21189: Replace -commit-X with Balance{Pull,Trash}Limit configs.
[arvados.git] / services / keep-balance / balance_run_test.go
index cbdde595e8b4b797c70422ae71a5dc7affb33dcf..b7b3fb61233249beb6c6df48e46c8de4ea678e22 100644 (file)
@@ -2,10 +2,10 @@
 //
 // SPDX-License-Identifier: AGPL-3.0
 
-package main
+package keepbalance
 
 import (
-       "bytes"
+       "context"
        "encoding/json"
        "fmt"
        "io"
@@ -21,8 +21,8 @@ import (
        "git.arvados.org/arvados.git/sdk/go/arvados"
        "git.arvados.org/arvados.git/sdk/go/arvadostest"
        "git.arvados.org/arvados.git/sdk/go/ctxlog"
+       "github.com/jmoiron/sqlx"
        "github.com/prometheus/client_golang/prometheus"
-       "github.com/prometheus/common/expfmt"
        check "gopkg.in/check.v1"
 )
 
@@ -86,20 +86,32 @@ var stubServices = []arvados.KeepService{
 
 var stubMounts = map[string][]arvados.KeepMount{
        "keep0.zzzzz.arvadosapi.com:25107": {{
-               UUID:     "zzzzz-ivpuk-000000000000000",
-               DeviceID: "keep0-vol0",
+               UUID:           "zzzzz-ivpuk-000000000000000",
+               DeviceID:       "keep0-vol0",
+               StorageClasses: map[string]bool{"default": true},
+               AllowWrite:     true,
+               AllowTrash:     true,
        }},
        "keep1.zzzzz.arvadosapi.com:25107": {{
-               UUID:     "zzzzz-ivpuk-100000000000000",
-               DeviceID: "keep1-vol0",
+               UUID:           "zzzzz-ivpuk-100000000000000",
+               DeviceID:       "keep1-vol0",
+               StorageClasses: map[string]bool{"default": true},
+               AllowWrite:     true,
+               AllowTrash:     true,
        }},
        "keep2.zzzzz.arvadosapi.com:25107": {{
-               UUID:     "zzzzz-ivpuk-200000000000000",
-               DeviceID: "keep2-vol0",
+               UUID:           "zzzzz-ivpuk-200000000000000",
+               DeviceID:       "keep2-vol0",
+               StorageClasses: map[string]bool{"default": true},
+               AllowWrite:     true,
+               AllowTrash:     true,
        }},
        "keep3.zzzzz.arvadosapi.com:25107": {{
-               UUID:     "zzzzz-ivpuk-300000000000000",
-               DeviceID: "keep3-vol0",
+               UUID:           "zzzzz-ivpuk-300000000000000",
+               DeviceID:       "keep3-vol0",
+               StorageClasses: map[string]bool{"default": true},
+               AllowWrite:     true,
+               AllowTrash:     true,
        }},
 }
 
@@ -250,26 +262,32 @@ func (s *stubServer) serveKeepstoreMounts() *reqTracker {
 }
 
 func (s *stubServer) serveKeepstoreIndexFoo4Bar1() *reqTracker {
+       fooLine := func(mt int) string { return fmt.Sprintf("acbd18db4cc2f85cedef654fccc4a4d8+3 %d\n", 12345678+mt) }
+       barLine := "37b51d194a7513e45b56f6524f2d51f2+3 12345678\n"
        rt := &reqTracker{}
        s.mux.HandleFunc("/index/", func(w http.ResponseWriter, r *http.Request) {
                count := rt.Add(r)
-               if r.Host == "keep0.zzzzz.arvadosapi.com:25107" {
-                       io.WriteString(w, "37b51d194a7513e45b56f6524f2d51f2+3 12345678\n")
+               if r.Host == "keep0.zzzzz.arvadosapi.com:25107" && strings.HasPrefix(barLine, r.URL.Path[7:]) {
+                       io.WriteString(w, barLine)
                }
-               fmt.Fprintf(w, "acbd18db4cc2f85cedef654fccc4a4d8+3 %d\n\n", 12345678+count)
+               if strings.HasPrefix(fooLine(count), r.URL.Path[7:]) {
+                       io.WriteString(w, fooLine(count))
+               }
+               io.WriteString(w, "\n")
        })
        for _, mounts := range stubMounts {
                for i, mnt := range mounts {
                        i := i
                        s.mux.HandleFunc(fmt.Sprintf("/mounts/%s/blocks", mnt.UUID), func(w http.ResponseWriter, r *http.Request) {
                                count := rt.Add(r)
-                               if i == 0 && r.Host == "keep0.zzzzz.arvadosapi.com:25107" {
-                                       io.WriteString(w, "37b51d194a7513e45b56f6524f2d51f2+3 12345678\n")
+                               r.ParseForm()
+                               if i == 0 && r.Host == "keep0.zzzzz.arvadosapi.com:25107" && strings.HasPrefix(barLine, r.Form.Get("prefix")) {
+                                       io.WriteString(w, barLine)
                                }
-                               if i == 0 {
-                                       fmt.Fprintf(w, "acbd18db4cc2f85cedef654fccc4a4d8+3 %d\n", 12345678+count)
+                               if i == 0 && strings.HasPrefix(fooLine(count), r.Form.Get("prefix")) {
+                                       io.WriteString(w, fooLine(count))
                                }
-                               fmt.Fprintf(w, "\n")
+                               io.WriteString(w, "\n")
                        })
                }
        }
@@ -277,21 +295,44 @@ func (s *stubServer) serveKeepstoreIndexFoo4Bar1() *reqTracker {
 }
 
 func (s *stubServer) serveKeepstoreIndexFoo1() *reqTracker {
+       fooLine := "acbd18db4cc2f85cedef654fccc4a4d8+3 12345678\n"
        rt := &reqTracker{}
        s.mux.HandleFunc("/index/", func(w http.ResponseWriter, r *http.Request) {
                rt.Add(r)
-               io.WriteString(w, "acbd18db4cc2f85cedef654fccc4a4d8+3 12345678\n\n")
+               if r.Host == "keep0.zzzzz.arvadosapi.com:25107" && strings.HasPrefix(fooLine, r.URL.Path[7:]) {
+                       io.WriteString(w, fooLine)
+               }
+               io.WriteString(w, "\n")
        })
        for _, mounts := range stubMounts {
                for i, mnt := range mounts {
                        i := i
                        s.mux.HandleFunc(fmt.Sprintf("/mounts/%s/blocks", mnt.UUID), func(w http.ResponseWriter, r *http.Request) {
                                rt.Add(r)
-                               if i == 0 {
-                                       io.WriteString(w, "acbd18db4cc2f85cedef654fccc4a4d8+3 12345678\n\n")
-                               } else {
-                                       io.WriteString(w, "\n")
+                               if i == 0 && strings.HasPrefix(fooLine, r.Form.Get("prefix")) {
+                                       io.WriteString(w, fooLine)
                                }
+                               io.WriteString(w, "\n")
+                       })
+               }
+       }
+       return rt
+}
+
+func (s *stubServer) serveKeepstoreIndexIgnoringPrefix() *reqTracker {
+       fooLine := "acbd18db4cc2f85cedef654fccc4a4d8+3 12345678\n"
+       rt := &reqTracker{}
+       s.mux.HandleFunc("/index/", func(w http.ResponseWriter, r *http.Request) {
+               rt.Add(r)
+               io.WriteString(w, fooLine)
+               io.WriteString(w, "\n")
+       })
+       for _, mounts := range stubMounts {
+               for _, mnt := range mounts {
+                       s.mux.HandleFunc(fmt.Sprintf("/mounts/%s/blocks", mnt.UUID), func(w http.ResponseWriter, r *http.Request) {
+                               rt.Add(r)
+                               io.WriteString(w, fooLine)
+                               io.WriteString(w, "\n")
                        })
                }
        }
@@ -309,6 +350,7 @@ func (s *stubServer) serveKeepstorePull() *reqTracker {
 type runSuite struct {
        stub   stubServer
        config *arvados.Cluster
+       db     *sqlx.DB
        client *arvados.Client
 }
 
@@ -320,6 +362,7 @@ func (s *runSuite) newServer(options *RunOptions) *Server {
                Metrics:    newMetrics(prometheus.NewRegistry()),
                Logger:     options.Logger,
                Dumper:     options.Dumper,
+               DB:         s.db,
        }
        return srv
 }
@@ -329,6 +372,8 @@ func (s *runSuite) SetUpTest(c *check.C) {
        c.Assert(err, check.Equals, nil)
        s.config, err = cfg.GetCluster("")
        c.Assert(err, check.Equals, nil)
+       s.db, err = sqlx.Open("postgres", s.config.PostgreSQL.Connection.String())
+       c.Assert(err, check.IsNil)
 
        s.config.Collections.BalancePeriod = arvados.Duration(time.Second)
        arvadostest.SetServiceURL(&s.config.Services.Keepbalance, "http://localhost:/")
@@ -347,10 +392,11 @@ func (s *runSuite) TearDownTest(c *check.C) {
 }
 
 func (s *runSuite) TestRefuseZeroCollections(c *check.C) {
+       defer arvados.NewClientFromEnv().RequestAndDecode(nil, "POST", "database/reset", nil, nil)
+       _, err := s.db.Exec(`delete from collections`)
+       c.Assert(err, check.IsNil)
        opts := RunOptions{
-               CommitPulls: true,
-               CommitTrash: true,
-               Logger:      ctxlog.TestLogger(c),
+               Logger: ctxlog.TestLogger(c),
        }
        s.stub.serveCurrentUserAdmin()
        s.stub.serveZeroCollections()
@@ -360,18 +406,37 @@ func (s *runSuite) TestRefuseZeroCollections(c *check.C) {
        trashReqs := s.stub.serveKeepstoreTrash()
        pullReqs := s.stub.serveKeepstorePull()
        srv := s.newServer(&opts)
-       _, err := srv.runOnce()
+       _, err = srv.runOnce(context.Background())
        c.Check(err, check.ErrorMatches, "received zero collections")
        c.Check(trashReqs.Count(), check.Equals, 4)
        c.Check(pullReqs.Count(), check.Equals, 0)
 }
 
-func (s *runSuite) TestRefuseNonAdmin(c *check.C) {
+func (s *runSuite) TestRefuseBadIndex(c *check.C) {
        opts := RunOptions{
-               CommitPulls: true,
-               CommitTrash: true,
+               ChunkPrefix: "abc",
                Logger:      ctxlog.TestLogger(c),
        }
+       s.stub.serveCurrentUserAdmin()
+       s.stub.serveFooBarFileCollections()
+       s.stub.serveKeepServices(stubServices)
+       s.stub.serveKeepstoreMounts()
+       s.stub.serveKeepstoreIndexIgnoringPrefix()
+       trashReqs := s.stub.serveKeepstoreTrash()
+       pullReqs := s.stub.serveKeepstorePull()
+       srv := s.newServer(&opts)
+       bal, err := srv.runOnce(context.Background())
+       c.Check(err, check.ErrorMatches, ".*Index response included block .* despite asking for prefix \"abc\"")
+       c.Check(trashReqs.Count(), check.Equals, 4)
+       c.Check(pullReqs.Count(), check.Equals, 0)
+       c.Check(bal.stats.trashes, check.Equals, 0)
+       c.Check(bal.stats.pulls, check.Equals, 0)
+}
+
+func (s *runSuite) TestRefuseNonAdmin(c *check.C) {
+       opts := RunOptions{
+               Logger: ctxlog.TestLogger(c),
+       }
        s.stub.serveCurrentUserNotAdmin()
        s.stub.serveZeroCollections()
        s.stub.serveKeepServices(stubServices)
@@ -379,29 +444,62 @@ func (s *runSuite) TestRefuseNonAdmin(c *check.C) {
        trashReqs := s.stub.serveKeepstoreTrash()
        pullReqs := s.stub.serveKeepstorePull()
        srv := s.newServer(&opts)
-       _, err := srv.runOnce()
+       _, err := srv.runOnce(context.Background())
        c.Check(err, check.ErrorMatches, "current user .* is not .* admin user")
        c.Check(trashReqs.Count(), check.Equals, 0)
        c.Check(pullReqs.Count(), check.Equals, 0)
 }
 
-func (s *runSuite) TestDetectSkippedCollections(c *check.C) {
+func (s *runSuite) TestInvalidChunkPrefix(c *check.C) {
+       for _, trial := range []struct {
+               prefix string
+               errRe  string
+       }{
+               {"123ABC", "invalid char \"A\" in chunk prefix.*"},
+               {"123xyz", "invalid char \"x\" in chunk prefix.*"},
+               {"123456789012345678901234567890123", "invalid chunk prefix .* longer than a block hash"},
+       } {
+               s.SetUpTest(c)
+               c.Logf("trying invalid prefix %q", trial.prefix)
+               opts := RunOptions{
+                       ChunkPrefix: trial.prefix,
+                       Logger:      ctxlog.TestLogger(c),
+               }
+               s.stub.serveCurrentUserAdmin()
+               s.stub.serveFooBarFileCollections()
+               s.stub.serveKeepServices(stubServices)
+               s.stub.serveKeepstoreMounts()
+               trashReqs := s.stub.serveKeepstoreTrash()
+               pullReqs := s.stub.serveKeepstorePull()
+               srv := s.newServer(&opts)
+               _, err := srv.runOnce(context.Background())
+               c.Check(err, check.ErrorMatches, trial.errRe)
+               c.Check(trashReqs.Count(), check.Equals, 0)
+               c.Check(pullReqs.Count(), check.Equals, 0)
+       }
+}
+
+func (s *runSuite) TestRefuseSameDeviceDifferentVolumes(c *check.C) {
        opts := RunOptions{
-               CommitPulls: true,
-               CommitTrash: true,
-               Logger:      ctxlog.TestLogger(c),
+               Logger: ctxlog.TestLogger(c),
        }
        s.stub.serveCurrentUserAdmin()
-       s.stub.serveCollectionsButSkipOne()
+       s.stub.serveZeroCollections()
        s.stub.serveKeepServices(stubServices)
-       s.stub.serveKeepstoreMounts()
-       s.stub.serveKeepstoreIndexFoo4Bar1()
+       s.stub.mux.HandleFunc("/mounts", func(w http.ResponseWriter, r *http.Request) {
+               hostid := r.Host[:5] // "keep0.zzzzz.arvadosapi.com:25107" => "keep0"
+               json.NewEncoder(w).Encode([]arvados.KeepMount{{
+                       UUID:           "zzzzz-ivpuk-0000000000" + hostid,
+                       DeviceID:       "keep0-vol0",
+                       StorageClasses: map[string]bool{"default": true},
+               }})
+       })
        trashReqs := s.stub.serveKeepstoreTrash()
        pullReqs := s.stub.serveKeepstorePull()
        srv := s.newServer(&opts)
-       _, err := srv.runOnce()
-       c.Check(err, check.ErrorMatches, `Retrieved 2 collections with modtime <= .* but server now reports there are 3 collections.*`)
-       c.Check(trashReqs.Count(), check.Equals, 4)
+       _, err := srv.runOnce(context.Background())
+       c.Check(err, check.ErrorMatches, "cannot continue with config errors.*")
+       c.Check(trashReqs.Count(), check.Equals, 0)
        c.Check(pullReqs.Count(), check.Equals, 0)
 }
 
@@ -411,9 +509,7 @@ func (s *runSuite) TestWriteLostBlocks(c *check.C) {
        s.config.Collections.BlobMissingReport = lostf.Name()
        defer os.Remove(lostf.Name())
        opts := RunOptions{
-               CommitPulls: true,
-               CommitTrash: true,
-               Logger:      ctxlog.TestLogger(c),
+               Logger: ctxlog.TestLogger(c),
        }
        s.stub.serveCurrentUserAdmin()
        s.stub.serveFooBarFileCollections()
@@ -424,18 +520,18 @@ func (s *runSuite) TestWriteLostBlocks(c *check.C) {
        s.stub.serveKeepstorePull()
        srv := s.newServer(&opts)
        c.Assert(err, check.IsNil)
-       _, err = srv.runOnce()
+       _, err = srv.runOnce(context.Background())
        c.Check(err, check.IsNil)
        lost, err := ioutil.ReadFile(lostf.Name())
        c.Assert(err, check.IsNil)
-       c.Check(string(lost), check.Equals, "37b51d194a7513e45b56f6524f2d51f2 fa7aeb5140e2848d39b416daeef4ffc5+45\n")
+       c.Check(string(lost), check.Matches, `(?ms).*37b51d194a7513e45b56f6524f2d51f2.* fa7aeb5140e2848d39b416daeef4ffc5\+45.*`)
 }
 
 func (s *runSuite) TestDryRun(c *check.C) {
+       s.config.Collections.BalanceTrashLimit = 0
+       s.config.Collections.BalancePullLimit = 0
        opts := RunOptions{
-               CommitPulls: false,
-               CommitTrash: false,
-               Logger:      ctxlog.TestLogger(c),
+               Logger: ctxlog.TestLogger(c),
        }
        s.stub.serveCurrentUserAdmin()
        collReqs := s.stub.serveFooBarFileCollections()
@@ -445,7 +541,7 @@ func (s *runSuite) TestDryRun(c *check.C) {
        trashReqs := s.stub.serveKeepstoreTrash()
        pullReqs := s.stub.serveKeepstorePull()
        srv := s.newServer(&opts)
-       bal, err := srv.runOnce()
+       bal, err := srv.runOnce(context.Background())
        c.Check(err, check.IsNil)
        for _, req := range collReqs.reqs {
                c.Check(req.Form.Get("include_trash"), check.Equals, "true")
@@ -453,23 +549,20 @@ func (s *runSuite) TestDryRun(c *check.C) {
        }
        c.Check(trashReqs.Count(), check.Equals, 0)
        c.Check(pullReqs.Count(), check.Equals, 0)
-       c.Check(bal.stats.pulls, check.Not(check.Equals), 0)
+       c.Check(bal.stats.pulls, check.Equals, 0)
+       c.Check(bal.stats.pullsDeferred, check.Not(check.Equals), 0)
+       c.Check(bal.stats.trashes, check.Equals, 0)
+       c.Check(bal.stats.trashesDeferred, check.Not(check.Equals), 0)
        c.Check(bal.stats.underrep.replicas, check.Not(check.Equals), 0)
        c.Check(bal.stats.overrep.replicas, check.Not(check.Equals), 0)
 }
 
 func (s *runSuite) TestCommit(c *check.C) {
-       lostf, err := ioutil.TempFile("", "keep-balance-lost-blocks-test-")
-       c.Assert(err, check.IsNil)
-       s.config.Collections.BlobMissingReport = lostf.Name()
-       defer os.Remove(lostf.Name())
-
+       s.config.Collections.BlobMissingReport = c.MkDir() + "/keep-balance-lost-blocks-test-"
        s.config.ManagementToken = "xyzzy"
        opts := RunOptions{
-               CommitPulls: true,
-               CommitTrash: true,
-               Logger:      ctxlog.TestLogger(c),
-               Dumper:      ctxlog.TestLogger(c),
+               Logger: ctxlog.TestLogger(c),
+               Dumper: ctxlog.TestLogger(c),
        }
        s.stub.serveCurrentUserAdmin()
        s.stub.serveFooBarFileCollections()
@@ -479,7 +572,7 @@ func (s *runSuite) TestCommit(c *check.C) {
        trashReqs := s.stub.serveKeepstoreTrash()
        pullReqs := s.stub.serveKeepstorePull()
        srv := s.newServer(&opts)
-       bal, err := srv.runOnce()
+       bal, err := srv.runOnce(context.Background())
        c.Check(err, check.IsNil)
        c.Check(trashReqs.Count(), check.Equals, 8)
        c.Check(pullReqs.Count(), check.Equals, 4)
@@ -489,26 +582,52 @@ func (s *runSuite) TestCommit(c *check.C) {
        // in a poor rendezvous position
        c.Check(bal.stats.pulls, check.Equals, 2)
 
-       lost, err := ioutil.ReadFile(lostf.Name())
+       lost, err := ioutil.ReadFile(s.config.Collections.BlobMissingReport)
        c.Assert(err, check.IsNil)
-       c.Check(string(lost), check.Equals, "")
+       c.Check(string(lost), check.Not(check.Matches), `(?ms).*acbd18db4cc2f85cedef654fccc4a4d8.*`)
 
-       buf, err := s.getMetrics(c, srv)
+       metrics := arvadostest.GatherMetricsAsString(srv.Metrics.reg)
+       c.Check(metrics, check.Matches, `(?ms).*\narvados_keep_total_bytes 15\n.*`)
+       c.Check(metrics, check.Matches, `(?ms).*\narvados_keepbalance_changeset_compute_seconds_sum [0-9\.]+\n.*`)
+       c.Check(metrics, check.Matches, `(?ms).*\narvados_keepbalance_changeset_compute_seconds_count 1\n.*`)
+       c.Check(metrics, check.Matches, `(?ms).*\narvados_keep_dedup_byte_ratio [1-9].*`)
+       c.Check(metrics, check.Matches, `(?ms).*\narvados_keep_dedup_block_ratio [1-9].*`)
+}
+
+func (s *runSuite) TestChunkPrefix(c *check.C) {
+       s.config.Collections.BlobMissingReport = c.MkDir() + "/keep-balance-lost-blocks-test-"
+       opts := RunOptions{
+               ChunkPrefix: "ac", // catch "foo" but not "bar"
+               Logger:      ctxlog.TestLogger(c),
+               Dumper:      ctxlog.TestLogger(c),
+       }
+       s.stub.serveCurrentUserAdmin()
+       s.stub.serveFooBarFileCollections()
+       s.stub.serveKeepServices(stubServices)
+       s.stub.serveKeepstoreMounts()
+       s.stub.serveKeepstoreIndexFoo4Bar1()
+       trashReqs := s.stub.serveKeepstoreTrash()
+       pullReqs := s.stub.serveKeepstorePull()
+       srv := s.newServer(&opts)
+       bal, err := srv.runOnce(context.Background())
        c.Check(err, check.IsNil)
-       c.Check(buf, check.Matches, `(?ms).*\narvados_keep_total_bytes 15\n.*`)
-       c.Check(buf, check.Matches, `(?ms).*\narvados_keepbalance_changeset_compute_seconds_sum [0-9\.]+\n.*`)
-       c.Check(buf, check.Matches, `(?ms).*\narvados_keepbalance_changeset_compute_seconds_count 1\n.*`)
-       c.Check(buf, check.Matches, `(?ms).*\narvados_keep_dedup_byte_ratio 1\.5\n.*`)
-       c.Check(buf, check.Matches, `(?ms).*\narvados_keep_dedup_block_ratio 1\.5\n.*`)
+       c.Check(trashReqs.Count(), check.Equals, 8)
+       c.Check(pullReqs.Count(), check.Equals, 4)
+       // "foo" block is overreplicated by 2
+       c.Check(bal.stats.trashes, check.Equals, 2)
+       // "bar" block is underreplicated but does not match prefix
+       c.Check(bal.stats.pulls, check.Equals, 0)
+
+       lost, err := ioutil.ReadFile(s.config.Collections.BlobMissingReport)
+       c.Assert(err, check.IsNil)
+       c.Check(string(lost), check.Equals, "")
 }
 
 func (s *runSuite) TestRunForever(c *check.C) {
        s.config.ManagementToken = "xyzzy"
        opts := RunOptions{
-               CommitPulls: true,
-               CommitTrash: true,
-               Logger:      ctxlog.TestLogger(c),
-               Dumper:      ctxlog.TestLogger(c),
+               Logger: ctxlog.TestLogger(c),
+               Dumper: ctxlog.TestLogger(c),
        }
        s.stub.serveCurrentUserAdmin()
        s.stub.serveFooBarFileCollections()
@@ -518,13 +637,14 @@ func (s *runSuite) TestRunForever(c *check.C) {
        trashReqs := s.stub.serveKeepstoreTrash()
        pullReqs := s.stub.serveKeepstorePull()
 
-       stop := make(chan interface{})
+       ctx, cancel := context.WithCancel(context.Background())
+       defer cancel()
        s.config.Collections.BalancePeriod = arvados.Duration(time.Millisecond)
        srv := s.newServer(&opts)
 
        done := make(chan bool)
        go func() {
-               srv.runForever(stop)
+               srv.runForever(ctx)
                close(done)
        }()
 
@@ -532,31 +652,17 @@ func (s *runSuite) TestRunForever(c *check.C) {
        // first run should also send 4 empty trash lists at
        // startup. We should complete all four runs in much less than
        // a second.
-       for t0 := time.Now(); pullReqs.Count() < 16 && time.Since(t0) < 10*time.Second; {
+       for t0 := time.Now(); time.Since(t0) < 10*time.Second; {
+               if pullReqs.Count() >= 16 && trashReqs.Count() == pullReqs.Count()+4 {
+                       break
+               }
                time.Sleep(time.Millisecond)
        }
-       stop <- true
+       cancel()
        <-done
        c.Check(pullReqs.Count() >= 16, check.Equals, true)
        c.Check(trashReqs.Count(), check.Equals, pullReqs.Count()+4)
 
-       buf, err := s.getMetrics(c, srv)
-       c.Check(err, check.IsNil)
-       c.Check(buf, check.Matches, `(?ms).*\narvados_keepbalance_changeset_compute_seconds_count `+fmt.Sprintf("%d", pullReqs.Count()/4)+`\n.*`)
-}
-
-func (s *runSuite) getMetrics(c *check.C, srv *Server) (*bytes.Buffer, error) {
-       mfs, err := srv.Metrics.reg.Gather()
-       if err != nil {
-               return nil, err
-       }
-
-       var buf bytes.Buffer
-       for _, mf := range mfs {
-               if _, err := expfmt.MetricFamilyToText(&buf, mf); err != nil {
-                       return nil, err
-               }
-       }
-
-       return &buf, nil
+       metrics := arvadostest.GatherMetricsAsString(srv.Metrics.reg)
+       c.Check(metrics, check.Matches, `(?ms).*\narvados_keepbalance_changeset_compute_seconds_count `+fmt.Sprintf("%d", pullReqs.Count()/4)+`\n.*`)
 }