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Allow for URI aliases when connecting to libvirt

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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.

It allows one parameter

 uri_aliases = [
   "hail=qemu+ssh://root@hail.cloud.example.com/system",
   "sleet=qemu+ssh://root@sleet.cloud.example.com/system",
 ]

Any call to virConnectOpen with a non-NULL URI will first
attempt to match against the uri_aliases list. An application
can disable this by using VIR_CONNECT_NO_ALIASES

* docs/uri.html.in: Document URI aliases
* include/libvirt/libvirt.h.in: Add VIR_CONNECT_NO_ALIASES
* libvirt.spec.in, mingw32-libvirt.spec.in: Add /etc/libvirt/libvirt.conf
* src/Makefile.am: Install default config file
* src/libvirt.c: Add support for URI aliases
* src/remote/remote_driver.c: Don't try to handle URIs
  with no scheme and which clearly are not paths
* src/util/conf.c: Don't raise error on virConfFree(NULL)
* src/xen/xen_driver.c: Don't raise error on URIs
  with no scheme
This commit is contained in:
Daniel P. Berrange 2011-10-13 11:49:45 +01:00
parent 02e92dc470
commit 777ffbd0e2
10 changed files with 226 additions and 80 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

103
docs/uri.html.in
View File

@ -2,6 +2,8 @@
<html>
<body>
<h1 >Connection URIs</h1>
<ul id="toc"></ul>
<p>
Since libvirt supports many different kinds of virtualization
(often referred to as "drivers" or "hypervisors"), we need a
@ -13,41 +15,46 @@ machine over the network.
To this end, libvirt uses URIs as used on the Web and as defined in <a href="http://www.ietf.org/rfc/rfc2396.txt">RFC 2396</a>. This page
documents libvirt URIs.
</p>
<ul>
<li>
<a href="#URI_libvirt">Specifying URIs to libvirt</a>
</li>
<li>
<a href="#URI_virsh">Specifying URIs to virsh, virt-manager and virt-install</a>
</li>
<li>
<a href="#URI_xen">xen:/// URI</a>
</li>
<li>
<a href="#URI_qemu">qemu:///... QEMU and KVM URIs</a>
</li>
<li>
<a href="#URI_remote">Remote URIs</a>
</li>
<li>
<a href="#URI_test">test:///... Test URIs</a>
</li>
<li>
<a href="#URI_legacy">Other &amp; legacy URI formats</a>
</li>
</ul>
<h3>
<a name="URI_libvirt">Specifying URIs to libvirt</a>
</h3>
<h2><a name="URI_libvirt">Specifying URIs to libvirt</a></h2>
<p>
The URI is passed as the <code>name</code> parameter to <a href="html/libvirt-libvirt.html#virConnectOpen"><code>virConnectOpen</code></a> or <a href="html/libvirt-libvirt.html#virConnectOpenReadOnly"><code>virConnectOpenReadOnly</code></a>. For example:
</p>
<pre>
virConnectPtr conn = virConnectOpenReadOnly (<b>"test:///default"</b>);
</pre>
<h3>
<h2>
<a name="URI_config">Configuring URI aliases</a>
</h2>
<p>
To simplify life for administrators, it is possible to setup URI aliases in a
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.
In this file, the following syntax can be used to setup aliases
</p>
<pre>
uri_aliases = [
"hail=qemu+ssh://root@hail.cloud.example.com/system",
"sleet=qemu+ssh://root@sleet.cloud.example.com/system",
]
</pre>
<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>. If the passed in
URI contains characters outside the allowed alias character
set, no alias lookup will be attempted.
</p>
<h2>
<a name="URI_virsh">Specifying URIs to virsh, virt-manager and virt-install</a>
</h3>
</h2>
<p>
In virsh use the <code>-c</code> or <code>--connect</code> option:
</p>
@ -76,9 +83,9 @@ In virt-install use the <code>--connect=</code><i>URI</i> option:
<pre>
virt-install <b>--connect=test:///default</b> <i>[other options]</i>
</pre>
<h3>
<h2>
<a name="URI_xen">xen:/// URI</a>
</h3>
</h2>
<p>
<i>This section describes a feature which is new in libvirt &gt;
0.2.3. For libvirt &#x2264; 0.2.3 use <a href="#URI_legacy_xen"><code>"xen"</code></a>.</i>
@ -87,9 +94,9 @@ virt-install <b>--connect=test:///default</b> <i>[other options]</i>
To access a Xen hypervisor running on the local machine
use the URI <code>xen:///</code>.
</p>
<h3>
<h2>
<a name="URI_qemu">qemu:///... QEMU and KVM URIs</a>
</h3>
</h2>
<p>
To use QEMU support in libvirt you must be running the
<code>libvirtd</code> daemon (named <code>libvirt_qemud</code>
@ -119,9 +126,9 @@ KVM URIs are identical. You select between qemu, qemu accelerated and
KVM guests in the <a href="format.html#KVM1">guest XML as described
here</a>.
</p>
<h3>
<h2>
<a name="URI_remote">Remote URIs</a>
</h3>
</h2>
<p>
Remote URIs are formed by taking ordinary local URIs and adding a
hostname and/or transport name. As a special case, using a URI
@ -182,9 +189,9 @@ We refer you to <a href="remote.html#Remote_URI_reference">the libvirt
remote URI reference</a> and <a href="remote.html">full documentation
for libvirt remote support</a>.
</p>
<h3>
<h2>
<a name="URI_test">test:///... Test URIs</a>
</h3>
</h2>
<p>
The test driver is a dummy hypervisor for test purposes.
The URIs supported are:
@ -196,12 +203,12 @@ host definitions built into the driver. </li>
a set of host definitions held in the named file.
</li>
</ul>
<h3>
<h2>
<a name="URI_legacy">Other &amp; legacy URI formats</a>
</h3>
<h4>
</h2>
<h3>
<a name="URI_NULL">NULL and empty string URIs</a>
</h4>
</h3>
<p>
Libvirt allows you to pass a <code>NULL</code> pointer to
<code>virConnectOpen*</code>. Empty string (<code>""</code>) acts in
@ -223,9 +230,9 @@ the user to type a URI in directly (if that is appropriate). If your
application wishes to connect specifically to a Xen hypervisor, then
for future proofing it should choose a full <a href="#URI_xen"><code>xen:///</code> URI</a>.
</p>
<h4>
<h3>
<a name="URI_file">File paths (xend-unix-server)</a>
</h4>
</h3>
<p>
If XenD is running and configured in <code>/etc/xen/xend-config.sxp</code>:
</p>
@ -240,9 +247,9 @@ using a file URI such as:
<pre>
virsh -c ///var/run/xend/xend-socket
</pre>
<h4>
<h3>
<a name="URI_http">Legacy: <code>http://...</code> (xend-http-server)</a>
</h4>
</h3>
<p>
If XenD is running and configured in <code>/etc/xen/xend-config.sxp</code>:
@ -276,17 +283,17 @@ Notes:
libvirt, only the old-style sexpr interface known in the Xen
documentation as "unix server" or "http server".</li>
</ol>
<h4>
<h3>
<a name="URI_legacy_xen">Legacy: <code>"xen"</code></a>
</h4>
</h3>
<p>
Another legacy URI is to specify name as the string
<code>"xen"</code>. This will continue to refer to the Xen
hypervisor. However you should prefer a full <a href="#URI_xen"><code>xen:///</code> URI</a> in all future code.
</p>
<h4>
<h3>
<a name="URI_legacy_proxy">Legacy: Xen proxy</a>
</h4>
</h3>
<p>
Libvirt continues to support connections to a separately running Xen
proxy daemon. This provides a way to allow non-root users to make a

3
include/libvirt/libvirt.h.in
View File

@ -844,7 +844,8 @@ 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 */
} virConnectFlags;

1
libvirt.spec.in
View File

@ -1084,6 +1084,7 @@ rm -f $RPM_BUILD_ROOT%{_sysconfdir}/sysctl.d/libvirtd
%defattr(-, root, root)
%doc AUTHORS ChangeLog.gz NEWS README COPYING.LIB TODO
%config(noreplace) %{_sysconfdir}/libvirt/libvirt.conf
%{_mandir}/man1/virsh.1*
%{_mandir}/man1/virt-xml-validate.1*
%{_mandir}/man1/virt-pki-validate.1*

4
mingw32-libvirt.spec.in
View File

@ -110,7 +110,7 @@ rm -rf $RPM_BUILD_ROOT
make DESTDIR=$RPM_BUILD_ROOT install
rm -rf $RPM_BUILD_ROOT%{_mingw32_sysconfdir}/libvirt
rm -rf $RPM_BUILD_ROOT%{_mingw32_sysconfdir}/libvirt/nwfilter
rm -rf $RPM_BUILD_ROOT%{_mingw32_datadir}/doc/*
rm -rf $RPM_BUILD_ROOT%{_mingw32_datadir}/gtk-doc/*
@ -126,6 +126,8 @@ rm -rf $RPM_BUILD_ROOT
%files
%defattr(-,root,root)
%config(noreplace) %{_mingw32_sysconfdir}/libvirt/libvirt.conf
%{_mingw32_bindir}/libvirt-0.dll
%{_mingw32_bindir}/virsh.exe
%{_mingw32_bindir}/virt-xml-validate

2
src/Makefile.am
View File

@ -39,7 +39,7 @@ moddir = $(libdir)/libvirt/connection-driver
mod_LTLIBRARIES =
confdir = $(sysconfdir)/libvirt
conf_DATA =
conf_DATA = libvirt.conf
augeasdir = $(datadir)/augeas/lenses
augeas_DATA =

158
src/libvirt.c
View File

@ -40,6 +40,7 @@
#include "memory.h"
#include "configmake.h"
#include "intprops.h"
#include "conf.h"
#include "rpc/virnettlscontext.h"
#ifndef WITH_DRIVER_MODULES
@ -968,6 +969,126 @@ error:
return -1;
}
static char *
virConnectConfigFile(void)
{
char *path;
if (geteuid() == 0) {
if (virAsprintf(&path, "%s/libvirt/libvirt.conf",
SYSCONFDIR) < 0)
goto no_memory;
} else {
char *userdir = virGetUserDirectory(geteuid());
if (!userdir)
goto error;
if (virAsprintf(&path, "%s/.libvirt/libvirt.conf",
userdir) < 0)
goto no_memory;
}
return path;
no_memory:
virReportOOMError();
error:
return NULL;
}
#define URI_ALIAS_CHARS "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789_-"
static int
virConnectOpenFindURIAliasMatch(virConfValuePtr value, const char *alias, char **uri)
{
virConfValuePtr entry;
if (value->type != VIR_CONF_LIST) {
virLibConnError(VIR_ERR_INTERNAL_ERROR, "%s",
_("Expected a list for 'uri_aliases' config parameter"));
return -1;
}
entry = value->list;
while (entry) {
char *offset;
size_t safe;
if (entry->type != VIR_CONF_STRING) {
virLibConnError(VIR_ERR_CONF_SYNTAX, "%s",
_("Expected a string for 'uri_aliases' config parameter list entry"));
return -1;
}
if (!(offset = strchr(entry->str, '='))) {
virLibConnError(VIR_ERR_CONF_SYNTAX,
_("Malformed 'uri_aliases' config entry '%s', expected 'alias=uri://host/path'"),
entry->str);
return -1;
}
safe = strspn(entry->str, URI_ALIAS_CHARS);
if (safe < (offset - entry->str)) {
virLibConnError(VIR_ERR_CONF_SYNTAX,
_("Malformed 'uri_aliases' config entry '%s', aliases may only container 'a-Z, 0-9, _, -'"),
entry->str);
return -1;
}
if (STREQLEN(entry->str, alias, offset-entry->str)) {
VIR_DEBUG("Resolved alias '%s' to '%s'",
alias, offset+1);
if (!(*uri = strdup(offset+1))) {
virReportOOMError();
return -1;
}
return 0;
}
entry = entry->next;
}
VIR_DEBUG("No alias found for '%s', passing through to drivers",
alias);
return 0;
}
static int
virConnectOpenResolveURIAlias(const char *alias, char **uri)
{
char *config = NULL;
int ret = -1;
virConfPtr conf = NULL;
virConfValuePtr value = NULL;
*uri = NULL;
/* Short circuit to avoid doing URI alias resolution
* when it clearly isn't an valid alias */
if (strspn(alias, URI_ALIAS_CHARS) != strlen(alias))
return 0;
if (!(config = virConnectConfigFile()))
goto cleanup;
if (!virFileExists(config)) {
ret = 0;
goto cleanup;
}
VIR_DEBUG("Loading config file '%s'", config);
if (!(conf = virConfReadFile(config, 0)))
goto cleanup;
if ((value = virConfGetValue(conf, "uri_aliases")))
ret = virConnectOpenFindURIAliasMatch(value, alias, uri);
else
ret = 0;
cleanup:
virConfFree(conf);
VIR_FREE(config);
return ret;
}
static virConnectPtr
do_open (const char *name,
virConnectAuthPtr auth,
@ -998,6 +1119,7 @@ do_open (const char *name,
}
if (name) {
char *alias = NULL;
/* Convert xen -> xen:/// for back compat */
if (STRCASEEQ(name, "xen"))
name = "xen:///";
@ -1008,26 +1130,34 @@ do_open (const char *name,
if (STREQ (name, "xen://"))
name = "xen:///";
ret->uri = xmlParseURI (name);
if (!(flags & VIR_CONNECT_NO_ALIASES) &&
virConnectOpenResolveURIAlias(name, &alias) < 0)
goto failed;
ret->uri = xmlParseURI (alias ? alias : name);
if (!ret->uri) {
virLibConnError(VIR_ERR_INVALID_ARG,
_("could not parse connection URI"));
_("could not parse connection URI %s"),
alias ? alias : name);
VIR_FREE(alias);
goto failed;
}
VIR_DEBUG("name \"%s\" to URI components:\n"
" scheme %s\n"
" opaque %s\n"
" authority %s\n"
" server %s\n"
" user %s\n"
" port %d\n"
" path %s\n",
name,
NULLSTR(ret->uri->scheme), NULLSTR(ret->uri->opaque),
NULLSTR(ret->uri->authority), NULLSTR(ret->uri->server),
NULLSTR(ret->uri->user), ret->uri->port,
NULLSTR(ret->uri->path));
" scheme %s\n"
" opaque %s\n"
" authority %s\n"
" server %s\n"
" user %s\n"
" port %d\n"
" path %s\n",
alias ? alias : name,
NULLSTR(ret->uri->scheme), NULLSTR(ret->uri->opaque),
NULLSTR(ret->uri->authority), NULLSTR(ret->uri->server),
NULLSTR(ret->uri->user), ret->uri->port,
NULLSTR(ret->uri->path));
VIR_FREE(alias);
} else {
VIR_DEBUG("no name, allowing driver auto-select");
}

12
src/libvirt.conf Normal file
View File

@ -0,0 +1,12 @@
#
# This can be used to setup URI aliases for frequently
# used connection URIs. Aliases may contain only the
# characters a-Z, 0-9, _, -.
#
# Following the '=' may be any valid libvirt connection
# URI, including arbitrary parameters
#uri_aliases = [
# "hail=qemu+ssh://root@hail.cloud.example.com/system",
# "sleet=qemu+ssh://root@sleet.cloud.example.com/system",
#]

5
src/remote/remote_driver.c
View File

@ -313,6 +313,11 @@ doRemoteOpen (virConnectPtr conn,
if (conn->uri) {
if (!conn->uri->scheme) {
/* This is the ///var/lib/xen/xend-socket local path style */
if (!conn->uri->path)
return VIR_DRV_OPEN_DECLINED;
if (conn->uri->path[0] != '/')
return VIR_DRV_OPEN_DECLINED;
transport = trans_unix;
} else {
transport_str = get_transport_from_scheme (conn->uri->scheme);

6
src/util/conf.c
View File

@ -808,10 +808,8 @@ int
virConfFree(virConfPtr conf)
{
virConfEntryPtr tmp;
if (conf == NULL) {
virConfError(NULL, VIR_ERR_INVALID_ARG, __FUNCTION__);
return(-1);
}
if (conf == NULL)
return 0;
tmp = conf->entries;
while (tmp) {

12
src/xen/xen_driver.c
View File

@ -296,17 +296,7 @@ xenUnifiedOpen (virConnectPtr conn, virConnectAuthPtr auth, unsigned int flags)
conn->uri->server)
return VIR_DRV_OPEN_DECLINED;
} else {
/* Special case URI for Xen driver only:
*
* Treat a plain path as a Xen UNIX socket path, and give
* error unless path is absolute
*/
if (!conn->uri->path || conn->uri->path[0] != '/') {
xenUnifiedError(VIR_ERR_INTERNAL_ERROR,
_("unexpected Xen URI path '%s', try ///var/lib/xen/xend-socket"),
NULLSTR(conn->uri->path));
return VIR_DRV_OPEN_ERROR;
}
return VIR_DRV_OPEN_DECLINED;
}
}