Add --volumes-from flag to podman run and create

podman now supports --volumes-from flag, which allows users
to add all the volumes an existing container has to a new one.

Signed-off-by: umohnani8 <umohnani@redhat.com>

Closes: #931
Approved by: mheon

4 files changed, 34 insertions, 2 deletions

diff --git a/libpod/container.go b/libpod/container.go
index 24a5f93af..9486986ab 100644
--- a/libpod/container.go
+++ b/libpod/container.go
@@ -313,6 +313,9 @@ type ContainerConfig struct {
 	// ExitCommand is the container's exit command.
 	// This Command will be executed when the container exits
 	ExitCommand []string `json:"exitCommand,omitempty"`
+	// LocalVolumes are the built-in volumes we get from the --volumes-from flag
+	// It picks up the built-in volumes of the container used by --volumes-from
+	LocalVolumes []string
 }
 
 // ContainerStatus returns a string representation for users
diff --git a/libpod/container_internal.go b/libpod/container_internal.go
index 94cd74c09..eb9b39a02 100644
--- a/libpod/container_internal.go
+++ b/libpod/container_internal.go
@@ -1108,7 +1108,7 @@ func (c *Container) generateHosts() (string, error) {
 	return c.writeStringToRundir("hosts", hosts)
 }
 
-func (c *Container) addImageVolumes(ctx context.Context, g *generate.Generator) error {
+func (c *Container) addLocalVolumes(ctx context.Context, g *generate.Generator) error {
 	mountPoint := c.state.Mountpoint
 	if !c.state.Mounted {
 		return errors.Wrapf(ErrInternal, "container is not mounted")
@@ -1121,6 +1121,17 @@ func (c *Container) addImageVolumes(ctx context.Context, g *generate.Generator)
 	if err != nil {
 		return err
 	}
+	// Add the built-in volumes of the container passed in to --volumes-from
+	for _, vol := range c.config.LocalVolumes {
+		if imageData.ContainerConfig.Volumes == nil {
+			imageData.ContainerConfig.Volumes = map[string]struct{}{
+				vol: {},
+			}
+		} else {
+			imageData.ContainerConfig.Volumes[vol] = struct{}{}
+		}
+	}
+
 	for k := range imageData.ContainerConfig.Volumes {
 		mount := spec.Mount{
 			Destination: k,
diff --git a/libpod/container_internal_linux.go b/libpod/container_internal_linux.go
index 0dc02d117..9ad825458 100644
--- a/libpod/container_internal_linux.go
+++ b/libpod/container_internal_linux.go
@@ -127,7 +127,7 @@ func (c *Container) generateSpec(ctx context.Context) (*spec.Spec, error) {
 
 	// Bind builtin image volumes
 	if c.config.Rootfs == "" && c.config.ImageVolumes {
-		if err := c.addImageVolumes(ctx, &g); err != nil {
+		if err := c.addLocalVolumes(ctx, &g); err != nil {
 			return nil, errors.Wrapf(err, "error mounting image volumes")
 		}
 	}
diff --git a/libpod/options.go b/libpod/options.go
index 9f07db7ed..c02bd4336 100644
--- a/libpod/options.go
+++ b/libpod/options.go
@@ -885,6 +885,24 @@ func WithUserVolumes(volumes []string) CtrCreateOption {
 	}
 }
 
+// WithLocalVolumes sets the built-in volumes of the container retrieved
+// from a container passed in to the --volumes-from flag.
+// This stores the built-in volume information in the ContainerConfig so we can
+// add them when creating the container.
+func WithLocalVolumes(volumes []string) CtrCreateOption {
+	return func(ctr *Container) error {
+		if ctr.valid {
+			return ErrCtrFinalized
+		}
+
+		if volumes != nil {
+			ctr.config.LocalVolumes = append(ctr.config.LocalVolumes, volumes...)
+		}
+
+		return nil
+	}
+}
+
 // WithEntrypoint sets the entrypoint of the container.
 // This is not used to change the container's spec, but will instead be used
 // during commit to populate the entrypoint of the new image.