[template] Wait some time for stdin

Due to kubectl race condition with attaching stdin,
we should wait some time for it

src/commands/template

@@ -17,19 +17,23 @@ fi
 
 readonly REPO_PATH="${REPO_PATH:-sumologic/sumologic}"
 readonly REPO_URL="${REPO_URL:-https://sumologic.github.io/sumologic-kubernetes-collection}"
+readonly STDIN_WAIT_S="${STDIN_WAIT_S:10}"
+
+echoerr '# Add sumologic repository'
+helm repo add sumologic "${REPO_URL}" 1>/dev/null 2>&1
+echoerr '# Update repository'
+helm repo update 1>/dev/null 2>&1
 
 # Take data from stdin if available and put into tmpfile
 tmpfile="$(mktemp /tmp/values.yaml.XXXXXX)"
 extra_params=''
-if read -t 0; then
+# Kubectl can take some time before stdin is available for reading
+# thats why we check if just before it's required
+if read -t "${STDIN_WAIT_S}"; then
   cat <&0 > "${tmpfile}"
   extra_params="-f${tmpfile}"
 fi
 
-echoerr '# Add sumologic repository'
-helm repo add sumologic "${REPO_URL}" 1>/dev/null 2>&1
-echoerr '# Update repository'
-helm repo update 1>/dev/null 2>&1
 echoerr '# Generating template'
 helm template "${REPO_PATH}" ${extra_params} "$@" 2>&1 | grep -vE '^manifest_sorter.go'
 rm "${tmpfile}"