move rootfs to its own package
This commit is contained in:
parent
ce445b19b7
commit
3279b52973
10
BUILD
10
BUILD
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@ -2,13 +2,13 @@ load("@io_bazel_rules_go//go:def.bzl", "go_binary", "go_library")
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go_library(
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name = "undocker_lib",
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srcs = [
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"main.go",
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"rootfs.go",
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],
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srcs = ["main.go"],
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importpath = "github.com/motiejus/code/undocker",
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visibility = ["//visibility:private"],
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deps = ["@com_github_jessevdk_go_flags//:go-flags"],
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deps = [
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"//src/undocker/rootfs:rootfs_lib",
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"@com_github_jessevdk_go_flags//:go-flags",
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],
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)
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go_binary(
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28
main.go
28
main.go
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@ -1,9 +1,11 @@
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package main
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import (
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"errors"
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"os"
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goflags "github.com/jessevdk/go-flags"
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"github.com/motiejus/code/undocker/rootfs"
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)
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type (
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@ -31,3 +33,29 @@ func run(args []string) error {
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return nil
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}
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type cmdRootFS struct {
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PositionalArgs struct {
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Infile goflags.Filename `long:"infile" description:"Input tarball"`
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Outfile string `long:"outfile" description:"Output tarball (flattened file system)"`
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} `positional-args:"yes" required:"yes"`
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}
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func (r *cmdRootFS) Execute(args []string) error {
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if len(args) != 0 {
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return errors.New("too many args")
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}
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in, err := os.Open(string(r.PositionalArgs.Infile))
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if err != nil {
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return err
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}
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defer in.Close()
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out, err := os.Create(string(r.PositionalArgs.Outfile))
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if err != nil {
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return err
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}
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defer out.Close()
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return rootfs.Rootfs(in, out)
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}
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@ -0,0 +1,8 @@
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load("@io_bazel_rules_go//go:def.bzl", "go_library")
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go_library(
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name = "rootfs_lib",
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srcs = ["rootfs.go"],
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importpath = "github.com/motiejus/code/undocker/rootfs",
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visibility = ["//visibility:public"],
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)
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@ -1,53 +1,23 @@
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package main
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package rootfs
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import (
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"archive/tar"
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"encoding/json"
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"errors"
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"fmt"
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"io"
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"os"
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"strings"
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goflags "github.com/jessevdk/go-flags"
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)
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type cmdRootFS struct {
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PositionalArgs struct {
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Infile goflags.Filename `long:"infile" description:"Input tarball"`
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Outfile string `long:"outfile" description:"Output tarball (flattened file system)"`
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} `positional-args:"yes" required:"yes"`
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}
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const (
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_manifestJSON = "manifest.json"
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)
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func (r *cmdRootFS) Execute(args []string) error {
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if len(args) != 0 {
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return errors.New("too many args")
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}
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in, err := os.Open(string(r.PositionalArgs.Infile))
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if err != nil {
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return err
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}
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defer in.Close()
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out, err := os.Create(string(r.PositionalArgs.Outfile))
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if err != nil {
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return err
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}
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defer out.Close()
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return r.rootfs(in, out)
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}
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type dockerManifestJSON []struct {
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Config string `json:"Config"`
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Layers []string `json:"Layers"`
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}
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// rootfs accepts a docker layer tarball and writes it to outfile.
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// Rootfs accepts a docker layer tarball and writes it to outfile.
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// 1. create map[string]io.ReadSeeker for each layer.
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// 2. parse manifest.json and get the layer order.
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// 3. go through each layer in order and write:
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@ -56,7 +26,7 @@ type dockerManifestJSON []struct {
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// I) layer name
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// II) offset (0 being the first file in the layer)
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// 4. go through
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func (r *cmdRootFS) rootfs(in io.ReadSeeker, out io.Writer) error {
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func Rootfs(in io.ReadSeeker, out io.Writer) error {
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tr := tar.NewReader(in)
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tw := tar.NewWriter(out)
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// layerOffsets maps a layer name (a9b123c0daa/layer.tar) to it's offset
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@ -88,7 +58,6 @@ func (r *cmdRootFS) rootfs(in io.ReadSeeker, out io.Writer) error {
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return fmt.Errorf("seek: %w", err)
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}
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layerOffsets[hdr.Name] = here
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//fmt.Printf("%s\t%x\n", hdr.Name, here)
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}
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}
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