Update Dockerfile-alpine (#166)

* Dockerfile-alpine: update Alpine to v3.9

ttyd in Alpine v3.6 repository is v1.3.2, in Alpine v3.9, it's v1.4.2

* Dockerfile-alpine: simplify package installation

Use `--no-cache` to avoid the need to use `--update` and remove
`/var/cache/apk/*` manually

diff --git a/Dockerfile-alpine b/Dockerfile-alpine
index 767529ae02712d266ac029f4b84d98e919546b61..b427373742760430fade45a7a3118c6cabfe5504 100644 (file)
--- a/Dockerfile-alpine
+++ b/Dockerfile-alpine
@@ -1,11 +1,10 @@
-FROM alpine:3.6
+FROM alpine:3.9
 LABEL maintainer "Shuanglei Tao - tsl0922@gmail.com" \
     maintainer "Damien Duportal - damien.duportal@gmail.com"
 
-RUN apk add --update \
+RUN apk add --no-cache \
     bash \
-    ttyd \
-  && rm -rf /var/cache/apk/*
+    ttyd
 
 EXPOSE 7681