// To avoid complexity of having a sort-of public host, and to ensure we
// can just instead easily store images on S3 (or similar) we attempt to
// sync images in a similar fashion to the LXC image downloader. This means
// that when we attempt to run the image, the download will look for our
// existing cache (that we've correctly populated) and just reference the
// image from there.
func (c *Container) ensureImageCached(snapshot string, clientLog *client.Log) error {
var err error
relPath := c.getImagePath(snapshot)
localPath := filepath.Join("/var/cache/lxc/download", relPath)
// list of files required to avoid network hit
fileList := []string{fmt.Sprintf("rootfs.tar.%s", c.Compression), "config", "snapshot_id"}
var missingFiles bool = false
for n := range fileList {
if _, err = os.Stat(filepath.Join(localPath, fileList[n])); os.IsNotExist(err) {
missingFiles = true
break
}
}
if !missingFiles {
return nil
}
if c.S3Bucket == "" {
return errors.New("Unable to find cached image, and no S3 bucket defined.")
}
err = os.MkdirAll(localPath, 0755)
if err != nil {
return err
}
remotePath := fmt.Sprintf("s3://%s/%s", c.S3Bucket, relPath)
clientLog.Writeln(fmt.Sprintf("==> Downloading image %s", snapshot))
// TODO(dcramer): verify env is passed correctly here
cw := client.NewCmdWrapper([]string{"aws", "s3", "sync", "--quiet", remotePath, localPath}, "", []string{
"HOME=/root",
})
start := time.Now()
result, err := cw.Run(false, clientLog)
dur := time.Since(start)
if err != nil {
return err
}
if !result.Success {
return errors.New("Failed downloading image")
}
clientLog.Writeln(fmt.Sprintf("==> Image downloaded in %s", dur))
return nil
}
// Compresses the root of the filesystem into the desired compressed tarball.
// The compression here can vary based on flags.
func (c *Container) createImageRootFs(snapshotPath string, clientLog *client.Log) error {
rootFsTxz := filepath.Join(snapshotPath, fmt.Sprintf("rootfs.tar.%s", c.Compression))
clientLog.Writeln(fmt.Sprintf("==> Creating rootfs.tar.%s", c.Compression))
var cw *client.CmdWrapper
if c.Compression == "xz" {
cw = client.NewCmdWrapper([]string{"tar", "-Jcf", rootFsTxz, "-C", c.RootFs(), "."}, "", []string{})
} else {
cw = client.NewCmdWrapper([]string{"tar", "-cf", rootFsTxz, "-I", "lz4", "-C", c.RootFs(), "."}, "", []string{})
}
result, err := cw.Run(false, clientLog)
if err != nil {
return err
}
if !result.Success {
return errors.New(fmt.Sprintf("Failed creating rootfs.tar.%s", c.Compression))
}
return nil
}
// Runs the prelaunch script which is essentially responsible for setting up
// the environment for the post-launch script. It runs within the host
// environment with the container mounted at LXC_ROOTFS. Runs as the user
// that changes-client runs as (usually root).
func (c *Container) runPreLaunch(clientLog *client.Log) error {
preEnv := []string{fmt.Sprintf("LXC_ROOTFS=%s", c.RootFs()), fmt.Sprintf("LXC_NAME=%s", c.Name)}
cw := client.NewCmdWrapper([]string{c.PreLaunch}, "", preEnv)
result, err := cw.Run(false, clientLog)
if err != nil {
return err
}
if !result.Success {
return errors.New("Post-launch script failed")
}
return nil
}
// Uploads a snapshot outcome to an s3 bucket, at the same path that
// changes-client will expect to download it from. The snapshot itself
// is just a tarball of the rootfs of the container - compressed with
// either xz for high compression or lz4 for raw speed.
func (c *Container) UploadImage(snapshot string, clientLog *client.Log) error {
relPath := c.getImagePath(snapshot)
localPath := filepath.Join("/var/cache/lxc/download", relPath)
remotePath := fmt.Sprintf("s3://%s/%s", c.S3Bucket, relPath)
clientLog.Writeln(fmt.Sprintf("==> Uploading image %s", snapshot))
// TODO(dcramer): verify env is passed correctly here
cw := client.NewCmdWrapper([]string{"aws", "s3", "sync", "--quiet", localPath, remotePath}, "", []string{})
start := time.Now()
result, err := cw.Run(false, clientLog)
dur := time.Since(start)
if err != nil {
return err
}
if !result.Success {
return errors.New("Failed uploading image")
}
clientLog.Writeln(fmt.Sprintf("==> Image uploaded in %s", dur))
return nil
}
// Runs a given command. This may be called multiple times depending
func (a *Adapter) Run(cmd *client.Command, clientLog *client.Log) (*client.CommandResult, error) {
cw := client.NewCmdWrapper([]string{cmd.Path}, cmd.Cwd, cmd.Env)
return cw.Run(cmd.CaptureOutput, clientLog)
}