Merge pull request #4208 from influxdb/show_diag_m

Support module-selection for SHOW DIAGNOSTICS

CHANGELOG.md

@@ -6,6 +6,7 @@
 - [#4140](https://github.com/influxdb/influxdb/pull/4140): Make storage engine configurable
 - [#4161](https://github.com/influxdb/influxdb/pull/4161): Implement bottom selector function
 - [#4204](https://github.com/influxdb/influxdb/pull/4204): Allow module-level selection for SHOW STATS
+- [#4208](https://github.com/influxdb/influxdb/pull/4208): Allow module-level selection for SHOW DIAGNOSTICS
 - [#4196](https://github.com/influxdb/influxdb/pull/4196): Export tsdb.Iterator
 - [#4198](https://github.com/influxdb/influxdb/pull/4198): Add basic cluster-service stats
 

influxql/ast.go

@@ -1999,6 +1999,7 @@ func (s *ShowStatsStatement) String() string {
 	var buf bytes.Buffer
 	_, _ = buf.WriteString("SHOW STATS ")
 	if s.Module != "" {
+		_, _ = buf.WriteString("FOR ")
 		_, _ = buf.WriteString(s.Module)
 	}
 	return buf.String()
@@ -2021,10 +2022,21 @@ func (s *ShowShardsStatement) RequiredPrivileges() ExecutionPrivileges {
 }
 
 // ShowDiagnosticsStatement represents a command for show node diagnostics.
-type ShowDiagnosticsStatement struct{}
+type ShowDiagnosticsStatement struct {
+	// Module
+	Module string
+}
 
 // String returns a string representation of the ShowDiagnosticsStatement.
-func (s *ShowDiagnosticsStatement) String() string { return "SHOW DIAGNOSTICS" }
+func (s *ShowDiagnosticsStatement) String() string {
+	var buf bytes.Buffer
+	_, _ = buf.WriteString("SHOW DIAGNOSTICS ")
+	if s.Module != "" {
+		_, _ = buf.WriteString("FOR ")
+		_, _ = buf.WriteString(s.Module)
+	}
+	return buf.String()
+}
 
 // RequiredPrivileges returns the privilege required to execute a ShowDiagnosticsStatement
 func (s *ShowDiagnosticsStatement) RequiredPrivileges() ExecutionPrivileges {

influxql/parser.go

@@ -1445,7 +1445,15 @@ func (p *Parser) parseShowStatsStatement() (*ShowStatsStatement, error) {
 // parseShowDiagnostics parses a string and returns a ShowDiagnosticsStatement.
 func (p *Parser) parseShowDiagnosticsStatement() (*ShowDiagnosticsStatement, error) {
 	stmt := &ShowDiagnosticsStatement{}
-	return stmt, nil
+	var err error
+
+	if tok, _, _ := p.scanIgnoreWhitespace(); tok == FOR {
+		stmt.Module, err = p.parseString()
+	} else {
+		p.unscan()
+	}
+
+	return stmt, err
 }
 
 // parseDropContinuousQueriesStatement parses a string and returns a DropContinuousQueryStatement.

influxql/parser_test.go

@@ -1417,6 +1417,12 @@ func TestParser_ParseStatement(t *testing.T) {
 			s:    `SHOW DIAGNOSTICS`,
 			stmt: &influxql.ShowDiagnosticsStatement{},
 		},
+		{
+			s: `SHOW DIAGNOSTICS FOR 'build'`,
+			stmt: &influxql.ShowDiagnosticsStatement{
+				Module: "build",
+			},
+		},
 
 		// Errors
 		{s: ``, err: `found EOF, expected SELECT, DELETE, SHOW, CREATE, DROP, GRANT, REVOKE, ALTER, SET at line 1, char 1`},
@@ -1501,6 +1507,7 @@ func TestParser_ParseStatement(t *testing.T) {
 		{s: `SHOW RETENTION POLICIES ON`, err: `found EOF, expected identifier at line 1, char 28`},
 		{s: `SHOW FOO`, err: `found FOO, expected CONTINUOUS, DATABASES, FIELD, GRANTS, MEASUREMENTS, RETENTION, SERIES, SERVERS, TAG, USERS at line 1, char 6`},
 		{s: `SHOW STATS FOR`, err: `found EOF, expected string at line 1, char 16`},
+		{s: `SHOW DIAGNOSTICS FOR`, err: `found EOF, expected string at line 1, char 22`},
 		{s: `SHOW GRANTS`, err: `found EOF, expected FOR at line 1, char 13`},
 		{s: `SHOW GRANTS FOR`, err: `found EOF, expected identifier at line 1, char 17`},
 		{s: `DROP CONTINUOUS`, err: `found EOF, expected QUERY at line 1, char 17`},

monitor/README.md

@@ -14,7 +14,7 @@ An example of statistical information would be the number of points received ove
 All statistics are written, by default, by each node to a "monitor" database within the InfluxDB system, allowing analysis of aggregated statistical data using the standard InfluxQL language. This allows users to track the performance of their system. Importantly, this allows cluster-level statistics to be viewed, since by querying the monitor database, statistics from all nodes may be queried. This can be a very powerful approach for troubleshooting your InfluxDB system and understanding its behaviour.
 
 ## System Diagnostics
-`SHOW DIAGNOSTICS` displays various diagnostic information about the `influxd` process. This information is not stored persistently within the InfluxDB system.
+`SHOW DIAGNOSTICS [FOR <module>]` displays various diagnostic information about the `influxd` process. This information is not stored persistently within the InfluxDB system. If _module_ is specified, it must be single-quoted. For example `SHOW STATS FOR 'build'`.
 
 ## Standard expvar support
 All statistical information is available at HTTP API endpoint `/debug/vars`, in [expvar](https://golang.org/pkg/expvar/) format, allowing external systems to monitor an InfluxDB node. By default, the full path to this endpoint is `http://localhost:8086/debug/vars`.

monitor/statement_executor.go

@@ -21,7 +21,7 @@ func (s *StatementExecutor) ExecuteStatement(stmt influxql.Statement) *influxql.
 	case *influxql.ShowStatsStatement:
 		return s.executeShowStatistics(stmt.Module)
 	case *influxql.ShowDiagnosticsStatement:
-		return s.executeShowDiagnostics()
+		return s.executeShowDiagnostics(stmt.Module)
 	default:
 		panic(fmt.Sprintf("unsupported statement type: %T", stmt))
 	}
@@ -51,7 +51,7 @@ func (s *StatementExecutor) executeShowStatistics(module string) *influxql.Resul
 	return &influxql.Result{Series: rows}
 }
 
-func (s *StatementExecutor) executeShowDiagnostics() *influxql.Result {
+func (s *StatementExecutor) executeShowDiagnostics(module string) *influxql.Result {
 	diags, err := s.Monitor.Diagnostics()
 	if err != nil {
 		return &influxql.Result{Err: err}
@@ -59,6 +59,10 @@ func (s *StatementExecutor) executeShowDiagnostics() *influxql.Result {
 	rows := make([]*models.Row, 0, len(diags))
 
 	for k, v := range diags {
+		if module != "" && k != module {
+			continue
+		}
+
 		row := &models.Row{Name: k}
 
 		row.Columns = v.Columns