通过capistrano部署安装pg时出错

Question

I have rails 2.3.8 app I have pg in my gemfile but showing error after deployment

servers: ["apphost"]
    [apphost] executing command
 ** [out :: apphost] Gem::Installer::ExtensionBuildError: ERROR: Failed to build gem native extension.
 ** [out :: apphost] 
 ** [out :: apphost] /usr/local/bin/ruby extconf.rb
 ** [out :: apphost] checking for pg_config... no
 ** [out :: apphost] No pg_config... trying anyway. If building fails, please try again with
 ** [out :: apphost] --with-pg-config=/path/to/pg_config
 ** [out :: apphost] checking for libpq-fe.h... no
 ** [out :: apphost] Can't find the 'libpq-fe.h header
 ** [out :: apphost] *** extconf.rb failed ***
 ** [out :: apphost] Could not create Makefile due to some reason, probably lack of
 ** [out :: apphost] necessary libraries and/or headers.  Check the mkmf.log file for more
 ** [out :: apphost] details.  You may need configuration options.
 ** [out :: apphost] 
 ** [out :: apphost] Provided configuration options:

Answer 1

You're missing postgres header files required for compilation of C code in the gem.

If you're on a source based distribution like gentoo, installing postgresql package should be enough.

If you're on a debian-like system, they traditionally do not include header files along with libraries, and you have to install corresponding *-dev package. In your case, on ubuntu, it's libpq-dev :

sudo apt-get install libpq-dev

Answer 2

通过解析日志，Gem找不到pg-config，或者该服务器上尚未安装postgres，或者您需要正确配置路径。