postgres_exporter編譯運行過程

前言

如果想對postgres_exporter內容做修改，需要自己進行編譯。下面是postgres_exporter的README說明

# PostgreSQL Server Exporter

Prometheus exporter for PostgreSQL server metrics.

CI Tested PostgreSQL versions: `9.4`, `9.5`, `9.6`, `10`, `11`

## Quick Start
This package is available for Docker:
```
# Start an example database
docker run --net=host -it --rm -e POSTGRES_PASSWORD=password postgres
# Connect to it
docker run --net=host -e DATA_SOURCE_NAME="postgresql://postgres:password@localhost:5432/postgres?sslmode=disable" wrouesnel/postgres_exporter
```

## Building and running

The build system is based on [Mage](https://magefile.org)

The default make file behavior is to build the binary:
```
$ go get github.com/wrouesnel/postgres_exporter
$ cd ${GOPATH-$HOME/go}/src/github.com/wrouesnel/postgres_exporter
$ go run mage.go binary
$ export DATA_SOURCE_NAME="postgresql://login:password@hostname:port/dbname"
$ ./postgres_exporter <flags>
```

To build the dockerfile, run `go run mage.go docker`.

This will build the docker image as `wrouesnel/postgres_exporter:latest`. This
is a minimal docker image containing *just* postgres_exporter. By default no SSL
certificates are included, if you need to use SSL you should either bind-mount
`/etc/ssl/certs/ca-certificates.crt` or derive a new image containing them.

下載安裝

去官網https://golang.google.cn/dl/，下載go安裝程序(推薦linux，後面使用起來會很方便)

在下載頁中會有一套安裝使用教程，大概意思就是解壓、配置環境變量、寫個hello word、build生成可執行文件

這些過程最好都做一遍，也算對go的瞭解。

構建和運行

構建運行就四步

The default make file behavior is to build the binary:
```
$ go get github.com/wrouesnel/postgres_exporter
$ cd ${GOPATH-$HOME/go}/src/github.com/wrouesnel/postgres_exporter
$ go run mage.go binary
$ export DATA_SOURCE_NAME="postgresql://login:password@hostname:port/dbname"
$ ./postgres_exporter <flags>
```

[root@baidu ~]# go get github.com/wrouesnel/postgres_exporter
go: missing Git command. See https://golang.org/s/gogetcmd
package github.com/wrouesnel/postgres_exporter: exec: "git": executable file not found in $PATH
[root@baidu ~]# yum install git
Loaded plugins: fastestmirror, langpacks
base                                                                                | 3.6 kB  00:00:00     
extras                                                                              | 2.9 kB  00:00:00     
updates                                                                             | 2.9 kB  00:00:00     
Loading mirror speeds from cached hostfile
 * base: mirrors.aliyun.com
 * extras: mirrors.tuna.tsinghua.edu.cn
 * updates: mirrors.tuna.tsinghua.edu.cn
Resolving Dependencies
--> Running transaction check
---> Package git.x86_64 0:1.8.3.1-23.el7_8 will be installed
......
.....
  git.x86_64 0:1.8.3.1-23.el7_8                                                                            

Dependency Installed:
  perl-Git.noarch 0:1.8.3.1-23.el7_8                 perl-TermReadKey.x86_64 0:2.30-20.el7                

Complete!
[root@baidu ~]# go get github.com/wrouesnel/postgres_exporter
package github.com/wrouesnel/postgres_exporter: build constraints exclude all Go files in 
/root/go/src/github.com/wrouesnel/postgres_exporter

1)執行go get github.com/wrouesnel/postgres_exporter可能會缺少依賴包，yum install去下載即可

2)進入/root/go/src/github.com/wrouesnel/postgres_exporter目錄，執行go run mage.go binary

[root@baidu postgres_exporter]# ll
total 84
drwxr-xr-x. 3 root root    41 Jun 19 16:45 assets
drwxr-xr-x. 3 root root    50 Jun 19 16:45 bin
drwxr-xr-x. 3 root root    31 Jun 19 16:34 cmd
-rw-r--r--. 1 root root   178 Jun 19 16:34 Dockerfile
-rw-r--r--. 1 root root  3470 Jun 19 16:34 example.alerts.yml
-rwxr-xr-x. 1 root root   524 Jun 19 16:34 gh-assets-clone.sh
-rwxr-xr-x. 1 root root   697 Jun 19 16:34 gh-metrics-push.sh
-rw-r--r--. 1 root root   584 Jun 19 16:34 LICENSE
-rw-r--r--. 1 root root 19795 Jun 19 16:34 magefile.go
-rw-r--r--. 1 root root   121 Jun 19 16:34 mage.go
lrwxrwxrwx. 1 root root   110 Jun 19 16:47 postgres_exporter -> /root/go/src/github.com/wrouesnel/postgres_exporter/bin/postgres_exporter_v0.8.0_linux-amd64/postgres_exporter
-rwxr-xr-x. 1 root root   384 Jun 19 16:34 postgres_exporter_integration_test_script
-rw-r--r--. 1 root root  3196 Jun 19 16:34 postgres_exporter.rc
-rwxr-xr-x. 1 root root  1154 Jun 19 16:34 postgres-metrics-get-changes.sh
-rw-r--r--. 1 root root  8934 Jun 19 16:34 queries.yaml
-rw-r--r--. 1 root root 11265 Jun 19 16:34 README.md
-rw-r--r--. 1 root root  1558 Jun 19 16:34 README-RDS.md
drwxr-xr-x. 2 root root     6 Jun 19 16:43 release
drwxr-xr-x. 4 root root    77 Jun 19 16:43 tools
drwxr-xr-x. 5 root root    77 Jun 19 16:34 vendor
[root@baidu postgres_exporter]# 

進行編譯，會多出幾個文件夾(時間較新的)，比較重要的是bin，存放postgres_exporter源碼，以及postgres_exporter外連接

3)設置環境變量，export DATA_SOURCE_NAME=postgresql://hgdb:[email protected]:4102/hgdb?sslmode=disable

4)運行應用

[root@baidu postgres_exporter]# export DATA_SOURCE_NAME=postgresql://hgdb:[email protected]:4102/hgdb?sslmode=disable

[root@baidu postgres_exporter]# ./postgres_exporter --log.level="debug"
INFO[0000] Established new database connection to "192.168.90.124:4102".  source="postgres_exporter.go:881"
DEBU[0000] Querying Postgres Version on "192.168.90.124:4102"  source="postgres_exporter.go:1391"
INFO[0000] Semantic Version Changed on "192.168.90.124:4102": 0.0.0 -> 12.1.0  source="postgres_exporter.go:1408"
DEBU[0000] procpid is being forced to discard due to version incompatibility.  source="postgres_exporter.go:599"
DEBU[0000] pg_xlog_location_diff is being forced to discard due to version incompatibility.  source="postgres_exporter.go:599"
DEBU[0000] write_location is being forced to discard due to version incompatibility.  source="postgres_exporter.go:599"
DEBU[0000] replay_location is being forced to discard due to version incompatibility.  source="postgres_exporter.go:599"
DEBU[0000] flush_location is being forced to discard due to version incompatibility.  source="postgres_exporter.go:599"
DEBU[0000] sent_location is being forced to discard due to version incompatibility.  source="postgres_exporter.go:599"
DEBU[0000] Querying pg_setting view on "192.168.90.124:4102"  source="pg_setting.go:15"
DEBU[0000] Querying namespace:  pg_stat_replication      source="postgres_exporter.go:1326"
DEBU[0000] Querying namespace:  pg_stat_archiver         source="postgres_exporter.go:1326"
DEBU[0000] Querying namespace:  pg_stat_activity         source="postgres_exporter.go:1326"
DEBU[0000] Querying namespace:  pg_stat_bgwriter         source="postgres_exporter.go:1326"
DEBU[0000] Querying namespace:  pg_stat_database         source="postgres_exporter.go:1326"
DEBU[0000] Querying namespace:  pg_stat_database_conflicts  source="postgres_exporter.go:1326"
DEBU[0000] Querying namespace:  pg_locks                 source="postgres_exporter.go:1326"
INFO[0000] Starting Server: :9187                        source="postgres_exporter.go:1675"
DEBU[0011] Querying Postgres Version on "192.168.90.124:4102"  source="postgres_exporter.go:1391"
DEBU[0011] Querying pg_setting view on "192.168.90.124:4102"  source="pg_setting.go:15"
DEBU[0011] Querying namespace:  pg_stat_replication      source="postgres_exporter.go:1326"
DEBU[0011] Querying namespace:  pg_stat_archiver         source="postgres_exporter.go:1326"
DEBU[0011] Querying namespace:  pg_stat_activity         source="postgres_exporter.go:1326"
DEBU[0011] Querying namespace:  pg_stat_bgwriter         source="postgres_exporter.go:1326"
DEBU[0011] Querying namespace:  pg_stat_database         source="postgres_exporter.go:1326"
DEBU[0011] Querying namespace:  pg_stat_database_conflicts  source="postgres_exporter.go:1326"
DEBU[0011] Querying namespace:  pg_locks                 source="postgres_exporter.go:1326"

到此爲止，二進制文件啓動就搞完了。

docker文件

官方還給出了打包成dockerfile，這是一個包含的最小 Docker 圖像，只包含 postgres_exporter

1）執行go run mage.go docker打包命令，發現docker不在$PATH，然後yum install docker，

[root@baidu postgres_exporter]# go run mage.go docker
2020/06/19 16:58:45 exec: git rev-parse --abbrev-ref HEAD
2020/06/19 16:58:45 exec: git rev-parse HEAD
2020/06/19 16:58:45 exec: git describe --dirty
2020/06/19 16:58:45 exec: git describe --abbrev=0
2020/06/19 16:58:45 exec: go list ./...
Building /root/go/src/github.com/wrouesnel/postgres_exporter/bin/postgres_exporter_v0.8.0_linux-amd64/postgres_exporter
Error: failed to run "docker build --build-arg=binary=bin/postgres_exporter_v0.8.0_linux-amd64/postgres_exporter -t wrouesnel/postgres_exporter:latest .: exec: "docker": executable file not found in $PATH"
exit status 1
[root@baidu postgres_exporter]# yum install docker
...
...
Complete!
[root@baidu postgres_exporter]#

2) 再次執行，出現超時問題

[root@baidu postgres_exporter]# go run mage.go docker
2020/06/19 10:42:41 exec: git rev-parse --abbrev-ref HEAD
2020/06/19 10:42:41 exec: git rev-parse HEAD
2020/06/19 10:42:41 exec: git describe --dirty
2020/06/19 10:42:41 exec: git describe --abbrev=0
2020/06/19 10:42:41 exec: go list ./...
Building /root/go/src/github.com/wrouesnel/postgres_exporter/bin/postgres_exporter_v0.8.0_linux-amd64/postgres_exporter
Sending build context to Docker daemon 13.72 MB
Step 1/7 : FROM debian:10-slim
Trying to pull repository docker.io/library/debian ... 
10-slim: Pulling from docker.io/library/debian
8559a31e96f4: Pulling fs layer 
error pulling image configuration: Get https://production.cloudflare.docker.com/registry-v2/docker/registry/v2/blobs/sha256/43/43e3995ee54ac008271bfcf2d8ac7278c33f4c5e83d2f02bfcddd350034e3357/data?verify=1592537642-YR%2BjUslatzaYnU4y8s5krkaEcz0%3D: dial tcp 104.18.123.25:443: i/o timeout
Error: running "docker build --build-arg=binary=bin/postgres_exporter_v0.8.0_linux-amd64/postgres_exporter -t wrouesnel/postgres_exporter:latest ." failed with exit code 1
exit status 1
[root@baidu postgres_exporter]# 

在/etc/resolv.conf文件中新增一個參數，nameserver 8.8.8.8

然後重啓docker,再次執行

[root@baidu postgres_exporter]# service docker restart
Redirecting to /bin/systemctl restart docker.service
[root@baidu postgres_exporter]# go run mage.go docker
2020/06/19 17:06:45 exec: git rev-parse --abbrev-ref HEAD
2020/06/19 17:06:45 exec: git rev-parse HEAD
2020/06/19 17:06:45 exec: git describe --dirty
2020/06/19 17:06:45 exec: git describe --abbrev=0
2020/06/19 17:06:45 exec: go list ./...
Building /root/go/src/github.com/wrouesnel/postgres_exporter/bin/postgres_exporter_v0.8.0_linux-amd64/postgres_exporter
Sending build context to Docker daemon 13.72 MB
Step 1/7 : FROM debian:10-slim
...
...
Step 7/7 : ENTRYPOINT /postgres_exporter
 ---> Running in 75c1d2148368
 ---> 7844bb03e427
Removing intermediate container 75c1d2148368
Successfully built 7844bb03e427
[root@baidu postgres_exporter]# 

根據生成目錄Building ，進入查看

[root@baidu postgres_exporter]# cd /root/go/src/github.com/wrouesnel/postgres_exporter/bin/postgres_exporter_v0.8.0_linux-amd64
[root@baidu postgres_exporter_v0.8.0_linux-amd64]# ll
total 13396
-rwxr-xr-x. 1 root root 13716800 Jun 19 17:08 postgres_exporter
[root@baidu postgres_exporter_v0.8.0_linux-amd64]# 

到此docker打包結束