upgrade base image from alpine v3.8 to v3.12; pin package versions

CHANGELOG.md

@@ -5,8 +5,12 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## [Unreleased]
+### Changed
+- upgrade base image from alpine v3.8 to v3.12
+
 ### Fixed
 - empty passwords (redundant as sshd config disables password authentication)
+- pin package versions
 
 ## [0.1.0] - 2019-01-01
 ### Added

Dockerfile

@@ -1,6 +1,12 @@
-FROM alpine:3.8
+FROM alpine:3.12
 
-RUN apk add --no-cache rsync rrsync openssh-server
+ARG RSYNC_PACKAGE_VERSION=3.1.3-r3
+ARG RRSYNC_PACKAGE_VERSION=3.1.3-r3
+ARG OPENSSH_SERVER_PACKAGE_VERSION=8.3_p1-r0
+RUN apk add --no-cache \
+    openssh-server=$OPENSSH_SERVER_PACKAGE_VERSION \
+    rrsync=$RRSYNC_PACKAGE_VERSION \
+    rsync=$RSYNC_PACKAGE_VERSION
 
 ENV SSHD_HOST_KEYS_DIR /etc/ssh/host_keys
 VOLUME $SSHD_HOST_KEYS_DIR

README.md

@@ -23,8 +23,8 @@ $ docker run --name rsync-sshd \
     --publish 2022:22 --env USERS=alice,bob \
     --volume accessible-data:/data:ro \
     --volume host-keys:/etc/ssh/host_keys \
-    --volume alice-ssh-config:/home/alice/.ssh:ro \ 
-    --volume bob-ssh-config:/home/bob/.ssh:ro \ 
+    --volume alice-ssh-config:/home/alice/.ssh:ro \
+    --volume bob-ssh-config:/home/bob/.ssh:ro \
     --init --rm \
     fphammerle/rsync-sshd
 $ rsync -av --rsh='ssh -p 2022' alice@localhost:/source /target