A Kerberos context manager
krbcontext does the initialization of credential cache (ticket file) in a kerberos-related context. It provides a context manager that allows developers to put codes, which needs kerberos environment, into a kerberos context.
One important thing is that you should configure /etc/krb5.conf correctly before doing anything with Kerberos.
krbcontext will initialize the credential cache when be invoked each time.
You can use krbcontext with a regular Kerberos user or a service Keytab file. When you work as a regular user, krbcontext prompts you to enter password of your Kerberos account. Whatever in which way, krbcontext accepts a set of default values and specified values.
There are several concept you must know before using krbcontext, principal of user and service, service Keytab file, and credential cache (ticket file). Therefore, the arguments passed to krbcontext are mapped to these concepts.
Before running client’s code, krbcontext checks credential krbtgt/REALM@REALM in credentials cache locally to see whether it is necessary to be initialized.
If your want krbcontext to initialize credential in Kerberos standard credenticial cache, or pass a file name to argument ccache_file explicitly, krbcontext is thread-safe. However, it is still suggestion that you pass credentials cache file name for each thread individually.
krbcontext depends on python-krbV. This is a Python extension module for Kerberos 5. It is hosted in fedorahosted.org, you can follow this URL to get more details. https://fedorahosted.org/python-krbV/
If you choose to install krbcontext using the RPM distribution, the dependency will be solved automatically. On the other hand, if easy_install or pip is used, it is necessary to run yum or build from source to install python-krbV first.
Specify necessary argument for initializing credential cache. You can pass:
krbcontext can be used as a normal context manager simply.
with krbcontext(): # your code here pass
with krbcontext(): pass
This is the most simplest way. It uses default values. It gets current effective user name rather than login name, and initialize the default credential cache, /tmp/krb5cc_xxx, where xxx is the current user ID returned by os.getuid method.
Specifying custom values
with krbcontext(principal='qcxhome@PYPI.PYTHON.COM', ccache_file='/tmp/krb5cc_my'): pass with krbcontext(principal='qcxhome', ccache_file='/tmp/krb5cc_my'): pass
with krbcontext(using_keytab=True, principal='HTTP/localhost@PYPI.PYTHON.COM'): pass
You can also use default values here except the using_keytab and principal. The default Keytab locates /etc/krb5.keytab, and default credential cache locates /tmp/krb5cc_xxx, like above.
with krbcontext(using_keytab=True, principal='HTTP/localhost@PYPI.PYTHON.COM'): keytab_file='/etc/httpd/conf/httpd.keytab', ccache_file='/tmp/krb5cc_pid_appname'): pass
If you have another Keytab that is be elsewhere and a credential cache for special purpose, you may pass the keytab_file and ccache_file.