promtool: add support of selecting timeseries for TSDB dump

Dumping without any limit on the data being dumped will generate
a large amount of data. Also, sometimes it is necessary to dump
only a part of the data in order to change or transfer it.

This change allows to specify a part of the data to dump and
by default works same as before. (no public API change)

Signed-off-by: Amin Borjian <borjianamin98@outlook.com>

cmd/promtool/main.go

@@ -190,6 +190,7 @@ func main() {
 	dumpPath := tsdbDumpCmd.Arg("db path", "Database path (default is "+defaultDBPath+").").Default(defaultDBPath).String()
 	dumpMinTime := tsdbDumpCmd.Flag("min-time", "Minimum timestamp to dump.").Default(strconv.FormatInt(math.MinInt64, 10)).Int64()
 	dumpMaxTime := tsdbDumpCmd.Flag("max-time", "Maximum timestamp to dump.").Default(strconv.FormatInt(math.MaxInt64, 10)).Int64()
+	dumpMatch := tsdbDumpCmd.Flag("match", "Series selector.").Default("{__name__=~'(?s:.*)'}").String()
 
 	importCmd := tsdbCmd.Command("create-blocks-from", "[Experimental] Import samples from input and produce TSDB blocks. Please refer to the storage docs for more details.")
 	importHumanReadable := importCmd.Flag("human-readable", "Print human readable values.").Short('r').Bool()
@@ -296,7 +297,7 @@ func main() {
 		os.Exit(checkErr(listBlocks(*listPath, *listHumanReadable)))
 
 	case tsdbDumpCmd.FullCommand():
-		os.Exit(checkErr(dumpSamples(*dumpPath, *dumpMinTime, *dumpMaxTime)))
+		os.Exit(checkErr(dumpSamples(*dumpPath, *dumpMinTime, *dumpMaxTime, *dumpMatch)))
 	// TODO(aSquare14): Work on adding support for custom block size.
 	case openMetricsImportCmd.FullCommand():
 		os.Exit(backfillOpenMetrics(*importFilePath, *importDBPath, *importHumanReadable, *importQuiet, *maxBlockDuration))

cmd/promtool/tsdb.go

@@ -30,6 +30,7 @@ import (
 	"text/tabwriter"
 	"time"
 
+	"github.com/prometheus/prometheus/promql/parser"
 	"github.com/prometheus/prometheus/storage"
 	"github.com/prometheus/prometheus/tsdb/chunkenc"
 	"github.com/prometheus/prometheus/tsdb/index"
@@ -624,7 +625,7 @@ func analyzeCompaction(block tsdb.BlockReader, indexr tsdb.IndexReader) (err err
 	return nil
 }
 
-func dumpSamples(path string, mint, maxt int64) (err error) {
+func dumpSamples(path string, mint, maxt int64, match string) (err error) {
 	db, err := tsdb.OpenDBReadOnly(path, nil)
 	if err != nil {
 		return err
@@ -638,7 +639,11 @@ func dumpSamples(path string, mint, maxt int64) (err error) {
 	}
 	defer q.Close()
 
-	ss := q.Select(false, nil, labels.MustNewMatcher(labels.MatchRegexp, "", ".*"))
+	matchers, err := parser.ParseMetricSelector(match)
+	if err != nil {
+		return err
+	}
+	ss := q.Select(false, nil, matchers...)
 
 	for ss.Next() {
 		series := ss.At()