Thanks Joseph, it was really helpful.

I am pushing a python app and I can see a zip file for a python
buildpack when I did - 'cf buildpacks'. But its still cf push is not
able to identify python_buildpack.

Then I gave buildpack: python_buildpack in my manifest.yml it gave me
below error

--------------------------------------------------------------------
2015-08-04T10:45:24.93+0000 [API/0] OUT Created app with guid
9bccc468-b1b4-413b-88f1-f8b510064d78
2015-08-04T10:45:25.40+0000 [API/0] OUT Updated app with guid
9bccc468-b1b4-413b-88f1-f8b510064d78
({"route"=>"5ff72553-4031-4747-ad27-9102f00a3d3a"})
2015-08-04T10:45:31.78+0000 [DEA/0] OUT Got staging request for
app with id 9bccc468-b1b4-413b-88f1-f8b510064d78
2015-08-04T10:45:32.78+0000 [API/0] OUT Updated app with guid
9bccc468-b1b4-413b-88f1-f8b510064d78 ({"state"=>"STARTED"})
2015-08-04T10:45:32.88+0000 [STG/0] OUT -----> Downloaded app
package (4.0K)
2015-08-04T10:45:33.47+0000 [STG/0] OUT Staging failed: An
application could not be detected by any available buildpack
2015-08-04T10:45:33.48+0000 [STG/0] ERR
2015-08-04T10:45:33.62+0000 [API/0] ERR encountered error: An app
was not successfully detected by any available buildpack
2015-08-04T10:51:17.31+0000 [API/0] OUT Updated app with guid
9bccc468-b1b4-413b-88f1-f8b510064d78 ({"name"=>"myapp",
"command"=>"PRIVATE DATA HIDDEN", "memory"=>128, "disk_quota"=>256,
"buildpack"=>"https://github.com/cloudfoundry/buildpack-python.git",
"environment_json"=>"PRIVATE DATA HIDDEN"})
2015-08-04T10:51:27.64+0000 [API/0] OUT Updated app with guid
9bccc468-b1b4-413b-88f1-f8b510064d78 ({"state"=>"STOPPED"})
2015-08-04T10:51:28.84+0000 [DEA/0] OUT Got staging request for
app with id 9bccc468-b1b4-413b-88f1-f8b510064d78
2015-08-04T10:51:29.86+0000 [API/0] OUT Updated app with guid
9bccc468-b1b4-413b-88f1-f8b510064d78 ({"state"=>"STARTED"})
2015-08-04T10:51:29.94+0000 [STG/0] OUT -----> Downloaded app
package (4.0K)
2015-08-04T10:51:30.01+0000 [STG/0] ERR Cloning into
'/tmp/buildpacks/buildpack-python'...
2015-08-04T10:51:30.98+0000 [STG/0] OUT Submodule
'compile-extensions'
(https://github.com/cloudfoundry-incubator/compile-extensions.git)
registered for path 'compile-extensions'
2015-08-04T10:51:31.02+0000 [STG/0] ERR Cloning into
'compile-extensions'...
2015-08-04T10:51:31.36+0000 [STG/0] OUT Submodule path
'compile-extensions': checked out
'ce9345a9a6e7b00266194cadd18dbef37e791a7b'
2015-08-04T10:51:31.48+0000 [STG/0] OUT -------> Buildpack version 1.5.0
2015-08-04T10:51:31.51+0000 [STG/0] OUT -----> Installing runtime
(python-2.7.10)
2015-08-04T10:51:36.34+0000 [STG/0] OUT -----> Installing
dependencies with pip
2015-08-04T10:51:36.67+0000 [STG/0] ERR Directory '.' is not
installable. File 'setup.py' not found.
2015-08-04T10:51:36.70+0000 [STG/0] OUT Staging failed: Buildpack
compilation step failed
2015-08-04T10:51:36.86+0000 [API/0] ERR encountered error: App
staging failed in the buildpack compile phase
2015-08-04T10:56:18.81+0000 [API/0] OUT Updated app with guid
9bccc468-b1b4-413b-88f1-f8b510064d78 ({"name"=>"myapp",
"command"=>"PRIVATE DATA HIDDEN", "memory"=>128, "disk_quota"=>256,
"buildpack"=>"python_buildpack", "environment_json"=>"PRIVATE DATA
HIDDEN"})
2015-08-04T10:56:24.10+0000 [API/0] OUT Updated app with guid
9bccc468-b1b4-413b-88f1-f8b510064d78 ({"state"=>"STOPPED"})
2015-08-04T10:56:25.24+0000 [DEA/0] OUT Got staging request for
app with id 9bccc468-b1b4-413b-88f1-f8b510064d78
2015-08-04T10:56:26.26+0000 [API/0] OUT Updated app with guid
9bccc468-b1b4-413b-88f1-f8b510064d78 ({"state"=>"STARTED"})
2015-08-04T10:56:26.36+0000 [STG/0] OUT -----> Downloaded app
package (4.0K)
2015-08-04T10:56:26.68+0000 [STG/0] OUT -------> Buildpack version 1.4.0
2015-08-04T10:56:26.71+0000 [STG/0] OUT -----> Installing runtime
(python-2.7.10)
2015-08-04T10:56:31.21+0000 [STG/0] OUT -----> Installing
dependencies with pip
2015-08-04T10:56:31.99+0000 [STG/0] ERR You are using pip version
7.0.1, however version 7.1.0 is available.
2015-08-04T10:56:31.99+0000 [STG/0] ERR You should consider
upgrading via the 'pip install --upgrade pip' command.
2015-08-04T10:56:32.43+0000 [STG/0] ERR Directory '.' is not
installable. File 'setup.py' not found.
2015-08-04T10:56:32.46+0000 [STG/0] OUT Staging failed: Buildpack
compilation step failed
2015-08-04T10:56:32.60+0000 [API/0] ERR encountered error: App
staging failed in the buildpack compile phase
2015-08-04T11:00:56.58+0000 [API/0] OUT Updated app with guid
9bccc468-b1b4-413b-88f1-f8b510064d78 ({"name"=>"myapp",
"command"=>"PRIVATE DATA HIDDEN", "memory"=>128, "disk_quota"=>256,
"buildpack"=>"python_buildpack", "environment_json"=>"PRIVATE DATA
HIDDEN"})
2015-08-04T11:01:01.91+0000 [API/0] OUT Updated app with guid
9bccc468-b1b4-413b-88f1-f8b510064d78 ({"state"=>"STOPPED"})
2015-08-04T11:01:03.53+0000 [DEA/0] OUT Got staging request for
app with id 9bccc468-b1b4-413b-88f1-f8b510064d78
2015-08-04T11:01:04.55+0000 [API/0] OUT Updated app with guid
9bccc468-b1b4-413b-88f1-f8b510064d78 ({"state"=>"STARTED"})
2015-08-04T11:01:04.63+0000 [STG/0] OUT -----> Downloaded app
package (4.0K)
2015-08-04T11:01:04.94+0000 [STG/0] OUT -------> Buildpack version 1.4.0
2015-08-04T11:01:04.98+0000 [STG/0] OUT -----> Installing runtime
(python-2.7.10)
2015-08-04T11:01:09.55+0000 [STG/0] OUT -----> Installing
dependencies with pip
2015-08-04T11:01:10.29+0000 [STG/0] ERR You are using pip version
7.0.1, however version 7.1.0 is available.
2015-08-04T11:01:10.29+0000 [STG/0] ERR You should consider
upgrading via the 'pip install --upgrade pip' command.
2015-08-04T11:01:10.73+0000 [STG/0] ERR Directory '.' is not
installable. File 'setup.py' not found.
2015-08-04T11:01:10.76+0000 [STG/0] OUT Staging failed: Buildpack
compilation step failed
2015-08-04T11:01:10.97+0000 [API/0] ERR encountered error: App
staging failed in the buildpack compile phase

-------------------------------------------------------

If I gave python buildpack url of git as buildpack: then
it gives below error

2015-08-04T11:01:10.29+0000 [STG/0] ERR You are using pip version
7.0.1, however version 7.1.0 is available.
2015-08-04T11:01:10.29+0000 [STG/0] ERR You should consider
upgrading via the 'pip install --upgrade pip' command.
2015-08-04T11:01:10.73+0000 [STG/0] ERR Directory '.' is not
installable. File 'setup.py' not found.
2015-08-04T11:01:10.76+0000 [STG/0] OUT Staging failed: Buildpack
compilation step failed
2015-08-04T11:01:10.97+0000 [API/0] ERR encountered error: App
staging failed in the buildpack compile phase

-------------------------------------------

I am just pushing this simple sample of python -
https://github.com/ihuston/python-cf-examples/tree/master/01-simple-python-app