healthcheck: replace dig with pre-installed nslookup

CHANGELOG.md

@@ -14,6 +14,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Removed
 - `curl`
+- `bin-tools` package including `dig`
 
 ## [3.0.0] - 2020-10-03
 ### Added

Dockerfile

@@ -1,10 +1,7 @@
 FROM alpine:3.12.3
 
-ARG BIND_TOOLS_PACKAGE_VERSION=9.16.6-r0
 ARG TOR_PACKAGE_VERSION=0.4.3.7-r0
-RUN apk add --no-cache \
-        bind-tools=$BIND_TOOLS_PACKAGE_VERSION `# dig` \
-        tor=$TOR_PACKAGE_VERSION
+RUN apk add --no-cache tor=$TOR_PACKAGE_VERSION
 VOLUME /var/lib/tor
 
 #RUN apk add --no-cache \
@@ -28,5 +25,5 @@ CMD ["tor", "-f", "/tmp/torrc"]
 HEALTHCHECK CMD \
     printf "AUTHENTICATE\nGETINFO network-liveness\nQUIT\n" | nc localhost 9051 \
         | grep -q network-liveness=up \
-    && dig -p 9053 +notcp +short google.com @localhost \
+    && nslookup -port=9053 google.com localhost | grep -v NXDOMAIN | grep -q google \
     || exit 1