Provide flag to compress the tsdb WAL

Signed-off-by: NChris Marchbanks <csmarchbanks@gmail.com>

cmd/prometheus/main.go

@@ -207,6 +207,9 @@ func main() {
 	a.Flag("storage.tsdb.allow-overlapping-blocks", "[EXPERIMENTAL] Allow overlapping blocks, which in turn enables vertical compaction and vertical query merge.").
 		Default("false").BoolVar(&cfg.tsdb.AllowOverlappingBlocks)
 
+	a.Flag("storage.tsdb.wal-compression", "Compress the tsdb WAL.").
+		Default("false").BoolVar(&cfg.tsdb.WALCompression)
+
 	a.Flag("storage.remote.flush-deadline", "How long to wait flushing sample on shutdown or config reload.").
 		Default("1m").PlaceHolder("<duration>").SetValue(&cfg.RemoteFlushDeadline)
 
@@ -671,6 +674,7 @@ func main() {
 					"RetentionDuration", cfg.tsdb.RetentionDuration,
 					"WALSegmentSize", cfg.tsdb.WALSegmentSize,
 					"AllowOverlappingBlocks", cfg.tsdb.AllowOverlappingBlocks,
+					"WALCompression", cfg.tsdb.WALCompression,
 				)
 
 				startTimeMargin := int64(2 * time.Duration(cfg.tsdb.MinBlockDuration).Seconds() * 1000)

storage/tsdb/tsdb.go

@@ -130,6 +130,9 @@ type Options struct {
 	// When true it disables the overlapping blocks check.
 	// This in-turn enables vertical compaction and vertical query merge.
 	AllowOverlappingBlocks bool
+
+	// When true records in the WAL will be compressed.
+	WALCompression bool
 }
 
 var (
@@ -195,6 +198,7 @@ func Open(path string, l log.Logger, r prometheus.Registerer, opts *Options) (*t
 		BlockRanges:            rngs,
 		NoLockfile:             opts.NoLockfile,
 		AllowOverlappingBlocks: opts.AllowOverlappingBlocks,
+		WALCompression:         opts.WALCompression,
 	})
 	if err != nil {
 		return nil, err