Prometheus远端数据存储方案之PostgreSQL

今天看到德哥分享的基于postgresql的prometheus数据远端存储方案，于是有了本文的实验。

通常，prometheus的外置存储方案有好几种选择，例如influxdb，m3db， es，postgresql。

m3db一般在云原生环境下，用的更趁手些。

这里我们演示下postgresql的远端存储方案（可读可写），具体看下面的实验。

实验环境：

CentOS7.4

PG11-git-1921 编译安装版

参考文档：

https://blog.csdn.net/qq_43303221/article/details/88574693#cmake_34_50 编译安装 TimescaleDB 扩展

https://studygolang.com/articles/13522?fr=sidebar 远端存储的介绍

https://github.com/timescale/prometheus-postgresql-adapter prometheus-postgresql-adapter的官方文档介绍

https://prometheus.io/docs/prometheus/latest/configuration/configuration/#remote_write 官方文档

https://github.com/digoal/blog/blob/master/201910/20191027_04.md 德哥blog

https://github.com/timescale/pg_prometheus pg_prometheus扩展的官方文档

1、安装llvm

yum install centos-release-scl-rhyum install llvm-toolset-7-clangyum install llvm5.0 yum install llvm5.0-libsyum install llvm5.0-develyum install clang

2、安装cmake-3.4以上的版本

cd /usr/local/wget https://github.com/Kitware/CMake/releases/download/v3.16.0-rc2/cmake-3.16.0-rc2-Linux-x86_64.shsh cmake-3.16.0-rc2-Linux-x86_64.sh即可在当前路径下安装cmake-3.16载入cmake-3.16到环境变量：export PATH=/usr/local/cmake-3.16.0-rc2-Linux-x86_64/bin:$PATH

3、编译安装PG11带jit模块

su - postgrescd /home/postgres/wget  yum localinstall epel-release-latest-7.noarch.rpmyum install llvm5.0 llvm5.0-devel clangcd /home/postgres/pg_sources/postgresql-11./configure --prefix=/usr/local/pgsql-11.5-jit-1921 \--with-python --with-perl --with-tcl --with-pam \--with-openssl --with-libxml --with-libxslt \--with-llvm LLVM_CONFIG='/usr/lib64/llvm5.0/bin/llvm-config'make make install 然后，还有些数据库的基础配置，这里就不细说了。

4、安装TimescaleDB扩展

su - postgrescd /home/postgres/cd timescaledb-1.4.2/export PATH=/usr/local/pgsql-11.5-jit-1921/bin:$PATH./bootstrap 输入ycd ./build && makemake install  日志如下：[  0%] Built target sqlfile[ 25%] Built target sqlupdatescripts[ 81%] Built target timescaledb[ 85%] Built target timescaledb-loader[100%] Built target timescaledb-tslInstall the project...-- Install configuration: "Release"-- Installing: /usr/local/pgsql-11.5-jit-1921/share/extension/timescaledb.control-- Installing: /usr/local/pgsql-11.5-jit-1921/share/extension/timescaledb--1.4.2.sql-- Installing: /usr/local/pgsql-11.5-jit-1921/share/extension/timescaledb--1.4.1--1.4.2.sql-- Installing: /usr/local/pgsql-11.5-jit-1921/share/extension/timescaledb--1.4.1--1.4.2.sql-- Installing: /usr/local/pgsql-11.5-jit-1921/share/extension/timescaledb--1.4.0--1.4.2.sql-- Installing: /usr/local/pgsql-11.5-jit-1921/share/extension/timescaledb--1.3.2--1.4.2.sql-- Installing: /usr/local/pgsql-11.5-jit-1921/share/extension/timescaledb--1.3.1--1.4.2.sql-- Installing: /usr/local/pgsql-11.5-jit-1921/share/extension/timescaledb--1.3.0--1.4.2.sql-- Installing: /usr/local/pgsql-11.5-jit-1921/share/extension/timescaledb--1.2.2--1.4.2.sql-- Installing: /usr/local/pgsql-11.5-jit-1921/share/extension/timescaledb--1.2.1--1.4.2.sql-- Installing: /usr/local/pgsql-11.5-jit-1921/share/extension/timescaledb--1.2.0--1.4.2.sql-- Installing: /usr/local/pgsql-11.5-jit-1921/share/extension/timescaledb--1.1.1--1.4.2.sql-- Installing: /usr/local/pgsql-11.5-jit-1921/share/extension/timescaledb--1.1.0--1.4.2.sql-- Installing: /usr/local/pgsql-11.5-jit-1921/share/extension/timescaledb--1.0.1--1.4.2.sql-- Installing: /usr/local/pgsql-11.5-jit-1921/share/extension/timescaledb--1.0.0--1.4.2.sql-- Installing: /usr/local/pgsql-11.5-jit-1921/share/extension/timescaledb--1.0.0-rc3--1.4.2.sql-- Installing: /usr/local/pgsql-11.5-jit-1921/share/extension/timescaledb--1.0.0-rc2--1.4.2.sql-- Installing: /usr/local/pgsql-11.5-jit-1921/share/extension/timescaledb--1.0.0-rc1--1.4.2.sql-- Installing: /usr/local/pgsql-11.5-jit-1921/share/extension/timescaledb--0.12.1--1.4.2.sql-- Installing: /usr/local/pgsql-11.5-jit-1921/share/extension/timescaledb--0.12.0--1.4.2.sql-- Installing: /usr/local/pgsql-11.5-jit-1921/share/extension/timescaledb--0.11.0--1.4.2.sql-- Installing: /usr/local/pgsql-11.5-jit-1921/share/extension/timescaledb--0.10.1--1.4.2.sql-- Installing: /usr/local/pgsql-11.5-jit-1921/share/extension/timescaledb--0.10.0--1.4.2.sql-- Installing: /usr/local/pgsql-11.5-jit-1921/share/extension/timescaledb--0.9.2--1.4.2.sql-- Installing: /usr/local/pgsql-11.5-jit-1921/share/extension/timescaledb--0.9.1--1.4.2.sql-- Installing: /usr/local/pgsql-11.5-jit-1921/share/extension/timescaledb--0.9.0--1.4.2.sql-- Installing: /usr/local/pgsql-11.5-jit-1921/share/extension/timescaledb--0.8.0--1.4.2.sql-- Installing: /usr/local/pgsql-11.5-jit-1921/share/extension/timescaledb--0.7.1--1.4.2.sql-- Installing: /usr/local/pgsql-11.5-jit-1921/share/extension/timescaledb--0.7.0--1.4.2.sql-- Installing: /usr/local/pgsql-11.5-jit-1921/share/extension/timescaledb--0.6.1--1.4.2.sql-- Installing: /usr/local/pgsql-11.5-jit-1921/share/extension/timescaledb--0.6.0--1.4.2.sql-- Installing: /usr/local/pgsql-11.5-jit-1921/share/extension/timescaledb--0.5.0--1.4.2.sql-- Installing: /usr/local/pgsql-11.5-jit-1921/share/extension/timescaledb--0.4.2--1.4.2.sql-- Installing: /usr/local/pgsql-11.5-jit-1921/share/extension/timescaledb--0.4.1--1.4.2.sql-- Installing: /usr/local/pgsql-11.5-jit-1921/share/extension/timescaledb--0.4.0--1.4.2.sql-- Installing: /usr/local/pgsql-11.5-jit-1921/share/extension/timescaledb--0.3.0--1.4.2.sql-- Installing: /usr/local/pgsql-11.5-jit-1921/share/extension/timescaledb--0.2.0--1.4.2.sql-- Installing: /usr/local/pgsql-11.5-jit-1921/share/extension/timescaledb--0.1.0--1.4.2.sql-- Installing: /usr/local/pgsql-11.5-jit-1921/lib/timescaledb-1.4.2.so-- Installing: /usr/local/pgsql-11.5-jit-1921/lib/timescaledb.so-- Installing: /usr/local/pgsql-11.5-jit-1921/lib/timescaledb-tsl-1.4.2.so

即可完成timescaledb扩展的安装

编辑pg的配置文件，修改如下：

shared_preload_libraries = 'timescaledb'

完成后重启PG进程

然后，登录到PG中，创建扩展：

postgres=# CREATE EXTENSION timescaledb;

5、安装pg_prometheus扩展

su - postgrescd /home/postgres/export PATH=/usr/local/pgsql-11.5-jit-1921/bin:$PATHUSE_PGXS=1 make  USE_PGXS=1 make install

编辑pg的配置文件，修改如下：

shared_preload_libraries = 'timescaledb,pg_prometheus'

完成后重启PG进程

然后，登录到PG中，创建扩展：

postgres=# CREATE EXTENSION pg_prometheus ;postgres=# SELECT create_prometheus_table('metrics');   或者使用 SELECT create_prometheus_table('metrics',use_timescaledb=>true);postgres=# INSERT INTO metrics VALUES ('cpu_usage{service="nginx",host="machine1"} 34.6 1494595898000');  postgres=# \d                  List of relations Schema |         Name          |   Type   |  Owner   --------+-----------------------+----------+---------- public | metrics               | view     | postgres public | metrics_copy          | table    | postgres public | metrics_labels        | table    | postgres public | metrics_labels_id_seq | sequence | postgres public | metrics_values        | table    | postgres(5 rows)

6、启动prometheus-postgresql-adapter

直接到https://github.com/timescale/prometheus-postgresql-adapter 下载解压prometheus-postgresql-adapter

./prometheus-postgresql-adapter -pg-port 1921 --pg-user postgres  即可在前台启动adapter进程

7、使用prometheus连接adapter端口：

vim /usr/local/prometheus/prometheus.yml 在最后加2个配置；

remote_write: - url: "http://192.168.2.4:9201/write"   write_relabel_configs:      - source_labels: [__name__]        regex: 'go_.*'        action: dropremote_read:  - url: "http://192.168.2.4:9201/read"    read_recent: false

说明： 我这里设置的read_recent为false，表示查询prometheus近期数据不要到PG库里来捞数据，而是直接查prometheus本地缓存的数据，这样提高查询的速度并且能降低PG库的负载。

不足：

目前的配置来看，我们同事运行的prometheus和PG库， 存放同样历史周期的的metrics，PG库的体积远远超过了prometheus的体积。

PG库的metrics_values表已经 40 MB，此时的prometheus的data目录才 16MB 。 磁盘空间占用上，相差接近3倍。

优化方案待定：

调整remote_write 写入策略，通过drop操作来降低存储到PG的metrics的体积？