[libvirt] [PATCH] Allow overriding default URI in config file

[Daniel P. Berrange]

On Wed, Mar 14, 2012 at 06:54:40AM -0600, Eric Blake wrote:
> On 03/14/2012 06:37 AM, Daniel P. Berrange wrote:
> > From: "Daniel P. Berrange" <berrange at redhat.com>
> > 
> > Currently if the URI passed to virConnectOpen* is NULL, then we
> > 
> >  - Look for LIBVIRT_DEFAULT_URI env var
> >  - Probe for drivers
> > 
> > This changes it so that
> > 
> >  - Look for LIBVIRT_DEFAULT_URI env var
> >  - Look for 'uri_default' in $HOME/.libvirt/libvirt.conf
> >  - Probe for drivers
> 
> Nice.  Do we need any followup patches for virsh?  That is, where should
> VIRSH_DEFAULT_CONNECT_URI fit into the hierarchy?

We should deprecate it :-)

> 
> >  docs/uri.html.in |   13 +++++++
> >  src/libvirt.c    |  107 +++++++++++++++++++++++++++++++++++++-----------------
> >  2 files changed, 87 insertions(+), 33 deletions(-)
> 
> Where is the change to src/libvirt.conf to document this feature?

Missing :-)

> > +++ b/docs/uri.html.in
> > @@ -52,6 +52,19 @@ uri_aliases = [
> >    set, no alias lookup will be attempted.
> >  </p>
> >  
> > +    <h2><a name="URI_default">Default URI choice</a></h2>
> > +
> > +    <p>
> > +If the URI passed to <code>virConnectOpen*</code> is NULL, then libvirt will use the following
> > +logic to determine what URI to use.
> > +</p>
> > +
> > +    <ol>
> > +      <li>The environment variable <code>LIBVIRT_DEFAULT_URI</code></li>
> > +      <li>The client configuration file <code>uri_default</code> parameter</li>
> > +      <li>Probe each hypervisor in turn until one that works is found</li>
> > +    </ol>
> > +
> 
> Looks good.  The location of the client configuration file was mentioned
> earlier on the same page.
> 
> >      <h2>
> >        <a name="URI_virsh">Specifying URIs to virsh, virt-manager and virt-install</a>
> 
> Maybe this section should mention that without any -c option and without
> VIRSH_DEFAULT_CONNECT_URI, then virsh passes NULL to the virConnectOpen,
> which then falls back on the above hierarchy for libvirt in general.
> 
> 
> >  
> > +static int virConnectGetConfigFile(virConfPtr *conf)
> 
> Formatting nit - should this be two lines?
> 
> 
> > +
> > +static int virConnectGetDefaultURI(virConfPtr conf,
> 
> And this one?
> 
> > +                                   const char **name)
> > +{
> > +    int ret = -1;
> > +    virConfValuePtr value = NULL;
> > +    char *defname = getenv("LIBVIRT_DEFAULT_URI");
> > +    if (defname && *defname) {
> > +        VIR_DEBUG("Using LIBVIRT_DEFAULT_URI %s", defname);
> > +        *name = defname;
> 
> Needs a 'ret = 0; goto cleanup;' here, otherwise...
> 
> > +    }
> > +
> > +    if ((value = virConfGetValue(conf, "uri_default"))) {
> > +        if (value->type != VIR_CONF_STRING) {
> > +            virLibConnError(VIR_ERR_INTERNAL_ERROR, "%s",
> > +                            _("Expected a string for 'uri_default' config parameter"));
> > +            goto cleanup;
> > +        }
> > +
> > +        *name = value->str;
> 
> this assignment is a memory leak if both the envvar and config file are
> present.

We're returning const strings here, so there's no leak to deal with


Daniel
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