Initial implementation of renaming containers

Basic theory: We remove the container, but *only from the DB*.
We leave it in c/storage, we leave the lock allocated, we leave
it running (if it is). Then we create an identical container with
an altered name, and add that back to the database. Theoretically
we now have a renamed container.

The advantage of this approach is that it doesn't just apply to
rename - we can use this to make *any* configuration change to a
container that does not alter its container ID.

Potential problems are numerous. This process is *THOROUGHLY*
non-atomic at present - if you `kill -9` Podman mid-rename things
will be in a bad place, for example. Also, we can't rename
containers that can't be removed normally - IE, containers with
dependencies (pod infra containers, for example).

The largest potential improvement will be to move the majority of
the work into the DB, with a `RecreateContainer()` method - that
will add atomicity, and let us remove the container without
worrying about depencies and similar issues.

Potential problems: long-running processes that edit the DB and
may have an older version of the configuration around. Most
notable example is `podman run --rm` - the removal command needed
to be manually edited to avoid this one. This begins to get at
the heart of me not wanting to do this in the first place...

This provides CLI and API implementations for frontend, but no
tunnel implementation. It will be added in a future release (just
held back for time now - we need this in 3.0 and are running low
on time).

This is honestly kind of horrifying, but I think it will work.

Signed-off-by: Matthew Heon <mheon@redhat.com>

2 files changed, 90 insertions, 3 deletions

diff --git a/pkg/api/handlers/compat/containers.go b/pkg/api/handlers/compat/containers.go
index 0f89c859e..6e1945db1 100644
--- a/pkg/api/handlers/compat/containers.go
+++ b/pkg/api/handlers/compat/containers.go
@@ -465,3 +465,34 @@ func formatCapabilities(slice []string) {
 		slice[i] = strings.TrimPrefix(slice[i], "CAP_")
 	}
 }
+
+func RenameContainer(w http.ResponseWriter, r *http.Request) {
+	runtime := r.Context().Value("runtime").(*libpod.Runtime)
+	decoder := r.Context().Value("decoder").(*schema.Decoder)
+
+	name := utils.GetName(r)
+	query := struct {
+		Name string `schema:"name"`
+	}{}
+	if err := decoder.Decode(&query, r.URL.Query()); err != nil {
+		utils.Error(w, "Something went wrong.", http.StatusBadRequest, errors.Wrapf(err, "failed to parse parameters for %s", r.URL.String()))
+		return
+	}
+
+	ctr, err := runtime.LookupContainer(name)
+	if err != nil {
+		utils.ContainerNotFound(w, name, err)
+		return
+	}
+
+	if _, err := runtime.RenameContainer(r.Context(), ctr, query.Name); err != nil {
+		if errors.Cause(err) == define.ErrPodExists || errors.Cause(err) == define.ErrCtrExists {
+			utils.Error(w, "Something went wrong.", http.StatusConflict, err)
+			return
+		}
+		utils.InternalServerError(w, err)
+		return
+	}
+
+	utils.WriteResponse(w, http.StatusNoContent, nil)
+}
diff --git a/pkg/api/server/register_containers.go b/pkg/api/server/register_containers.go
index b80dea545..74a04b2e6 100644
--- a/pkg/api/server/register_containers.go
+++ b/pkg/api/server/register_containers.go
@@ -291,9 +291,6 @@ func (s *APIServer) registerContainersHandlers(r *mux.Router) error {
 	r.HandleFunc(VersionedPath("/containers/{name}/pause"), s.APIHandler(compat.PauseContainer)).Methods(http.MethodPost)
 	// Added non version path to URI to support docker non versioned paths
 	r.HandleFunc("/containers/{name}/pause", s.APIHandler(compat.PauseContainer)).Methods(http.MethodPost)
-	r.HandleFunc(VersionedPath("/containers/{name}/rename"), s.APIHandler(compat.UnsupportedHandler)).Methods(http.MethodPost)
-	// Added non version path to URI to support docker non versioned paths
-	r.HandleFunc("/containers/{name}/rename", s.APIHandler(compat.UnsupportedHandler)).Methods(http.MethodPost)
 	// swagger:operation POST /containers/{name}/restart compat restartContainer
 	// ---
 	// tags:
@@ -610,6 +607,36 @@ func (s *APIServer) registerContainersHandlers(r *mux.Router) error {
 	//     $ref: "#/responses/InternalError"
 	r.HandleFunc(VersionedPath("/containers/{name}/export"), s.APIHandler(compat.ExportContainer)).Methods(http.MethodGet)
 	r.HandleFunc("/containers/{name}/export", s.APIHandler(compat.ExportContainer)).Methods(http.MethodGet)
+	// swagger:operation POST /containers/{name}/rename compat renameContainer
+	// ---
+	// tags:
+	//   - containers (compat)
+	// summary: Rename an existing container
+	// description: Change the name of an existing container.
+	// parameters:
+	//  - in: path
+	//    name: name
+	//    type: string
+	//    required: true
+	//    description: Full or partial ID or full name of the container to rename
+	//  - in: query
+	//    name: name
+	//    type: string
+	//    required: true
+	//    description: New name for the container
+	// produces:
+	// - application/json
+	// responses:
+	//   204:
+	//     description: no error
+	//   404:
+	//     $ref: "#/responses/NoSuchContainer"
+	//   409:
+	//     $ref: "#/responses/ConflictError"
+	//   500:
+	//     $ref: "#/responses/InternalError"
+	r.HandleFunc(VersionedPath("/containers/{name}/rename"), s.APIHandler(compat.RenameContainer)).Methods(http.MethodPost)
+	r.HandleFunc("/containers/{name}/rename", s.APIHandler(compat.RenameContainer)).Methods(http.MethodPost)
 
 	/*
 		libpod endpoints
@@ -1463,5 +1490,34 @@ func (s *APIServer) registerContainersHandlers(r *mux.Router) error {
 	//   500:
 	//     $ref: "#/responses/InternalError"
 	r.HandleFunc(VersionedPath("/libpod/containers/{name}/init"), s.APIHandler(libpod.InitContainer)).Methods(http.MethodPost)
+	// swagger:operation POST /libpod/containers/{name}/rename libpod libpodRenameContainer
+	// ---
+	// tags:
+	//   - containers
+	// summary: Rename an existing container
+	// description: Change the name of an existing container.
+	// parameters:
+	//  - in: path
+	//    name: name
+	//    type: string
+	//    required: true
+	//    description: Full or partial ID or full name of the container to rename
+	//  - in: query
+	//    name: name
+	//    type: string
+	//    required: true
+	//    description: New name for the container
+	// produces:
+	// - application/json
+	// responses:
+	//   204:
+	//     description: no error
+	//   404:
+	//     $ref: "#/responses/NoSuchContainer"
+	//   409:
+	//     $ref: "#/responses/ConflictError"
+	//   500:
+	//     $ref: "#/responses/InternalError"
+	r.HandleFunc(VersionedPath("/libpod/containers/{name}/rename"), s.APIHandler(compat.RenameContainer)).Methods(http.MethodPost)
 	return nil
 }