From c4c89353f6ddc94c259fe895e319f09e4d2879fa Mon Sep 17 00:00:00 2001
From: Nathan VanBenschoten <nvanbenschoten@gmail.com>
Date: Wed, 30 May 2018 16:44:47 -0400
Subject: [PATCH] roachtest: perform spec validation on existing clusters

This change adds in a new validation step when running tests with the
`--cluster` flag to verify that the cluster matches the test spec. This
is particularly important for benchmarks, which can produce vastly
different results depending on the machine type they run on.

Release note: None
---
 pkg/cmd/roachtest/cluster.go | 52 +++++++++++++++++++++++++++++++-----
 1 file changed, 46 insertions(+), 6 deletions(-)

diff --git a/pkg/cmd/roachtest/cluster.go b/pkg/cmd/roachtest/cluster.go
index 69766508115d..d09f4e233db3 100644
--- a/pkg/cmd/roachtest/cluster.go
+++ b/pkg/cmd/roachtest/cluster.go
@@ -20,6 +20,7 @@ import (
 	"bytes"
 	"context"
 	gosql "database/sql"
+	"encoding/json"
 	"fmt"
 	"io"
 	"math/rand"
@@ -345,7 +346,7 @@ type nodeSpec struct {
 func (s *nodeSpec) args() []string {
 	var args []string
 	if s.MachineType != "" {
-		args = append(args, s.MachineType)
+		args = append(args, "--gce-machine-type="+s.MachineType)
 	}
 	if s.Geo {
 		args = append(args, "--geo")
@@ -370,9 +371,9 @@ func (o nodeCPUOption) apply(spec *nodeSpec) {
 		// configurations, but the rules for the amount of RAM per CPU need to be
 		// determined (you can't request any arbitrary amount of RAM).
 		if spec.CPUs < 16 {
-			spec.MachineType = fmt.Sprintf("--gce-machine-type=n1-standard-%d", spec.CPUs)
+			spec.MachineType = fmt.Sprintf("n1-standard-%d", spec.CPUs)
 		} else {
-			spec.MachineType = fmt.Sprintf("--gce-machine-type=n1-highcpu-%d", spec.CPUs)
+			spec.MachineType = fmt.Sprintf("n1-highcpu-%d", spec.CPUs)
 		}
 	}
 }
@@ -487,9 +488,48 @@ func newCluster(ctx context.Context, t testI, nodes []nodeSpec) *cluster {
 			return nil
 		}
 	} else {
-		// NB: if the existing cluster is not as large as the desired cluster, the
-		// test will fail when trying to perform various operations such as putting
-		// binaries or starting the cockroach nodes.
+		// Perform validation on the existing cluster.
+		c.status("checking that existing cluster matches spec")
+		sargs := []string{roachprod, "list", c.name, "--json"}
+		out, err := execCmdWithBuffer(ctx, l, sargs...)
+		if err != nil {
+			t.Fatal(err)
+			return nil
+		}
+
+		// jsonOutput matches the structure of the output from `roachprod list`
+		// when in json mode.
+		type jsonOutput struct {
+			Clusters map[string]struct {
+				VMs []struct {
+					MachineType string `json:"machine_type"`
+				} `json:"vms"`
+			} `json:"clusters"`
+		}
+		var details jsonOutput
+		if err := json.Unmarshal(out, &details); err != nil {
+			t.Fatal(err)
+			return nil
+		}
+
+		cDetails, ok := details.Clusters[c.name]
+		if !ok {
+			t.Fatalf("cluster %q not found", c.name)
+			return nil
+		}
+		if len(cDetails.VMs) < c.nodes {
+			t.Fatalf("cluster has %d nodes, test requires at least %d", len(cDetails.VMs), c.nodes)
+			return nil
+		}
+		if typ := nodes[0].MachineType; typ != "" {
+			for i, vm := range cDetails.VMs {
+				if vm.MachineType != typ {
+					t.Fatalf("node %d has machine type %s, test requires %s", i, vm.MachineType, typ)
+					return nil
+				}
+			}
+		}
+
 		c.status("stopping cluster")
 		c.Stop(ctx, c.All())
 		if clusterWipe {