Hacker News Reader

Comment by hbbio | Hacker News Reader

What seems to be missing is _updating_ the nginx.conf with sed or something.

In the article, you're just copying a new magic configuration from somewhere vs. "proper" sed use (in reality, it can be a bit more than that) in the shell script.

View on HN

Initially I was using Ansible's `lineinfile` module to do exactly that. It's pretty trivial to do if you want to compare true Apples to Apples. Here's an article with some examples: http://fabian-affolter.ch/blog/the-lineinfile-module-of-ansi...

However, I wanted to show the actual process I went through. Editing the file in place seemed silly to do with Ansible, so I went with putting the config file in version control and copying it over. That also had the benefit of showing how Ansible encourages better practices than shell scripts.

Of course, that's totally subjective, so for some folks that use shell scripts, they may already know to put their config files in version control. However, in practice, I've not seen that be the case.

Also worth noting, ansible comes with a 'template' module which allows you to generate custom files with variables.

Proper way is to install a known version of nginx and use a known conf, not editing some file which might be different based on linux distro or package maintainer.

Problem is sometime platforms differ a bit, so it's better to patch the config file.

For instance (I know there's vagrant and stuff), I develop on a Mac but deploy on linux. My sed handles that pretty well.

The platforms may differ, but a known version should be able to use the same config on the different platforms.

Just looked up a real "sed" example in linux vs linux.

DigitalOcean ships VM that don't have an admin group. So when I tried DO, I added:

grep -q 'admin' /etc/group || groupadd admin

Or, for changing the sshd port:

sed -i -r 's/^#?Port [0-9]*/Port '"$PORT"'/' /etc/ssh/sshd_config

Works great on all platforms... regardless of the default sshd_config.

You realise that the tools like ansible are made for making sure the groups and users you specify in your config are going to be on the server? That's the point of them. Don't rely on a presetup environment, you'r ansible scripts should setup the environment for everything you need.

If the compile options in both platform matches.

And nginx is full of compile options and modules to enable and disable, so maybe "the same config in the same version" does not work on different platforms.

Then that's not a same known version is. Nginx doesn't support different loadable modules so compiling it differently make them different versions.

If you're reliant on modules being in there you compile it yourself with a source deb/rpm/etc from nginx. If you don't need a module then don't compile it in.

While possible to patch using Ansible (lineinfile), it's typically easier to use templates with host vars instead. i.e. define a set of default values which are for your deploys, and then a host specific variable for your local machine which provides the alternate values.

Does it beat sed? Probably not in the short term, but it makes it easier to not forget to sed a file when deploying (not to mention adding the ability to skip changing the remote file and sighup nginx when the file hasn't changed).

Augeas is a safer way of updating config files http://augeas.net/, though I have to admit I've mostly ended up just using sed myself.

Lenses are hard for people to write and error handling is poor though, so it can be very frustrating. The lineinfile method does work fine for simple files, and there's also an INI file module.

In most cases, we recommend using the 'template' module for this reason, in cases where you know what you'd like to put down for the file contents.

Reply on news.ycombinator.com