Alpine镜像中telnet转移至busybox-extras

Alpine镜像中的telnet在3.7版本后被转移至busybox-extras包中，需要使用apk单独安装。

现象

Alpine版本为3.8, 不再有指向busybox的telent

~ # cat /etc/alpine-release
3.8.0
~ #
~ # ls /usr/bin/ |grep -w busybox |grep telnet
~ #

原因

确认了相关的issue发现，在Alpine3.7时就已经有了这个变化：https://github.com/gliderlabs/docker-alpine/issues/397

对应

使用apk安装即可

apk update

/var/atlassian/jira # apk update
fetch http://dl-cdn.alpinelinux.org/alpine/v3.8/main/x86_64/APKINDEX.tar.gz
fetch http://dl-cdn.alpinelinux.org/alpine/v3.8/community/x86_64/APKINDEX.tar.gz
v3.8.0-28-g923d74cddf [http://dl-cdn.alpinelinux.org/alpine/v3.8/main]
v3.8.0-28-g923d74cddf [http://dl-cdn.alpinelinux.org/alpine/v3.8/community]
OK: 9536 distinct packages available
/var/atlassian/jira #

apk add busybox-extras

/var/atlassian/jira # apk add busybox-extras
(1/1) Installing busybox-extras (1.28.4-r1)
Executing busybox-extras-1.28.4-r1.post-install
Executing busybox-1.28.4-r0.trigger
OK: 133 MiB in 76 packages
/var/atlassian/jira #

安装后确认

确认telnet安装路径

/var/atlassian/jira # which telnet
/usr/bin/telnet
/var/atlassian/jira #
~ # ls -l /usr/bin/telnet
lrwxrwxrwx  1 root   root      19 Jul 24 01:40 /usr/bin/telnet -> /bin/busybox-extras
~ # ls /bin/busybox

确认动作

在网络通的情况下，telnet可以与smtp服务器进行通信

~ # telnet smtp.163.com 25
220 163.com Anti-spam GT for Coremail System (163com[20141201])
HELO liumiaocn
250 OK