refactor(main): Split HTTP handlers into separate functions
There is a new handler coming up to fix #102 and I want to avoid falling into the classic Go trap of creating thousand-line functions.
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5ce745d104
2 changed files with 65 additions and 60 deletions
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@ -140,7 +140,7 @@ func pkgSourceFromEnv() (PkgSource, error) {
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}
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if git := os.Getenv("NIXERY_PKGS_REPO"); git != "" {
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log.WithField("repo", git).Info("using NIx package set from git repository")
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log.WithField("repo", git).Info("using Nix package set from git repository")
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return &GitSource{
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repository: git,
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@ -53,8 +53,8 @@ var version string = "devel"
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// routes required for serving images, since pushing and other such
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// functionality is not available.
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var (
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manifestRegex = regexp.MustCompile(`^/v2/([\w|\-|\.|\_|\/]+)/manifests/([\w|\-|\.|\_]+)$`)
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layerRegex = regexp.MustCompile(`^/v2/([\w|\-|\.|\_|\/]+)/blobs/sha256:(\w+)$`)
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manifestTagRegex = regexp.MustCompile(`^/v2/([\w|\-|\.|\_|\/]+)/manifests/([\w|\-|\.|\_]+)$`)
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layerRegex = regexp.MustCompile(`^/v2/([\w|\-|\.|\_|\/]+)/blobs/sha256:(\w+)$`)
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)
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// Downloads the popularity information for the package set from the
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@ -112,75 +112,80 @@ type registryHandler struct {
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state *builder.State
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}
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// Serve a manifest by tag, building it via Nix and populating caches
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// if necessary.
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func (h *registryHandler) serveManifestTag(w http.ResponseWriter, r *http.Request, name string, tag string) {
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log.WithFields(log.Fields{
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"image": name,
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"tag": tag,
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}).Info("requesting image manifest")
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image := builder.ImageFromName(name, tag)
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buildResult, err := builder.BuildImage(r.Context(), h.state, &image)
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if err != nil {
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writeError(w, 500, "UNKNOWN", "image build failure")
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log.WithError(err).WithFields(log.Fields{
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"image": name,
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"tag": tag,
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}).Error("failed to build image manifest")
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return
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}
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// Some error types have special handling, which is applied
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// here.
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if buildResult.Error == "not_found" {
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s := fmt.Sprintf("Could not find Nix packages: %v", buildResult.Pkgs)
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writeError(w, 404, "MANIFEST_UNKNOWN", s)
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log.WithFields(log.Fields{
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"image": name,
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"tag": tag,
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"packages": buildResult.Pkgs,
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}).Warn("could not find Nix packages")
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return
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}
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// This marshaling error is ignored because we know that this
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// field represents valid JSON data.
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manifest, _ := json.Marshal(buildResult.Manifest)
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w.Header().Add("Content-Type", manifestMediaType)
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w.Write(manifest)
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}
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// serveLayer serves an image layer from storage (if it exists).
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func (h *registryHandler) serveLayer(w http.ResponseWriter, r *http.Request, digest string) {
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storage := h.state.Storage
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err := storage.ServeLayer(digest, r, w)
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if err != nil {
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log.WithError(err).WithFields(log.Fields{
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"layer": digest,
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"backend": storage.Name(),
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}).Error("failed to serve layer from storage backend")
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}
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}
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// ServeHTTP dispatches HTTP requests to the matching handlers.
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func (h *registryHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
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// Acknowledge that we speak V2 with an empty response
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if r.RequestURI == "/v2/" {
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return
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}
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// Serve the manifest (straight from Nix)
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manifestMatches := manifestRegex.FindStringSubmatch(r.RequestURI)
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// Build & serve a manifest by tag
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manifestMatches := manifestTagRegex.FindStringSubmatch(r.RequestURI)
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if len(manifestMatches) == 3 {
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imageName := manifestMatches[1]
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imageTag := manifestMatches[2]
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log.WithFields(log.Fields{
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"image": imageName,
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"tag": imageTag,
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}).Info("requesting image manifest")
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image := builder.ImageFromName(imageName, imageTag)
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buildResult, err := builder.BuildImage(r.Context(), h.state, &image)
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if err != nil {
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writeError(w, 500, "UNKNOWN", "image build failure")
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log.WithError(err).WithFields(log.Fields{
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"image": imageName,
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"tag": imageTag,
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}).Error("failed to build image manifest")
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return
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}
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// Some error types have special handling, which is applied
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// here.
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if buildResult.Error == "not_found" {
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s := fmt.Sprintf("Could not find Nix packages: %v", buildResult.Pkgs)
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writeError(w, 404, "MANIFEST_UNKNOWN", s)
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log.WithFields(log.Fields{
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"image": imageName,
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"tag": imageTag,
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"packages": buildResult.Pkgs,
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}).Warn("could not find Nix packages")
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return
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}
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// This marshaling error is ignored because we know that this
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// field represents valid JSON data.
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manifest, _ := json.Marshal(buildResult.Manifest)
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w.Header().Add("Content-Type", manifestMediaType)
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w.Write(manifest)
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h.serveManifestTag(w, r, manifestMatches[1], manifestMatches[2])
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return
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}
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// Serve an image layer. For this we need to first ask Nix for
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// the manifest, then proceed to extract the correct layer from
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// it.
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// Serve an image layer
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layerMatches := layerRegex.FindStringSubmatch(r.RequestURI)
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if len(layerMatches) == 3 {
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digest := layerMatches[2]
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storage := h.state.Storage
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err := storage.ServeLayer(digest, r, w)
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if err != nil {
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log.WithError(err).WithFields(log.Fields{
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"layer": digest,
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"backend": storage.Name(),
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}).Error("failed to serve layer from storage backend")
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}
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h.serveLayer(w, r, layerMatches[2])
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return
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}
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