From 51aabb929ac9f0f5821b00c8f66f7db796208b77 Mon Sep 17 00:00:00 2001
From: Pavel Nemirovsky <pavelnemirovsky@icloud.com>
Date: Wed, 12 May 2021 22:23:21 +0300
Subject: [PATCH 01/16] Adjusted logic

---
 proxy.go |  5 +++--
 scope.go | 28 +++++++++++++++++++++++-----
 utils.go | 13 +++++++++++++
 3 files changed, 39 insertions(+), 7 deletions(-)

diff --git a/proxy.go b/proxy.go
index 9ce26dbf..eb24ce71 100644
--- a/proxy.go
+++ b/proxy.go
@@ -435,7 +435,7 @@ func (rp *reverseProxy) applyConfig(cfg *config.Config) error {
 	return nil
 }
 
-// refreshCacheMetrics refresehs cacheSize and cacheItems metrics.
+// refreshCacheMetrics refreshes cacheSize and cacheItems metrics.
 func (rp *reverseProxy) refreshCacheMetrics() {
 	rp.lock.RLock()
 	defer rp.lock.RUnlock()
@@ -452,7 +452,7 @@ func (rp *reverseProxy) refreshCacheMetrics() {
 
 func (rp *reverseProxy) getScope(req *http.Request) (*scope, int, error) {
 	name, password := getAuth(req)
-
+	sessionId := getSessionId(req)
 	var (
 		u  *user
 		c  *cluster
@@ -467,6 +467,7 @@ func (rp *reverseProxy) getScope(req *http.Request) (*scope, int, error) {
 		// Fix applyConfig if c or cu equal to nil.
 		c = rp.clusters[u.toCluster]
 		cu = c.users[u.toUser]
+		c.sessionId = sessionId
 	}
 	rp.lock.RUnlock()
 
diff --git a/scope.go b/scope.go
index c5701dba..a750ebfa 100644
--- a/scope.go
+++ b/scope.go
@@ -19,6 +19,8 @@ import (
 	"github.com/prometheus/client_golang/prometheus"
 )
 
+// var route = make(map[int]*host)
+
 type scopeID uint64
 
 func (sid scopeID) String() string {
@@ -305,6 +307,8 @@ var allowedParams = []string{
 	"extremes",
 	// what to do if the volume of the result exceeds one of the limits
 	"result_overflow_mode",
+	// session stickiness
+	"session_id",
 }
 
 // This regexp must match params needed to describe a way to use external data
@@ -718,6 +722,8 @@ type cluster struct {
 	killQueryUserName     string
 	killQueryUserPassword string
 
+	sessionId string
+
 	heartBeat *heartBeat
 }
 
@@ -829,18 +835,30 @@ func (r *replica) getHost() *host {
 		reqs = ^uint32(0)
 	}
 
-	if reqs == 0 {
-		return h
-	}
-
 	// Scan all the hosts for the least loaded host.
 	for i := uint32(1); i < n; i++ {
 		tmpIdx := (idx + i) % n
 		tmpH := r.hosts[tmpIdx]
+
+		// handling sticky session
+		if r.cluster.sessionId != "" {
+			sessionId := hash(r.cluster.sessionId)
+			tmpIdx = (sessionId) % n
+			tmpHSticky := r.hosts[tmpIdx]
+			if !tmpHSticky.isActive() {
+				log.Debugf("Sticky Session Server has been picked up but not available")
+				continue
+			}
+			log.Debugf("Sticky Session Server is: %s, session: %d, idx mod: %d - %d", tmpH.addr, sessionId, tmpIdx, n)
+			return tmpH
+		}
+
+		// continue as usual
+		tmpReqs := tmpH.load()
+
 		if !tmpH.isActive() {
 			continue
 		}
-		tmpReqs := tmpH.load()
 		if tmpReqs == 0 {
 			return tmpH
 		}
diff --git a/utils.go b/utils.go
index b14c0d62..58474fa0 100644
--- a/utils.go
+++ b/utils.go
@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"compress/gzip"
 	"fmt"
+	"hash/fnv"
 	"io"
 	"io/ioutil"
 	"net/http"
@@ -43,6 +44,12 @@ func getAuth(req *http.Request) (string, string) {
 	return "default", ""
 }
 
+// getSessionId retrieves session id
+func getSessionId(req *http.Request) string {
+	params := req.URL.Query()
+	return params.Get("session_id")
+}
+
 // getQuerySnippet returns query snippet.
 //
 // getQuerySnippet must be called only for error reporting.
@@ -57,6 +64,12 @@ func getQuerySnippet(req *http.Request) string {
 	return query + body
 }
 
+func hash(s string) uint32 {
+	h := fnv.New32a()
+	h.Write([]byte(s))
+	return h.Sum32()
+}
+
 func getQuerySnippetFromBody(req *http.Request) string {
 	if req.Body == nil {
 		return ""

From 8d905da242b8cd951a8981b9221bc17539647a45 Mon Sep 17 00:00:00 2001
From: Pavel Nemirovsky <pavelnemirovsky@icloud.com>
Date: Wed, 12 May 2021 23:54:49 +0300
Subject: [PATCH 02/16] Error handling

---
 scope.go | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/scope.go b/scope.go
index a750ebfa..fa94b4c5 100644
--- a/scope.go
+++ b/scope.go
@@ -846,14 +846,14 @@ func (r *replica) getHost() *host {
 			tmpIdx = (sessionId) % n
 			tmpHSticky := r.hosts[tmpIdx]
 			if !tmpHSticky.isActive() {
-				log.Debugf("Sticky Session Server has been picked up but not available")
+				log.Debugf("Sticky Session Server has been picked up, but it is not available")
 				continue
 			}
 			log.Debugf("Sticky Session Server is: %s, session: %d, idx mod: %d - %d", tmpH.addr, sessionId, tmpIdx, n)
 			return tmpH
 		}
 
-		// continue as usual
+		// handling least loaded host flow
 		tmpReqs := tmpH.load()
 
 		if !tmpH.isActive() {

From 669e5a7959eca3e5323cae9be86d0a52948c119a Mon Sep 17 00:00:00 2001
From: Pavel Nemirovsky <pavelnemirovsky@icloud.com>
Date: Thu, 13 May 2021 01:03:15 +0300
Subject: [PATCH 03/16] tests

---
 main_test.go                 | 22 ++++++++++++++++++++++
 proxy.go                     |  4 ++--
 testdata/http-session-id.yml | 15 +++++++++++++++
 utils.go                     |  4 +++-
 4 files changed, 42 insertions(+), 3 deletions(-)
 create mode 100644 testdata/http-session-id.yml

diff --git a/main_test.go b/main_test.go
index 6492585e..0e626461 100644
--- a/main_test.go
+++ b/main_test.go
@@ -284,6 +284,28 @@ func TestServe(t *testing.T) {
 			},
 			startHTTP,
 		},
+		{
+			"http POST request with session id",
+			"testdata/http-session-id.yml",
+			func(t *testing.T) {
+				// buf := bytes.NewBufferString("SELECT * FROM system.numbers LIMIT 10")
+				data := url.Values{}
+				data.Set("query", `SELECT * FROM system.numbers LIMIT 10`)
+				data.Add("session_id", "1234")
+				data.Add("query_id", "1234")
+				req, err := http.NewRequest("POST", "http://127.0.0.1:9090/", bytes.NewBufferString(data.Encode()))
+				req.Header.Set("Content-Type", "application/x-www-form-urlencoded; param=value") // This makes it work
+
+				checkErr(t, err)
+				resp, err := http.DefaultClient.Do(req)
+				checkErr(t, err)
+				if resp.StatusCode != http.StatusOK {
+					t.Fatalf("unexpected status code: %d; expected: %d", resp.StatusCode, http.StatusOK)
+				}
+				resp.Body.Close()
+			},
+			startHTTP,
+		},
 		{
 			"http request",
 			"testdata/http.yml",
diff --git a/proxy.go b/proxy.go
index eb24ce71..a893f8ed 100644
--- a/proxy.go
+++ b/proxy.go
@@ -110,9 +110,9 @@ func (rp *reverseProxy) ServeHTTP(rw http.ResponseWriter, req *http.Request) {
 	q := getQuerySnippet(req)
 	if srw.statusCode == http.StatusOK {
 		requestSuccess.With(s.labels).Inc()
-		log.Debugf("%s: request success; query: %q; URL: %q", s, q, req.URL.String())
+		log.Debugf("%s: request success; query: %q; Method: %s; URL: %q", s, q, req.Method, req.URL.String())
 	} else {
-		log.Debugf("%s: request failure: non-200 status code %d; query: %q; URL: %q", s, srw.statusCode, q, req.URL.String())
+		log.Debugf("%s: request failure: non-200 status code %d; query: %q; Method: %s; URL: %q", s, srw.statusCode, q, req.Method, req.URL.String())
 	}
 
 	statusCodes.With(
diff --git a/testdata/http-session-id.yml b/testdata/http-session-id.yml
new file mode 100644
index 00000000..2c00146d
--- /dev/null
+++ b/testdata/http-session-id.yml
@@ -0,0 +1,15 @@
+log_debug: true
+server:
+  http:
+      listen_addr: ":9090"
+      allowed_networks: ["127.0.0.1/24"]
+
+users:
+  - name: "default"
+    to_cluster: "default"
+    to_user: "default"
+
+clusters:
+  - name: "default"
+    nodes:
+      - 127.0.0.1:8124
diff --git a/utils.go b/utils.go
index 58474fa0..55290631 100644
--- a/utils.go
+++ b/utils.go
@@ -47,7 +47,9 @@ func getAuth(req *http.Request) (string, string) {
 // getSessionId retrieves session id
 func getSessionId(req *http.Request) string {
 	params := req.URL.Query()
-	return params.Get("session_id")
+	sessionId := params.Get("session_id")
+	req.Header.Set("X-ClickHouse-Session-ID", sessionId)
+	return sessionId
 }
 
 // getQuerySnippet returns query snippet.

From 881b17a499260c38428e1ac935b68ed48ad45e84 Mon Sep 17 00:00:00 2001
From: Pavel Nemirovsky <pavelnemirovsky@icloud.com>
Date: Thu, 13 May 2021 12:55:20 +0300
Subject: [PATCH 04/16] Adjust

---
 proxy.go |  7 ++---
 scope.go | 78 +++++++++++++++++++++++++++++++++++++++++---------------
 utils.go |  1 -
 3 files changed, 62 insertions(+), 24 deletions(-)

diff --git a/proxy.go b/proxy.go
index a893f8ed..2c18f61c 100644
--- a/proxy.go
+++ b/proxy.go
@@ -51,8 +51,10 @@ func newReverseProxy() *reverseProxy {
 
 func (rp *reverseProxy) ServeHTTP(rw http.ResponseWriter, req *http.Request) {
 	startTime := time.Now()
-
 	s, status, err := rp.getScope(req)
+	if s.sessionId != "" {
+		rw.Header().Set("X-ClickHouse-Session-Id", s.sessionId)
+	}
 	if err != nil {
 		q := getQuerySnippet(req)
 		err = fmt.Errorf("%q: %s; query: %q", req.RemoteAddr, err, q)
@@ -467,7 +469,6 @@ func (rp *reverseProxy) getScope(req *http.Request) (*scope, int, error) {
 		// Fix applyConfig if c or cu equal to nil.
 		c = rp.clusters[u.toCluster]
 		cu = c.users[u.toUser]
-		c.sessionId = sessionId
 	}
 	rp.lock.RUnlock()
 
@@ -490,6 +491,6 @@ func (rp *reverseProxy) getScope(req *http.Request) (*scope, int, error) {
 		return nil, http.StatusForbidden, fmt.Errorf("cluster user %q is not allowed to access", cu.name)
 	}
 
-	s := newScope(req, u, c, cu)
+	s := newScope(req, u, c, cu, sessionId)
 	return s, 0, nil
 }
diff --git a/scope.go b/scope.go
index fa94b4c5..75a377d5 100644
--- a/scope.go
+++ b/scope.go
@@ -42,6 +42,8 @@ type scope struct {
 	user        *user
 	clusterUser *clusterUser
 
+	sessionId string
+
 	remoteAddr string
 	localAddr  string
 
@@ -51,9 +53,12 @@ type scope struct {
 	labels prometheus.Labels
 }
 
-func newScope(req *http.Request, u *user, c *cluster, cu *clusterUser) *scope {
-	h := c.getHost()
+func newScope(req *http.Request, u *user, c *cluster, cu *clusterUser, sessionId string) *scope {
 
+	h := c.getHost()
+	if sessionId != "" {
+		h = c.getHostSticky(sessionId)
+	}
 	var localAddr string
 	if addr, ok := req.Context().Value(http.LocalAddrContextKey).(net.Addr); ok {
 		localAddr = addr.String()
@@ -65,6 +70,7 @@ func newScope(req *http.Request, u *user, c *cluster, cu *clusterUser) *scope {
 		cluster:     c,
 		user:        u,
 		clusterUser: cu,
+		sessionId:   sessionId,
 
 		remoteAddr: req.RemoteAddr,
 		localAddr:  localAddr,
@@ -722,8 +728,6 @@ type cluster struct {
 	killQueryUserName     string
 	killQueryUserPassword string
 
-	sessionId string
-
 	heartBeat *heartBeat
 }
 
@@ -816,10 +820,10 @@ func (c *cluster) getReplica() *replica {
 	return r
 }
 
-// getHost returns least loaded + round-robin host from replica.
+// getHostSticky returns host by stickiness from replica.
 //
 // Always returns non-nil.
-func (r *replica) getHost() *host {
+func (r *replica) getHostSticky(sessionId string) *host {
 	idx := atomic.AddUint32(&r.nextHostIdx, 1)
 	n := uint32(len(r.hosts))
 	if n == 1 {
@@ -828,37 +832,63 @@ func (r *replica) getHost() *host {
 
 	idx %= n
 	h := r.hosts[idx]
-	reqs := h.load()
-
-	// Set least priority to inactive host.
-	if !h.isActive() {
-		reqs = ^uint32(0)
-	}
 
 	// Scan all the hosts for the least loaded host.
 	for i := uint32(1); i < n; i++ {
 		tmpIdx := (idx + i) % n
-		tmpH := r.hosts[tmpIdx]
 
 		// handling sticky session
-		if r.cluster.sessionId != "" {
-			sessionId := hash(r.cluster.sessionId)
+		if sessionId != "" {
+			sessionId := hash(sessionId)
 			tmpIdx = (sessionId) % n
 			tmpHSticky := r.hosts[tmpIdx]
+			log.Debugf("Sticky server candidate is: %s", tmpHSticky.addr)
 			if !tmpHSticky.isActive() {
-				log.Debugf("Sticky Session Server has been picked up, but it is not available")
+				log.Debugf("Sticky session server has been picked up, but it is not available")
 				continue
 			}
-			log.Debugf("Sticky Session Server is: %s, session: %d, idx mod: %d - %d", tmpH.addr, sessionId, tmpIdx, n)
-			return tmpH
+			log.Debugf("Sticky session server is: %s, session_id: %d, server_idx: %d, max nodes in pool: %d", tmpHSticky.addr, sessionId, tmpIdx, n)
+			return tmpHSticky
 		}
+	}
 
-		// handling least loaded host flow
-		tmpReqs := tmpH.load()
+	// The returned host may be inactive. This is OK,
+	// since this means all the hosts are inactive,
+	// so let's try proxying the request to any host.
+	return h
+}
+
+// getHost returns least loaded + round-robin host from replica.
+//
+// Always returns non-nil.
+func (r *replica) getHost() *host {
+	idx := atomic.AddUint32(&r.nextHostIdx, 1)
+	n := uint32(len(r.hosts))
+	if n == 1 {
+		return r.hosts[0]
+	}
+
+	idx %= n
+	h := r.hosts[idx]
+	reqs := h.load()
+
+	// Set least priority to inactive host.
+	if !h.isActive() {
+		reqs = ^uint32(0)
+	}
+
+	if reqs == 0 {
+		return h
+	}
 
+	// Scan all the hosts for the least loaded host.
+	for i := uint32(1); i < n; i++ {
+		tmpIdx := (idx + i) % n
+		tmpH := r.hosts[tmpIdx]
 		if !tmpH.isActive() {
 			continue
 		}
+		tmpReqs := tmpH.load()
 		if tmpReqs == 0 {
 			return tmpH
 		}
@@ -874,6 +904,14 @@ func (r *replica) getHost() *host {
 	return h
 }
 
+// getHostSticky returns host based on stickiness from cluster.
+//
+// Always returns non-nil.
+func (c *cluster) getHostSticky(sessionId string) *host {
+	r := c.getReplica()
+	return r.getHostSticky(sessionId)
+}
+
 // getHost returns least loaded + round-robin host from cluster.
 //
 // Always returns non-nil.
diff --git a/utils.go b/utils.go
index 55290631..15c8d5b8 100644
--- a/utils.go
+++ b/utils.go
@@ -48,7 +48,6 @@ func getAuth(req *http.Request) (string, string) {
 func getSessionId(req *http.Request) string {
 	params := req.URL.Query()
 	sessionId := params.Get("session_id")
-	req.Header.Set("X-ClickHouse-Session-ID", sessionId)
 	return sessionId
 }
 

From fc7db12d1d8d73cdfb486d58bcdbb380bd628278 Mon Sep 17 00:00:00 2001
From: Pavel Nemirovsky <pavelnemirovsky@icloud.com>
Date: Thu, 13 May 2021 13:02:24 +0300
Subject: [PATCH 05/16] session_id

---
 proxy.go | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/proxy.go b/proxy.go
index 2c18f61c..72f7fb6f 100644
--- a/proxy.go
+++ b/proxy.go
@@ -52,9 +52,6 @@ func newReverseProxy() *reverseProxy {
 func (rp *reverseProxy) ServeHTTP(rw http.ResponseWriter, req *http.Request) {
 	startTime := time.Now()
 	s, status, err := rp.getScope(req)
-	if s.sessionId != "" {
-		rw.Header().Set("X-ClickHouse-Session-Id", s.sessionId)
-	}
 	if err != nil {
 		q := getQuerySnippet(req)
 		err = fmt.Errorf("%q: %s; query: %q", req.RemoteAddr, err, q)
@@ -117,6 +114,11 @@ func (rp *reverseProxy) ServeHTTP(rw http.ResponseWriter, req *http.Request) {
 		log.Debugf("%s: request failure: non-200 status code %d; query: %q; Method: %s; URL: %q", s, srw.statusCode, q, req.Method, req.URL.String())
 	}
 
+	// publish session_id if needed
+	if s.sessionId != "" {
+		rw.Header().Set("X-ClickHouse-Session-Id", s.sessionId)
+	}
+
 	statusCodes.With(
 		prometheus.Labels{
 			"user":         s.user.name,

From 444a437746b6a86d535dba65af0212647be81247 Mon Sep 17 00:00:00 2001
From: Pavel Nemirovsky <pavelnemirovsky@icloud.com>
Date: Thu, 13 May 2021 15:05:10 +0300
Subject: [PATCH 06/16] test adjustment

---
 main_test.go | 12 ++++--------
 proxy.go     | 10 +++++-----
 2 files changed, 9 insertions(+), 13 deletions(-)

diff --git a/main_test.go b/main_test.go
index 0e626461..5dfc72f1 100644
--- a/main_test.go
+++ b/main_test.go
@@ -288,18 +288,14 @@ func TestServe(t *testing.T) {
 			"http POST request with session id",
 			"testdata/http-session-id.yml",
 			func(t *testing.T) {
-				// buf := bytes.NewBufferString("SELECT * FROM system.numbers LIMIT 10")
-				data := url.Values{}
-				data.Set("query", `SELECT * FROM system.numbers LIMIT 10`)
-				data.Add("session_id", "1234")
-				data.Add("query_id", "1234")
-				req, err := http.NewRequest("POST", "http://127.0.0.1:9090/", bytes.NewBufferString(data.Encode()))
-				req.Header.Set("Content-Type", "application/x-www-form-urlencoded; param=value") // This makes it work
+				req, err := http.NewRequest("POST", "http://127.0.0.1:9090/?query_id=45395792-a432-4b92-8cc9-536c14e1e1a9&extremes=0&session_id=default-session-id233", bytes.NewBufferString("SELECT * FROM system.numbers LIMIT 10"))
+				req.Header.Set("Content-Type", "application/x-www-form-urlencoded;") // This makes it work
 
 				checkErr(t, err)
 				resp, err := http.DefaultClient.Do(req)
 				checkErr(t, err)
-				if resp.StatusCode != http.StatusOK {
+
+				if resp.StatusCode != http.StatusOK || resp.Header.Get("X-Clickhouse-Server-Session-Id") == "" {
 					t.Fatalf("unexpected status code: %d; expected: %d", resp.StatusCode, http.StatusOK)
 				}
 				resp.Body.Close()
diff --git a/proxy.go b/proxy.go
index 72f7fb6f..cd9d54f1 100644
--- a/proxy.go
+++ b/proxy.go
@@ -98,6 +98,11 @@ func (rp *reverseProxy) ServeHTTP(rw http.ResponseWriter, req *http.Request) {
 		ReadCloser: req.Body,
 	}
 
+	// publish session_id if needed
+	if s.sessionId != "" {
+		rw.Header().Set("X-ClickHouse-Server-Session-Id", s.sessionId)
+	}
+
 	if s.user.cache == nil {
 		rp.proxyRequest(s, srw, srw, req)
 	} else {
@@ -114,11 +119,6 @@ func (rp *reverseProxy) ServeHTTP(rw http.ResponseWriter, req *http.Request) {
 		log.Debugf("%s: request failure: non-200 status code %d; query: %q; Method: %s; URL: %q", s, srw.statusCode, q, req.Method, req.URL.String())
 	}
 
-	// publish session_id if needed
-	if s.sessionId != "" {
-		rw.Header().Set("X-ClickHouse-Session-Id", s.sessionId)
-	}
-
 	statusCodes.With(
 		prometheus.Labels{
 			"user":         s.user.name,

From 4f7a4e84a82ae1e80eb005af2b9b5aa9b4ff00df Mon Sep 17 00:00:00 2001
From: Pavel Nemirovsky <pavelnemirovsky@icloud.com>
Date: Fri, 21 May 2021 20:03:37 +0300
Subject: [PATCH 07/16] session_timeout logic

---
 proxy.go |  3 ++-
 scope.go | 26 ++++++++++++++++----------
 utils.go | 11 +++++++++++
 3 files changed, 29 insertions(+), 11 deletions(-)

diff --git a/proxy.go b/proxy.go
index cd9d54f1..11684b6d 100644
--- a/proxy.go
+++ b/proxy.go
@@ -457,6 +457,7 @@ func (rp *reverseProxy) refreshCacheMetrics() {
 func (rp *reverseProxy) getScope(req *http.Request) (*scope, int, error) {
 	name, password := getAuth(req)
 	sessionId := getSessionId(req)
+	sessionTimeout := getSessionTimeout(req)
 	var (
 		u  *user
 		c  *cluster
@@ -493,6 +494,6 @@ func (rp *reverseProxy) getScope(req *http.Request) (*scope, int, error) {
 		return nil, http.StatusForbidden, fmt.Errorf("cluster user %q is not allowed to access", cu.name)
 	}
 
-	s := newScope(req, u, c, cu, sessionId)
+	s := newScope(req, u, c, cu, sessionId, sessionTimeout)
 	return s, 0, nil
 }
diff --git a/scope.go b/scope.go
index 75a377d5..fec32513 100644
--- a/scope.go
+++ b/scope.go
@@ -9,6 +9,7 @@ import (
 	"net/http"
 	"net/url"
 	"regexp"
+	"strconv"
 	"strings"
 	"sync/atomic"
 	"time"
@@ -42,7 +43,8 @@ type scope struct {
 	user        *user
 	clusterUser *clusterUser
 
-	sessionId string
+	sessionId      string
+	sessionTimeout int
 
 	remoteAddr string
 	localAddr  string
@@ -53,8 +55,7 @@ type scope struct {
 	labels prometheus.Labels
 }
 
-func newScope(req *http.Request, u *user, c *cluster, cu *clusterUser, sessionId string) *scope {
-
+func newScope(req *http.Request, u *user, c *cluster, cu *clusterUser, sessionId string, sessionTimeout int) *scope {
 	h := c.getHost()
 	if sessionId != "" {
 		h = c.getHostSticky(sessionId)
@@ -64,13 +65,14 @@ func newScope(req *http.Request, u *user, c *cluster, cu *clusterUser, sessionId
 		localAddr = addr.String()
 	}
 	s := &scope{
-		startTime:   time.Now(),
-		id:          newScopeID(),
-		host:        h,
-		cluster:     c,
-		user:        u,
-		clusterUser: cu,
-		sessionId:   sessionId,
+		startTime:      time.Now(),
+		id:             newScopeID(),
+		host:           h,
+		cluster:        c,
+		user:           u,
+		clusterUser:    cu,
+		sessionId:      sessionId,
+		sessionTimeout: sessionTimeout,
 
 		remoteAddr: req.RemoteAddr,
 		localAddr:  localAddr,
@@ -315,6 +317,8 @@ var allowedParams = []string{
 	"result_overflow_mode",
 	// session stickiness
 	"session_id",
+	// session timeout
+	"session_timeout",
 }
 
 // This regexp must match params needed to describe a way to use external data
@@ -359,6 +363,8 @@ func (s *scope) decorateRequest(req *http.Request) (*http.Request, url.Values) {
 
 	// Set query_id as scope_id to have possibility to kill query if needed.
 	params.Set("query_id", s.id.String())
+	// Set session_timeout an idle timeout for session
+	params.Set("session_timeout", strconv.Itoa(s.sessionTimeout))
 
 	req.URL.RawQuery = params.Encode()
 
diff --git a/utils.go b/utils.go
index 15c8d5b8..c3de05fb 100644
--- a/utils.go
+++ b/utils.go
@@ -9,6 +9,7 @@ import (
 	"io/ioutil"
 	"net/http"
 	"sort"
+	"strconv"
 	"strings"
 
 	"github.com/Vertamedia/chproxy/chdecompressor"
@@ -51,6 +52,16 @@ func getSessionId(req *http.Request) string {
 	return sessionId
 }
 
+// getSessionId retrieves session id
+func getSessionTimeout(req *http.Request) int {
+	params := req.URL.Query()
+	sessionTimeout, err := strconv.Atoi(params.Get("session_timeout"))
+	if err != nil && sessionTimeout > 0 {
+		return sessionTimeout
+	}
+	return 60
+}
+
 // getQuerySnippet returns query snippet.
 //
 // getQuerySnippet must be called only for error reporting.

From 2ebaa8805c17e08fdf9506ca3782e1686bd93bee Mon Sep 17 00:00:00 2001
From: Pavel Nemirovsky <pavelnemirovsky@icloud.com>
Date: Fri, 21 May 2021 20:11:05 +0300
Subject: [PATCH 08/16] session_timeout tests

---
 main_test.go  |  4 +++-
 scope_test.go | 12 ++++++------
 2 files changed, 9 insertions(+), 7 deletions(-)

diff --git a/main_test.go b/main_test.go
index 5dfc72f1..63d1e1b1 100644
--- a/main_test.go
+++ b/main_test.go
@@ -288,7 +288,9 @@ func TestServe(t *testing.T) {
 			"http POST request with session id",
 			"testdata/http-session-id.yml",
 			func(t *testing.T) {
-				req, err := http.NewRequest("POST", "http://127.0.0.1:9090/?query_id=45395792-a432-4b92-8cc9-536c14e1e1a9&extremes=0&session_id=default-session-id233", bytes.NewBufferString("SELECT * FROM system.numbers LIMIT 10"))
+				req, err := http.NewRequest("POST",
+					"http://127.0.0.1:9090/?query_id=45395792-a432-4b92-8cc9-536c14e1e1a9&extremes=0&session_id=default-session-id233",
+					bytes.NewBufferString("SELECT * FROM system.numbers LIMIT 10"))
 				req.Header.Set("Content-Type", "application/x-www-form-urlencoded;") // This makes it work
 
 				checkErr(t, err)
diff --git a/scope_test.go b/scope_test.go
index af3180ac..284c4458 100644
--- a/scope_test.go
+++ b/scope_test.go
@@ -330,14 +330,14 @@ func TestDecorateRequest(t *testing.T) {
 			"text/plain",
 			"GET",
 			nil,
-			[]string{"query_id", "query"},
+			[]string{"query_id", "session_timeout", "query"},
 		},
 		{
 			"http://127.0.0.1?user=default&password=default&query=SELECT&database=default&wait_end_of_query=1",
 			"text/plain",
 			"GET",
 			nil,
-			[]string{"query_id", "query", "database"},
+			[]string{"query_id", "session_timeout", "query", "database"},
 		},
 		{
 			"http://127.0.0.1?user=default&password=default&query=SELECT&testdata_structure=id+UInt32&testdata_format=TSV",
@@ -352,7 +352,7 @@ func TestDecorateRequest(t *testing.T) {
 					},
 				},
 			},
-			[]string{"query_id", "query", "max_threads"},
+			[]string{"query_id", "session_timeout", "query", "max_threads"},
 		},
 		{
 			"http://127.0.0.1?user=default&password=default&query=SELECT&testdata_structure=id+UInt32&testdata_format=TSV",
@@ -367,7 +367,7 @@ func TestDecorateRequest(t *testing.T) {
 					},
 				},
 			},
-			[]string{"query_id", "query"},
+			[]string{"query_id", "session_timeout", "query"},
 		},
 		{
 			"http://127.0.0.1?user=default&password=default&query=SELECT&testdata_type_buzz=1&testdata_structure_foo=id+UInt32&testdata_format-bar=TSV",
@@ -386,14 +386,14 @@ func TestDecorateRequest(t *testing.T) {
 					},
 				},
 			},
-			[]string{"query_id", "query", "max_threads", "background_pool_size"},
+			[]string{"query_id", "session_timeout", "query", "max_threads", "background_pool_size"},
 		},
 		{
 			"http://127.0.0.1?user=default&password=default&query=SELECT&testdata_structure=id+UInt32&testdata_format=TSV",
 			"multipart/form-data; boundary=foobar",
 			"POST",
 			nil,
-			[]string{"query_id", "testdata_structure", "testdata_format", "query"},
+			[]string{"query_id", "session_timeout", "testdata_structure", "testdata_format", "query"},
 		},
 	}
 

From 14fc89fdc5ccb7d0bf0917ccc1cd053d0e9d24fe Mon Sep 17 00:00:00 2001
From: Pavel Nemirovsky <pavelnemirovsky@icloud.com>
Date: Fri, 21 May 2021 20:13:04 +0300
Subject: [PATCH 09/16] header test

---
 main_test.go | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/main_test.go b/main_test.go
index 63d1e1b1..d1c63b1b 100644
--- a/main_test.go
+++ b/main_test.go
@@ -297,7 +297,7 @@ func TestServe(t *testing.T) {
 				resp, err := http.DefaultClient.Do(req)
 				checkErr(t, err)
 
-				if resp.StatusCode != http.StatusOK || resp.Header.Get("X-Clickhouse-Server-Session-Id") == "" {
+				if resp.StatusCode != http.StatusOK || resp.StatusCode != http.StatusOK && resp.Header.Get("X-Clickhouse-Server-Session-Id") == "" {
 					t.Fatalf("unexpected status code: %d; expected: %d", resp.StatusCode, http.StatusOK)
 				}
 				resp.Body.Close()

From 26ca1f58de1e5dea02aa65dbc2fba6eda869765e Mon Sep 17 00:00:00 2001
From: Pavel Nemirovsky <pavelnemirovsky@icloud.com>
Date: Fri, 21 May 2021 20:14:20 +0300
Subject: [PATCH 10/16] cleaning unused code

---
 scope.go | 2 --
 1 file changed, 2 deletions(-)

diff --git a/scope.go b/scope.go
index fec32513..9b85ef8f 100644
--- a/scope.go
+++ b/scope.go
@@ -20,8 +20,6 @@ import (
 	"github.com/prometheus/client_golang/prometheus"
 )
 
-// var route = make(map[int]*host)
-
 type scopeID uint64
 
 func (sid scopeID) String() string {

From dce7872666145bde90bd43ec145d3a2739dd2a63 Mon Sep 17 00:00:00 2001
From: Pavel Nemirovsky <pavelnemirovsky@icloud.com>
Date: Fri, 21 May 2021 21:18:03 +0300
Subject: [PATCH 11/16] handling session_id verification

---
 scope.go | 20 +++++++++-----------
 1 file changed, 9 insertions(+), 11 deletions(-)

diff --git a/scope.go b/scope.go
index 9b85ef8f..951f927f 100644
--- a/scope.go
+++ b/scope.go
@@ -842,18 +842,16 @@ func (r *replica) getHostSticky(sessionId string) *host {
 		tmpIdx := (idx + i) % n
 
 		// handling sticky session
-		if sessionId != "" {
-			sessionId := hash(sessionId)
-			tmpIdx = (sessionId) % n
-			tmpHSticky := r.hosts[tmpIdx]
-			log.Debugf("Sticky server candidate is: %s", tmpHSticky.addr)
-			if !tmpHSticky.isActive() {
-				log.Debugf("Sticky session server has been picked up, but it is not available")
-				continue
-			}
-			log.Debugf("Sticky session server is: %s, session_id: %d, server_idx: %d, max nodes in pool: %d", tmpHSticky.addr, sessionId, tmpIdx, n)
-			return tmpHSticky
+		sessionId := hash(sessionId)
+		tmpIdx = (sessionId) % n
+		tmpHSticky := r.hosts[tmpIdx]
+		log.Debugf("Sticky server candidate is: %s", tmpHSticky.addr)
+		if !tmpHSticky.isActive() {
+			log.Debugf("Sticky session server has been picked up, but it is not available")
+			continue
 		}
+		log.Debugf("Sticky session server is: %s, session_id: %d, server_idx: %d, max nodes in pool: %d", tmpHSticky.addr, sessionId, tmpIdx, n)
+		return tmpHSticky
 	}
 
 	// The returned host may be inactive. This is OK,

From 456d694cbc71c1fa974684ed6a30d462a1d85216 Mon Sep 17 00:00:00 2001
From: Pavel Nemirovsky <pavelnemirovsky@icloud.com>
Date: Sun, 23 May 2021 22:59:16 +0300
Subject: [PATCH 12/16] Ability to build version under Docker (Native go build
 doesn't work due to Datadog lib)

---
 Dockerfile |  2 ++
 Makefile   | 12 +++++++++++-
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/Dockerfile b/Dockerfile
index d36cb9c8..36e45588 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -5,6 +5,8 @@ RUN go get golang.org/x/lint/golint
 RUN mkdir -p /go/src/github.com/Vertamedia/chproxy
 WORKDIR /go/src/github.com/Vertamedia/chproxy
 COPY . ./
+ARG EXT_BUILD_TAG
+ENV EXT_BUILD_TAG ${EXT_BUILD_TAG}
 RUN make release-build
 
 FROM alpine
diff --git a/Makefile b/Makefile
index e5f137d8..9617aace 100644
--- a/Makefile
+++ b/Makefile
@@ -1,7 +1,8 @@
+current_dir = $(pwd)
 pkgs = $(shell go list ./...)
 gofiles := $(shell find . -name "*.go" -type f -not -path "./vendor/*")
 
-BUILD_TAG = $(shell git tag --points-at HEAD)
+BUILD_TAG = $(or $(shell git tag --points-at HEAD), $(EXT_BUILD_TAG), latest)
 
 BUILD_CONSTS = \
 	-X main.buildTime=`date -u '+%Y-%m-%d_%H:%M:%S'` \
@@ -36,7 +37,16 @@ clean:
 	rm -f chproxy
 
 release-build:
+	@echo "Ver: $(BUILD_TAG), OPTS: $(BUILD_OPTS)"
 	GOOS=linux GOARCH=amd64 go build $(BUILD_OPTS)
+	rm chproxy-linux-amd64-*.tar.gz
+	tar czf chproxy-linux-amd64-$(BUILD_TAG).tar.gz chproxy
 
 release: format lint test clean release-build
+	@echo "Ver: $(BUILD_TAG), OPTS: $(BUILD_OPTS)"
 	tar czf chproxy-linux-amd64-$(BUILD_TAG).tar.gz chproxy
+
+release-build-docker:
+	@echo "Ver: $(BUILD_TAG)"
+	@DOCKER_BUILDKIT=1 docker build --target build --build-arg EXT_BUILD_TAG=$(BUILD_TAG) --progress plain -t chproxy-build .
+	@docker run --rm --entrypoint "/bin/sh" -v $(CURDIR):/host chproxy-build -c "/bin/cp /go/src/github.com/Vertamedia/chproxy/*.tar.gz /host"

From eca0b6c15ba9704850d4a5a1141b4eaf548708c1 Mon Sep 17 00:00:00 2001
From: Pavel Nemirovsky <pavelnemirovsky@icloud.com>
Date: Mon, 24 May 2021 12:19:21 +0300
Subject: [PATCH 13/16] Error handling in Makefile

---
 Makefile | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Makefile b/Makefile
index 9617aace..87b74a9e 100644
--- a/Makefile
+++ b/Makefile
@@ -39,7 +39,7 @@ clean:
 release-build:
 	@echo "Ver: $(BUILD_TAG), OPTS: $(BUILD_OPTS)"
 	GOOS=linux GOARCH=amd64 go build $(BUILD_OPTS)
-	rm chproxy-linux-amd64-*.tar.gz
+	@if [ -f chproxy-linux-amd64-*.tar.gz ]; then rm chproxy-linux-amd64-*.tar.gz; fi
 	tar czf chproxy-linux-amd64-$(BUILD_TAG).tar.gz chproxy
 
 release: format lint test clean release-build

From 4304395eededb678a179adc1414d5c39913ea166 Mon Sep 17 00:00:00 2001
From: Pavel Nemirovsky <pavelnemirovsky@icloud.com>
Date: Mon, 24 May 2021 14:41:49 +0300
Subject: [PATCH 14/16] Bump to newer go + make sure static linking works
 correctly

---
 Dockerfile | 4 ++--
 Makefile   | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/Dockerfile b/Dockerfile
index 36e45588..efa4a22f 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,6 +1,6 @@
-FROM golang:1.13-alpine AS build
+FROM golang:1.16-alpine AS build
 
-RUN apk add --update zstd-static zstd-dev make gcc musl-dev git
+RUN apk add --no-cache --update zstd-static zstd-dev make gcc musl-dev git libc6-compat
 RUN go get golang.org/x/lint/golint
 RUN mkdir -p /go/src/github.com/Vertamedia/chproxy
 WORKDIR /go/src/github.com/Vertamedia/chproxy
diff --git a/Makefile b/Makefile
index 87b74a9e..a66b71fc 100644
--- a/Makefile
+++ b/Makefile
@@ -38,7 +38,7 @@ clean:
 
 release-build:
 	@echo "Ver: $(BUILD_TAG), OPTS: $(BUILD_OPTS)"
-	GOOS=linux GOARCH=amd64 go build $(BUILD_OPTS)
+	@GOOS=linux GOARCH=amd64 go build $(BUILD_OPTS)
 	@if [ -f chproxy-linux-amd64-*.tar.gz ]; then rm chproxy-linux-amd64-*.tar.gz; fi
 	tar czf chproxy-linux-amd64-$(BUILD_TAG).tar.gz chproxy
 

From e5d9dcaf23f852e6777f89da62370d45085468da Mon Sep 17 00:00:00 2001
From: Pavel Nemirovsky <pavelnemirovsky@icloud.com>
Date: Fri, 4 Jun 2021 01:37:29 +0300
Subject: [PATCH 15/16] Session_id typo fix

---
 utils.go | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/utils.go b/utils.go
index c3de05fb..cd40e976 100644
--- a/utils.go
+++ b/utils.go
@@ -56,7 +56,7 @@ func getSessionId(req *http.Request) string {
 func getSessionTimeout(req *http.Request) int {
 	params := req.URL.Query()
 	sessionTimeout, err := strconv.Atoi(params.Get("session_timeout"))
-	if err != nil && sessionTimeout > 0 {
+	if err == nil && sessionTimeout > 0 {
 		return sessionTimeout
 	}
 	return 60

From 15a760920166656286be53a960887edd6942a411 Mon Sep 17 00:00:00 2001
From: Pavel Nemirovsky <pavelnemirovsky@icloud.com>
Date: Fri, 4 Jun 2021 20:58:12 +0300
Subject: [PATCH 16/16] Adjust tests for session-name and session-timeout

---
 main_test.go | 22 +++++++++++++++++++---
 proxy.go     |  5 +++++
 2 files changed, 24 insertions(+), 3 deletions(-)

diff --git a/main_test.go b/main_test.go
index d1c63b1b..77414cab 100644
--- a/main_test.go
+++ b/main_test.go
@@ -13,6 +13,7 @@ import (
 	"net/http/httptest"
 	"net/url"
 	"os"
+	"strconv"
 	"strings"
 	"sync"
 	"testing"
@@ -285,11 +286,13 @@ func TestServe(t *testing.T) {
 			startHTTP,
 		},
 		{
-			"http POST request with session id",
+			"http POST request with session_id and session_timeout",
 			"testdata/http-session-id.yml",
 			func(t *testing.T) {
+				sessionName := "name"
+				sessionTimeout := 900
 				req, err := http.NewRequest("POST",
-					"http://127.0.0.1:9090/?query_id=45395792-a432-4b92-8cc9-536c14e1e1a9&extremes=0&session_id=default-session-id233",
+					"http://127.0.0.1:9090/?query_id=45395792-a432-4b92-8cc9-536c14e1e1a9&extremes=0&session_id="+sessionName+"&session_timeout="+strconv.Itoa(sessionTimeout),
 					bytes.NewBufferString("SELECT * FROM system.numbers LIMIT 10"))
 				req.Header.Set("Content-Type", "application/x-www-form-urlencoded;") // This makes it work
 
@@ -297,9 +300,22 @@ func TestServe(t *testing.T) {
 				resp, err := http.DefaultClient.Do(req)
 				checkErr(t, err)
 
-				if resp.StatusCode != http.StatusOK || resp.StatusCode != http.StatusOK && resp.Header.Get("X-Clickhouse-Server-Session-Id") == "" {
+				if resp.StatusCode != http.StatusOK {
 					t.Fatalf("unexpected status code: %d; expected: %d", resp.StatusCode, http.StatusOK)
 				}
+
+				// verify correctness of session_id
+				_sessionName := resp.Header.Get("X-Clickhouse-Server-Session-Id")
+				if _sessionName != sessionName {
+					t.Fatalf("unexpected value of X-Clickhouse-Server-Session-Id: %s; expected: %s", _sessionName, sessionName)
+				}
+
+				// verify correctness of session_id
+				_sessionTimeout, _ := strconv.Atoi(resp.Header.Get("X-Clickhouse-Server-Session-Timeout"))
+				if _sessionTimeout != sessionTimeout {
+					t.Fatalf("unexpected value of X-Clickhouse-Server-Session-Timeout: %d; expected: %d", _sessionTimeout, sessionTimeout)
+				}
+
 				resp.Body.Close()
 			},
 			startHTTP,
diff --git a/proxy.go b/proxy.go
index 11684b6d..134dfe71 100644
--- a/proxy.go
+++ b/proxy.go
@@ -103,6 +103,11 @@ func (rp *reverseProxy) ServeHTTP(rw http.ResponseWriter, req *http.Request) {
 		rw.Header().Set("X-ClickHouse-Server-Session-Id", s.sessionId)
 	}
 
+	// publish session_timeout if needed
+	if s.sessionId != "" {
+		rw.Header().Set("X-ClickHouse-Server-Session-Timeout", strconv.Itoa(s.sessionTimeout))
+	}
+
 	if s.user.cache == nil {
 		rp.proxyRequest(s, srw, srw, req)
 	} else {