Simple LevelDB sample dumper tool.

This very simple tool dumps all samples in a LevelDB metrics storage
together with their chunk information. This is very crude for now - I
just whipped it up because I needed to debug something. We should add
printf-style formatting support for it in the future to indicate what
information to output for each sample in the database. We could also
support inspecting the index databases.

tools/Makefile

@@ -11,16 +11,19 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-all: pruner
+all: dumper pruner
 
 SUFFIXES:
 
 include ../Makefile.INCLUDE
 
+dumper:
+	$(MAKE) -C dumper
+
 pruner:
 	$(MAKE) -C pruner
 
 clean:
-	$(MAKE) -C pruner clean
+	$(MAKE) -C dumper pruner clean
 
-.PHONY: clean pruner
+.PHONY: clean dumper pruner

tools/dumper/Makefile

@@ -0,0 +1,28 @@
+# Copyright 2013 Prometheus Team
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+MAKE_ARTIFACTS = dumper
+
+all: dumper
+
+SUFFIXES:
+
+include ../../Makefile.INCLUDE
+
+dumper: $(shell find . -iname '*.go')
+	go build -o dumper .
+
+clean:
+	rm -rf $(MAKE_ARTIFACTS)
+
+.PHONY: clean

tools/dumper/main.go

@@ -0,0 +1,114 @@
+// Copyright 2013 Prometheus Team
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Dumper is responsible for dumping all samples along with metadata contained
+// in a given Prometheus metrics storage. It prints samples in unquoted CSV
+// format, with commas as field separators:
+//
+// <fingerprint>,<chunk_first_time>,<chunk_last_time>,<chunk_sample_count>,<chunk_index>,<timestamp>,<value>
+package main
+
+import (
+	"code.google.com/p/goprotobuf/proto"
+	"encoding/csv"
+	"flag"
+	"fmt"
+	"github.com/prometheus/prometheus/model"
+	dto "github.com/prometheus/prometheus/model/generated"
+	"github.com/prometheus/prometheus/storage"
+	"github.com/prometheus/prometheus/storage/metric"
+	"log"
+	"os"
+	"strconv"
+)
+
+var (
+	storageRoot = flag.String("storage.root", "", "The path to the storage root for Prometheus.")
+)
+
+type SamplesDumper struct {
+	*csv.Writer
+}
+
+func (d SamplesDumper) DecodeKey(in interface{}) (interface{}, error) {
+	key := &dto.SampleKey{}
+	err := proto.Unmarshal(in.([]byte), key)
+	if err != nil {
+		return nil, err
+	}
+
+	return model.NewSampleKeyFromDTO(key), nil
+}
+
+func (d SamplesDumper) DecodeValue(in interface{}) (interface{}, error) {
+	values := &dto.SampleValueSeries{}
+	err := proto.Unmarshal(in.([]byte), values)
+	if err != nil {
+		return nil, err
+	}
+
+	return model.NewValuesFromDTO(values), nil
+}
+
+func (d SamplesDumper) Filter(_, _ interface{}) storage.FilterResult {
+	return storage.ACCEPT
+}
+
+func (d SamplesDumper) Operate(key, value interface{}) *storage.OperatorError {
+	sampleKey := key.(model.SampleKey)
+	for i, sample := range value.(model.Values) {
+		d.Write([]string{
+			sampleKey.Fingerprint.String(),
+			strconv.FormatInt(sampleKey.FirstTimestamp.Unix(), 10),
+			strconv.FormatInt(sampleKey.LastTimestamp.Unix(), 10),
+			strconv.FormatUint(uint64(sampleKey.SampleCount), 10),
+			strconv.Itoa(i),
+			strconv.FormatInt(sample.Timestamp.Unix(), 10),
+			fmt.Sprintf("%v", sample.Value),
+		})
+		if err := d.Error(); err != nil {
+			return &storage.OperatorError{
+				error:       err,
+				Continuable: false,
+			}
+		}
+	}
+	return nil
+}
+
+func main() {
+	flag.Parse()
+
+	if storageRoot == nil || *storageRoot == "" {
+		log.Fatal("Must provide a path...")
+	}
+
+	persistence, err := metric.NewLevelDBMetricPersistence(*storageRoot)
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer persistence.Close()
+
+	dumper := SamplesDumper{csv.NewWriter(os.Stdout)}
+	entire, err := persistence.MetricSamples.ForEach(dumper, dumper, dumper)
+	if err != nil {
+		log.Fatalf("Error dumping samples: %s", err)
+	}
+	if !entire {
+		log.Fatalf("Didn't scan entire corpus")
+	}
+	dumper.Flush()
+	if err = dumper.Error(); err != nil {
+		log.Fatalf("Error flushing CSV: %s", err)
+	}
+}