Missing certificates and keys in the keychain while using Jenkins/Hudson as Continuous Integration for iOS and Mac development

I'm trying to improve Hudson CI for iOS and start Hudson as soon as system starts up. To do this I'm using the following launchd script:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
    <key>Label</key>
    <string>Hudson CI</string>
    <key>ProgramArguments</key>
    <array>
    <string>/usr/bin/java</string>
    <string>-jar</string>
    <string>/Users/user/Hudson/hudson.war</string>
    </array>
    <key>RunAtLoad</key>
    <true/>
    <key>UserName</key>
    <string>user</string>
</dict>
</plist>

This works OK but when xcodebuild, which is started by Hudson, tries to sign an app it fails because it cant find the proper key/certificate in the keychain. However key/certificate pair is there since it's working correct if I start Hudson from command line.

Do you have any ideas why it happens?

Solution

After spending hours and days with this issue I found a fairly easy solution to this. It doesn't matter if you have a distinct username in your launchd configuration as stated above:

<key>UserName</key>
<string>user</string>

The missing certificates and keys have to be on the system keychain (/Library/Keychains/System.keychain). I found this after I setup a jenkins job which executes several security shell calls. The one which's interesting is security list-keychains:

+ security list-keychains
    "/Library/Keychains/System.keychain"
    "/Library/Keychains/applepushserviced.keychain"
    "/Library/Keychains/System.keychain"

That are the keychains jenkins will search the certificates and keys for so they should be there. After I moved my certs there it works. Make sure you also copy the »Apple Worldwide Developer Relations Certification Authority« certificate to the system keychain, otherwise you will see a CSSMERR_TP_NOT_TRUSTED error from codesign.

It is also possible to register more keychains with security list-keychains -s [path to additional keychains]. I haven't tried it but something like security list-keychains -s $HOME/Library/Keychains/login.keychain as a pre-build shell execution in jenkins might work.

EDIT: I've tried to add a user keychain to the search path with -s but I wasn't able to get it to work. So for now, we have to copy our certs and keys into the system keychain.

EDIT^2: Read and use joensson' solution instead of mine, he managed it to access the users keychain instead of just the system keychain.