The reason is that the pecan module which ceilometer depends on requires WebOb>=1.2dev, while the OS already have a WebOb=1.1.1.
However, running "sudo pip install -r ceilometer.egg-info/requirement.txt" doesn't upgrade the WebOb, but running "sudo pip install pecan" did the upgrading.
The reason is that the pecan module which ceilometer depends on requires WebOb>=1.2dev, while the OS already have a WebOb=1.1.1.
However, running "sudo pip install -r ceilometer. egg-info/ requirement. txt" doesn't upgrade the WebOb, but running "sudo pip install pecan" did the upgrading.