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Add Google Cloud DNS plugin (coredns#3011)
Signed-off-by: Palash Nigam <npalash25@gmail.com> Closes: coredns#2822
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| { | ||
| // Use IntelliSense to learn about possible attributes. | ||
| // Hover to view descriptions of existing attributes. | ||
| // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387 | ||
| "version": "0.2.0", | ||
| "configurations": [ | ||
| { | ||
| "name": "Launch", | ||
| "type": "go", | ||
| "request": "launch", | ||
| "mode": "auto", | ||
| "program": "${fileDirname}", | ||
| "env": {}, | ||
| "args": [] | ||
| } | ||
| ] | ||
| } |
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| # clouddns | ||
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| ## Name | ||
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| *clouddns* - enables serving zone data from GCP clouddns. | ||
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| ## Description | ||
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| The clouddns plugin is useful for serving zones from resource record | ||
| sets in GCP clouddns. This plugin supports all [Google Cloud DNS records](https://cloud.google.com/dns/docs/overview#supported_dns_record_types). | ||
| The clouddns plugin can be used when coredns is deployed on GCP or elsewhere. | ||
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| ## Syntax | ||
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| ~~~ txt | ||
| clouddns [ZONE:PROJECT_NAME:HOSTED_ZONE_NAME...] { | ||
| credentials [FILENAME] | ||
| fallthrough [ZONES...] | ||
| } | ||
| ~~~ | ||
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| * **ZONE** the name of the domain to be accessed. When there are multiple zones with overlapping | ||
| domains (private vs. public hosted zone), CoreDNS does the lookup in the given order here. | ||
| Therefore, for a non-existing resource record, SOA response will be from the rightmost zone. | ||
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| * **HOSTED_ZONE_NAME** the name of the hosted zone that contains the resource record sets to be | ||
| accessed. | ||
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| * `credentials` is used for reading the credential file. | ||
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| * **FILENAME** GCP credentials file path. | ||
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| * `fallthrough` If zone matches and no record can be generated, pass request to the next plugin. | ||
| If **[ZONES...]** is omitted, then fallthrough happens for all zones for which the plugin is | ||
| authoritative. If specific zones are listed (for example `in-addr.arpa` and `ip6.arpa`), then | ||
| only queries for those zones will be subject to fallthrough. | ||
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| * **ZONES** zones it should be authoritative for. If empty, the zones from the configuration block | ||
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| ## Examples | ||
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| Enable clouddns with implicit GCP credentials and resolve CNAMEs via 10.0.0.1: | ||
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| ~~~ txt | ||
| . { | ||
| clouddns example.org.:gcp-example-project:example-zone | ||
| forward . 10.0.0.1 | ||
| } | ||
| ~~~ | ||
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| Enable clouddns with fallthrough: | ||
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| ~~~ txt | ||
| . { | ||
| clouddns example.org.:gcp-example-project:example-zone clouddns example.com.:gcp-example-project:example-zone-2 { | ||
| fallthrough example.gov. | ||
| } | ||
| } | ||
| ~~~ | ||
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| Enable clouddns with multiple hosted zones with the same domain: | ||
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| ~~~ txt | ||
| . { | ||
| clouddns example.org.:gcp-example-project:example-zone example.com.:gcp-example-project:other-example-zone | ||
| } | ||
| ~~~ |
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| // Package clouddns implements a plugin that returns resource records | ||
| // from GCP Cloud DNS. | ||
| package clouddns | ||
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| import ( | ||
| "context" | ||
| "errors" | ||
| "fmt" | ||
| "strings" | ||
| "sync" | ||
| "time" | ||
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| "github.com/coredns/coredns/plugin" | ||
| "github.com/coredns/coredns/plugin/file" | ||
| "github.com/coredns/coredns/plugin/pkg/fall" | ||
| "github.com/coredns/coredns/plugin/pkg/upstream" | ||
| "github.com/coredns/coredns/request" | ||
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| "github.com/miekg/dns" | ||
| gcp "google.golang.org/api/dns/v1" | ||
| ) | ||
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| // CloudDNS is a plugin that returns RR from GCP Cloud DNS. | ||
| type CloudDNS struct { | ||
| Next plugin.Handler | ||
| Fall fall.F | ||
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| zoneNames []string | ||
| client gcpDNS | ||
| upstream *upstream.Upstream | ||
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| zMu sync.RWMutex | ||
| zones zones | ||
| } | ||
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| type zone struct { | ||
| projectName string | ||
| zoneName string | ||
| z *file.Zone | ||
| dns string | ||
| } | ||
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| type zones map[string][]*zone | ||
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| // New reads from the keys map which uses domain names as its key and a colon separated | ||
| // string of project name and hosted zone name lists as its values, validates | ||
| // that each domain name/zone id pair does exist, and returns a new *CloudDNS. | ||
| // In addition to this, upstream is passed for doing recursive queries against CNAMEs. | ||
| // Returns error if it cannot verify any given domain name/zone id pair. | ||
| func New(ctx context.Context, c gcpDNS, keys map[string][]string, up *upstream.Upstream) (*CloudDNS, error) { | ||
| zones := make(map[string][]*zone, len(keys)) | ||
| zoneNames := make([]string, 0, len(keys)) | ||
| for dnsName, hostedZoneDetails := range keys { | ||
| for _, hostedZone := range hostedZoneDetails { | ||
| ss := strings.SplitN(hostedZone, ":", 2) | ||
| if len(ss) != 2 { | ||
| return nil, errors.New("either project or zone name missing") | ||
| } | ||
| err := c.zoneExists(ss[0], ss[1]) | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
| fqdnDNSName := dns.Fqdn(dnsName) | ||
| if _, ok := zones[fqdnDNSName]; !ok { | ||
| zoneNames = append(zoneNames, fqdnDNSName) | ||
| } | ||
| zones[fqdnDNSName] = append(zones[fqdnDNSName], &zone{projectName: ss[0], zoneName: ss[1], dns: fqdnDNSName, z: file.NewZone(fqdnDNSName, "")}) | ||
| } | ||
| } | ||
| return &CloudDNS{ | ||
| client: c, | ||
| zoneNames: zoneNames, | ||
| zones: zones, | ||
| upstream: up, | ||
| }, nil | ||
| } | ||
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| // Run executes first update, spins up an update forever-loop. | ||
| // Returns error if first update fails. | ||
| func (h *CloudDNS) Run(ctx context.Context) error { | ||
| if err := h.updateZones(ctx); err != nil { | ||
| return err | ||
| } | ||
| go func() { | ||
| for { | ||
| select { | ||
| case <-ctx.Done(): | ||
| log.Infof("Breaking out of CloudDNS update loop: %v", ctx.Err()) | ||
| return | ||
| case <-time.After(1 * time.Minute): | ||
| if err := h.updateZones(ctx); err != nil && ctx.Err() == nil /* Don't log error if ctx expired. */ { | ||
| log.Errorf("Failed to update zones: %v", err) | ||
| } | ||
| } | ||
| } | ||
| }() | ||
| return nil | ||
| } | ||
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| // ServeDNS implements the plugin.Handler interface. | ||
| func (h *CloudDNS) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) { | ||
| state := request.Request{W: w, Req: r} | ||
| qname := state.Name() | ||
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| zName := plugin.Zones(h.zoneNames).Matches(qname) | ||
| if zName == "" { | ||
| return plugin.NextOrFailure(h.Name(), h.Next, ctx, w, r) | ||
| } | ||
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| z, ok := h.zones[zName] // ok true if we are authoritive for the zone | ||
| if !ok || z == nil { | ||
| return dns.RcodeServerFailure, nil | ||
| } | ||
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| m := new(dns.Msg) | ||
| m.SetReply(r) | ||
| m.Authoritative = true | ||
| var result file.Result | ||
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| for _, hostedZone := range z { | ||
| h.zMu.RLock() | ||
| m.Answer, m.Ns, m.Extra, result = hostedZone.z.Lookup(ctx, state, qname) | ||
| h.zMu.RUnlock() | ||
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| // Take the answer if it's non-empty OR if there is another | ||
| // record type exists for this name (NODATA). | ||
| if len(m.Answer) != 0 || result == file.NoData { | ||
| break | ||
| } | ||
| } | ||
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| if len(m.Answer) == 0 && result != file.NoData && h.Fall.Through(qname) { | ||
| return plugin.NextOrFailure(h.Name(), h.Next, ctx, w, r) | ||
| } | ||
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| switch result { | ||
| case file.Success: | ||
| case file.NoData: | ||
| case file.NameError: | ||
| m.Rcode = dns.RcodeNameError | ||
| case file.Delegation: | ||
| m.Authoritative = false | ||
| case file.ServerFailure: | ||
| return dns.RcodeServerFailure, nil | ||
| } | ||
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| w.WriteMsg(m) | ||
| return dns.RcodeSuccess, nil | ||
| } | ||
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| func updateZoneFromRRS(rrs *gcp.ResourceRecordSetsListResponse, z *file.Zone) error { | ||
| for _, rr := range rrs.Rrsets { | ||
| var rfc1035 string | ||
| var r dns.RR | ||
| var err error | ||
| for _, value := range rr.Rrdatas { | ||
| if rr.Type == "CNAME" || rr.Type == "PTR" { | ||
| value = dns.Fqdn(value) | ||
| } | ||
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| // Assemble RFC 1035 conforming record to pass into dns scanner. | ||
| rfc1035 = fmt.Sprintf("%s %d IN %s %s", dns.Fqdn(rr.Name), rr.Ttl, rr.Type, value) | ||
| r, err = dns.NewRR(rfc1035) | ||
| if err != nil { | ||
| return fmt.Errorf("failed to parse resource record: %v", err) | ||
| } | ||
| } | ||
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| z.Insert(r) | ||
| } | ||
| return nil | ||
| } | ||
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| // updateZones re-queries resource record sets for each zone and updates the | ||
| // zone object. | ||
| // Returns error if any zones error'ed out, but waits for other zones to | ||
| // complete first. | ||
| func (h *CloudDNS) updateZones(ctx context.Context) error { | ||
| errc := make(chan error) | ||
| defer close(errc) | ||
| for zName, z := range h.zones { | ||
| go func(zName string, z []*zone) { | ||
| var err error | ||
| var rrListResponse *gcp.ResourceRecordSetsListResponse | ||
| defer func() { | ||
| errc <- err | ||
| }() | ||
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| for i, hostedZone := range z { | ||
| newZ := file.NewZone(zName, "") | ||
| newZ.Upstream = h.upstream | ||
| rrListResponse, err = h.client.listRRSets(hostedZone.projectName, hostedZone.zoneName) | ||
| if err != nil { | ||
| err = fmt.Errorf("failed to list resource records for %v:%v:%v from gcp: %v", zName, hostedZone.projectName, hostedZone.zoneName, err) | ||
| return | ||
| } | ||
| updateZoneFromRRS(rrListResponse, newZ) | ||
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| h.zMu.Lock() | ||
| (*z[i]).z = newZ | ||
| h.zMu.Unlock() | ||
| } | ||
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| }(zName, z) | ||
| } | ||
| // Collect errors (if any). This will also sync on all zones updates | ||
| // completion. | ||
| var errs []string | ||
| for i := 0; i < len(h.zones); i++ { | ||
| err := <-errc | ||
| if err != nil { | ||
| errs = append(errs, err.Error()) | ||
| } | ||
| } | ||
| if len(errs) != 0 { | ||
| return fmt.Errorf("errors updating zones: %v", errs) | ||
| } | ||
| return nil | ||
| } | ||
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| // Name implements the Handler interface. | ||
| func (h *CloudDNS) Name() string { return "clouddns" } |
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