How to use nginx(intsalled on docker) reverse proxy gitlab(installed on docker too) – Ubuntu

Now i figure out why i could not make it works,I mixed up Using an existing Passenger/NGINX installation and Using a non-bundled web-server If you just need to use your own nginx to proxy gitlab(both of them was installed on docker) you just need to add two lines to gitlab.rb.

# Disable the built-in nginx
nginx['enable'] = false
# Define the web server process user (ubuntu/nginx)
web_server['external_users'] = ['nginx']

and here is nginx's conf

upstream gitlab-workhorse {
  server unix://var/opt/gitlab/gitlab-workhorse/sockets/socket fail_timeout=0;
}

server {
  listen *:80;
  server_name git.example.com;
  server_tokens off;
  root /opt/gitlab/embedded/service/gitlab-rails/public;

  client_max_body_size 250m;

  access_log  /var/log/gitlab/nginx/gitlab_access.log;
  error_log   /var/log/gitlab/nginx/gitlab_error.log;

  # Ensure Passenger uses the bundled Ruby version
  passenger_ruby /opt/gitlab/embedded/bin/ruby;

  # Correct the $PATH variable to included packaged executables
  passenger_env_var PATH "/opt/gitlab/bin:/opt/gitlab/embedded/bin:/usr/local/bin:/usr/bin:/bin";

  # Make sure Passenger runs as the correct user and group to
  # prevent permission issues
  passenger_user git;
  passenger_group git;

  # Enable Passenger & keep at least one instance running at all times
  passenger_enabled on;
  passenger_min_instances 1;

  location ~ ^/[w.-]+/[w.-]+/(info/refs|git-upload-pack|git-receive-pack)$ {
    # 'Error' 418 is a hack to re-use the @gitlab-workhorse block
    error_page 418 = @gitlab-workhorse;
    return 418;
  }

  location ~ ^/[w.-]+/[w.-]+/repository/archive {
    # 'Error' 418 is a hack to re-use the @gitlab-workhorse block
    error_page 418 = @gitlab-workhorse;
    return 418;
  }

  location ~ ^/api/v3/projects/.*/repository/archive {
    # 'Error' 418 is a hack to re-use the @gitlab-workhorse block
    error_page 418 = @gitlab-workhorse;
    return 418;
  }

  # Build artifacts should be submitted to this location
  location ~ ^/[w.-]+/[w.-]+/builds/download {
      client_max_body_size 0;
      # 'Error' 418 is a hack to re-use the @gitlab-workhorse block
      error_page 418 = @gitlab-workhorse;
      return 418;
  }

  # Build artifacts should be submitted to this location
  location ~ /ci/api/v1/builds/[0-9]+/artifacts {
      client_max_body_size 0;
      # 'Error' 418 is a hack to re-use the @gitlab-workhorse block
      error_page 418 = @gitlab-workhorse;
      return 418;
  }

  # Build artifacts should be submitted to this location
  location ~ /api/v4/jobs/[0-9]+/artifacts {
      client_max_body_size 0;
      # 'Error' 418 is a hack to re-use the @gitlab-workhorse block
      error_page 418 = @gitlab-workhorse;
      return 418;
  }


  # For protocol upgrades from HTTP/1.0 to HTTP/1.1 we need to provide Host header if its missing
  if ($http_host = "") {
  # use one of values defined in server_name
    set $http_host_with_default "git.example.com";
  }

  if ($http_host != "") {
    set $http_host_with_default $http_host;
  }

  location @gitlab-workhorse {

    ## https://github.com/gitlabhq/gitlabhq/issues/694
    ## Some requests take more than 30 seconds.
    proxy_read_timeout      3600;
    proxy_connect_timeout   300;
    proxy_redirect          off;

    # Do not buffer Git HTTP responses
    proxy_buffering off;

    proxy_set_header    Host                $http_host_with_default;
    proxy_set_header    X-Real-IP           $remote_addr;
    proxy_set_header    X-Forwarded-For     $proxy_add_x_forwarded_for;
    proxy_set_header    X-Forwarded-Proto   $scheme;

    proxy_pass http://gitlab-workhorse;

    ## The following settings only work with NGINX 1.7.11 or newer
    #
    ## Pass chunked request bodies to gitlab-workhorse as-is
    # proxy_request_buffering off;
    # proxy_http_version 1.1;
  }

  ## Enable gzip compression as per rails guide:
  ## http://guides.rubyonrails.org/asset_pipeline.html#gzip-compression
  ## WARNING: If you are using relative urls remove the block below
  ## See config/application.rb under "Relative url support" for the list of
  ## other files that need to be changed for relative url support
  location ~ ^/(assets)/ {
    root /opt/gitlab/embedded/service/gitlab-rails/public;
    gzip_static on; # to serve pre-gzipped version
    expires max;
    add_header Cache-Control public;
  }

  ## To access Grafana
  location /-/grafana/ {
    proxy_pass http://localhost:3000/;
  }

  error_page 502 /502.html;
}

last but not least,you need to add another bash to your nginx's container,

-v /var/opt/gitlab:/var/opt/gitlab

This will let your nginx container connect to gitlab container.Otherwise you will get "cannot find var/opt/gitlab/gitlab-workhorse/sockets/socket".