Fix some markdownlint, yamllint + shellcheck warnings

Fixed:

* MD040/fenced-code-language Fenced code blocks should have a language specified [Context: "```"]
* MD034/no-bare-urls Bare URL used [Context: "https://synpro.solutions"]
* SC1091 (info): Not following: ./megacli.cfg: openBinaryFile: does not exist (No such file or directory)
* SC2086 (info): Double quote to prevent globbing and word splitting.
* SC2236 (style): Use -n instead of ! -z.

Removed ansible molecule because I was not able to install checkmkagent
in the docker enviroment. Mainly because the docker image has no systemd
enabled, see: geerlingguy/docker-debian11-ansible#4

Also, there used to be public Checkmk demo instance: https://demo.checkmk.com/demo
But it is not reachable anymore, so I have no way downloading the
checkmkagent. Decided to not put any more efforts into it.

README.md

@@ -23,7 +23,7 @@ For currently available local checks, see: [files/check-mk/local](https://github
 
 Currently the following checkmk agent plugins are supported:
 
-```
+```yaml
 checkmkagent_plugins_available: [ 'mk_ceph', 'mk_logwatch.py', 'mk_mysql' ]
 ```
 
@@ -37,7 +37,7 @@ N/A
 Example Playbook
 ----------------
 
-```
+```yaml
     - hosts: site
       vars:
         checkmkagent_host_url: 'http://monitor01.example.com/mysite'
@@ -59,7 +59,7 @@ Older versions of this role used the variable `checkmkagent_baseurl` instead `ch
 `mk_apt` was installed in `/usr/lib/check_mk_agent/plugins/60` instead of `/usr/lib/check_mk_agent/plugins/3600`.
 To delete the check on all hosts from the wrong location you could use ansible like this:
 
-```
+```console
 % ansible -i hosts all -m shell -a "ls -l /usr/lib/check_mk_agent/plugins/60/mk_apt"
 % ansible -i hosts all -b -m shell -a "rm /usr/lib/check_mk_agent/plugins/60/mk_apt"
 % ansible -i hosts all -b -m shell -a "rmdir /usr/lib/check_mk_agent/plugins/60"
@@ -74,4 +74,4 @@ MIT
 Author Information
 ------------------
 
-Darshaka Pathirana - https://synpro.solutions
+Darshaka Pathirana - <https://synpro.solutions>

files/check-mk/local/check_megacli_battery

@@ -13,10 +13,12 @@ fi
 # battery_adapter=ALL or an adapter
 
 if [ -e "$MK_CONFDIR/megacli.cfg" ]; then
-  . $MK_CONFDIR/megacli.cfg
+  # shellcheck disable=SC1090
+  . "$MK_CONFDIR/megacli.cfg"
 fi
 
 # if unconfigured then default to all adapters
+# shellcheck disable=SC2154
 if [ -z "$battery_adapter" ] ; then
   exit 0
 fi

files/check-mk/local/check_megacli_diskgroups

@@ -14,9 +14,11 @@ fi
 # num_disk_groups=0
 
 if [ -e "$MK_CONFDIR/megacli.cfg" ]; then
-  . $MK_CONFDIR/megacli.cfg
+  # shellcheck disable=SC1090
+  . "$MK_CONFDIR/megacli.cfg"
 fi
 
+# shellcheck disable=SC2154
 if [ -z "$num_disk_groups" ]; then
   exit 0
 fi
@@ -38,7 +40,7 @@ for adapter in $adapters ; do
   fi
 
   if [ "$num_disk_groups_adapter" -eq 0 ] ; then
-    [ ! -z "$output" ] && output="${output}, "
+    [ -n "$output" ] && output="${output}, "
     output="${output}Adapter $adapter: no disk group"
     continue
   else
@@ -57,7 +59,7 @@ for adapter in $adapters ; do
     echo "2 ${check_name} - $STATUS on adapter $adapter [see 'megacli -CfgDsply -a$adapter -NoLog']"
     exit 1
   else
-    [ ! -z "$output" ] && output="${output}, "
+    [ -n "$output" ] && output="${output}, "
     output="${output}Adapter $adapter: $STATUS"
   fi
 done
@@ -70,7 +72,7 @@ elif [ "$num_disk_groups_present" -gt "$num_disk_groups_expected" ] ; then
   exit 1
 fi
 
-[ ! -z "$output" ] && output="${output}, "
+[ -n "$output" ] && output="${output}, "
 output="${output}$num_disk_groups_present disk group(s) found"
 
 echo "0 ${check_name} - $output"

files/check-mk/local/check_megacli_num_disks

@@ -14,9 +14,11 @@ fi
 # num_disks=[number of disks to be expected]
 
 if [ -e "$MK_CONFDIR/megacli.cfg" ]; then
-  . $MK_CONFDIR/megacli.cfg
+  # shellcheck disable=SC1090
+  . "$MK_CONFDIR/megacli.cfg"
 fi
 
+# shellcheck disable=SC2154
 if [ -z "$num_disks" ] ; then
   exit 0
 fi