Kubernetes agent fails to connect to GitLab with "expected handshake response status code 101 but got 426"

Infrastructure as Code & Cloud Native
3

@melkamar @markushe
I had the same issue described here because my Nginx reverse proxy wasn’t passing along the Upgrade and Connection headers to GitLab, resulting in GitLab returning a 426. The Nginx docs talk about why this header isn’t passed along and how to do it.

I just added a new location block to my virtual host that adds the headers:

location /-/kubernetes-agent/ {
    proxy_set_header Host $host;
    proxy_set_header Upgrade $http_upgrade;
    proxy_set_header Connection "upgrade";

    proxy_pass https://gitlab-server;
}