Make one env optional and warn about optional missing envs (#110)

* Make one env optional and warn about optional missing envs

* Restrict visibility of var

* Fix warning

* Dont print empty warning list

bin/restic_check.sh

@@ -25,10 +25,29 @@ assert_envvars() {
 		fi
 	done
 }
-assert_envvars \
-	B2_ACCOUNT_ID B2_ACCOUNT_KEY B2_CONNECTIONS \
+
+warn_on_missing_envvars() {
+	local unset_envs=()
+	local varnames=("$@")
+	for varname in "${varnames[@]}"; do
+		if [ -z "${!varname}" ]; then
+			unset_envs=("${unset_envs[@]}" "$varname")
+		fi
+	done
+	
+	if [ ${#unset_envs[@]} -gt 0 ]; then
+		printf "The following env variables are recommended, but have not been set. This script may not work as expected: %s\n" "${unset_envs[*]}" >&2
+	fi
+}
+
+assert_envvars\
 	RESTIC_PASSWORD_FILE RESTIC_REPOSITORY RESTIC_VERBOSITY_LEVEL
 
+warn_on_missing_envvars \
+	B2_ACCOUNT_ID B2_ACCOUNT_KEY B2_CONNECTIONS
+
+B2_ARG=
+[ -z "${B2_CONNECTIONS+x}" ] || B2_ARG=(--option b2.connections="$B2_CONNECTIONS")
 
 # Remove locks from other stale processes to keep the automated backup running.
 # NOTE nope, don't unlock like restic_backup.sh. restic_backup.sh should take precedence over this script.
@@ -36,7 +55,7 @@ assert_envvars \
 #wait $!
 
 # Check repository for errors.
-restic check \
-	--option b2.connections="$B2_CONNECTIONS" \
+echo restic check \
+	"${B2_ARG[@]}" \
 	--verbose="$RESTIC_VERBOSITY_LEVEL" &
 wait $!