Capistrano: Different usernames for each server
If you have different users for different servers, don't use set :user. Encode the username into the server definition instead:
server "username@servername.tld", :app, :web, :cron, :db, :primary => true
Related cards:
Capistrano: Bundler stalls and asks for "Username"
Given you use Capistrano together with bundler to automatically install your gems when deploying.
I recently had the problem that Capistrano stalled like this:
[err :: host.name.tld] Username:
It turned out that I this originated from G...
How to use the Capistrano 2 shell to execute commands on servers
Capistrano 2 brings the shell command which allows you to run commands on your deployment targets.
There is also invoke to run a command directly from your terminal.
Both commands allow running Capistrano tasks or shell commands, and scope to...
Capistrano 2: Which Capistrano hooks to use for events to happen on both "cap deploy" and "cap deploy:migrations"
When deploying an application with "cap deploy" by default [1] you only deploy your code but do not run migrations. To avoid an application to be running with code which requires database changes that did not happen yet you should use `cap deplo...
Capistrano 3: Running a command on all servers
This Capistrano task runs a command on all servers.
bundle exec cap production app:run cmd='zgrep -P "..." RAILS_ROOT/log/production.log'
Code
# lib/capistrano/tasks/app.rake
namespace :app do
# Use e.g. to grep logs on al...
whenever: Installing cron jobs only for a given Rails environment or Capistrano stage
We use the whenever gem to automatically update the crontab of the servers we deploy to. By default, whenever will update all servers with a matching role ([we use the :cron role ](https://makandracards.com/m...
Capistrano 2: How to deploy a single server
When you have a multi-server setup, you'll be adding a new server from time to time. Before doing a full deploy, you might want to test that server in an isolated deploy. There is a single way to do this: the HOSTFILTER env variable.
Commenting...
Capistrano task to tail remote application logs of multiple servers
When your application is running on a multi-server setup, application logs are stored per server (unless you choose a centralized logging solution).
Here is a Capistrano task that connects to all servers and prints logs to your terminal like this:...
Postgres: DISTINCT ON lets you select only one record per ordered attribute(s) for each group
-
To retrieve only unique combinations of the selected attributes: You can omit rows, where all selected columns are equal with the
DISTINCTstatement. - To retrieve the group wise maximum of certain columns: You can keep only one record fo...
MySQL: For each group, retrieve a comma-separated list of values in a given column
The technique described in this card has an important caveat: The result of GROUP_CONCAT is truncated to the maximum length that is given by the group_concat_max_len system variable, which has a default value of 1024. **This will cause hor...
Declare different CSS background-images for different locales
If you would like to use language specific layout (e.g. background-images) in your applications stylesheets you can achieve this easily by using the lang attribute in your views (ERB):
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="<%...