nvidia-container-toolkit/cmd/nvidia-container-runtime/modifier/experimental.go
Evan Lezar 239b6d3739 Implement experimental modifier for NVIDIA Container Runtime
This change enables the experimental mode of the NVIDIA Container Runtime. If
enabled, the nvidia-container-runtime.discover-mode config option is
queried to determine how required OCI spec modifications should be defined.
If "legacy" is selected, the existing NVIDIA Container Runtime hooks is
discovered and injected into the OCI spec.

Signed-off-by: Evan Lezar <elezar@nvidia.com>
2022-04-04 14:16:25 +02:00

120 lines
3.5 KiB
Go

/**
# Copyright (c) 2022, NVIDIA CORPORATION. All rights reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
**/
package modifier
import (
"fmt"
"path/filepath"
"github.com/NVIDIA/nvidia-container-toolkit/internal/config"
"github.com/NVIDIA/nvidia-container-toolkit/internal/discover"
"github.com/NVIDIA/nvidia-container-toolkit/internal/edits"
"github.com/NVIDIA/nvidia-container-toolkit/internal/oci"
"github.com/opencontainers/runtime-spec/specs-go"
"github.com/sirupsen/logrus"
)
// experiemental represents the modifications required by the experimental runtime
type experimental struct {
logger *logrus.Logger
discoverer discover.Discover
}
// NewExperimentalModifier creates a modifier that applied the experimental
// modications to an OCI spec if required by the runtime wrapper.
func NewExperimentalModifier(logger *logrus.Logger, cfg *config.RuntimeConfig) (oci.SpecModifier, error) {
logger.Infof("Constructing modifier from config: %+v", cfg)
// TODO: We need to specify the root
root := ""
var d discover.Discover
switch cfg.DiscoverMode {
case "legacy":
legacyDiscoverer, err := discover.NewLegacyDiscoverer(logger, root)
if err != nil {
return nil, fmt.Errorf("failed to create legacy discoverer: %v", err)
}
d = legacyDiscoverer
default:
return nil, fmt.Errorf("invalid discover mode: %v", cfg.DiscoverMode)
}
return newExperimentalModifierFromDiscoverer(logger, d)
}
// newExperimentalModifierFromDiscoverer created a modifier that aplies the discovered
// modifications to an OCI spec if require by the runtime wrapper.
func newExperimentalModifierFromDiscoverer(logger *logrus.Logger, d discover.Discover) (oci.SpecModifier, error) {
m := experimental{
logger: logger,
discoverer: d,
}
return &m, nil
}
// Modify applies the required modifications to the incomming OCI spec. These modifications
// are applied in-place.
func (m experimental) Modify(spec *specs.Spec) error {
err := m.assertSpecIsCompatible(spec)
if err != nil {
return fmt.Errorf("OCI specification cannot be modified: %v", err)
}
specEdits, err := edits.NewSpecEdits(m.logger, m.discoverer)
if err != nil {
return fmt.Errorf("failed to get required container edits: %v", err)
}
return specEdits.Modify(spec)
}
func (m experimental) assertSpecIsCompatible(spec *specs.Spec) error {
if spec == nil {
return nil
}
if spec.Hooks == nil {
return nil
}
if hookPath := findStableHook(spec.Hooks.Prestart); hookPath != "" {
return fmt.Errorf("spec already contains required 'prestart' hook: %v", hookPath)
}
return nil
}
// findStableHook checks the list of OCI hooks for the nvidia-container-runtime-hook
// or nvidia-container-toolkit hook. These are included, for example, by the non-experimental
// nvidia-container-runtime or docker when specifying the --gpus flag.
func findStableHook(hooks []specs.Hook) string {
lookFor := map[string]bool{
nvidiaContainerRuntimeHookExecuable: true,
nvidiaContainerToolkitExecutable: true,
}
for _, h := range hooks {
base := filepath.Base(h.Path)
if lookFor[base] {
return h.Path
}
}
return ""
}