roachtest: log expanded command

This change now logs expanded commands if they differ from
the original command. This should ease debugging as we can
know what command was actually run on the node.

pkg/cmd/roachtest/cluster.go

@@ -2508,7 +2508,7 @@ func (c *clusterImpl) RunE(ctx context.Context, options install.RunOptions, args
 	}
 	if err := roachprod.Run(
 		ctx, l, c.MakeNodes(nodes), "", "", c.IsSecure(),
-		l.Stdout, l.Stderr, args, options.WithExpanderConfig(expanderCfg),
+		l.Stdout, l.Stderr, args, options.WithExpanderConfig(expanderCfg).WithLogExpandedCommand(),
 	); err != nil {
 		if err := ctx.Err(); err != nil {
 			l.Printf("(note: incoming context was canceled: %s)", err)
@@ -2578,7 +2578,7 @@ func (c *clusterImpl) RunWithDetails(
 	}
 	results, err := roachprod.RunWithDetails(
 		ctx, l, c.MakeNodes(nodes), "" /* SSHOptions */, "", /* processTag */
-		c.IsSecure(), args, options.WithExpanderConfig(expanderCfg),
+		c.IsSecure(), args, options.WithExpanderConfig(expanderCfg).WithLogExpandedCommand(),
 	)
 
 	var logFileFull string

pkg/roachprod/install/cluster_synced.go

@@ -782,6 +782,7 @@ func (r *RunResultDetails) Output(decorate bool) string {
 type RunCmdOptions struct {
 	combinedOut             bool
 	includeRoachprodEnvVars bool
+	logExpandedCmd          bool // log expanded result if it differs from the original command
 	stdin                   io.Reader
 	stdout, stderr          io.Writer
 	remoteOptions           []remoteSessionOption
@@ -826,6 +827,9 @@ func (c *SyncedCluster) runCmdOnSingleNode(
 	if err != nil {
 		return &noResult, errors.WithDetailf(err, "error expanding command: %s", cmd)
 	}
+	if opts.logExpandedCmd && expandedCmd != cmd {
+		l.Printf("Node %d expanded cmd > %s", e.node, expandedCmd)
+	}
 
 	nodeCmd := expandedCmd
 	// Be careful about changing these command strings. In particular, we need
@@ -931,6 +935,7 @@ func (c *SyncedCluster) Run(
 			stdout:                  stdout,
 			stderr:                  stderr,
 			expanderConfig:          options.ExpanderConfig,
+			logExpandedCmd:          options.LogExpandedCmd,
 		}
 		result, err := c.runCmdOnSingleNode(ctx, l, node, cmd, opts)
 		return result, err
@@ -1015,6 +1020,7 @@ func (c *SyncedCluster) RunWithDetails(
 			stdout:                  l.Stdout,
 			stderr:                  l.Stderr,
 			expanderConfig:          options.ExpanderConfig,
+			logExpandedCmd:          options.LogExpandedCmd,
 		}
 		result, err := c.runCmdOnSingleNode(ctx, l, node, cmd, opts)
 		return result, err

pkg/roachprod/install/run_options.go

@@ -25,6 +25,8 @@ type RunOptions struct {
 	// ExpanderConfig configures the behaviour of the roachprod expander
 	// during a run.
 	ExpanderConfig ExpanderConfig
+	// LogExpandedCmd will log the expanded command if it differs from the original.
+	LogExpandedCmd bool
 
 	// These are private to roachprod
 	Nodes       Nodes
@@ -106,3 +108,8 @@ func (r RunOptions) WithExpanderConfig(cfg ExpanderConfig) RunOptions {
 	r.ExpanderConfig = cfg
 	return r
 }
+
+func (r RunOptions) WithLogExpandedCommand() RunOptions {
+	r.LogExpandedCmd = true
+	return r
+}