This answer helped me a lot. He indicates you how to config the secrets.yml file in production and how to read it from the environment:
I had the same problem and I solved it by creating an environment
variable to be loaded every time that I logged in to the production
server and made a mini guide of the steps to configure it:
https://gist.github.com/pablosalgadom/4d75f30517edc6230a67
I was using Rails 4.1 with Unicorn v4.8.2, when I tried to deploy my
app it didn't start properly and in the unicorn.log file I found this
error message:
"app error: Missing secret_key_base for 'production' environment, set
this value in config/secrets.yml (RuntimeError)"
After some research I found out that Rails 4.1 changed the way to
manage the secret_key, so if you read the secrets.yml file located at
[exampleRailsProject]/config/secrets.yml you'll find something like
this:
Do not keep production secrets in the repository,
instead read values from the environment. production: secret_key_base: <%= ENV["SECRET_KEY_BASE"] %> This means that rails
recommends you to use an environment variable for the secret_key_base
in your production server, in order to solve this error you should
follow this steps to create an environment variable for Linux (in my
case Ubuntu) in your production server:
1.- In the terminal of your production server execute the next command:
$ RAILS_ENV=production rake secret This returns a large string with
letters and numbers, copy that (we will refer to that code as
GENERATED_CODE).
2.1- Login as root user to your server, find this file and edit it: $ vi /etc/profile
Go to the bottom of the file ("SHIFT + G" for capital G in VI)
Write your environment variable with the GENERATED_CODE (Press "i" key
to write in VI), be sure to be in a new line at the end of the file:
export SECRET_KEY_BASE=GENERATED_CODE Save the changes and close the
file (we push "ESC" key and then write ":x" and "ENTER" key for save
and exit in VI)
2.2 But if you login as normal user, lets call it example_user for this gist, you will need to find one of this other files:
$ vi ~/.bash_profile $ vi ~/.bash_login $ vi ~/.profile These files
are in order of importance, that means that if you have the first
file, then you wouldn't need to write in the others. So if you found
this 2 files in your directory "~/.bash_profile" and "~/.profile" you
only will have to write in the first one "~/.bash_profile", because
Linux will read only this one and the other will be ignored.
Then we go to the bottom of the file ("SHIFT + G" for capital G in VI)
And we will write our environment variable with our GENERATED_CODE
(Press "i" key to write in VI), be sure to be in a new line at the end
of the file:
export SECRET_KEY_BASE=GENERATED_CODE Having written the code, save
the changes and close the file (we push "ESC" key and then write ":x"
and "ENTER" key for save and exit in VI)
3.- You can verify that our environment variable is properly set in Linux with this command:
$ printenv | grep SECRET_KEY_BASE or with:
$ echo $SECRET_KEY_BASE When you execute this command, if everything
went ok, it will show you the GENERATED_CODE from before. Finally with
all the configuration done you should be able to deploy without
problems your Rails app with Unicorn or other.
When you close your shell terminal and login again to the production
server you will have this environment variable set and ready to use
it.
And thats it!! I hope this mini guide help you to solve this error.
Disclaimer: I'm not a Linux or Rails guru, so if you find something
wrong or any error I will be glad to fix it!