PMM-11727: make promscrape.maxScrapeSize 64MiB by default, allow over…

…ride via ENV (#1862)

managed/services/agents/vmagent.go

@@ -16,19 +16,31 @@
 package agents
 
 import (
+	"os"
 	"sort"
 
 	"github.com/percona/pmm/api/agentpb"
 	"github.com/percona/pmm/api/inventorypb"
 )
 
+var (
+	maxScrapeSizeEnv     = "PMM_PROMSCRAPE_MAX_SCRAPE_SIZE"
+	maxScrapeSizeDefault = "64MiB"
+)
+
 // vmAgentConfig returns desired configuration of vmagent process.
 func vmAgentConfig(scrapeCfg string) *agentpb.SetStateRequest_AgentProcess {
+	maxScrapeSize := maxScrapeSizeDefault
+	if space := os.Getenv(maxScrapeSizeEnv); space != "" {
+		maxScrapeSize = space
+	}
+
 	args := []string{
 		"-remoteWrite.url={{.server_url}}/victoriametrics/api/v1/write",
 		"-remoteWrite.tlsInsecureSkipVerify={{.server_insecure}}",
 		"-remoteWrite.tmpDataPath={{.tmp_dir}}/vmagent-temp-dir",
 		"-promscrape.config={{.TextFiles.vmagentscrapecfg}}",
+		"-promscrape.maxScrapeSize=" + maxScrapeSize,
 		// 1GB disk queue size.
 		"-remoteWrite.maxDiskUsagePerURL=1073741824",
 		"-loggerLevel=INFO",

managed/services/agents/vmagent_test.go

@@ -0,0 +1,35 @@
+// Copyright (C) 2017 Percona LLC
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program. If not, see <https://www.gnu.org/licenses/>.
+
+package agents
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestMaxScrapeSize(t *testing.T) {
+	t.Run("by default 64MiB", func(t *testing.T) {
+		actual := vmAgentConfig("")
+		assert.Contains(t, actual.Args, "-promscrape.maxScrapeSize="+maxScrapeSizeDefault)
+	})
+	t.Run("overridden with ENV", func(t *testing.T) {
+		newValue := "16MiB"
+		t.Setenv(maxScrapeSizeEnv, newValue)
+		actual := vmAgentConfig("")
+		assert.Contains(t, actual.Args, "-promscrape.maxScrapeSize="+newValue)
+	})
+}