# How do I find all gem dependencies?

**URL:** <https://www.ruby-forum.com/t/how-do-i-find-all-gem-dependencies/181887>\
**Category:** Rails\
**Created:** [January 19, 2010, 7:01pm UTC](https://www.ruby-forum.com/t/how-do-i-find-all-gem-dependencies/181887 "2010-01-19T19:01:29Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![matt](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/a6a055/32.png) [@matt](https://www.ruby-forum.com/u/matt)\
**Post date:** [January 19, 2010, 7:01pm UTC](https://www.ruby-forum.com/t/how-do-i-find-all-gem-dependencies/181887/1 "2010-01-19T19:01:29Z")

</div>

I am looking to deploy my rails app into an environment that I don’t  
control. I don’t want some (future) change in gems to break the app.  
So I am using

```
rake rails:freeze:gems

```

to freeze the rails version and

```
rake gems:unpack
rake gems:unpack:dependencies

```

to freeze the gems in use.

As I understand it this will make the app use the versions of code in  
vendor/ and it doesn’t matter what gems are added/removed/upgraded on  
the server. Is this correct?

Now to my real question, ‘rake gems:unpack’ only works for gems listed  
in config/environment.rb. How do I find gems that are in use by my  
app, but are not listed there? I know all gems should be listed, but  
I didn’t always know that and I still need to future-proof my older  
apps.

Thanks,

Matt