PMM-13082 Backwards compatibility with PMM v2 (#3227)

* PMM-13082 Backward-compatibility with PMM 2 Client.

* PMM-13082 Strip prefixes, revert changes to collector.proto

* PMM-13082 remove unused proto imports

* PMM-13082 renumber agent_status.proto fields

* PMM-13082 fix the lint rules for pb/agent.proto pkg

* PMM-13082 fix the proto field numbers for AGENT_TYPE

* PMM-13082 fix the function comment

* PMM-13082 revert stripping the IDs

* PMM-13082 revert the text fix

* PMM-13082 revert slowlog_test fix

* PMM-13082 re-generate the code

* PMM-13082 fix agent_type in slowlog_test payload

* PMM-13082 leave a TODO comment

---------

Co-authored-by: Nurlan Moldomurov <[email protected]>

agent/agents/mongodb/internal/profiler/profiler_test.go

@@ -185,7 +185,7 @@ func testProfiler(t *testing.T, url string) {
 		assert.Equal(t, "INSERT people", bucket.Common.Fingerprint)
 		assert.Equal(t, []string{"people"}, bucket.Common.Tables)
 		assert.Equal(t, "test-id", bucket.Common.AgentId)
-		assert.Equal(t, inventoryv1.AgentType(10), bucket.Common.AgentType)
+		assert.Equal(t, inventoryv1.AgentType(9), bucket.Common.AgentType)
 		expected := &agentv1.MetricsBucket_MongoDB{
 			MDocsReturnedCnt:   docsCount,
 			MResponseLengthCnt: docsCount,

agent/agents/mysql/slowlog/slowlog_expected.json

@@ -7,7 +7,7 @@
 			"fingerprint": "select name, subsystem, type, comment, count from information_schema.innodb_metrics where status = ?",
 			"username": "root",
 			"agent_id": "73ee2f92-d5aa-45f0-8b09-6d3df605fd44",
-			"agent_type": 9,
+			"agent_type": 8,
 			"period_start_unix_secs": 1557137220,
 			"period_length_secs": 60,
 			"example": "SELECT\n\t\t  name, subsystem, type, comment,\n\t\t  count\n\t\t  FROM information_schema.innodb_metrics\n\t\t  WHERE status = 'enabled'",
@@ -52,7 +52,7 @@
 			"schema": "sbtest",
 			"username": "root",
 			"agent_id": "73ee2f92-d5aa-45f0-8b09-6d3df605fd44",
-			"agent_type": 9,
+			"agent_type": 8,
 			"period_start_unix_secs": 1557137220,
 			"period_length_secs": 60,
 			"example": "SELECT pad FROM sbtest1 WHERE id=775815",
@@ -95,7 +95,7 @@
 			"fingerprint": "ping",
 			"username": "root",
 			"agent_id": "73ee2f92-d5aa-45f0-8b09-6d3df605fd44",
-			"agent_type": 9,
+			"agent_type": 8,
 			"period_start_unix_secs": 1557137220,
 			"period_length_secs": 60,
 			"example": "Ping",
@@ -126,7 +126,7 @@
 			"fingerprint": "show global status",
 			"username": "root",
 			"agent_id": "73ee2f92-d5aa-45f0-8b09-6d3df605fd44",
-			"agent_type": 9,
+			"agent_type": 8,
 			"period_start_unix_secs": 1557137220,
 			"period_length_secs": 60,
 			"example": "SHOW GLOBAL STATUS",
@@ -170,7 +170,7 @@
 			"fingerprint": "set lock_wait_timeout=?",
 			"username": "root",
 			"agent_id": "73ee2f92-d5aa-45f0-8b09-6d3df605fd44",
-			"agent_type": 9,
+			"agent_type": 8,
 			"period_start_unix_secs": 1557137220,
 			"period_length_secs": 60,
 			"example": "SET lock_wait_timeout=2",
@@ -201,7 +201,7 @@
 			"fingerprint": "select @@version",
 			"username": "root",
 			"agent_id": "73ee2f92-d5aa-45f0-8b09-6d3df605fd44",
-			"agent_type": 9,
+			"agent_type": 8,
 			"period_start_unix_secs": 1557137220,
 			"period_length_secs": 60,
 			"example": "SELECT @@version",

api/agent/pb/agent.proto

@@ -0,0 +1,13 @@
+syntax = "proto3";
+
+package agent;
+
+import "agent/v1/agent.proto";
+
+option go_package = "api/agentpb;agentpb";
+
+// Agent service provides private methods for pmm-agent <-> pmm-managed interactions.
+service Agent {
+  // Connect establishes two-way communication channel between pmm-agent and pmm-managed.
+  rpc Connect(stream agent.v1.AgentMessage) returns (stream agent.v1.ServerMessage);
+}