Fix gitlab runner error after VM backup restore processes

Background

The gitlab runner service is unable to start after performing VM backup and restore process (for the sake of increasing storage size)

Problems

The error messages come as follows when I try to start the gitlab runner manually

prodev@storage:~$ sudo gitlab-runner run
Runtime platform                                    arch=amd64 os=linux pid=20037 revision=ac8e767a version=12.6.0
Starting multi-runner from/etc/gitlab-runner/config.toml...  builds=0
Running in system-mode.

Configuration loaded                                builds=0
listen_address not defined, metrics & debug endpoints disabled  builds=0
[session_server].listen_address not defined, session endpoints disabled  builds=0
ERROR: Checking for jobs... forbidden               runner=99ab6a69
ERROR: Checking for jobs... forbidden               runner=eac73045
ERROR: Checking for jobs... forbidden               runner=99ab6a69
ERROR: Checking for jobs... forbidden               runner=eac73045
ERROR: Checking for jobs... forbidden               runner=99ab6a69
ERROR: Runner https://repo.gitlab.dev.hkg.internal.p2mt.com99ab6a6972442b2a52ffe7358cbf8f is not healthy and will be disabled!
ERROR: Checking for jobs... forbidden               runner=eac73045
ERROR: Runner https://gitlab.com/eac73045875b618fea0464590a0fb2 is not healthy and will be disabled!

Solutions

1. Rename config.toml in /etc/gitlab-runner to config.toml.bk

2. Restart gitlab service by "gitlab-runner start"

3. Re-name config.toml.bk back to config.toml

4. Re-start the service again by "gitlab-runner restart"