s3: verify configured bucket exists at start-up.

Change-Id: I43d0795641fe9dbc345a1f0916b828ede76cf4a6

pkg/blobserver/s3/s3.go

@@ -52,9 +52,17 @@ func newFromConfig(_ blobserver.Loader, config jsonconfig.Obj) (storage blobserv
 		// TODO: skip this check if a file
 		// ~/.camli/.configcheck/sha1-("IS GOOD: s3: sha1(access key +
 		// secret key)") exists and has recent time?
-		if _, err := client.Buckets(); err != nil {
+		buckets, err := client.Buckets()
+		if err != nil {
 			return nil, fmt.Errorf("Failed to get bucket list from S3: %v", err)
 		}
+		haveBucket := make(map[string]bool)
+		for _, b := range buckets {
+			haveBucket[b.Name] = true
+		}
+		if !haveBucket[sto.bucket] {
+			return nil, fmt.Errorf("S3 bucket %q doesn't exist. Create it first at https://console.aws.amazon.com/s3/home")
+		}
 	}
 	return sto, nil
 }

pkg/misc/amazon/s3/client.go

@@ -71,13 +71,20 @@ func (c *Client) Buckets() ([]*Bucket, error) {
 	if res.StatusCode != 200 {
 		return nil, fmt.Errorf("s3: Unexpected status code %d fetching bucket list", res.StatusCode)
 	}
-	slurp, err := ioutil.ReadAll(res.Body)
-	if err != nil {
-		return nil, fmt.Errorf("s3: Error reading Buckets response: %v", err)
+	return parseListAllMyBuckets(res.Body)
+}
+
+func parseListAllMyBuckets(r io.Reader) ([]*Bucket, error) {
+	type allMyBuckets struct {
+		Buckets struct {
+			Bucket []*Bucket
+		}
 	}
-	// TODO: parse this XML
-	log.Printf("s3: TODO: parse bucket list: %q", slurp)
-	return nil, nil
+	var res allMyBuckets
+	if err := xml.NewDecoder(r).Decode(&res); err != nil {
+		return nil, err
+	}
+	return res.Buckets.Bucket, nil
 }
 
 // Returns 0, os.ErrNotExist if not on S3, otherwise reterr is real.

pkg/misc/amazon/s3/client_test.go

@@ -19,6 +19,8 @@ package s3
 import (
 	"net/http"
 	"os"
+	"reflect"
+	"strings"
 	"testing"
 )
 
@@ -56,4 +58,30 @@ func TestMarker(t *testing.T) {
 			t.Errorf("marker(%q) = %q; want %q", tt.s, got, tt.want)
 		}
 	}
-}
+}
+
+func TestParseBuckets(t *testing.T) {
+	res := "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n<ListAllMyBucketsResult xmlns=\"http://s3.amazonaws.com/doc/2006-03-01/\"><Owner><ID>ownerIDField</ID><DisplayName>bobDisplayName</DisplayName></Owner><Buckets><Bucket><Name>bucketOne</Name><CreationDate>2006-06-21T07:04:31.000Z</CreationDate></Bucket><Bucket><Name>bucketTwo</Name><CreationDate>2006-06-21T07:04:32.000Z</CreationDate></Bucket></Buckets></ListAllMyBucketsResult>"
+	buckets, err := parseListAllMyBuckets(strings.NewReader(res))
+	if err != nil {
+		t.Fatal(err)
+	}
+	if g, w := len(buckets), 2; g != w {
+		t.Errorf("num parsed buckets = %d; want %d", g, w)
+	}
+	want := []*Bucket{
+		{Name: "bucketOne", CreationDate: "2006-06-21T07:04:31.000Z"},
+		{Name: "bucketTwo", CreationDate: "2006-06-21T07:04:32.000Z"},
+	}
+	dump := func(v []*Bucket) {
+		for i, b := range v {
+			t.Logf("Bucket #%d: %#v", i, b)
+		}
+	}
+	if !reflect.DeepEqual(buckets, want) {
+		t.Error("mismatch; GOT:")
+		dump(buckets)
+		t.Error("WANT:")
+		dump(want)
+	}
+}