[libvirt] [PATCH] Allow for URI aliases when connecting to libvirt

[Daniel P. Berrange]

On Thu, Oct 13, 2011 at 09:24:49AM -0600, Eric Blake wrote:
> On 10/13/2011 04:53 AM, Daniel P. Berrange wrote:
> >From: "Daniel P. Berrange"<berrange at redhat.com>
> >
> >I finally got fed up of typing URIs when using virsh....
> >
> >This adds support for a libvirt client configuration file
> >either /etc/libvirt/libvirt.conf for privileged clients,
> >or $HOME/.libvirt/libvirt.conf for unprivileged clients.
> 
> Cool idea!
> 
> Potential problem - our testsuite uses -c test:///default (or
> similar); there's a case where we _don't_ want to use alias lookup.
> But I guess if valid alias names cannot contain ':', then the
> presence of ':' in the target name is sufficient to prove that we
> don't want to use aliases. [This is a review as I go reply, so I'll
> see what the code actually does...]
> 
> >+<h2>
> >+<a name="URI_config">Configuring URI aliases</a>
> >+</h2>
> >+
> >+<p>
> >+To simplify live for administrators, it is possible to setup URI aliases in a
> 
> s/live/life/
> 
> >+libvirt client configuration file. The configuration file is<code>/etc/libvirt/libvirt.conf</code>
> >+for the root user, or<code>$HOME/.libvirt/libvirt.conf</code>  for any unprivileged user.
> 
> Really?  Shouldn't it instead be that /etc is for qemu:///system,
> and $HOME/.libvirt is for any user, _including root_, for
> qemu:///session.

The location is for the *client* application. Regardless of what
URI the client eventually connects to, the location of its config
file is the same and unrelated to the URI.


> 
> >+<p>
> >+  A URI alias should be a string made up from the characters
> >+<code>a-Z, 0-9, _, -</code>. Following the<code>=</code>
> >+  can be any libvirt URI string, including arbitrary URI parameters.
> >+  URI aliases will apply to any application opening a libvirt
> >+  connection, unless it has explicitly passed the<code>VIR_CONNECT_NO_ALIASES</code>
> >+  parameter to<code>virConnectOpenAuth</code>.
> 
> Should we document that aliases are not consulted if the non-NULL
> connection name includes ':'?
> 
> >+++ b/include/libvirt/libvirt.h.in
> >@@ -843,7 +843,8 @@ typedef virNodeMemoryStats *virNodeMemoryStatsPtr;
> >   * Flags when opening a connection to a hypervisor
> >   */
> >  typedef enum {
> >-    VIR_CONNECT_RO = 1,    /* A readonly connection */
> >+    VIR_CONNECT_RO         = (1<<  0),  /* A readonly connection */
> >+    VIR_CONNECT_NO_ALIASES = (1<<  1),  /* Don't try to resolve URI aliases */
> 
> At first glance, I didn't see a use for this bit: it seems like the
> decision to use aliases is unambiguous - if the name contains ':',
> there is no alias, and if it lacks ':', then the only way it can
> succeed is if an alias lookup is successful.  Oh, I see - you use
> VIR_CONNECT_NO_ALIASES to force failure rather than attempt an alias
> lookup for the case where name has no ':'.  Okay, it makes sense.
> 

> >+
> >+    entry = value->list;
> >+    while (entry) {
> >+        char *offset;
> >+        size_t safe;
> >+
> >+        if (entry->type != VIR_CONF_STRING) {
> >+            virLibConnError(VIR_ERR_INTERNAL_ERROR, "%s",
> 
> Wouldn't VIR_ERR_CONF_SYNTAX go better here?
> 
> >+                            _("Expected a string for 'uri_aliases' config parameter list entry"));
> >+            return -1;
> >+        }
> >+
> >+        if (!(offset = strchr(entry->str, '='))) {
> >+            virLibConnError(VIR_ERR_INTERNAL_ERROR,
> 
> and here
> 
> >+                            _("Malformed 'uri_aliases' config entry '%s', expected 'alias=uri://host/path'"),
> >+                            entry->str);
> >+            return -1;
> >+        }
> >+
> >+        safe  = strspn(entry->str, "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789_-");
> >+        if (safe<  (offset - entry->str)) {
> >+            virLibConnError(VIR_ERR_INTERNAL_ERROR,
> 
> and here

Yep, I guess we could.


Daniel
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