forked from hashicorp/consul
/
prepared_query_endpoint.go
579 lines (496 loc) · 17.7 KB
/
prepared_query_endpoint.go
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package consul
import (
"errors"
"fmt"
"log"
"strings"
"time"
"github.com/armon/go-metrics"
"github.com/hashicorp/consul/consul/structs"
)
var (
// ErrQueryNotFound is returned if the query lookup failed.
ErrQueryNotFound = errors.New("Query not found")
)
// PreparedQuery manages the prepared query endpoint.
type PreparedQuery struct {
srv *Server
}
// Apply is used to apply a modifying request to the data store. This should
// only be used for operations that modify the data. The ID of the session is
// returned in the reply.
func (p *PreparedQuery) Apply(args *structs.PreparedQueryRequest, reply *string) (err error) {
if done, err := p.srv.forward("PreparedQuery.Apply", args, args, reply); done {
return err
}
defer metrics.MeasureSince([]string{"consul", "prepared-query", "apply"}, time.Now())
// Validate the ID. We must create new IDs before applying to the Raft
// log since it's not deterministic.
if args.Op == structs.PreparedQueryCreate {
if args.Query.ID != "" {
return fmt.Errorf("ID must be empty when creating a new prepared query")
}
// We are relying on the fact that UUIDs are random and unlikely
// to collide since this isn't inside a write transaction.
state := p.srv.fsm.State()
for {
args.Query.ID = generateUUID()
_, query, err := state.PreparedQueryGet(args.Query.ID)
if err != nil {
return fmt.Errorf("Prepared query lookup failed: %v", err)
}
if query == nil {
break
}
}
}
*reply = args.Query.ID
// Grab the ACL because we need it in several places below.
acl, err := p.srv.resolveToken(args.Token)
if err != nil {
return err
}
// Enforce that any modify operation has the same token used when the
// query was created, or a management token with sufficient rights.
if args.Op != structs.PreparedQueryCreate {
state := p.srv.fsm.State()
_, query, err := state.PreparedQueryGet(args.Query.ID)
if err != nil {
return fmt.Errorf("Prepared Query lookup failed: %v", err)
}
if query == nil {
return fmt.Errorf("Cannot modify non-existent prepared query: '%s'", args.Query.ID)
}
if (query.Token != args.Token) && (acl != nil && !acl.QueryModify()) {
p.srv.logger.Printf("[WARN] consul.prepared_query: Operation on prepared query '%s' denied because ACL didn't match ACL used to create the query, and a management token wasn't supplied", args.Query.ID)
return permissionDeniedErr
}
}
// Parse the query and prep it for the state store.
switch args.Op {
case structs.PreparedQueryCreate, structs.PreparedQueryUpdate:
if err := parseQuery(args.Query); err != nil {
return fmt.Errorf("Invalid prepared query: %v", err)
}
if acl != nil && !acl.ServiceRead(args.Query.Service.Service) {
p.srv.logger.Printf("[WARN] consul.prepared_query: Operation on prepared query for service '%s' denied due to ACLs", args.Query.Service.Service)
return permissionDeniedErr
}
case structs.PreparedQueryDelete:
// Nothing else to verify here, just do the delete (we only look
// at the ID field for this op).
default:
return fmt.Errorf("Unknown prepared query operation: %s", args.Op)
}
// At this point the token has been vetted, so make sure the token that
// is stored in the state store matches what was supplied.
args.Query.Token = args.Token
resp, err := p.srv.raftApply(structs.PreparedQueryRequestType, args)
if err != nil {
p.srv.logger.Printf("[ERR] consul.prepared_query: Apply failed %v", err)
return err
}
if respErr, ok := resp.(error); ok {
return respErr
}
return nil
}
// parseQuery makes sure the entries of a query are valid for a create or
// update operation. Some of the fields are not checked or are partially
// checked, as noted in the comments below. This also updates all the parsed
// fields of the query.
func parseQuery(query *structs.PreparedQuery) error {
// We skip a few fields:
// - ID is checked outside this fn.
// - Name is optional with no restrictions, except for uniqueness which
// is checked for integrity during the transaction. We also make sure
// names do not overlap with IDs, which is also checked during the
// transaction. Otherwise, people could "steal" queries that they don't
// have proper ACL rights to change.
// - Session is optional and checked for integrity during the transaction.
// - Token is checked outside this fn.
// Parse the service query sub-structure.
if err := parseService(&query.Service); err != nil {
return err
}
// Parse the DNS options sub-structure.
if err := parseDNS(&query.DNS); err != nil {
return err
}
return nil
}
// parseService makes sure the entries of a query are valid for a create or
// update operation. Some of the fields are not checked or are partially
// checked, as noted in the comments below. This also updates all the parsed
// fields of the query.
func parseService(svc *structs.ServiceQuery) error {
// Service is required. We check integrity during the transaction.
if svc.Service == "" {
return fmt.Errorf("Must provide a service name to query")
}
// NearestN can be 0 which means "don't fail over by RTT".
if svc.Failover.NearestN < 0 {
return fmt.Errorf("Bad NearestN '%d', must be >= 0", svc.Failover.NearestN)
}
// We skip a few fields:
// - There's no validation for Datacenters; we skip any unknown entries
// at execution time.
// - OnlyPassing is just a boolean so doesn't need further validation.
// - Tags is a free-form list of tags and doesn't need further validation.
return nil
}
// parseDNS makes sure the entries of a query are valid for a create or
// update operation. This also updates all the parsed fields of the query.
func parseDNS(dns *structs.QueryDNSOptions) error {
if dns.TTL != "" {
ttl, err := time.ParseDuration(dns.TTL)
if err != nil {
return fmt.Errorf("Bad DNS TTL '%s': %v", dns.TTL, err)
}
if ttl < 0 {
return fmt.Errorf("DNS TTL '%d', must be >=0", ttl)
}
}
return nil
}
// Get returns a single prepared query by ID.
func (p *PreparedQuery) Get(args *structs.PreparedQuerySpecificRequest,
reply *structs.IndexedPreparedQueries) error {
if done, err := p.srv.forward("PreparedQuery.Get", args, args, reply); done {
return err
}
// We will use this in the loop to see if the caller is allowed to see
// the query.
acl, err := p.srv.resolveToken(args.Token)
if err != nil {
return err
}
// Get the requested query.
state := p.srv.fsm.State()
return p.srv.blockingRPC(
&args.QueryOptions,
&reply.QueryMeta,
state.GetQueryWatch("PreparedQueryGet"),
func() error {
index, query, err := state.PreparedQueryGet(args.QueryID)
if err != nil {
return err
}
if query == nil {
return ErrQueryNotFound
}
if (query.Token != args.Token) && (acl != nil && !acl.QueryList()) {
p.srv.logger.Printf("[WARN] consul.prepared_query: Request to get prepared query '%s' denied because ACL didn't match ACL used to create the query, and a management token wasn't supplied", args.QueryID)
return permissionDeniedErr
}
reply.Index = index
reply.Queries = structs.PreparedQueries{query}
return nil
})
}
// List returns all the prepared queries.
func (p *PreparedQuery) List(args *structs.DCSpecificRequest, reply *structs.IndexedPreparedQueries) error {
if done, err := p.srv.forward("PreparedQuery.List", args, args, reply); done {
return err
}
// This always requires a management token.
acl, err := p.srv.resolveToken(args.Token)
if err != nil {
return err
}
if acl != nil && !acl.QueryList() {
p.srv.logger.Printf("[WARN] consul.prepared_query: Request to list prepared queries denied due to ACLs")
return permissionDeniedErr
}
// Get the list of queries.
state := p.srv.fsm.State()
return p.srv.blockingRPC(
&args.QueryOptions,
&reply.QueryMeta,
state.GetQueryWatch("PreparedQueryList"),
func() error {
index, queries, err := state.PreparedQueryList()
if err != nil {
return err
}
reply.Index, reply.Queries = index, queries
return nil
})
}
// Execute runs a prepared query and returns the results. This will perform the
// failover logic if no local results are available. This is typically called as
// part of a DNS lookup, or when executing prepared queries from the HTTP API.
func (p *PreparedQuery) Execute(args *structs.PreparedQueryExecuteRequest,
reply *structs.PreparedQueryExecuteResponse) error {
if done, err := p.srv.forward("PreparedQuery.Execute", args, args, reply); done {
return err
}
defer metrics.MeasureSince([]string{"consul", "prepared-query", "execute"}, time.Now())
// We have to do this ourselves since we are not doing a blocking RPC.
p.srv.setQueryMeta(&reply.QueryMeta)
if args.RequireConsistent {
if err := p.srv.consistentRead(); err != nil {
return err
}
}
// Try to locate the query.
state := p.srv.fsm.State()
_, query, err := state.PreparedQueryLookup(args.QueryIDOrName)
if err != nil {
return err
}
if query == nil {
return ErrQueryNotFound
}
// Execute the query for the local DC.
if err := p.execute(query, reply); err != nil {
return err
}
// Shuffle the results in case coordinates are not available if they
// requested an RTT sort.
reply.Nodes.Shuffle()
if err := p.srv.sortNodesByDistanceFrom(args.Source, reply.Nodes); err != nil {
return err
}
// Apply the limit if given.
if args.Limit > 0 && len(reply.Nodes) > args.Limit {
reply.Nodes = reply.Nodes[:args.Limit]
}
// In the happy path where we found some healthy nodes we go with that
// and bail out. Otherwise, we fail over and try remote DCs, as allowed
// by the query setup.
if len(reply.Nodes) == 0 {
wrapper := &queryServerWrapper{p.srv}
if err := queryFailover(wrapper, query, args.Limit, args.QueryOptions, reply); err != nil {
return err
}
}
return nil
}
// ExecuteRemote is used when a local node doesn't have any instances of a
// service available and needs to probe remote DCs. This sends the full query
// over since the remote side won't have it in its state store, and this doesn't
// do the failover logic since that's already being run on the originating DC.
// We don't want things to fan out further than one level.
func (p *PreparedQuery) ExecuteRemote(args *structs.PreparedQueryExecuteRemoteRequest,
reply *structs.PreparedQueryExecuteResponse) error {
if done, err := p.srv.forward("PreparedQuery.ExecuteRemote", args, args, reply); done {
return err
}
defer metrics.MeasureSince([]string{"consul", "prepared-query", "execute_remote"}, time.Now())
// We have to do this ourselves since we are not doing a blocking RPC.
p.srv.setQueryMeta(&reply.QueryMeta)
if args.RequireConsistent {
if err := p.srv.consistentRead(); err != nil {
return err
}
}
// Run the query locally to see what we can find.
if err := p.execute(&args.Query, reply); err != nil {
return err
}
// We don't bother trying to do an RTT sort here since we are by
// definition in another DC. We just shuffle to make sure that we
// balance the load across the results.
reply.Nodes.Shuffle()
// Apply the limit if given.
if args.Limit > 0 && len(reply.Nodes) > args.Limit {
reply.Nodes = reply.Nodes[:args.Limit]
}
return nil
}
// execute runs a prepared query in the local DC without any failover. We don't
// apply any sorting options at this level - it should be done up above.
func (p *PreparedQuery) execute(query *structs.PreparedQuery,
reply *structs.PreparedQueryExecuteResponse) error {
state := p.srv.fsm.State()
_, nodes, err := state.CheckServiceNodes(query.Service.Service)
if err != nil {
return err
}
// This is kind of a paranoia ACL check, in case something changed with
// the token from the time the query was registered. Note that we use
// the token stored with the query, NOT the passed-in one, which is
// critical to how queries work (the query becomes a proxy for a lookup
// using the ACL it was created with).
acl, err := p.srv.resolveToken(query.Token)
if err != nil {
return err
}
if acl != nil && !acl.ServiceRead(query.Service.Service) {
p.srv.logger.Printf("[WARN] consul.prepared_query: Execute of prepared query for service '%s' denied due to ACLs", query.Service.Service)
return permissionDeniedErr
}
// Filter out any unhealthy nodes.
nodes = nodes.Filter(query.Service.OnlyPassing)
// Apply the tag filters, if any.
if len(query.Service.Tags) > 0 {
nodes = tagFilter(query.Service.Tags, nodes)
}
// Capture the nodes and pass the DNS information through to the reply.
reply.Service = query.Service.Service
reply.Nodes = nodes
reply.DNS = query.DNS
// Stamp the result for this datacenter.
reply.Datacenter = p.srv.config.Datacenter
return nil
}
// tagFilter returns a list of nodes who satisfy the given tags. Nodes must have
// ALL the given tags, and NONE of the forbidden tags (prefixed with !). Note
// for performance this modifies the original slice.
func tagFilter(tags []string, nodes structs.CheckServiceNodes) structs.CheckServiceNodes {
// Build up lists of required and disallowed tags.
must, not := make([]string, 0), make([]string, 0)
for _, tag := range tags {
tag = strings.ToLower(tag)
if strings.HasPrefix(tag, "!") {
tag = tag[1:]
not = append(not, tag)
} else {
must = append(must, tag)
}
}
n := len(nodes)
for i := 0; i < n; i++ {
node := nodes[i]
// Index the tags so lookups this way are cheaper.
index := make(map[string]struct{})
if node.Service != nil {
for _, tag := range node.Service.Tags {
tag = strings.ToLower(tag)
index[tag] = struct{}{}
}
}
// Bail if any of the required tags are missing.
for _, tag := range must {
if _, ok := index[tag]; !ok {
goto DELETE
}
}
// Bail if any of the disallowed tags are present.
for _, tag := range not {
if _, ok := index[tag]; ok {
goto DELETE
}
}
// At this point, the service is ok to leave in the list.
continue
DELETE:
nodes[i], nodes[n-1] = nodes[n-1], structs.CheckServiceNode{}
n--
i--
}
return nodes[:n]
}
// queryServer is a wrapper that makes it easier to test the failover logic.
type queryServer interface {
GetLogger() *log.Logger
GetOtherDatacentersByDistance() ([]string, error)
ForwardDC(method, dc string, args interface{}, reply interface{}) error
}
// queryServerWrapper applies the queryServer interface to a Server.
type queryServerWrapper struct {
srv *Server
}
// GetLogger returns the server's logger.
func (q *queryServerWrapper) GetLogger() *log.Logger {
return q.srv.logger
}
// GetOtherDatacentersByDistance calls into the server's fn and filters out the
// server's own DC.
func (q *queryServerWrapper) GetOtherDatacentersByDistance() ([]string, error) {
dcs, err := q.srv.getDatacentersByDistance()
if err != nil {
return nil, err
}
var result []string
for _, dc := range dcs {
if dc != q.srv.config.Datacenter {
result = append(result, dc)
}
}
return result, nil
}
// ForwardDC calls into the server's RPC forwarder.
func (q *queryServerWrapper) ForwardDC(method, dc string, args interface{}, reply interface{}) error {
return q.srv.forwardDC(method, dc, args, reply)
}
// queryFailover runs an algorithm to determine which DCs to try and then calls
// them to try to locate alternative services.
func queryFailover(q queryServer, query *structs.PreparedQuery,
limit int, options structs.QueryOptions,
reply *structs.PreparedQueryExecuteResponse) error {
// Pull the list of other DCs. This is sorted by RTT in case the user
// has selected that.
nearest, err := q.GetOtherDatacentersByDistance()
if err != nil {
return err
}
// This will help us filter unknown DCs supplied by the user.
known := make(map[string]struct{})
for _, dc := range nearest {
known[dc] = struct{}{}
}
// Build a candidate list of DCs to try, starting with the nearest N
// from RTTs.
var dcs []string
index := make(map[string]struct{})
if query.Service.Failover.NearestN > 0 {
for i, dc := range nearest {
if !(i < query.Service.Failover.NearestN) {
break
}
dcs = append(dcs, dc)
index[dc] = struct{}{}
}
}
// Then add any DCs explicitly listed that weren't selected above.
for _, dc := range query.Service.Failover.Datacenters {
// This will prevent a log of other log spammage if we do not
// attempt to talk to datacenters we don't know about.
if _, ok := known[dc]; !ok {
q.GetLogger().Printf("[DEBUG] consul.prepared_query: Skipping unknown datacenter '%s' in prepared query", dc)
continue
}
// This will make sure we don't re-try something that fails
// from the NearestN list.
if _, ok := index[dc]; !ok {
dcs = append(dcs, dc)
}
}
// Now try the selected DCs in priority order.
failovers := 0
for _, dc := range dcs {
// This keeps track of how many iterations we actually run.
failovers++
// Be super paranoid and set the nodes slice to nil since it's
// the same slice we used before. We know there's nothing in
// there, but the underlying msgpack library has a policy of
// updating the slice when it's non-nil, and that feels dirty.
// Let's just set it to nil so there's no way to communicate
// through this slice across successive RPC calls.
reply.Nodes = nil
// Note that we pass along the limit since it can be applied
// remotely to save bandwidth. We also pass along the consistency
// mode information we were given, so that applies to the remote
// query as well.
remote := &structs.PreparedQueryExecuteRemoteRequest{
Datacenter: dc,
Query: *query,
Limit: limit,
QueryOptions: options,
}
if err := q.ForwardDC("PreparedQuery.ExecuteRemote", dc, remote, reply); err != nil {
q.GetLogger().Printf("[WARN] consul.prepared_query: Failed querying for service '%s' in datacenter '%s': %s", query.Service.Service, dc, err)
continue
}
// We can stop if we found some nodes.
if len(reply.Nodes) > 0 {
break
}
}
// Set this at the end because the response from the remote doesn't have
// this information.
reply.Failovers = failovers
return nil
}