diff --git a/docs/config/monitor.en.md b/docs/config/monitor.en.md
index c91bde56..eb0e0dcc 100644
--- a/docs/config/monitor.en.md
+++ b/docs/config/monitor.en.md
@@ -8,6 +8,13 @@
 
 These parameters only apply to Monitors.
 
+- [enable_prometheus](#enable_prometheus)
+- [mon_http_port](#mon_http_port)
+- [mon_http_ip](#mon_http_ip)
+- [mon_https_cert](#mon_https_cert)
+- [mon_https_key](#mon_https_key)
+- [mon_https_client_auth](#mon_https_client_auth)
+- [mon_https_ca](#mon_https_ca)
 - [etcd_mon_ttl](#etcd_mon_ttl)
 - [etcd_mon_timeout](#etcd_mon_timeout)
 - [etcd_mon_retries](#etcd_mon_retries)
@@ -17,6 +24,51 @@ These parameters only apply to Monitors.
 - [placement_levels](#placement_levels)
 - [use_old_pg_combinator](#use_old_pg_combinator)
 
+## enable_prometheus
+
+- Type: boolean
+- Default: true
+
+Enable built-in Prometheus metrics exporter
+
+## mon_http_port
+
+- Type: integer
+- Default: 8060
+
+HTTP port for monitors to listen on (including metrics exporter)
+
+## mon_http_ip
+
+- Type: string
+
+IP address for monitors to listen on (all addresses by default)
+
+## mon_https_cert
+
+- Type: string
+
+Path to PEM SSL certificate file for monitor to listen using HTTPS
+
+## mon_https_key
+
+- Type: string
+
+Path to PEM SSL private key file for monitor to listen using HTTPS
+
+## mon_https_client_auth
+
+- Type: boolean
+- Default: false
+
+Enable HTTPS client certificate-based authorization for monitor connections
+
+## mon_https_ca
+
+- Type: string
+
+Path to CA certificate for client HTTPS authorization
+
 ## etcd_mon_ttl
 
 - Type: seconds
diff --git a/docs/config/monitor.ru.md b/docs/config/monitor.ru.md
index 5d36860e..bac6b140 100644
--- a/docs/config/monitor.ru.md
+++ b/docs/config/monitor.ru.md
@@ -8,6 +8,13 @@
 
 Данные параметры используются только мониторами Vitastor.
 
+- [enable_prometheus](#enable_prometheus)
+- [mon_http_port](#mon_http_port)
+- [mon_http_ip](#mon_http_ip)
+- [mon_https_cert](#mon_https_cert)
+- [mon_https_key](#mon_https_key)
+- [mon_https_client_auth](#mon_https_client_auth)
+- [mon_https_ca](#mon_https_ca)
 - [etcd_mon_ttl](#etcd_mon_ttl)
 - [etcd_mon_timeout](#etcd_mon_timeout)
 - [etcd_mon_retries](#etcd_mon_retries)
@@ -17,6 +24,51 @@
 - [placement_levels](#placement_levels)
 - [use_old_pg_combinator](#use_old_pg_combinator)
 
+## enable_prometheus
+
+- Тип: булево (да/нет)
+- Значение по умолчанию: true
+
+Включить встроенный Prometheus-экспортер метри
+
+## mon_http_port
+
+- Тип: целое число
+- Значение по умолчанию: 8060
+
+Порт, на котором мониторы принимают HTTP-соединения (в том числе для отдачи метрик)
+
+## mon_http_ip
+
+- Тип: строка
+
+IP-адрес, на котором мониторы принимают HTTP-соединения (по умолчанию все адреса)
+
+## mon_https_cert
+
+- Тип: строка
+
+Путь к PEM-файлу SSL-сертификата для монитора, чтобы принимать соединения через HTTPS
+
+## mon_https_key
+
+- Тип: строка
+
+Путь к PEM-файлу секретного SSL-ключа для монитора, чтобы принимать соединения через HTTPS
+
+## mon_https_client_auth
+
+- Тип: булево (да/нет)
+- Значение по умолчанию: false
+
+Включить в HTTPS-сервере монитора авторизацию по клиентским сертификатам
+
+## mon_https_ca
+
+- Тип: строка
+
+Путь к удостоверяющему сертификату для авторизации клиентских HTTPS соединений
+
 ## etcd_mon_ttl
 
 - Тип: секунды
diff --git a/docs/config/src/monitor.yml b/docs/config/src/monitor.yml
index 83a93ef0..46b93e79 100644
--- a/docs/config/src/monitor.yml
+++ b/docs/config/src/monitor.yml
@@ -1,3 +1,34 @@
+- name: enable_prometheus
+  type: bool
+  default: true
+  info: Enable built-in Prometheus metrics exporter
+  info_ru: Включить встроенный Prometheus-экспортер метри
+- name: mon_http_port
+  type: int
+  default: 8060
+  info: HTTP port for monitors to listen on (including metrics exporter)
+  info_ru: Порт, на котором мониторы принимают HTTP-соединения (в том числе для отдачи метрик)
+- name: mon_http_ip
+  type: string
+  info: IP address for monitors to listen on (all addresses by default)
+  info_ru: IP-адрес, на котором мониторы принимают HTTP-соединения (по умолчанию все адреса)
+- name: mon_https_cert
+  type: string
+  info: Path to PEM SSL certificate file for monitor to listen using HTTPS
+  info_ru: Путь к PEM-файлу SSL-сертификата для монитора, чтобы принимать соединения через HTTPS
+- name: mon_https_key
+  type: string
+  info: Path to PEM SSL private key file for monitor to listen using HTTPS
+  info_ru: Путь к PEM-файлу секретного SSL-ключа для монитора, чтобы принимать соединения через HTTPS
+- name: mon_https_client_auth
+  type: bool
+  default: false
+  info: Enable HTTPS client certificate-based authorization for monitor connections
+  info_ru: Включить в HTTPS-сервере монитора авторизацию по клиентским сертификатам
+- name: mon_https_ca
+  type: string
+  info: Path to CA certificate for client HTTPS authorization
+  info_ru: Путь к удостоверяющему сертификату для авторизации клиентских HTTPS соединений
 - name: etcd_mon_ttl
   type: sec
   min: 5
diff --git a/mon/etcd_schema.js b/mon/etcd_schema.js
index 1e1174d6..a6cec0d8 100644
--- a/mon/etcd_schema.js
+++ b/mon/etcd_schema.js
@@ -245,6 +245,9 @@ const etcd_tree = {
         stats: {
             /* <osd_num_t>: {
                 time: number, // unix time
+                data_block_size: uint64_t, // bytes
+                bitmap_granularity: uint64_t, // bytes
+                immediate_commit: "all"|"small"|"none",
                 blockstore_ready: boolean,
                 size: uint64_t, // bytes
                 free: uint64_t, // bytes
@@ -282,7 +285,7 @@ const etcd_tree = {
         master: {
             /* ip: [ string ], id: uint64_t */
         },
-        standby: {
+        member: {
             /* <uint64_t>: { ip: [ string ] }, */
         },
     },
diff --git a/mon/http_server.js b/mon/http_server.js
new file mode 100644
index 00000000..88b6307c
--- /dev/null
+++ b/mon/http_server.js
@@ -0,0 +1,46 @@
+// Copyright (c) Vitaliy Filippov, 2019+
+// License: VNPL-1.1 (see README.md for details)
+
+const fsp = require('fs').promises;
+const http = require('http');
+const https = require('https');
+
+async function create_http_server(cfg, handler)
+{
+    let server;
+    if (cfg.mon_https_cert)
+    {
+        const tls = {
+            key: await fsp.readFile(cfg.mon_https_key),
+            cert: await fsp.readFile(cfg.mon_https_cert),
+        };
+        if (cfg.mon_https_ca)
+        {
+            tls.mon_https_ca = await fsp.readFile(cfg.mon_https_ca);
+        }
+        if (cfg.mon_https_client_auth)
+        {
+            tls.requestCert = true;
+        }
+        server = https.createServer(tls, handler);
+    }
+    else
+    {
+        server = http.createServer(handler);
+    }
+    try
+    {
+        server.listen(cfg.mon_http_port || 8060, cfg.mon_http_ip || undefined);
+    }
+    catch (e)
+    {
+        console.error(
+            'HTTP server disabled because listen at address: '+
+            (cfg.mon_http_ip || '')+':'+(cfg.mon_http_port || 9090)+' failed with error: '+e
+        );
+        return null;
+    }
+    return server;
+}
+
+module.exports = { create_http_server };
diff --git a/mon/mon.js b/mon/mon.js
index ea0fff74..7510c89c 100644
--- a/mon/mon.js
+++ b/mon/mon.js
@@ -1,10 +1,13 @@
 // Copyright (c) Vitaliy Filippov, 2019+
 // License: VNPL-1.1 (see README.md for details)
 
+const { URL } = require('url');
 const fs = require('fs');
 const crypto = require('crypto');
 const os = require('os');
 const EtcdAdapter = require('./etcd_adapter.js');
+const { create_http_server } = require('./http_server.js');
+const { export_prometheus_metrics } = require('./prometheus.js');
 const { etcd_tree, etcd_allow, etcd_nonempty_keys } = require('./etcd_schema.js');
 const { validate_pool_cfg } = require('./pool_config.js');
 const { sum_op_stats, sum_object_counts, sum_inode_stats, serialize_bigints } = require('./stats.js');
@@ -60,6 +63,32 @@ class Mon
         this.recheck_pgs_active = false;
         this.etcd = new EtcdAdapter(this);
         this.etcd.parse_config(this.config);
+        this.watcher_active = false;
+        if (this.config.enable_prometheus || !('enable_prometheus' in this.config))
+        {
+            this.http = create_http_server(this.config, (req, res) =>
+            {
+                const u = new URL(req.url, 'http://'+(req.headers.host || 'localhost'));
+                if (u.pathname.replace(/\/+$/, '') == (this.config.prometheus_path||'/metrics'))
+                {
+                    if (!this.watcher_active)
+                    {
+                        res.writeHead(503);
+                        res.write('Monitor is in standby mode. Please retrieve metrics from master monitor instance\n');
+                    }
+                    else
+                    {
+                        res.write(export_prometheus_metrics(this.state));
+                    }
+                }
+                else
+                {
+                    res.writeHead(404);
+                    res.write('Not found. Metrics path: '+(this.config.prometheus_path||'/metrics\n'));
+                }
+                res.end();
+            });
+        }
     }
 
     async start()
@@ -69,6 +98,7 @@ class Mon
         await this.etcd.become_master();
         await this.load_cluster_state();
         await this.etcd.start_watcher(this.config.etcd_mon_retries);
+        this.watcher_active = true;
         for (const pool_id in this.state.config.pools)
         {
             if (!this.state.pool.stats[pool_id] ||
diff --git a/mon/prometheus.js b/mon/prometheus.js
new file mode 100644
index 00000000..5883366c
--- /dev/null
+++ b/mon/prometheus.js
@@ -0,0 +1,202 @@
+// Copyright (c) Vitaliy Filippov, 2019+
+// License: VNPL-1.1 (see README.md for details)
+
+const metric_help =
+`# HELP vitastor_object_bytes Total size of objects in cluster in bytes
+# TYPE vitastor_object_bytes gauge
+# HELP vitastor_object_count Total number of objects in cluster
+# TYPE vitastor_object_count gauge
+# HELP vitastor_stat_count Total operation count
+# TYPE vitastor_stat_count counter
+# HELP vitastor_stat_usec Total operation latency in usec
+# TYPE vitastor_stat_usec counter
+# HELP vitastor_stat_bytes Total operation size in bytes
+# HELP vitastor_stat_bytes counter
+
+# HELP vitastor_image_raw_used Image raw used size in bytes
+# TYPE vitastor_image_raw_used counter
+# HELP vitastor_image_stat_count Per-image total operation count
+# TYPE vitastor_image_stat_count counter
+# HELP vitastor_image_stat_usec Per-image total operation latency
+# TYPE vitastor_image_stat_usec counter
+# HELP vitastor_image_stat_bytes Per-image total operation size in bytes
+# TYPE vitastor_image_stat_bytes counter
+
+# HELP vitastor_osd_status OSD up/down status
+# TYPE vitastor_osd_status gauge
+# HELP vitastor_osd_size_bytes OSD total space in bytes
+# TYPE vitastor_osd_size_bytes gauge
+# HELP vitastor_osd_free_bytes OSD free space in bytes
+# TYPE vitastor_osd_free_bytes gauge
+# HELP vitastor_osd_stat_count Per-image total operation count
+# TYPE vitastor_osd_stat_count counter
+# HELP vitastor_osd_stat_usec Per-image total operation latency
+# TYPE vitastor_osd_stat_usec counter
+# HELP vitastor_osd_stat_bytes Per-image total operation size in bytes
+# TYPE vitastor_osd_stat_bytes counter
+
+# HELP vitastor_monitor_info Monitor info, 1 is master, 0 is standby
+# TYPE vitastor_monitor_info gauge
+
+# HELP vitastor_pool_info Pool configuration (in labels)
+# TYPE vitastor_pool_info gauge
+# HELP vitastor_pool_status Pool up/down status
+# TYPE vitastor_pool_status gauge
+# HELP vitastor_pool_raw_to_usable Raw to usable space ratio
+# TYPE vitastor_pool_raw_to_usable gauge
+# HELP vitastor_pool_space_efficiency Pool space usage efficiency
+# TYPE vitastor_pool_space_efficiency gauge
+# HELP vitastor_pool_total_raw_tb Total raw space in pool in TB
+# TYPE vitastor_pool_total_raw_tb gauge
+# HELP vitastor_pool_used_raw_tb Used raw space in pool in TB
+# TYPE vitastor_pool_used_raw_tb gauge
+# HELP vitastor_pg_count PG counts by state
+# HELP vitastor_pg_count gauge
+
+`;
+
+function export_prometheus_metrics(st)
+{
+    let res = metric_help;
+
+    // Global statistics
+
+    for (const k in st.stats.object_bytes)
+    {
+        res += `vitastor_object_bytes{object_type="${k}"} ${st.stats.object_bytes[k]}\n`;
+    }
+
+    for (const k in st.stats.object_counts)
+    {
+        res += `vitastor_object_count{object_type="${k}"} ${st.stats.object_counts[k]}\n`;
+    }
+
+    for (const typ of [ 'op', 'subop', 'recovery' ])
+    {
+        for (const op in st.stats[typ+"_stats"]||{})
+        {
+            const op_stat = st.stats[typ+"_stats"][op];
+            for (const key of [ 'count', 'usec', 'bytes' ])
+            {
+                res += `vitastor_stat_${key}{op="${op}",op_type="${typ}"} ${op_stat[key]||0}\n`;
+            }
+        }
+    }
+
+    // Per-image statistics
+
+    for (const pool in st.inode.stats)
+    {
+        for (const inode in st.inode.stats[pool])
+        {
+            const ist = st.inode.stats[pool][inode];
+            const inode_name = ((st.config.inode[pool]||{})[inode]||{}).name||'';
+            const inode_label = `image_name="${addslashes(inode_name)}",inode_num="${inode}",pool_id="${pool}"`;
+            res += `vitastor_image_raw_used{${inode_label}} ${ist.raw_used||0}\n`;
+            for (const op of [ 'read', 'write', 'delete' ])
+            {
+                for (const k of [ 'count', 'usec', 'bytes' ])
+                {
+                    if (ist[op])
+                    {
+                        res += `vitastor_image_stat_${k}{${inode_label},op="${op}"} ${ist[op][k]||0}\n`;
+                    }
+                }
+            }
+        }
+    }
+
+    // Per-OSD statistics
+
+    for (const osd in st.osd.stats)
+    {
+        const osd_stat = st.osd.stats[osd];
+        const up = st.osd.state[osd] && st.osd.state[osd].state == 'up' ? 1 : 0;
+        res += `vitastor_osd_status{host="${addslashes(osd_stat.host)}",osd_num="${osd}"} ${up}\n`;
+        res += `vitastor_osd_size_bytes{osd_num="${osd}"} ${osd_stat.size||0}\n`;
+        res += `vitastor_osd_free_bytes{osd_num="${osd}"} ${osd_stat.free||0}\n`;
+        for (const op in osd_stat.op_stats)
+        {
+            const ist = osd_stat.op_stats[op];
+            for (const k of [ 'count', 'usec', 'bytes' ])
+            {
+                res += `vitastor_osd_stat_${k}{osd_num="${osd}",op="${op}",op_type="op"} ${ist[k]||0}\n`;
+            }
+        }
+        for (const op in osd_stat.subop_stats)
+        {
+            const ist = osd_stat.subop_stats[op];
+            for (const k of [ 'count', 'usec', 'bytes' ])
+            {
+                res += `vitastor_osd_stat_${k}{osd_num="${osd}",op="${op}",op_type="subop"} ${ist[k]||0}\n`;
+            }
+        }
+    }
+
+    // Monitor statistics
+
+    for (const mon_id in st.mon.member)
+    {
+        const mon = st.mon.member[mon_id];
+        const master = st.mon.master && st.mon.master.id == mon_id ? 1 : 0;
+        const ip = (mon.ip instanceof Array ? mon.ip[0] : mon.ip) || '';
+        res += `vitastor_monitor_info{monitor_hostname="${addslashes(mon.hostname)}",monitor_id="${mon_id}",monitor_ip="${addslashes(ip)}"} ${master}\n`;
+    }
+
+    // Per-pool statistics
+
+    for (const pool_id in st.config.pools)
+    {
+        const pool_cfg = st.config.pools[pool_id];
+        const pool_label = `pool_id="${pool_id}",pool_name="${addslashes(pool_cfg.name)}"`;
+        const pool_stat = st.pool.stats[pool_id];
+        res += `vitastor_pool_info{${pool_label}`+
+            `,pool_scheme="${addslashes(pool_cfg.scheme)}"`+
+            `,pg_size="${pool_cfg.pg_size||0}",pg_minsize="${pool_cfg.pg_minsize||0}"`+
+            `,parity_chunks="${pool_cfg.parity_chunks||0}",pg_count="${pool_cfg.pg_count||0}"`+
+            `,failure_domain="${addslashes(pool_cfg.failure_domain)}"`+
+            `} 1\n`;
+        if (!pool_stat)
+        {
+            continue;
+        }
+        res += `vitastor_pool_raw_to_usable{${pool_label}} ${pool_stat.raw_to_usable||0}\n`;
+        res += `vitastor_pool_space_efficiency{${pool_label}} ${pool_stat.space_efficiency||0}\n`;
+        res += `vitastor_pool_total_raw_tb{${pool_label}} ${pool_stat.total_raw_tb||0}\n`;
+        res += `vitastor_pool_used_raw_tb{${pool_label}} ${pool_stat.used_raw_tb||0}\n`;
+
+        // PG states and pool up/down status
+        const real_pg_count = (Object.keys(((st.config.pgs||{}).items||{})[pool_id]||{}).length) || (0|pool_cfg.pg_count);
+        const per_state = {};
+        const pool_pg_states = st.pg.state[pool_id] || {};
+        for (let i = 1; i <= real_pg_count; i++)
+        {
+            if (!pool_pg_states[i])
+            {
+                per_state['offline'] = 1 + (per_state['offline']|0);
+            }
+            else
+            {
+                for (const st_name of pool_pg_states[i].state)
+                {
+                    per_state[st_name] = 1 + (per_state[st_name]|0);
+                }
+            }
+        }
+        for (const st_name in per_state)
+        {
+            res += `vitastor_pg_count{pg_state="${st_name}",${pool_label}} ${per_state[st_name]}\n`;
+        }
+        const pool_active = per_state['active'] >= real_pg_count ? 1 : 0;
+        res += `vitastor_pool_status{${pool_label}} ${pool_active}\n`;
+    }
+
+    return res;
+}
+
+function addslashes(str)
+{
+    return ((str||'')+'').replace(/(["\n\\])/g, "\\$1"); // escape " \n \
+}
+
+module.exports = { export_prometheus_metrics };