在 Linux 跑 Docker 要對 Apache 的 Log 做 logrotate，會遇到 Apache 沒有 reload 的問題
- 註：會看到 logrotate 有執行，但是 Log 檔持續寫 access.log.1，若 Apache reload 成功，應該要寫 access.log
Docker Apache2 要做 logrotate 失敗解法
於 /etc/logrotate.d/apache2 可以看到此行：
- invoke-rc.d apache2 reload 2>&1 | logger -t apache2.logrotate
執行看看 invoke-rc.d apache2 status 會出現下述錯誤：
- invoke-rc.d: could not determine current runlevel
- invoke-rc.d: policy-rc.d denied execution of status.
- invoke-rc.d: emulating initscript action "status", returning "unknown"
一個比較簡單的作法，可以把那行改成
- apache2 restart 或 apache2 graceful
另外一個是查看 policy-rc.d，內容如下：
- cat /usr/sbin/policy-rc.d
- #!/bin/sh
- # For most Docker users, "apt-get install" only happens during "docker build",
- # where starting services doesn't work and often fails in humorous ways. This
- # prevents those failures by stopping the services from attempting to start.
- exit 101
這裡面提到 exit 101 的主因是因為 docker build 的時候，有 apt-get install，怕 service 會自動啟動，造成失敗
既然都已經在執行，已經過了 Dockerfile 的階段 (或者說，policy-rc.d 的內容，在 Dockerfile 的 apt install 之後，就可以改回原始樣貌了)
將 policy-rc.d 改回 (exit 101 → exit 0)
- #!/bin/sh
- # For most Docker users, "apt-get install" only happens during "docker build",
- # where starting services doesn't work and often fails in humorous ways. This
- # prevents those failures by stopping the services from attempting to start.
- exit 0
- 註：sed -i 's/exit 101/exit 0/g' /usr/sbin/policy-rc.d
這樣子 Apache 的 Logrotate 就可以正常執行囉~
