scripts, docs: specify lua version in `luarocks install`

On some systems luarocks defaults to other lua version (e.g. Fedora),
so the result would not be usable from kresd.  I didn't touch scripts
for older distro versions (Debian < 10, Ubuntu < 20.04, CentOS 7).

ci/debian-buster/Dockerfile

@@ -58,7 +58,7 @@ RUN wget https://github.com/LuaJIT/LuaJIT/raw/v2.1.0-beta3/src/lj.supp -O /lj.su
 
 # Lua lint for kresd CI
 RUN apt-get install luarocks -y -qqq
-RUN luarocks install luacheck
+RUN luarocks --lua-version 5.1 install luacheck
 
 # respdiff for kresd CI
 RUN apt-get install lmdb-utils -y -qqq
@@ -89,7 +89,7 @@ RUN apt-get install pdns-recursor -y -qqq
 
 # code coverage
 RUN apt-get install -y -qqq lcov
-RUN luarocks install luacov
+RUN luarocks --lua-version 5.1 install luacov
 
 # LuaJIT binary for stand-alone scripting
 RUN apt-get install -y -qqq luajit

modules/etcd/.packaging/debian/10/pre-test.sh

-luarocks install etcd --from=https://mah0x211.github.io/rocks/
+luarocks --lua-version 5.1 install etcd --from=https://mah0x211.github.io/rocks/

modules/etcd/.packaging/leap/15.2/pre-test.sh

-luarocks install etcd --from=https://mah0x211.github.io/rocks/
+luarocks --lua-version 5.1 install etcd --from=https://mah0x211.github.io/rocks/

modules/etcd/.packaging/ubuntu/20.04/pre-test.sh

-luarocks install etcd --from=https://mah0x211.github.io/rocks/
+luarocks --lua-version 5.1 install etcd --from=https://mah0x211.github.io/rocks/

modules/etcd/README.rst

@@ -42,5 +42,5 @@ Dependencies
 
 * `lua-etcd <https://github.com/mah0x211/lua-etcd>`_ library available in LuaRocks
 
-    ``$ luarocks install etcd --from=https://mah0x211.github.io/rocks/``
+    ``$ luarocks --lua-version 5.1 install etcd --from=https://mah0x211.github.io/rocks/``
 

modules/experimental_dot_auth/.packaging/leap/15.2/pre-test.sh

-luarocks install basexx --from=https://mah0x211.github.io/rocks/
+luarocks --lua-version 5.1 install basexx --from=https://mah0x211.github.io/rocks/

modules/graphite/.packaging/leap/15.2/pre-test.sh

-luarocks install cqueues --from=https://mah0x211.github.io/rocks/
+luarocks --lua-version 5.1 install cqueues --from=https://mah0x211.github.io/rocks/

modules/http/.packaging/leap/15.2/pre-test.sh

-luarocks install http --from=https://mah0x211.github.io/rocks/
+luarocks --lua-version 5.1 install http --from=https://mah0x211.github.io/rocks/

modules/http/README.rst

@@ -152,17 +152,17 @@ Dependencies
        $ brew install openssl
        $ brew link openssl --force # Override system OpenSSL
 
-    Any other system can install from LuaRocks directly:
+    Some other systems can install from LuaRocks directly:
 
     .. code-block:: bash
 
-       $ luarocks install http
+       $ luarocks --lua-version 5.1 install http
 
 * (*optional*) `mmdblua <https://github.com/daurnimator/mmdblua>`_ available in LuaRocks
 
     .. code-block:: bash
 
-       $ luarocks install --server=https://luarocks.org/dev mmdblua
+       $ luarocks --lua-version 5.1 install --server=https://luarocks.org/dev mmdblua
        $ curl -O https://geolite.maxmind.com/download/geoip/database/GeoLite2-City.mmdb.gz
        $ gzip -d GeoLite2-City.mmdb.gz