open-consul/agent/consul/txn_endpoint.go

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package consul
import (
"fmt"
"time"
"github.com/armon/go-metrics"
"github.com/armon/go-metrics/prometheus"
"github.com/hashicorp/go-hclog"
"github.com/hashicorp/consul/acl"
"github.com/hashicorp/consul/agent/structs"
"github.com/hashicorp/consul/api"
)
var TxnSummaries = []prometheus.SummaryDefinition{
{
Name: []string{"txn", "apply"},
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Help: "Measures the time spent applying a transaction operation.",
},
{
Name: []string{"txn", "read"},
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Help: "Measures the time spent returning a read transaction.",
},
}
// Txn endpoint is used to perform multi-object atomic transactions.
type Txn struct {
srv *Server
logger hclog.Logger
}
// preCheck is used to verify the incoming operations before any further
// processing takes place. This checks things like ACLs.
func (t *Txn) preCheck(authorizer ACLResolveResult, ops structs.TxnOps) structs.TxnErrors {
var errors structs.TxnErrors
// Perform the pre-apply checks for any KV operations.
for i, op := range ops {
switch {
case op.KV != nil:
ok, err := kvsPreApply(t.logger, t.srv, authorizer, op.KV.Verb, &op.KV.DirEnt)
if err != nil {
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errors = append(errors, &structs.TxnError{
OpIndex: i,
What: err.Error(),
})
} else if !ok {
err = fmt.Errorf("failed to lock key %q due to lock delay", op.KV.DirEnt.Key)
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errors = append(errors, &structs.TxnError{
OpIndex: i,
What: err.Error(),
})
}
case op.Node != nil:
// Skip the pre-apply checks if this is a GET.
if op.Node.Verb == api.NodeGet {
break
}
node := op.Node.Node
if err := nodePreApply(node.Node, string(node.ID)); err != nil {
errors = append(errors, &structs.TxnError{
OpIndex: i,
What: err.Error(),
})
break
}
// Check that the token has permissions for the given operation.
if err := vetNodeTxnOp(op.Node, authorizer); err != nil {
errors = append(errors, &structs.TxnError{
OpIndex: i,
What: err.Error(),
})
}
case op.Service != nil:
// Skip the pre-apply checks if this is a GET.
if op.Service.Verb == api.ServiceGet {
break
}
service := &op.Service.Service
if err := servicePreApply(service, authorizer, op.Service.FillAuthzContext); err != nil {
errors = append(errors, &structs.TxnError{
OpIndex: i,
What: err.Error(),
})
}
case op.Check != nil:
// Skip the pre-apply checks if this is a GET.
if op.Check.Verb == api.CheckGet {
break
}
checkPreApply(&op.Check.Check)
// Check that the token has permissions for the given operation.
if err := vetCheckTxnOp(op.Check, authorizer); err != nil {
errors = append(errors, &structs.TxnError{
OpIndex: i,
What: err.Error(),
})
}
}
}
return errors
}
// vetNodeTxnOp applies the given ACL policy to a node transaction operation.
func vetNodeTxnOp(op *structs.TxnNodeOp, authz ACLResolveResult) error {
var authzContext acl.AuthorizerContext
op.FillAuthzContext(&authzContext)
if err := authz.ToAllowAuthorizer().NodeWriteAllowed(op.Node.Node, &authzContext); err != nil {
return err
}
return nil
}
// vetCheckTxnOp applies the given ACL policy to a check transaction operation.
func vetCheckTxnOp(op *structs.TxnCheckOp, authz ACLResolveResult) error {
var authzContext acl.AuthorizerContext
op.FillAuthzContext(&authzContext)
if op.Check.ServiceID == "" {
// Node-level check.
if err := authz.ToAllowAuthorizer().NodeWriteAllowed(op.Check.Node, &authzContext); err != nil {
return err
}
} else {
// Service-level check.
if err := authz.ToAllowAuthorizer().ServiceWriteAllowed(op.Check.ServiceName, &authzContext); err != nil {
return err
}
}
return nil
}
// Apply is used to apply multiple operations in a single, atomic transaction.
func (t *Txn) Apply(args *structs.TxnRequest, reply *structs.TxnResponse) error {
if done, err := t.srv.ForwardRPC("Txn.Apply", args, reply); done {
return err
}
defer metrics.MeasureSince([]string{"txn", "apply"}, time.Now())
// Run the pre-checks before we send the transaction into Raft.
authz, err := t.srv.ResolveToken(args.Token)
if err != nil {
return err
}
reply.Errors = t.preCheck(authz, args.Ops)
if len(reply.Errors) > 0 {
return nil
}
// Apply the update.
resp, err := t.srv.raftApply(structs.TxnRequestType, args)
if err != nil {
return fmt.Errorf("raft apply failed: %w", err)
}
// Convert the return type. This should be a cheap copy since we are
// just taking the two slices.
if txnResp, ok := resp.(structs.TxnResponse); ok {
txnResp.Results = FilterTxnResults(authz, txnResp.Results)
*reply = txnResp
} else {
return fmt.Errorf("unexpected return type %T", resp)
}
return nil
}
// Read is used to perform a read-only transaction that doesn't modify the state
// store. This is much more scalable since it doesn't go through Raft and
// supports staleness, so this should be preferred if you're just performing
// reads.
func (t *Txn) Read(args *structs.TxnReadRequest, reply *structs.TxnReadResponse) error {
if done, err := t.srv.ForwardRPC("Txn.Read", args, reply); done {
return err
}
defer metrics.MeasureSince([]string{"txn", "read"}, time.Now())
// We have to do this ourselves since we are not doing a blocking RPC.
if args.RequireConsistent {
if err := t.srv.consistentRead(); err != nil {
return err
}
}
// Run the pre-checks before we perform the read.
authz, err := t.srv.ResolveToken(args.Token)
if err != nil {
return err
}
// There are currently two different ways we handle permission issues.
//
// For simple reads such as KVGet and KVGetTree, the txn succeeds but the
// offending results are omitted. For more involved operations such as
// KVCheckIndex, the txn fails and permission denied errors are returned.
//
// TODO: Maybe we should unify these, or at least cover it in the docs?
reply.Errors = t.preCheck(authz, args.Ops)
if len(reply.Errors) > 0 {
return nil
}
// Run the read transaction.
state := t.srv.fsm.State()
reply.Results, reply.Errors = state.TxnRO(args.Ops)
total := len(reply.Results)
reply.Results = FilterTxnResults(authz, reply.Results)
reply.QueryMeta.ResultsFilteredByACLs = total != len(reply.Results)
// We have to do this ourselves since we are not doing a blocking RPC.
t.srv.setQueryMeta(&reply.QueryMeta, args.Token)
return nil
}