "--argstr", "pkgSource", cfg.pkgs.renderSource(image.tag))
}
cmd := exec.Command("nixery-build-image", args...)
outpipe, err := cmd.StdoutPipe()
if err != nil {
return nil, err
}
errpipe, err := cmd.StderrPipe()
if err != nil {
return nil, err
}
if err = cmd.Start(); err != nil {
log.Println("Error starting nix-build:", err)
return nil, err
}
log.Printf("Started Nix image build for '%s'", image.name)
stdout, _ := ioutil.ReadAll(outpipe)
stderr, _ := ioutil.ReadAll(errpipe)
if err = cmd.Wait(); err != nil {
// TODO(tazjin): Propagate errors upwards in a usable format.
log.Printf("nix-build execution error: %s\nstdout: %s\nstderr: %s\n", err, stdout, stderr)
return nil, err
}
log.Println("Finished Nix image build")
buildOutput, err := ioutil.ReadFile(strings.TrimSpace(string(stdout)))
if err != nil {
return nil, err
}
// The build output returned by Nix is deserialised to add all
// contained layers to the bucket. Only the manifest itself is
// re-serialised to JSON and returned.
var result BuildResult
err = json.Unmarshal(buildOutput, &result)
if err != nil {
return nil, err
}
for layer, meta := range result.LayerLocations {
err = uploadLayer(ctx, bucket, layer, meta.Path, meta.Md5)
if err != nil {
return nil, err
}
}
return &result, nil
}
// uploadLayer uploads a single layer to Cloud Storage bucket. Before writing
// any data the bucket is probed to see if the file already exists.
//
// If the file does exist, its MD5 hash is verified to ensure that the stored
// file is not - for example - a fragment of a previous, incomplete upload.
func uploadLayer(ctx *context.Context, bucket *storage.BucketHandle, layer string, path string, md5 []byte) error {
layerKey := fmt.Sprintf("layers/%s", layer)
obj := bucket.Object(layerKey)
// Before uploading a layer to the bucket, probe whether it already
// exists.
//
// If it does and the MD5 checksum matches the expected one, the layer
// upload can be skipped.
attrs, err := obj.Attrs(*ctx)
if err == nil && bytes.Equal(attrs.MD5, md5) {
log.Printf("Layer sha256:%s already exists in bucket, skipping upload", layer)
} else {
writer := obj.NewWriter(*ctx)
file, err := os.Open(path)
if err != nil {
return fmt.Errorf("failed to open layer %s from path %s: %v", layer, path, err)
}
size, err := io.Copy(writer, file)
if err != nil {
return fmt.Errorf("failed to write layer %s to Cloud Storage: %v", layer, err)
}
if err = writer.Close(); err != nil {
return fmt.Errorf("failed to write layer %s to Cloud Storage: %v", layer, err)
}
log.Printf("Uploaded layer sha256:%s (%v bytes written)\n", layer, size)
}
return nil
}
// Regexes matching the V2 Registry API routes. This only includes the
// routes required for serving images, since pushing and other such
// functionality is not available.
var (
manifestRegex = regexp.MustCompile(`^/v2/([\w|\-|\.|\_|\/]+)/manifests/([\w|\-|\.|\_]+)$`)
layerRegex = regexp.MustCompile(`^/v2/([\w|\-|\.|\_|\/]+)/blobs/sha256:(\w+)$`)
)
// layerRedirect constructs the public URL of the layer object in the Cloud
// Storage bucket, signs it and redirects the user there.
@ -316,16 +61,16 @@ func uploadLayer(ctx *context.Context, bucket *storage.BucketHandle, layer strin
//
// The Docker client is known to follow redirects, but this might not be true
// for all other registry clients.
func constructLayerUrl(cfg *config, digest string) (string, error) {
log.Printf("Redirecting layer '%s' request to bucket '%s'\n", digest, cfg.bucket)
func constructLayerUrl(cfg *config.Config, digest string) (string, error) {
log.Printf("Redirecting layer '%s' request to bucket '%s'\n", digest, cfg.Bucket)
object := "layers/" + digest
if cfg.signing != nil {
opts := *cfg.signing
if cfg.Signing != nil {
opts := *cfg.Signing
opts.Expires = time.Now().Add(5 * time.Minute)
return storage.SignedURL(cfg.bucket, object, &opts)
return storage.SignedURL(cfg.Bucket, object, &opts)
} else {
return ("https://storage.googleapis.com/" + cfg.bucket + "/" + object), nil
return ("https://storage.googleapis.com/" + cfg.Bucket + "/" + object), nil
}
}
@ -336,13 +81,13 @@ func constructLayerUrl(cfg *config, digest string) (string, error) {
//
// The bucket is required for Nixery to function correctly, hence fatal errors
// are generated in case it fails to be set up correctly.
func prepareBucket(ctx *context.Context, cfg *config) *storage.BucketHandle {
func prepareBucket(ctx *context.Context, cfg *config.Config) *storage.BucketHandle {
client, err := storage.NewClient(*ctx)
if err != nil {
log.Fatalln("Failed to set up Cloud Storage client:", err)
}
bkt := client.Bucket(cfg.bucket)
bkt := client.Bucket(cfg.Bucket)
if _, err := bkt.Attrs(*ctx); err != nil {
log.Fatalln("Could not access configured bucket", err)
@ -351,14 +96,6 @@ func prepareBucket(ctx *context.Context, cfg *config) *storage.BucketHandle {
return bkt
}
// Regexes matching the V2 Registry API routes. This only includes the
// routes required for serving images, since pushing and other such
// functionality is not available.
var (
manifestRegex = regexp.MustCompile(`^/v2/([\w|\-|\.|\_|\/]+)/manifests/([\w|\-|\.|\_]+)$`)
layerRegex = regexp.MustCompile(`^/v2/([\w|\-|\.|\_|\/]+)/blobs/sha256:(\w+)$`)
)
// Error format corresponding to the registry protocol V2 specification. This
// allows feeding back errors to clients in a way that can be presented to
// users.
@ -385,7 +122,7 @@ func writeError(w http.ResponseWriter, status int, code, message string) {
}
type registryHandler struct {
cfg *config
cfg *config.Config
ctx *context.Context
bucket *storage.BucketHandle
}
@ -402,8 +139,8 @@ func (h *registryHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
imageName := manifestMatches[1]
imageTag := manifestMatches[2]
log.Printf("Requesting manifest for image %q at tag %q", imageName, imageTag)
image := imageFromName(imageName, imageTag)
buildResult, err := buildImage(h.ctx, h.cfg, &image, h.bucket)
image := builder.ImageFromName(imageName, imageTag)
buildResult, err := builder.BuildImage(h.ctx, h.cfg, &image, h.bucket)
if err != nil {
writeError(w, 500, "UNKNOWN", "image build failure")
@ -451,27 +188,12 @@ func (h *registryHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
w.WriteHeader(404)
}
func getConfig(key, desc string) string {
value := os.Getenv(key)
if value == "" {
log.Fatalln(desc + " must be specified")
}
return value
}
func main() {
cfg := &config{
bucket: getConfig("BUCKET", "GCS bucket for layer storage"),
port: getConfig("PORT", "HTTP port"),
pkgs: pkgSourceFromEnv(),
signing: signingOptsFromEnv(),
}
cfg := config.FromEnv()
ctx := context.Background()
bucket := prepareBucket(&ctx, cfg)
log.Printf("Starting Kubernetes Nix controller on port %s\n", cfg.port)
log.Printf("Starting Kubernetes Nix controller on port %s\n", cfg.Port)
// All /v2/ requests belong to the registry handler.
http.Handle("/v2/", &registryHandler{
@ -481,8 +203,8 @@ func main() {
})
// All other roots are served by the static file server.
webDir := http.Dir(getConfig("WEB_DIR", "Static web file dir"))
webDir := http.Dir(cfg.WebDir)
http.Handle("/", http.FileServer(webDir))
log.Fatal(http.ListenAndServe(":"+cfg.port, nil))
log.Fatal(http.ListenAndServe(":"+cfg.Port, nil))
}