From 8953724bab392fa3897c2fae62b5df6e9567047c Mon Sep 17 00:00:00 2001
From: Hank Donnay <hdonnay@redhat.com>
Date: Mon, 27 Jan 2020 14:25:01 -0500
Subject: [PATCH] indexer: QoL changes to headers

This commit adds some Link headers to indicate to clients next steps to
take and sets errors in the final JSON encode to be sent as trailers.
---
 indexer/httptransport.go | 47 ++++++++++++++++++----------------------
 1 file changed, 21 insertions(+), 26 deletions(-)

diff --git a/indexer/httptransport.go b/indexer/httptransport.go
index 575d16e0c4..18f297fec8 100644
--- a/indexer/httptransport.go
+++ b/indexer/httptransport.go
@@ -1,7 +1,6 @@
 package indexer
 
 import (
-	"context"
 	"encoding/json"
 	"fmt"
 	"net/http"
@@ -18,9 +17,10 @@ import (
 var _ http.Handler = (*HTTP)(nil)
 
 const (
-	IndexAPIPath       = "/api/v1/index_report"
-	IndexReportAPIPath = "/api/v1/index_report/"
-	StateAPIPath       = "/api/v1/state"
+	v1Root             = "/api/v1/"
+	IndexAPIPath       = v1Root + "index_report"
+	IndexReportAPIPath = v1Root + "index_report/"
+	StateAPIPath       = v1Root + "state"
 )
 
 type HTTP struct {
@@ -112,7 +112,13 @@ func (h *HTTP) IndexReportHandler(w http.ResponseWriter, r *http.Request) {
 	}
 }
 
+const (
+	linkIndex  = `<%s>; rel="https://projectquay.io/clair/v1/index_report"`
+	linkReport = `<%s>; rel="https://projectquay.io/clair/v1/vulnerability_report"`
+)
+
 func (h *HTTP) IndexHandler(w http.ResponseWriter, r *http.Request) {
+	ctx := r.Context()
 	w.Header().Set("content-type", "application/json")
 	if r.Method != http.MethodPost {
 		resp := &je.Response{
@@ -138,7 +144,7 @@ func (h *HTTP) IndexHandler(w http.ResponseWriter, r *http.Request) {
 
 	// TODO Do we need some sort of background context embedded in the HTTP
 	// struct?
-	report, err := h.serv.Index(context.TODO(), &m)
+	report, err := h.serv.Index(ctx, &m)
 	if err != nil {
 		resp := &je.Response{
 			Code:    "index-error",
@@ -149,16 +155,12 @@ func (h *HTTP) IndexHandler(w http.ResponseWriter, r *http.Request) {
 	}
 
 	next := path.Join(IndexReportAPIPath, m.Hash.String())
+	w.Header().Add("link", fmt.Sprintf(linkReport, path.Join(v1Root, "vulnerabilty_report", m.Hash.String())))
+	w.Header().Add("link", fmt.Sprintf(linkIndex, next))
 	w.Header().Set("location", next)
 	w.WriteHeader(http.StatusCreated)
-	err = json.NewEncoder(w).Encode(report)
-	if err != nil {
-		resp := &je.Response{
-			Code:    "encoding-error",
-			Message: fmt.Sprintf("failed to encode scan report: %v", err),
-		}
-		je.Error(w, resp, http.StatusInternalServerError)
-		return
+	if err := json.NewEncoder(w).Encode(report); err != nil {
+		w.Header().Set("clair-error", err.Error())
 	}
 }
 
@@ -176,21 +178,14 @@ func (h *HTTP) StateHandler(w http.ResponseWriter, r *http.Request) {
 		w.WriteHeader(http.StatusNotModified)
 		return
 	}
-	w.Header().Set("content-type", "application/json")
-
-	err := json.NewEncoder(w).Encode(struct {
-		State string `json:"state"`
-	}{
-		State: s,
-	})
+	err := json.NewEncoder(w).Encode(stateSuccess{s})
 	if err != nil {
-		resp := &je.Response{
-			Code:    "encoding-error",
-			Message: fmt.Sprintf("failed to encode scan report: %v", err),
-		}
-		je.Error(w, resp, http.StatusInternalServerError)
+		w.Header().Set("clair-error", err.Error())
 	}
-	return
+}
+
+type stateSuccess struct {
+	State string `json:"state"`
 }
 
 // Register will register the api on a given mux.