Re: [libvirt] [PATCH 2/2] add default migrate uri in definition file

15 Apr 2014

On Tue, Apr 15, 2014 at 06:31:09PM +0800, Chen Fan wrote:
...
Current virsh migrate command require specfying migration URI with
command option.
Here is current step.
1) If user specifies --migrateuri on virsh migrate command, then the command
   transfers the data to specified host.
2) If --migrateuri is not specified, the command transfers the data to host
   whose name is resolved by DNS or /etc/hosts.
but we are able to use virsh migrate command more usefull.
   User can specify a constant destination by definition file.
   if user want to specify other temporary destination, command option
   is good for it.
Signed-off-by: Chen Fan <chen.fan.fnst@cn.fujitsu.com>
---
 daemon/remote.c              | 11 ++++++++++-
 src/driver.h                 |  1 +
 src/libvirt.c                | 12 +++++++++++-
 src/libvirt.conf             |  7 +++++++
 src/libvirt_internal.h       |  1 +
 src/qemu/qemu_driver.c       | 37 ++++++++++++++++++++++++++++++++++---
 src/remote/remote_driver.c   | 13 +++++++++++++
 src/remote/remote_protocol.x |  1 +
 8 files changed, 78 insertions(+), 5 deletions(-)

diff --git a/daemon/remote.c b/daemon/remote.c
index 8476961..693f460 100644
--- a/daemon/remote.c
+++ b/daemon/remote.c
@@ -5331,6 +5331,7 @@ remoteDispatchDomainMigrateBegin3Params(virNetServerPtr server ATTRIBUTE_UNUSED,
     int nparams = 0;
     char *cookieout = NULL;
     int cookieoutlen = 0;
+    char **uri_out = NULL;
     int rv = -1;
     struct daemonClientPrivate *priv =
         virNetServerClientGetPrivateData(client);
@@ -5355,21 +5356,29 @@ remoteDispatchDomainMigrateBegin3Params(virNetServerPtr server ATTRIBUTE_UNUSED,
                                                     0, &nparams)))
         goto cleanup;
+    /* Wacky world of XDR ... */
+    if (VIR_ALLOC(uri_out) < 0)
+        goto cleanup;
+
     if (!(xml = virDomainMigrateBegin3Params(dom, params, nparams,
                                              &cookieout, &cookieoutlen,
+                                             uri_out,
                                              args->flags)))
         goto cleanup;
ret->cookie_out.cookie_out_len = cookieoutlen;
     ret->cookie_out.cookie_out_val = cookieout;
+    ret->uri_out = !*uri_out ? NULL : uri_out;
     ret->xml = xml;
rv = 0;
cleanup:
     virTypedParamsFree(params, nparams);
-    if (rv < 0)
+    if (rv < 0) {
         virNetMessageSaveError(rerr);
+        VIR_FREE(uri_out);
+     }
     if (dom)
         virDomainFree(dom);
     return rv;
diff --git a/src/driver.h b/src/driver.h
index e66fc7a..738ab3a 100644
--- a/src/driver.h
+++ b/src/driver.h
@@ -1094,6 +1094,7 @@ typedef char *
                                    int nparams,
                                    char **cookieout,
                                    int *cookieoutlen,
+                                   char **uri_out,
                                    unsigned int flags);
typedef int
diff --git a/src/libvirt.c b/src/libvirt.c
index f8d5240..257adbd 100644
--- a/src/libvirt.c
+++ b/src/libvirt.c
@@ -4738,7 +4738,7 @@ virDomainMigrateVersion3Full(virDomainPtr domain,
     VIR_DEBUG("Begin3 %p", domain->conn);
     if (useParams) {
         dom_xml = domain->conn->driver->domainMigrateBegin3Params
-            (domain, params, nparams, &cookieout, &cookieoutlen,
+            (domain, params, nparams, &cookieout, &cookieoutlen, &uri_out,
              flags | protection);
     } else {
         dom_xml = domain->conn->driver->domainMigrateBegin3
@@ -4748,6 +4748,14 @@ virDomainMigrateVersion3Full(virDomainPtr domain,
     if (!dom_xml)
         goto done;
+    /* Does domainMigrateBegin3Params() change URI? */
+    if (uri_out) {
+        if (virTypedParamsReplaceString(¶ms, &nparams,
+                                        VIR_MIGRATE_PARAM_URI,
+                                        uri_out) < 0)
+            goto done;
+    }
+
     if (useParams) {
         /* If source is new enough to support extensible migration parameters,
          * it's certainly new enough to support virDomainGetState. */
@@ -6778,6 +6786,7 @@ virDomainMigrateBegin3Params(virDomainPtr domain,
                              int nparams,
                              char **cookieout,
                              int *cookieoutlen,
+                             char **uri_out,
                              unsigned int flags)
 {
     virConnectPtr conn;
@@ -6798,6 +6807,7 @@ virDomainMigrateBegin3Params(virDomainPtr domain,
         char *xml;
         xml = conn->driver->domainMigrateBegin3Params(domain, params, nparams,
                                                       cookieout, cookieoutlen,
+                                                      uri_out,
                                                       flags);
         VIR_DEBUG("xml %s", NULLSTR(xml));
         if (!xml)
diff --git a/src/libvirt.conf b/src/libvirt.conf
index 016cd24..9cef343 100644
--- a/src/libvirt.conf
+++ b/src/libvirt.conf
@@ -16,3 +16,10 @@
 # driver when no URI is supplied by the application.
#uri_default = "qemu:///system"
+
+#
+# This can be used to provide the default migrate URI when
+# migrate to target host. if migrate URI had been specified
+# in command line, this URI was ignored.
+
+#uri_migrate = "tcp://dest-uri-example"
This is a client side configuration file...
...
diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index 1d08951..c82fbca 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
...
+
+    if (!uri_in) {
+        if (virConnectGetConfigFile(&conf) < 0) {
+            goto cleanup;
+        }
+
+        if ((value = virConfGetValue(conf, "uri_migrate"))) {
+            if (value->type != VIR_CONF_STRING) {
+                VIR_WARN("Expected a string for 'uri_migrate' config parameter");
+            } else {
+                if (VIR_STRDUP(*uri_out, value->str) < 0)
+                    goto cleanup;
+            }
+        }
+        virConfFree(conf);
...which you're attempting to read from the server side.
...
diff --git a/src/remote/remote_driver.c b/src/remote/remote_driver.c
index ed7dde6..3df59da 100644
--- a/src/remote/remote_driver.c
+++ b/src/remote/remote_driver.c
@@ -6970,6 +6970,7 @@ remoteDomainMigrateBegin3Params(virDomainPtr domain,
                                 int nparams,
                                 char **cookieout,
                                 int *cookieoutlen,
+                                char **uri_out,
                                 unsigned int flags)
 {
     char *rv = NULL;
@@ -7017,15 +7018,27 @@ remoteDomainMigrateBegin3Params(virDomainPtr domain,
         *cookieoutlen = ret.cookie_out.cookie_out_len;
     }
+    if (ret.uri_out) {
+        if (!uri_out) {
+            virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+                           _("caller ignores uri_out"));
+            goto error;
+        }
+        *uri_out = *ret.uri_out; /* Caller frees. */
+    }
+
     rv = ret.xml; /* caller frees */
cleanup:
     remoteFreeTypedParameters(args.params.params_val, args.params.params_len);
+    VIR_FREE(ret.uri_out);
     remoteDriverUnlock(priv);
     return rv;
error:
     VIR_FREE(ret.cookie_out.cookie_out_val);
+    if (ret.uri_out)
+        VIR_FREE(*ret.uri_out);
     goto cleanup;
 }
diff --git a/src/remote/remote_protocol.x b/src/remote/remote_protocol.x
index 6c445cc..202a0eb 100644
--- a/src/remote/remote_protocol.x
+++ b/src/remote/remote_protocol.x
@@ -2860,6 +2860,7 @@ struct remote_domain_migrate_begin3_params_args {
struct remote_domain_migrate_begin3_params_ret {
     opaque cookie_out<REMOTE_MIGRATE_COOKIE_MAX>;
+    remote_string uri_out;
     remote_nonnull_string xml;
 };
NACK, this breaks wire protocol compatibility. Changing any existing
APIs is absolutely forbidden.


IMHO the idea of storing the 'migration_uri' parameter in a configuration
file is just plain wrong. This value is inherantly associated with the
host that you're migrating to. So if you set 'migration_uri' to one host
in the config, but then invoke virDomainMigrate with a virConnectPtr that
is associated with a different host, this just crashes and burns. 

Regards,
Daniel
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Re: [libvirt] [PATCH 2/2] add default migrate uri in definition file

Daniel P. Berrange