[elasticsearch] Fix issue with readinessProbe causing outages

The `readinessProbe` was updated in elastic#586, however this appears to have
introduced a bug which can cause the pod to report as ready before it
actually is, due to a lack of quoting around the URL query params,
combined with the use of '&'.

This commit reworks the `readinessProbe` to correctly quote things.

Reintroduced the `http` function, and added support for passing `args`
in addition to the `path`.
Also borrowed the `set --` pattern from the Kibana chart.

elasticsearch/templates/statefulset.yaml

@@ -213,22 +213,32 @@ spec:
               - -c
               - |
                 #!/usr/bin/env bash -e
-                # If the node is starting up wait for the cluster to be ready (request params: '{{ .Values.clusterHealthCheckParams }}' )
+                # If the node is starting up wait for the cluster to be ready (request params: "{{ .Values.clusterHealthCheckParams }}" )
                 # Once it has started only check that the node itself is responding
                 START_FILE=/tmp/.es_start_file
 
-                if [ -n "${ELASTIC_USERNAME}" ] && [ -n "${ELASTIC_PASSWORD}" ]; then
-                  BASIC_AUTH="-u ${ELASTIC_USERNAME}:${ELASTIC_PASSWORD}"
-                else
-                  BASIC_AUTH=''
-                fi
+                http () {
+                  local path="${1}"
+                  local args="${2}"
+                  set -- -XGET -s
+
+                  if [ "$args" != "" ]; then
+                    set -- "$@" $args
+                  fi
+
+                  if [ -n "${ELASTIC_USERNAME}" ] && [ -n "${ELASTIC_PASSWORD}" ]; then
+                    set -- "$@" -u "${ELASTIC_USERNAME}:${ELASTIC_PASSWORD}"
+                  fi
+
+                  curl --output /dev/null -k "$@" "{{ .Values.protocol }}://127.0.0.1:{{ .Values.httpPort }}${path}"
+                }
 
                 if [ -f "${START_FILE}" ]; then
                   echo 'Elasticsearch is already running, lets check the node is healthy'
-                  HTTP_CODE=$(curl -XGET -s -k ${BASIC_AUTH} -o /dev/null -w '%{http_code}' {{ .Values.protocol }}://127.0.0.1:{{ .Values.httpPort }}/)
+                  HTTP_CODE=$(http "/" "-w %{http_code}")
                   RC=$?
                   if [[ ${RC} -ne 0 ]]; then
-                    echo "curl -XGET -s -k \${BASIC_AUTH} -o /dev/null -w '%{http_code}' {{ .Values.protocol }}://127.0.0.1:{{ .Values.httpPort }}/ failed with RC ${RC}"
+                    echo "curl --output /dev/null -k -XGET -s -w '%{http_code}' \${BASIC_AUTH} {{ .Values.protocol }}://127.0.0.1:{{ .Values.httpPort }}/ failed with RC ${RC}"
                     exit ${RC}
                   fi
                   # ready if HTTP code 200, 503 is tolerable if ES version is 6.x
@@ -237,13 +247,13 @@ spec:
                   elif [[ ${HTTP_CODE} == "503" && "{{ include "elasticsearch.esMajorVersion" . }}" == "6" ]]; then
                     exit 0
                   else
-                    echo "curl -XGET -s -k \${BASIC_AUTH} -o /dev/null -w '%{http_code}' {{ .Values.protocol }}://127.0.0.1:{{ .Values.httpPort }}/ failed with HTTP code ${HTTP_CODE}"
+                    echo "curl --output /dev/null -k -XGET -s -w '%{http_code}' \${BASIC_AUTH} {{ .Values.protocol }}://127.0.0.1:{{ .Values.httpPort }}/ failed with HTTP code ${HTTP_CODE}"
                     exit 1
                   fi
 
                 else
                   echo 'Waiting for elasticsearch cluster to become ready (request params: "{{ .Values.clusterHealthCheckParams }}" )'
-                  if curl -XGET -s -k --fail ${BASIC_AUTH} {{ .Values.protocol }}://127.0.0.1:{{ .Values.httpPort }}/_cluster/health?{{ .Values.clusterHealthCheckParams }} ; then
+                  if http "/_cluster/health?{{ .Values.clusterHealthCheckParams }}" "--fail" ; then
                     touch ${START_FILE}
                     exit 0
                   else