diff options
| -rw-r--r-- | cmd/c2vm/main.go | 120 | ||||
| -rw-r--r-- | go.mod | 3 | ||||
| -rw-r--r-- | go.sum | 6 |
3 files changed, 128 insertions, 1 deletions
diff --git a/cmd/c2vm/main.go b/cmd/c2vm/main.go index 5e9fbb0..c416e47 100644 --- a/cmd/c2vm/main.go +++ b/cmd/c2vm/main.go @@ -4,11 +4,18 @@ import ( "context" "flag" "fmt" + "io/ioutil" "log" + "os/exec" + "path/filepath" "github.com/containerd/containerd" + "github.com/containerd/containerd/content" + "github.com/containerd/containerd/images" "github.com/containerd/containerd/namespaces" "github.com/containerd/containerd/platforms" + "github.com/docker/docker/pkg/archive" + "github.com/google/renameio" ocispec "github.com/opencontainers/image-spec/specs-go/v1" ) @@ -27,6 +34,7 @@ var ( func main() { var ( containerName = flag.String("container", "", "Name of the container") + outFile = flag.String("out", "container.img", "firecracker output to create") ) flag.Parse() @@ -58,5 +66,115 @@ func main() { log.Fatalf("failed to get the size of the image: %v", err) } - fmt.Printf("pulled %s (%d bytes)\n", image.Name(), imageSize) + log.Printf("pulled %s (%d bytes)\n", image.Name(), imageSize) + + mntDir, err := ioutil.TempDir("", "c2vm") + if err != nil { + log.Fatalf("Failed to create mount temp dir: %v\n", err) + } + + if err := createLoopDevice(*outFile, mntDir); err != nil { + log.Fatalf("%v\n", err) + } + + if err := extract(ctx, client, image, mntDir); err != nil { + log.Fatalf("failed to extract the container: %v\n", err) + } + + if err = extraFiles(mntDir); err != nil { + log.Fatalf("failed to add extra files to the image: %v\n", err) + } + + if err := detachLoopDevice(mntDir); err != nil { + log.Fatalf("failed to umount %s: %v\n", mntDir, err) + } + + if err := resizeImage(*outFile); err != nil { + log.Fatalf("failed to resize the image %s: %s\n", *outFile, err) + } +} + +func extract(ctx context.Context, client *containerd.Client, image containerd.Image, mntDir string) error { + manifest, err := images.Manifest(ctx, client.ContentStore(), image.Target(), platform) + if err != nil { + log.Fatalf("failed to get the manifest: %v\n", err) + } + + for _, desc := range manifest.Layers { + log.Printf("extracting layer %s\n", desc.Digest.String()) + layer, err := client.ContentStore().ReaderAt(ctx, desc) + if err != nil { + return err + } + if err := archive.Untar(content.NewReader(layer), mntDir, &archive.TarOptions{NoLchown: true}); err != nil { + return err + } + } + + return nil +} + +func createLoopDevice(rawFile, mntDir string) error { + f, err := renameio.TempFile("", rawFile) + if err != nil { + return err + } + defer f.Cleanup() + + command := exec.Command("fallocate", "-l", "2G", f.Name()) + if err := command.Run(); err != nil { + return fmt.Errorf("fallocate error: %s", err) + } + + command = exec.Command("mkfs.ext4", "-F", f.Name()) + if err := command.Run(); err != nil { + return fmt.Errorf("mkfs.ext4 error: %s", err) + } + + f.CloseAtomicallyReplace() + + command = exec.Command("mount", "-o", "loop", rawFile, mntDir) + if err := command.Run(); err != nil { + return fmt.Errorf("mount error: %s", err) + } + log.Printf("mounted %s on %s\n", rawFile, mntDir) + return nil +} + +func detachLoopDevice(mntDir string) error { + log.Printf("umount %s\n", mntDir) + command := exec.Command("umount", mntDir) + return command.Run() +} + +func resizeImage(rawFile string) error { + // let's bring the image to a more reasonable size. We do this by + // first running e2fsck on the image then we can resize the image. + command := exec.Command("/usr/bin/e2fsck", "-p", "-f", rawFile) + if err := command.Run(); err != nil { + return fmt.Errorf("e2fsck error: %s", err) + } + + command = exec.Command("resize2fs", "-M", rawFile) + if err := command.Run(); err != nil { + return fmt.Errorf("resize2fs error: %s", err) + } + return nil +} + +func extraFiles(mntDir string) error { + if err := writeToFile(filepath.Join(mntDir, "etc", "hosts"), "127.0.0.1\tlocalhost\n"); err != nil { + return err + } + if err := writeToFile(filepath.Join(mntDir, "etc", "resolv.conf"), "nameserver 192.168.0.1\n"); err != nil { + return err + } + return nil +} + +func writeToFile(filepath string, content string) error { + if err := ioutil.WriteFile(filepath, []byte(content), 0644); err != nil { + return fmt.Errorf("writeToFile %s: %v", filepath, err) + } + return nil } diff --git a/go.mod b/go.mod index f4d6398..b033d54 100644 --- a/go.mod +++ b/go.mod @@ -9,9 +9,12 @@ require ( github.com/containerd/continuity v0.0.0-20210315143101-93e15499afd5 // indirect github.com/containerd/fifo v0.0.0-20210331061852-650e8a8a179d // indirect github.com/containerd/typeurl v1.0.2 // indirect + github.com/docker/docker v20.10.6+incompatible github.com/gogo/googleapis v1.4.1 // indirect github.com/google/go-cmp v0.5.5 // indirect + github.com/google/renameio v0.1.0 github.com/google/uuid v1.2.0 // indirect + github.com/moby/sys/mount v0.2.0 // indirect github.com/opencontainers/image-spec v1.0.1 github.com/sirupsen/logrus v1.8.1 // indirect golang.org/x/net v0.0.0-20210410081132-afb366fc7cd1 // indirect diff --git a/go.sum b/go.sum index e25329d..1d54d89 100644 --- a/go.sum +++ b/go.sum @@ -199,11 +199,14 @@ github.com/dnaeon/go-vcr v1.0.1/go.mod h1:aBB1+wY4s93YsC3HHjMBMrwTj2R9FHDzUr9KyG github.com/docker/distribution v0.0.0-20190905152932-14b96e55d84c/go.mod h1:0+TTO4EOBfRPhZXAeF1Vu+W3hHZ8eLp8PgKVZlcvtFY= github.com/docker/distribution v2.7.1-0.20190205005809-0d3efadf0154+incompatible/go.mod h1:J2gT2udsDAN96Uj4KfcMRqY0/ypR+oyYUYmja8H+y+w= github.com/docker/distribution v2.7.1+incompatible/go.mod h1:J2gT2udsDAN96Uj4KfcMRqY0/ypR+oyYUYmja8H+y+w= +github.com/docker/docker v20.10.6+incompatible h1:oXI3Vas8TI8Eu/EjH4srKHJBVqraSzJybhxY7Om9faQ= +github.com/docker/docker v20.10.6+incompatible/go.mod h1:eEKB0N0r5NX/I1kEveEz05bcu8tLC/8azJZsviup8Sk= github.com/docker/go-events v0.0.0-20170721190031-9461782956ad/go.mod h1:Uw6UezgYA44ePAFQYUehOuCzmy5zmg/+nl2ZfMWGkpA= github.com/docker/go-events v0.0.0-20190806004212-e31b211e4f1c h1:+pKlWGMw7gf6bQ+oDZB4KHQFypsfjYlq/C4rfL7D3g8= github.com/docker/go-events v0.0.0-20190806004212-e31b211e4f1c/go.mod h1:Uw6UezgYA44ePAFQYUehOuCzmy5zmg/+nl2ZfMWGkpA= github.com/docker/go-metrics v0.0.0-20180209012529-399ea8c73916/go.mod h1:/u0gXw0Gay3ceNrsHubL3BtdOL2fHf93USgMTe0W5dI= github.com/docker/go-metrics v0.0.1/go.mod h1:cG1hvH2utMXtqgqqYE9plW6lDxS3/5ayHzueweSI3Vw= +github.com/docker/go-units v0.4.0 h1:3uh0PgVws3nIA0Q+MwDC8yjEPf9zjRfZZWXZYDct3Tw= github.com/docker/go-units v0.4.0/go.mod h1:fgPhTUdO+D/Jk86RDLlptpiXQzgHJF7gydDDbaIK4Dk= github.com/docker/libtrust v0.0.0-20150114040149-fa567046d9b1/go.mod h1:cyGadeNEkKy96OOhEzfZl+yxihPEzKnqJwvfuSUqbZE= github.com/docker/spdystream v0.0.0-20160310174837-449fdfce4d96/go.mod h1:Qh8CwZgvJUkLughtfhJv5dyTYa91l1fOUCrgjqmcifM= @@ -307,6 +310,7 @@ github.com/google/pprof v0.0.0-20190515194954-54271f7e092f/go.mod h1:zfwlbNMJ+OI github.com/google/pprof v0.0.0-20191218002539-d4f498aebedc/go.mod h1:ZgVRPoUq/hfqzAqh7sHMqb3I9Rq5C59dIz2SbBwJ4eM= github.com/google/pprof v0.0.0-20200212024743-f11f1df84d12/go.mod h1:ZgVRPoUq/hfqzAqh7sHMqb3I9Rq5C59dIz2SbBwJ4eM= github.com/google/pprof v0.0.0-20200229191704-1ebb73c60ed3/go.mod h1:ZgVRPoUq/hfqzAqh7sHMqb3I9Rq5C59dIz2SbBwJ4eM= +github.com/google/renameio v0.1.0 h1:GOZbcHa3HfsPKPlmyPyN2KEohoMXOhdMbHrvbpl2QaA= github.com/google/renameio v0.1.0/go.mod h1:KWCgfxg9yswjAJkECMjeO8J8rahYeXnNhOm40UhjYkI= github.com/google/uuid v1.0.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo= github.com/google/uuid v1.1.1/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo= @@ -384,6 +388,8 @@ github.com/mistifyio/go-zfs v2.1.2-0.20190413222219-f784269be439+incompatible/go github.com/mitchellh/go-homedir v1.1.0/go.mod h1:SfyaCUpYCn1Vlf4IUYiD9fPX4A5wJrkLzIz1N1q0pr0= github.com/mitchellh/mapstructure v1.1.2/go.mod h1:FVVH3fgwuzCH5S8UJGiWEs2h04kUh9fWfEaFds41c1Y= github.com/mitchellh/osext v0.0.0-20151018003038-5e2d6d41470f/go.mod h1:OkQIRizQZAeMln+1tSwduZz7+Af5oFlKirV/MSYes2A= +github.com/moby/sys/mount v0.2.0 h1:WhCW5B355jtxndN5ovugJlMFJawbUODuW8fSnEH6SSM= +github.com/moby/sys/mount v0.2.0/go.mod h1:aAivFE2LB3W4bACsUXChRHQ0qKWsetY4Y9V7sxOougM= github.com/moby/sys/mountinfo v0.4.0/go.mod h1:rEr8tzG/lsIZHBtN/JjGG+LMYx9eXgW2JI+6q0qou+A= github.com/moby/sys/mountinfo v0.4.1 h1:1O+1cHA1aujwEwwVMa2Xm2l+gIpUHyd3+D+d7LZh1kM= github.com/moby/sys/mountinfo v0.4.1/go.mod h1:rEr8tzG/lsIZHBtN/JjGG+LMYx9eXgW2JI+6q0qou+A= |