package postgresql import ( "bytes" "database/sql" "fmt" "strings" "github.com/influxdb/telegraf/plugins" _ "github.com/lib/pq" ) type Postgresql struct { Address string Databases []string OrderedColumns []string } var ignoredColumns = map[string]bool{"datid": true, "datname": true, "stats_reset": true} var sampleConfig = ` # specify address via a url matching: # postgres://[pqgotest[:password]]@localhost[/dbname]?sslmode=[disable|verify-ca|verify-full] # or a simple string: # host=localhost user=pqotest password=... sslmode=... dbname=app_production # # All connection parameters are optional. # # Without the dbname parameter, the driver will default to a database # with the same name as the user. This dbname is just for instantiating a # connection with the server and doesn't restrict the databases we are trying # to grab metrics for. # address = "host=localhost user=postgres sslmode=disable" # A list of databases to pull metrics about. If not specified, metrics for all # databases are gathered. # databases = ["app_production", "testing"] ` func (p *Postgresql) SampleConfig() string { return sampleConfig } func (p *Postgresql) Description() string { return "Read metrics from one or many postgresql servers" } func (p *Postgresql) IgnoredColumns() map[string]bool { return ignoredColumns } var localhost = "host=localhost sslmode=disable" func (p *Postgresql) Gather(acc plugins.Accumulator) error { var query string if p.Address == "" || p.Address == "localhost" { p.Address = localhost } db, err := sql.Open("postgres", p.Address) if err != nil { return err } defer db.Close() if len(p.Databases) == 0 { query = `SELECT * FROM pg_stat_database` } else { query = fmt.Sprintf(`SELECT * FROM pg_stat_database WHERE datname IN ('%s')`, strings.Join(p.Databases, "','")) } rows, err := db.Query(query) if err != nil { return err } defer rows.Close() // grab the column information from the result p.OrderedColumns, err = rows.Columns() if err != nil { return err } for rows.Next() { err = p.accRow(rows, acc) if err != nil { return err } } return rows.Err() } type scanner interface { Scan(dest ...interface{}) error } func (p *Postgresql) accRow(row scanner, acc plugins.Accumulator) error { var columnVars []interface{} var dbname bytes.Buffer // this is where we'll store the column name with its *interface{} columnMap := make(map[string]*interface{}) for _, column := range p.OrderedColumns { columnMap[column] = new(interface{}) } // populate the array of interface{} with the pointers in the right order for i := 0; i < len(columnMap); i++ { columnVars = append(columnVars, columnMap[p.OrderedColumns[i]]) } // deconstruct array of variables and send to Scan err := row.Scan(columnVars...) if err != nil { return err } // extract the database name from the column map dbnameChars := (*columnMap["datname"]).([]uint8) for i := 0; i < len(dbnameChars); i++ { dbname.WriteString(string(dbnameChars[i])) } tags := map[string]string{"server": p.Address, "db": dbname.String()} fields := make(map[string]interface{}) for col, val := range columnMap { _, ignore := ignoredColumns[col] if !ignore { fields[col] = *val } } acc.AddFields("postgresql", fields, tags) return nil } func init() { plugins.Add("postgresql", func() plugins.Plugin { return &Postgresql{} }) }