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Re: [libvirt] [PATCH] Add a Python example that lists active ESX domains



On Sun, Nov 08, 2009 at 01:05:58AM +0100, Matthias Bolte wrote:
> It also demonstrates how to use the libvirt.openAuth() method.
> 
> * examples/python/Makefile.am: add esxlist.py to EXTRA_DIST
> * examples/python/README: add some notes about esxlist.py
> * examples/python/esxlist.py: the new example
> ---
>  examples/python/Makefile.am |    2 +-
>  examples/python/README      |   19 +++++
>  examples/python/esxlist.py  |  155 +++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 175 insertions(+), 1 deletions(-)
>  create mode 100755 examples/python/esxlist.py
> 
> diff --git a/examples/python/Makefile.am b/examples/python/Makefile.am
> index 0742226..dcd2c24 100644
> --- a/examples/python/Makefile.am
> +++ b/examples/python/Makefile.am
> @@ -1,3 +1,3 @@
>  EXTRA_DIST=						\
>  	README						\
> -	dominfo.py domrestore.py domsave.py domstart.py
> +	dominfo.py domrestore.py domsave.py domstart.py esxlist.py
> diff --git a/examples/python/README b/examples/python/README
> index 02c5bfb..f4db76c 100644
> --- a/examples/python/README
> +++ b/examples/python/README
> @@ -8,7 +8,26 @@ domstart.py - create a domU from an XML description if the domU isn't
>                running yet
>  domsave.py  - save all running domU's into a directory
>  domrestore.py - restore domU's from their saved files in a directory
> +esxlist.py  - list active domains of an VMware ESX host and print some info.
> +              also demonstrates how to use the libvirt.openAuth() method
>  
>  The XML files in this directory are examples of the XML format that libvirt
>  expects, and will have to be adapted for your setup. They are only needed
>  for domstart.py
> +
> +
> +Some additional notes for the esxlist.py example:
> +
> +You may see remote errors complaining about missing certificates:
> +
> +  Cannot access CA certificate '/usr/local/etc/pki/CA/cacert.pem': No such file
> +  or directory
> +
> +This is expected, libvirt tries to find network and storage drivers for ESX,
> +but those are not implemented yet (November 2009). While searching for this
> +drivers, libvirt may try to start a local libvirtd instance, but fails because
> +of the missing certificates. It'll warn about that:
> +
> +  Failed to find the network: Is the daemon running?
> +
> +This is also expected and can be ignored.
> diff --git a/examples/python/esxlist.py b/examples/python/esxlist.py
> new file mode 100755
> index 0000000..a0602e8
> --- /dev/null
> +++ b/examples/python/esxlist.py
> @@ -0,0 +1,155 @@
> +#! /usr/bin/python
> +# esxlist - list active domains of an ESX host and print some info.
> +#           also demonstrates how to use the libvirt.openAuth() method
> +
> +import libvirt
> +import sys
> +import os
> +import libxml2
> +import getpass
> +
> +
> +def usage():
> +    print "Usage: %s HOSTNAME" % sys.argv[0]
> +    print "       List active domains of HOSTNAME and print some info"
> +
> +
> +# This is the callback method passed to libvirt.openAuth() (see below).
> +#
> +# The credentials argument is a list of credentials that libvirt (actually
> +# the ESX driver) would like to request. An element of this list is itself a
> +# list containing 5 items (4 inputs, 1 output):
> +#   - the credential type, e.g. libvirt.VIR_CRED_AUTHNAME
> +#   - a prompt to be displayed to the user
> +#   - a challenge, the ESX driver sets this to the hostname to allow automatic
> +#     distinction between requests for ESX and vCenter credentials
> +#   - a default result for the request
> +#   - a place to store the actual result for the request
> +#
> +# The user_data argument is the user data item of the auth argument (see below)
> +# passed to libvirt.openAuth().
> +def request_credentials(credentials, user_data):
> +    for credential in credentials:
> +        if credential[0] == libvirt.VIR_CRED_AUTHNAME:
> +            # prompt the user to input a authname. display the provided message
> +            credential[4] = raw_input(credential[1] + ": ")
> +
> +            # if the user just hits enter raw_input() returns an empty string.
> +            # in this case return the default result through the last item of
> +            # the list
> +            if len(credential[4]) == 0:
> +                credential[4] = credential[3]
> +        elif credential[0] == libvirt.VIR_CRED_NOECHOPROMPT:
> +            # use the getpass module to prompt the user to input a password.
> +            # display the provided message and return the result through the
> +            # last item of the list
> +            credential[4] = getpass.getpass(credential[1] + ": ")
> +        else:
> +            return -1
> +
> +    return 0
> +
> +
> +def print_section(title):
> +    print "\n%s" % title
> +    print "=" * 60
> +
> +
> +def print_entry(key, value):
> +    print "%-10s %-10s" % (key, value)
> +
> +
> +def print_xml(key, ctx, path):
> +    res = ctx.xpathEval(path)
> +
> +    if res is None or len(res) == 0:
> +        value = "Unknown"
> +    else:
> +        value = res[0].content
> +
> +    print_entry(key, value)
> +
> +    return value
> +
> +
> +if len(sys.argv) != 2:
> +    usage()
> +    sys.exit(2)
> +
> +
> +hostname = sys.argv[1]
> +
> +# Connect to libvirt
> +uri = "esx://%s/?no_verify=1" % hostname
> +
> +# The auth argument is a list that contains 3 items:
> +#   - a list of supported credential types
> +#   - a callable that takes 2 arguments
> +#   - user data that will be passed to the callable as second argument
> +#
> +# In this example the supported credential types are VIR_CRED_AUTHNAME and
> +# VIR_CRED_NOECHOPROMPT, the callable is the unbound method request_credentials
> +# (see above) and the user data is None.
> +#
> +# libvirt (actually the ESX driver) will call the callable to request
> +# credentials in order to log into the ESX host. The callable would also be
> +# called if the connection URI would reference a vCenter to request credentials
> +# in order to log into the vCenter
> +auth = [[libvirt.VIR_CRED_AUTHNAME, libvirt.VIR_CRED_NOECHOPROMPT],
> +        request_credentials, None]
> +conn = libvirt.openAuth(uri, auth, 0)
> +
> +if conn is None:
> +    print "Failed to open connection to %s" % hostname
> +    sys.exit(1)
> +
> +state_names = { libvirt.VIR_DOMAIN_RUNNING  : "running",
> +                libvirt.VIR_DOMAIN_BLOCKED  : "idle",
> +                libvirt.VIR_DOMAIN_PAUSED   : "paused",
> +                libvirt.VIR_DOMAIN_SHUTDOWN : "in shutdown",
> +                libvirt.VIR_DOMAIN_SHUTOFF  : "shut off",
> +                libvirt.VIR_DOMAIN_CRASHED  : "crashed",
> +                libvirt.VIR_DOMAIN_NOSTATE  : "no state" }
> +
> +for id in conn.listDomainsID():
> +    domain = conn.lookupByID(id)
> +    info = domain.info()
> +
> +    print_section("Domain " + domain.name())
> +    print_entry("ID:", id)
> +    print_entry("UUID:", domain.UUIDString())
> +    print_entry("State:", state_names[info[0]])
> +    print_entry("MaxMem:", info[1])
> +    print_entry("UsedMem:", info[2])
> +    print_entry("VCPUs:", info[3])
> +
> +    # Read some info from the XML desc
> +    print_section("Devices of " + domain.name())
> +
> +    xmldesc = domain.XMLDesc(0)
> +    doc = libxml2.parseDoc(xmldesc)
> +    ctx = doc.xpathNewContext()
> +    devs = ctx.xpathEval("/domain/devices/*")
> +    first = True
> +
> +    for d in devs:
> +        ctx.setContextNode(d)
> +
> +        if not first:
> +            print "------------------------------------------------------------"
> +        else:
> +            first = False
> +
> +        print_entry("Device", d.name)
> +
> +        type = print_xml("Type:", ctx, "@type")
> +
> +        if type == "file":
> +            print_xml("Source:", ctx, "source/@file")
> +            print_xml("Target:", ctx, "target/@dev")
> +        elif type == "block":
> +            print_xml("Source:", ctx, "source/@dev")
> +            print_xml("Target:", ctx, "target/@dev")
> +        elif type == "bridge":
> +            print_xml("Source:", ctx, "source/@bridge")
> +            print_xml("MAC Addr:", ctx, "mac/@address")

  Excellent, ACK :-)

   thanks !

Daniel

-- 
Daniel Veillard      | libxml Gnome XML XSLT toolkit  http://xmlsoft.org/
daniel veillard com  | Rpmfind RPM search engine http://rpmfind.net/
http://veillard.com/ | virtualization library  http://libvirt.org/


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