allow specifying of target host machine on every individual resource/data source

README.md

@@ -104,6 +104,8 @@ The binary will be called `terraform-provider-libvirt`.
 
 You can target different libvirt hosts instantiating the [provider multiple times](https://www.terraform.io/docs/configuration/providers.html#multiple-provider-instances). [Example](examples/v0.12/multiple).
 
+Alternatively, you can specify the `host` argument on any of the data or resources. This can be useful if a module implements internal resource management that is distributed within a hosting environment (e.g. multiple servers in close proximity to each other)
+
 ### Using qemu-agent
 
 From its documentation, [qemu-agent](https://wiki.libvirt.org/page/Qemu_guest_agent):

go.mod

@@ -7,7 +7,7 @@ require (
 	github.com/google/uuid v1.3.0
 	github.com/hashicorp/terraform-plugin-sdk/v2 v2.24.1
 	github.com/hooklift/iso9660 v1.0.0
-	github.com/kevinburke/ssh_config v0.0.0-20201106050909-4977a11b4351
+	github.com/kevinburke/ssh_config v1.2.0
 	github.com/mattn/goveralls v0.0.11
 	github.com/stretchr/testify v1.8.1
 	golang.org/x/crypto v0.17.0

go.sum

@@ -286,6 +286,8 @@ github.com/jtolds/gls v4.2.1+incompatible/go.mod h1:QJZ7F/aHp+rZTRtaJ1ow/lLfFfVY
 github.com/kevinburke/ssh_config v0.0.0-20190725054713-01f96b0aa0cd/go.mod h1:CT57kijsi8u/K/BOFA39wgDQJ9CxiF4nAY/ojJ6r6mM=
 github.com/kevinburke/ssh_config v0.0.0-20201106050909-4977a11b4351 h1:DowS9hvgyYSX4TO5NpyC606/Z4SxnNYbT+WX27or6Ck=
 github.com/kevinburke/ssh_config v0.0.0-20201106050909-4977a11b4351/go.mod h1:CT57kijsi8u/K/BOFA39wgDQJ9CxiF4nAY/ojJ6r6mM=
+github.com/kevinburke/ssh_config v1.2.0 h1:x584FjTGwHzMwvHx18PXxbBVzfnxogHaAReU4gf13a4=
+github.com/kevinburke/ssh_config v1.2.0/go.mod h1:CT57kijsi8u/K/BOFA39wgDQJ9CxiF4nAY/ojJ6r6mM=
 github.com/keybase/go-crypto v0.0.0-20161004153544-93f5b35093ba/go.mod h1:ghbZscTyKdM07+Fw3KSi0hcJm+AlEUWj8QLlPtijN/M=
 github.com/kisielk/errcheck v1.2.0/go.mod h1:/BMXB+zMLi60iA8Vv6Ksmxu/1UDYcXs4uQLJ+jE2L00=
 github.com/kisielk/gotool v1.0.0/go.mod h1:XhKaO+MFFWcvkIS/tQcRk01m1F5IRFswLeQ+oQHNcck=

libvirt/client.go

@@ -0,0 +1,128 @@
+package libvirt
+
+import (
+	"fmt"
+	"log"
+	"sync"
+	"errors"
+	libvirt "github.com/digitalocean/go-libvirt"
+	"github.com/dmacvicar/terraform-provider-libvirt/libvirt/helper/mutexkv"
+	uri "github.com/dmacvicar/terraform-provider-libvirt/libvirt/uri"
+)
+
+type Connection struct {
+	connection *libvirt.Libvirt
+	poolMutexKV *mutexkv.MutexKV
+
+	// define only one network at a time
+	// https://gitlab.com/libvirt/libvirt/-/issues/78
+	// note: this issue has been resolved in 2021 https://gitlab.com/libvirt/libvirt/-/commit/ea0cfa11
+	networkMutex sync.Mutex
+}
+
+// Client libvirt.
+type Client struct {
+	defaultURI  string
+	connections map[string]*Connection
+}
+
+// obtain a connection for this provider, if target is empty, use the default provider connection
+func (c *Client) Connection(target *string) (*libvirt.Libvirt , error) {
+
+	URI := c.defaultURI
+	if target != nil && *target != "" {
+		URI = *target
+	}
+
+	if URI == "" {
+		return nil, errors.New("either the provider-wide default `uri` or the resource block `host` must be specified")
+	}
+
+	log.Printf("[DEBUG] Configuring connection for target host '%s'", URI)
+
+	if conn, ok := c.connections[URI] ; ok {
+		log.Printf("[DEBUG] Found existing connection for target host: '%s'", URI)
+		return conn.connection, nil
+	}
+
+	u, err := uri.Parse(URI)
+	if err != nil {
+		return nil, err
+	}
+
+	l := libvirt.NewWithDialer(u)
+
+	if err := l.ConnectToURI(libvirt.ConnectURI(u.RemoteName())); err != nil {
+		return nil, fmt.Errorf("failed to connect: %w", err)
+	}
+
+	v, err := l.ConnectGetLibVersion()
+	if err != nil {
+		return nil, fmt.Errorf("failed to retrieve libvirt version: %w", err)
+	}
+	log.Printf("[INFO] libvirt client libvirt version: %v\n", v)
+
+	conn := &Connection {
+		connection: l,
+			poolMutexKV: mutexkv.NewMutexKV(),
+		}
+	c.connections[URI] = conn
+	return conn.connection, nil
+}
+
+// obtain a Lock for this client, don't create if not found since the network connection must exist anyways to get this far
+func (c *Client) GetLock(target *string) (*mutexkv.MutexKV) {
+
+	URI := c.defaultURI
+	if target != nil && *target != "" {
+		URI = *target
+	}
+
+	if URI == "" {
+		// if we get here, somehow the calling code was able top get a live connection but the
+		// connection string doesn't exist. This breaks a code invariant and is indicative of a bug.
+		log.Printf("[WARN] unable to find mutex for '%v' - this is not expected behaviour", target)
+		return nil
+	}
+
+	if conn, ok := c.connections[URI] ; ok {
+		return conn.poolMutexKV
+	}
+
+	return nil
+}
+
+// obtain a Lock for this client, don't create if not found since the network connection must exist anyways to get this far
+func (c *Client) GetMutex(target *string) (*sync.Mutex) {
+
+	URI := c.defaultURI
+	if target != nil && *target != "" {
+		URI = *target
+	}
+
+	if URI == "" {
+		// if we get here, somehow the calling code was able top get a live connection but the
+		// connection string doesn't exist. This breaks a code invariant and is indicative of a bug.
+		log.Printf("[WARN] unable to find mutex for '%v' - this is not expected behaviour", target)
+		return nil
+	}
+
+	if conn, ok := c.connections[URI] ; ok {
+		return &conn.networkMutex
+	}
+
+	return nil
+}
+
+// Close all connections associated with this provider instance
+func (c *Client) Close() {
+
+	for uri, c := range c.connections {
+		log.Printf("[DEBUG] cleaning up connection for URI: %s", uri)
+		// TODO: Confirm appropriate IsAlive() validation
+		err := c.connection.ConnectClose()
+		if err != nil {
+			log.Printf("[ERROR] cannot close libvirt connection: %v", err)
+		}
+	}
+}

libvirt/cloudinit_def.go

@@ -54,19 +54,12 @@ func removeTmpIsoDirectory(iso string) {
 
 }
 
-func (ci *defCloudInit) UploadIso(client *Client, iso string) (string, error) {
-	virConn := client.libvirt
-	if virConn == nil {
-		return "", fmt.Errorf(LibVirtConIsNil)
-	}
-
+func (ci *defCloudInit) UploadIso(virConn *libvirt.Libvirt, iso string) (string, error) {
 	pool, err := virConn.StoragePoolLookupByName(ci.PoolName)
 	if err != nil {
 		return "", fmt.Errorf("can't find storage pool '%s'", ci.PoolName)
 	}
 
-	client.poolMutexKV.Lock(ci.PoolName)
-	defer client.poolMutexKV.Unlock(ci.PoolName)
 
 	// Refresh the pool of the volume so that libvirt knows it is
 	// not longer in use.

libvirt/coreos_ignition_def.go

@@ -30,19 +30,12 @@ func newIgnitionDef() defIgnition {
 // Create a ISO file based on the contents of the CloudInit instance and
 // uploads it to the libVirt pool
 // Returns a string holding terraform's internal ID of this resource.
-func (ign *defIgnition) CreateAndUpload(client *Client) (string, error) {
-	virConn := client.libvirt
-	if virConn == nil {
-		return "", fmt.Errorf(LibVirtConIsNil)
-	}
-
+func (ign *defIgnition) CreateAndUpload(virConn *libvirt.Libvirt) (string, error) {
 	pool, err := virConn.StoragePoolLookupByName(ign.PoolName)
 	if err != nil {
 		return "", fmt.Errorf("can't find storage pool '%s'", ign.PoolName)
 	}
 
-	client.poolMutexKV.Lock(ign.PoolName)
-	defer client.poolMutexKV.Unlock(ign.PoolName)
 
 	// Refresh the pool of the volume so that libvirt knows it is
 	// not longer in use.

libvirt/data_source_libvirt_node_device_info.go

@@ -208,6 +208,11 @@ func datasourceLibvirtNodeDeviceInfo() *schema.Resource {
 	return &schema.Resource{
 		Read: resourceLibvirtNodeDeviceInfoRead,
 		Schema: map[string]*schema.Schema{
+			"host" : {
+				Type:     schema.TypeString,
+				Optional: true,
+				ForceNew: true,
+			},
 			"name": {
 				Type:     schema.TypeString,
 				Required: true,
@@ -464,9 +469,10 @@ func datasourceLibvirtNodeDeviceInfo() *schema.Resource {
 func resourceLibvirtNodeDeviceInfoRead(d *schema.ResourceData, meta interface{}) error {
 	log.Printf("[DEBUG] Read data source libvirt_nodedevices")
 
-	virConn := meta.(*Client).libvirt
+	uri := d.Get("host").(string)
+	virConn, err := meta.(*Client).Connection(&uri)
 	if virConn == nil {
-		return fmt.Errorf(LibVirtConIsNil)
+		return fmt.Errorf("unable to connect for node deviceinfo read: %v", err)
 	}
 
 	var deviceName string

libvirt/data_source_libvirt_node_devices.go

@@ -25,6 +25,11 @@ func datasourceLibvirtNodeDevices() *schema.Resource {
 	return &schema.Resource{
 		Read: resourceLibvirtNodeDevicesRead,
 		Schema: map[string]*schema.Schema{
+			"host" : {
+				Type:     schema.TypeString,
+				Optional: true,
+				ForceNew: true,
+			},
 			"capability": {
 				Type:     schema.TypeString,
 				Optional: true,
@@ -43,9 +48,10 @@ func datasourceLibvirtNodeDevices() *schema.Resource {
 func resourceLibvirtNodeDevicesRead(d *schema.ResourceData, meta interface{}) error {
 	log.Printf("[DEBUG] Read data source libvirt_nodedevices")
 
-	virConn := meta.(*Client).libvirt
+	uri := d.Get("host").(string)
+	virConn, err := meta.(*Client).Connection(&uri)
 	if virConn == nil {
-		return fmt.Errorf(LibVirtConIsNil)
+		return fmt.Errorf("unable to connect for node devices read: %v", err)
 	}
 
 	var cap libvirt.OptString