add function to get prometheus version and check if compaction is dia…

…bled.

cmd/thanos/sidecar.go

@@ -125,9 +125,25 @@ func runSidecar(
 
 		ctx, cancel := context.WithCancel(context.Background())
 		g.Add(func() error {
+			// Get Prometheus version.
+			ver, err := promclient.GetPrometheusVersion(ctx, logger, promURL)
+			if err != nil {
+				return errors.Wrapf(err, "get Prometheus version")
+			}
+			// Check if Prometheus has /status/flags endpoint.
+			if ver.LessThan(promclient.FlagsVersion) {
+				level.Warn(logger).Log("msg",
+					"Prometheus doesn't support flags endpoint. Skip validation", "version", ver.Original())
+			} else {
+				// Check if Prometheus disables compaction.
+				if err := promclient.ValidateCompaction(ctx, logger, promURL); err != nil {
+					return errors.Wrap(err, "validate Prometheus compaction")
+				}
+			}
+
 			// Blocking query of external labels before joining as a Source Peer into gossip.
 			// We retry infinitely until we reach and fetch labels from our Prometheus.
-			err := runutil.Retry(2*time.Second, ctx.Done(), func() error {
+			err = runutil.Retry(2*time.Second, ctx.Done(), func() error {
 				if err := m.UpdateLabels(ctx, logger); err != nil {
 					level.Warn(logger).Log(
 						"msg", "failed to fetch initial external labels. Is Prometheus running? Retrying",
@@ -294,6 +310,7 @@ func runSidecar(
 	return nil
 }
 
+
 type promMetadata struct {
 	promURL *url.URL
 

pkg/promclient/promclient.go

@@ -6,6 +6,7 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
+	"github.com/hashicorp/go-version"
 	"io/ioutil"
 	"net/http"
 	"net/url"
@@ -28,6 +29,13 @@ import (
 	"gopkg.in/yaml.v2"
 )
 
+// flagsVersion is the version that Prometheus started to have /status/flags endpoint
+var FlagsVersion *version.Version
+
+func init() {
+	FlagsVersion, _ = version.NewVersion("2.2.0")
+}
+
 // IsWALFileAccesible returns no error if WAL dir can be found. This helps to tell
 // if we have access to Prometheus TSDB directory.
 func IsWALDirAccesible(dir string) error {
@@ -335,6 +343,62 @@ func PromqlQueryInstant(ctx context.Context, logger log.Logger, base *url.URL, q
 	return vec, nil
 }
 
+// GetPrometheusVersion returns the version of Prometheus.
+func GetPrometheusVersion(ctx context.Context, logger log.Logger, base *url.URL) (*version.Version, error) {
+	if logger == nil {
+		logger = log.NewNopLogger()
+	}
+
+	u := *base
+	u.Path = path.Join(u.Path, "/version")
+	req, err := http.NewRequest("GET", u.String(), nil)
+	if err != nil {
+		return nil, errors.Wrap(err, "create request")
+	}
+
+	resp, err := http.DefaultClient.Do(req.WithContext(ctx))
+	if err != nil {
+		return nil, errors.Wrapf(err, "request version against %s", u.String())
+	}
+	defer runutil.CloseWithLogOnErr(logger, resp.Body, "query body")
+
+	b, err := ioutil.ReadAll(resp.Body)
+	if err != nil {
+		return nil, errors.Errorf("failed to read body")
+	}
+
+	if resp.StatusCode != 200 {
+		return nil, errors.Errorf("got non-200 response code: %v, response: %v", resp.StatusCode, string(b))
+	}
+	var m struct {
+		Version string `json:"version"`
+	}
+	if err := json.Unmarshal(b, &m); err != nil {
+		return nil, errors.Wrapf(err, "unmarshal response: %v", string(b))
+	}
+	ver, err := version.NewVersion(m.Version)
+	if err != nil {
+		return nil, errors.Wrapf(err, "failed to init version %s", m.Version)
+	}
+
+	return ver, nil
+}
+
+// ValidateCompaction ensures that Prometheus disables compaction.
+func ValidateCompaction(ctx context.Context, logger log.Logger, promURL *url.URL) error {
+	flags, err := ConfiguredFlags(ctx, logger, promURL)
+	if err != nil {
+		return errors.Wrap(err, "configured flags; failed to check if compaction is disabled")
+	}
+	// Check if min-block-time and max-block-time are equal to 2h.
+	if flags.TSDBMinTime != model.Duration(2*time.Hour) || flags.TSDBMaxTime != model.Duration(2*time.Hour) {
+		return errors.Errorf("Found that TSDB Max time is %s and Min time is %s. "+
+			"Compaction needs to be disabled (storage.tsdb.min-block-duration = storage.tsdb.max-block-duration = 2h)", flags.TSDBMaxTime, flags.TSDBMinTime)
+	}
+
+	return nil
+}
+
 // Scalar response consists of array with mixed types so it needs to be
 // unmarshaled separately.
 func convertScalarJSONToVector(scalarJSONResult json.RawMessage) (model.Vector, error) {

pkg/shipper/shipper.go

@@ -5,15 +5,6 @@ package shipper
 import (
 	"context"
 	"encoding/json"
-	"io/ioutil"
-	"math"
-	"net/url"
-	"os"
-	"path"
-	"path/filepath"
-	"sort"
-	"time"
-
 	"github.com/go-kit/kit/log"
 	"github.com/go-kit/kit/log/level"
 	"github.com/improbable-eng/thanos/pkg/block"
@@ -24,10 +15,16 @@ import (
 	"github.com/oklog/ulid"
 	"github.com/pkg/errors"
 	"github.com/prometheus/client_golang/prometheus"
-	"github.com/prometheus/common/model"
 	"github.com/prometheus/tsdb"
 	"github.com/prometheus/tsdb/fileutil"
 	"github.com/prometheus/tsdb/labels"
+	"io/ioutil"
+	"math"
+	"net/url"
+	"os"
+	"path"
+	"path/filepath"
+	"sort"
 )
 
 type metrics struct {
@@ -135,15 +132,20 @@ func NewWithCompacted(
 	if lbls == nil {
 		lbls = func() labels.Labels { return nil }
 	}
-
-	flags, err := promclient.ConfiguredFlags(ctx, logger, prometheusURL)
+	// Get Prometheus version.
+	ver, err := promclient.GetPrometheusVersion(ctx, logger, prometheusURL)
 	if err != nil {
-		return nil, errors.Wrap(err, "configured flags; failed to check if compaction is disabled")
-	}
-
-	if flags.TSDBMinTime != model.Duration(2*time.Hour) || flags.TSDBMaxTime != model.Duration(2*time.Hour) {
-		return nil, errors.Errorf("Found that TSDB Max time is %s and Min time is %s. To use shipper with upload compacted option, "+
-			"compaction needs to be disabled (storage.tsdb.min-block-duration = storage.tsdb.max-block-duration = 2h", flags.TSDBMinTime, flags.TSDBMaxTime)
+		return nil, errors.Wrapf(err, "get Prometheus version")
+	}
+	// Check if Prometheus has /status/flags endpoint.
+	if ver.LessThan(promclient.FlagsVersion) {
+		level.Warn(logger).Log("msg",
+			"Prometheus doesn't support flags endpoint. Skip validation", "version", ver.Original())
+	} else {
+		// Check if Prometheus disables compaction.
+		if err := promclient.ValidateCompaction(ctx, logger, prometheusURL); err != nil {
+			return nil, errors.Wrap(err, "validate Prometheus compaction")
+		}
 	}
 
 	return &Shipper{