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cmd/devp2p: ensure Route53 changes are sorted
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@fjl
fjl committed Jan 16, 2020
1 parent 1ce4179 commit b9c87b0
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Showing 2 changed files with 150 additions and 16 deletions.
42 changes: 26 additions & 16 deletions cmd/devp2p/dns_route53.go
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Original file line number Diff line number Diff line change
Expand Up @@ -19,6 +19,7 @@ package main
import (
"errors"
"fmt"
"sort"
"strconv"
"strings"

Expand Down Expand Up @@ -82,18 +83,20 @@ func (c *route53Client) deploy(name string, t *dnsdisc.Tree) error {
}

// Compute DNS changes.
records := t.ToTXT(name)
changes, err := c.computeChanges(name, records)
existing, err := c.collectRecords(name)
if err != nil {
return err
}
log.Info(fmt.Sprintf("Found %d TXT records", len(existing)))
records := t.ToTXT(name)
changes := c.computeChanges(name, records, existing)
if len(changes) == 0 {
log.Info("No DNS changes needed")
return nil
}

// Submit change batches.
batches := splitChangeBatches(changes)
batches := splitChanges(changes, route53ChangeLimit)
for i, changes := range batches {
log.Info(fmt.Sprintf("Submitting %d changes to Route53", len(changes)))
batch := new(route53.ChangeBatch)
Expand Down Expand Up @@ -146,21 +149,14 @@ func (c *route53Client) findZoneID(name string) (string, error) {
}

// computeChanges creates DNS changes for the given record.
func (c *route53Client) computeChanges(name string, records map[string]string) ([]*route53.Change, error) {
func (c *route53Client) computeChanges(name string, records map[string]string, existing map[string][]string) []*route53.Change {
// Convert all names to lowercase.
lrecords := make(map[string]string, len(records))
for name, r := range records {
lrecords[strings.ToLower(name)] = r
}
records = lrecords

// Get existing records.
existing, err := c.collectRecords(name)
if err != nil {
return nil, err
}
log.Info(fmt.Sprintf("Found %d TXT records", len(existing)))

var changes []*route53.Change
for path, val := range records {
ttl := 1
Expand Down Expand Up @@ -192,18 +188,31 @@ func (c *route53Client) computeChanges(name string, records map[string]string) (
log.Info(fmt.Sprintf("Deleting %s = %q", path, combineTXT(values)))
changes = append(changes, newTXTChange("DELETE", path, 1, values))
}
return changes, nil

sortChanges(changes)
return changes
}

// sortChanges ensures DNS changes are in leaf-added -> root-changed -> leaf-deleted order.
func sortChanges(changes []*route53.Change) {
score := map[string]int{"CREATE": 1, "UPSERT": 2, "DELETE": 3}
sort.Slice(changes, func(i, j int) bool {
if *changes[i].Action == *changes[j].Action {
return *changes[i].ResourceRecordSet.Name < *changes[j].ResourceRecordSet.Name
}
return score[*changes[i].Action] < score[*changes[j].Action]
})
}

// splitChangeBatches splits up DNS changes such that each change batch
// is smaller than the limit.
func splitChangeBatches(changes []*route53.Change) [][]*route53.Change {
// splitChanges splits up DNS changes such that each change batch
// is smaller than the given RDATA limit.
func splitChanges(changes []*route53.Change, limit int) [][]*route53.Change {
var batches [][]*route53.Change
var batchSize int
for _, ch := range changes {
// Start new batch if this change pushes the current one over the limit.
size := changeSize(ch)
if len(batches) == 0 || batchSize+size > route53ChangeLimit {
if len(batches) == 0 || batchSize+size > limit {
batches = append(batches, nil)
batchSize = 0
}
Expand All @@ -213,6 +222,7 @@ func splitChangeBatches(changes []*route53.Change) [][]*route53.Change {
return batches
}

// changeSize returns the RDATA size of a DNS change.
func changeSize(ch *route53.Change) int {
size := 0
for _, rr := range ch.ResourceRecordSet.ResourceRecords {
Expand Down
124 changes: 124 additions & 0 deletions cmd/devp2p/dns_route53_test.go
View file
Original file line number Diff line number Diff line change
@@ -0,0 +1,124 @@
package main

import (
"reflect"
"testing"

"github.com/aws/aws-sdk-go/service/route53"
)

// This test checks that computeChanges/splitChanges create DNS changes in
// leaf-added -> root-changed -> leaf-deleted order.
func TestRoute53ChangeSort(t *testing.T) {
testTree0 := map[string][]string{
"fdxn3sn67na5dka4j2gok7bvqi.n": {"enrtree-branch:"},
"n": {"enrtree-root:v1 e=FDXN3SN67NA5DKA4J2GOK7BVQI l=FDXN3SN67NA5DKA4J2GOK7BVQI seq=0 sig=Me7k32DXwG06XmqzNW4b3opMrGXQV9Atv6hmJrVPuNx0QZ-PugeoYlMMndDxyN8cOkWGCxOze26WOyD2JAsAvgE"},
}

testTree1 := map[string]string{
"n": "enrtree-root:v1 e=JWXYDBPXYWG6FX3GMDIBFA6CJ4 l=C7HRFPF3BLGF3YR4DY5KX3SMBE seq=1 sig=o908WmNp7LibOfPsr4btQwatZJ5URBr2ZAuxvK4UWHlsB9sUOTJQaGAlLPVAhM__XJesCHxLISo94z5Z2a463gA",
"C7HRFPF3BLGF3YR4DY5KX3SMBE.n": "enrtree://AM5FCQLWIZX2QFPNJAP7VUERCCRNGRHWZG3YYHIUV7BVDQ5FDPRT2@morenodes.example.org",
"JWXYDBPXYWG6FX3GMDIBFA6CJ4.n": "enrtree-branch:2XS2367YHAXJFGLZHVAWLQD4ZY,H4FHT4B454P6UXFD7JCYQ5PWDY,MHTDO6TMUBRIA2XWG5LUDACK24",
"2XS2367YHAXJFGLZHVAWLQD4ZY.n": "enr:-HW4QOFzoVLaFJnNhbgMoDXPnOvcdVuj7pDpqRvh6BRDO68aVi5ZcjB3vzQRZH2IcLBGHzo8uUN3snqmgTiE56CH3AMBgmlkgnY0iXNlY3AyNTZrMaECC2_24YYkYHEgdzxlSNKQEnHhuNAbNlMlWJxrJxbAFvA",
"H4FHT4B454P6UXFD7JCYQ5PWDY.n": "enr:-HW4QAggRauloj2SDLtIHN1XBkvhFZ1vtf1raYQp9TBW2RD5EEawDzbtSmlXUfnaHcvwOizhVYLtr7e6vw7NAf6mTuoCgmlkgnY0iXNlY3AyNTZrMaECjrXI8TLNXU0f8cthpAMxEshUyQlK-AM0PW2wfrnacNI",
"MHTDO6TMUBRIA2XWG5LUDACK24.n": "enr:-HW4QLAYqmrwllBEnzWWs7I5Ev2IAs7x_dZlbYdRdMUx5EyKHDXp7AV5CkuPGUPdvbv1_Ms1CPfhcGCvSElSosZmyoqAgmlkgnY0iXNlY3AyNTZrMaECriawHKWdDRk2xeZkrOXBQ0dfMFLHY4eENZwdufn1S1o",
}

wantChanges := []*route53.Change{
{
Action: sp("CREATE"),
ResourceRecordSet: &route53.ResourceRecordSet{
Name: sp("2xs2367yhaxjfglzhvawlqd4zy.n"),
ResourceRecords: []*route53.ResourceRecord{{
Value: sp(`"enr:-HW4QOFzoVLaFJnNhbgMoDXPnOvcdVuj7pDpqRvh6BRDO68aVi5ZcjB3vzQRZH2IcLBGHzo8uUN3snqmgTiE56CH3AMBgmlkgnY0iXNlY3AyNTZrMaECC2_24YYkYHEgdzxlSNKQEnHhuNAbNlMlWJxrJxbAFvA"`),
}},
TTL: ip(2147483647),
Type: sp("TXT"),
},
},
{
Action: sp("CREATE"),
ResourceRecordSet: &route53.ResourceRecordSet{
Name: sp("c7hrfpf3blgf3yr4dy5kx3smbe.n"),
ResourceRecords: []*route53.ResourceRecord{{
Value: sp(`"enrtree://AM5FCQLWIZX2QFPNJAP7VUERCCRNGRHWZG3YYHIUV7BVDQ5FDPRT2@morenodes.example.org"`),
}},
TTL: ip(2147483647),
Type: sp("TXT"),
},
},
{
Action: sp("CREATE"),
ResourceRecordSet: &route53.ResourceRecordSet{
Name: sp("h4fht4b454p6uxfd7jcyq5pwdy.n"),
ResourceRecords: []*route53.ResourceRecord{{
Value: sp(`"enr:-HW4QAggRauloj2SDLtIHN1XBkvhFZ1vtf1raYQp9TBW2RD5EEawDzbtSmlXUfnaHcvwOizhVYLtr7e6vw7NAf6mTuoCgmlkgnY0iXNlY3AyNTZrMaECjrXI8TLNXU0f8cthpAMxEshUyQlK-AM0PW2wfrnacNI"`),
}},
TTL: ip(2147483647),
Type: sp("TXT"),
},
},
{
Action: sp("CREATE"),
ResourceRecordSet: &route53.ResourceRecordSet{
Name: sp("jwxydbpxywg6fx3gmdibfa6cj4.n"),
ResourceRecords: []*route53.ResourceRecord{{
Value: sp(`"enrtree-branch:2XS2367YHAXJFGLZHVAWLQD4ZY,H4FHT4B454P6UXFD7JCYQ5PWDY,MHTDO6TMUBRIA2XWG5LUDACK24"`),
}},
TTL: ip(2147483647),
Type: sp("TXT"),
},
},
{
Action: sp("CREATE"),
ResourceRecordSet: &route53.ResourceRecordSet{
Name: sp("mhtdo6tmubria2xwg5ludack24.n"),
ResourceRecords: []*route53.ResourceRecord{{
Value: sp(`"enr:-HW4QLAYqmrwllBEnzWWs7I5Ev2IAs7x_dZlbYdRdMUx5EyKHDXp7AV5CkuPGUPdvbv1_Ms1CPfhcGCvSElSosZmyoqAgmlkgnY0iXNlY3AyNTZrMaECriawHKWdDRk2xeZkrOXBQ0dfMFLHY4eENZwdufn1S1o"`),
}},
TTL: ip(2147483647),
Type: sp("TXT"),
},
},
{
Action: sp("UPSERT"),
ResourceRecordSet: &route53.ResourceRecordSet{
Name: sp("n"),
ResourceRecords: []*route53.ResourceRecord{{
Value: sp(`"enrtree-root:v1 e=JWXYDBPXYWG6FX3GMDIBFA6CJ4 l=C7HRFPF3BLGF3YR4DY5KX3SMBE seq=1 sig=o908WmNp7LibOfPsr4btQwatZJ5URBr2ZAuxvK4UWHlsB9sUOTJQaGAlLPVAhM__XJesCHxLISo94z5Z2a463gA"`),
}},
TTL: ip(1),
Type: sp("TXT"),
},
},
{
Action: sp("DELETE"),
ResourceRecordSet: &route53.ResourceRecordSet{
Name: sp("fdxn3sn67na5dka4j2gok7bvqi.n"),
ResourceRecords: []*route53.ResourceRecord{{
Value: sp("enrtree-branch:"),
}},
TTL: ip(1),
Type: sp("TXT"),
},
},
}

var client route53Client
changes := client.computeChanges("n", testTree1, testTree0)
if !reflect.DeepEqual(changes, wantChanges) {
t.Fatalf("wrong changes (got %d, want %d)", len(changes), len(wantChanges))
}

wantSplit := [][]*route53.Change{
wantChanges[:4],
wantChanges[4:7],
}
split := splitChanges(changes, 600)
if !reflect.DeepEqual(split, wantSplit) {
t.Fatalf("wrong split batches: got %d, want %d", len(split), len(wantSplit))
}
}

func sp(s string) *string { return &s }
func ip(i int64) *int64 { return &i }

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