Github SSH config containing multiple ssh keys capistrano deployment fails saying Repository not found - github

Question

~/.ssh/config
# User_A
Host github.com-User_A
HostName github.com
User git
PreferredAuthentications publickey
IdentityFile ~/.ssh/id_rsa
IdentitiesOnly yes
# User_B
Host github.com-User_B
HostName github.com
User git
PreferredAuthentications publickey
IdentityFile ~/.ssh/id_rsa_user_b
IdentitiesOnly yes
# http://serverfault.com/questions/400633/capistrano-deploying-to-different-servers-with-different-authentication-methods
Host example.com
IdentityFile ~/.ssh_keys/example_env.pem
ForwardAgent yes
On local machine:
$ ssh -T git#github.com
Hi User_B! You've successfully authenticated, but GitHub does not provide shell access.
On remote machine
~$ ssh remote_user#example.com
[remote_user#example ~]$ ssh -T git#github.com
Hi User_A! You've successfully authenticated, but GitHub does not provide shell access.
Note:
ssh-add -l shows all the mentioned keys enlisted
deploy.rb contains:
set :repository, "git#User_B:<REPO_NAME>"
ssh_options[:forward_agent] = true
I am trying to deploy my application using Capistrano to an Amazon EC2 instance for which I the .pem file is already added to my local machine using ssh-add and it can be seen enlisted in output for ssh-add -l.However I am facing following error while deploying:
** [example.com :: err] ERROR: Repository not found.
** fatal: The remote end hung up unexpectedly
Following is the full output of my cap deploy command:
$ cap bat deploy
triggering load callbacks
* executing `bat'
triggering start callbacks for `deploy'
* executing `multistage:ensure'
* executing `deploy'
* executing `deploy:update'
** transaction: start
* executing `deploy:update_code'
updating the cached checkout on all servers
executing locally: "git ls-remote git#User_B:<REPO_NAME> <BRANCH_NAME>"
command finished in 6296ms
* executing "if [ -d /srv/<APP_NAME>/shared/cached-copy ]; then cd /srv/<APP_NAME>/shared/cached-copy && git fetch -q origin && git fetch --tags -q origin && git reset -q --hard df84fadff305e1729991caddde47f6802e424d57 && git clean -q -d -x -f; else git clone -q git#User_B:<REPO_NAME> /srv/<APP_NAME>/shared/cached-copy && cd /srv/<APP_NAME>/shared/cached-copy && git checkout -q -b deploy df84fadff305e1729991caddde47f6802e424d57; fi"
servers: ["example.com"]
[example.com] executing command
** [example.com :: err] ERROR: Repository not found.
** fatal: The remote end hung up unexpectedly
command finished in 3811ms
*** [deploy:update_code] rolling back
* executing "rm -rf /srv/<APP_NAME>/releases/20130723222237; true"
servers: ["example.com"]
[example.com] executing command
command finished in 477ms
failed: "sh -c 'if [ -d /srv/<APP_NAME>/shared/cached-copy ]; then cd /srv/<APP_NAME>/shared/cached-copy && git fetch -q origin && git fetch --tags -q origin && git reset -q --hard df84fadff305e1729991caddde47f6802e424d57 && git clean -q -d -x -f; else git clone -q git#User_B:<REPO_NAME> /srv/<APP_NAME>/shared/cached-copy && cd /srv/<APP_NAME>/shared/cached-copy && git checkout -q -b deploy df84fadff305e1729991caddde47f6802e424d57; fi'" on example.com
So I guess this error is caused due to conflicts arising between multiple SSH keys getting detected i.e. on local machine User_B(who is a member of the repository) is used as default however on remote machine User_A(who is not having access to the repository) is used.
If my assumption is correct can anybody please help me in getting this problem solved? Is there any way in which a specific user config can be used while agent forwarding? If not then what could be the solution to this?
Thanks.

Answer 1

Ok it seems like the sequence in which keys are listed in ~/.ssh/config matters.
Initially it was
# User_A
Host github.com-User_A
HostName github.com
User git
PreferredAuthentications publickey
IdentityFile ~/.ssh/id_rsa
IdentitiesOnly yes
# User_B
Host github.com-User_B
HostName github.com
User git
PreferredAuthentications publickey
IdentityFile ~/.ssh/id_rsa_user_b
IdentitiesOnly yes
# http://serverfault.com/questions/400633/capistrano-deploying-to-different-servers-with-different-authentication-methods
Host example.com
IdentityFile ~/.ssh_keys/example_env.pem
ForwardAgent yes
Afterwards I did this:
# User_B
Host github.com-User_B
HostName github.com
User git
PreferredAuthentications publickey
IdentityFile ~/.ssh/id_rsa_user_b
IdentitiesOnly yes
# User_A
Host github.com-User_A
HostName github.com
User git
PreferredAuthentications publickey
IdentityFile ~/.ssh/id_rsa
IdentitiesOnly yes
# http://serverfault.com/questions/400633/capistrano-deploying-to-different-servers-with-different-authentication-methods
Host example.com
IdentityFile ~/.ssh_keys/example_env.pem
ForwardAgent yes
But after doing that I didn't restarted the machine, thus the changes were not in effect.
This morning after I started my machine after posting above problem I found that it is working:
On local machine:
$ ssh -T git#github.com
Hi User_B! You've successfully authenticated, but GitHub does not provide shell access.
On remote machine
$ ssh -T git#github.com
Hi User_B! You've successfully authenticated, but GitHub does not provide shell access.
Hope this helps somebody else in case he faces a similar problem.
Thanks.