umoci new: include host ARM variant by default

We generally need to specify the variant of the architecture if we are
running on ARM. Rather than reimplementing /proc/cpuinfo parsing, just
use containerd's platform parser since that is the standard thing used
by most container tools.

Signed-off-by: Aleksa Sarai <[email protected]>

Author: cyphar

CHANGELOG.md

@@ -66,6 +66,8 @@ update to move away from our ancient pinned version of the runtime-spec.
 * `umoci config` now supports specifying the architecture variant of the image
   with `--platform.variant`. In addition, `--os` and `--architecture` can now
   be set using `--platform.os` and `--platform.arch` respectively.
+* `umoci new` will not automatically fill the architecture variant on ARM
+  systems to match the host CPU.
 
 ### Changed ###
 * The output format of `umoci stat` has had some minor changes made to how

go.mod

@@ -23,6 +23,7 @@ require (
 	github.com/AdaLogics/go-fuzz-headers v0.0.0-20230106234847-43070de90fa1
 	github.com/apex/log v1.9.0
 	github.com/blang/semver/v4 v4.0.0
+	github.com/containerd/platforms v0.2.1
 	github.com/cyphar/filepath-securejoin v0.5.0
 	github.com/docker/go-units v0.5.0
 	github.com/klauspost/compress v1.11.3
@@ -42,6 +43,7 @@ require (
 )
 
 require (
+	github.com/containerd/log v0.1.0 // indirect
 	github.com/cpuguy83/go-md2man/v2 v2.0.7 // indirect
 	github.com/davecgh/go-spew v1.1.1 // indirect
 	github.com/fatih/color v1.18.0 // indirect

go.sum

@@ -10,6 +10,10 @@ github.com/aws/aws-sdk-go v1.20.6/go.mod h1:KmX6BPdI08NWTb3/sm4ZGu5ShLoqVDhKgpiN
 github.com/aybabtme/rgbterm v0.0.0-20170906152045-cc83f3b3ce59/go.mod h1:q/89r3U2H7sSsE2t6Kca0lfwTK8JdoNGS/yzM/4iH5I=
 github.com/blang/semver/v4 v4.0.0 h1:1PFHFE6yCCTv8C1TeyNNarDzntLi7wMI5i/pzqYIsAM=
 github.com/blang/semver/v4 v4.0.0/go.mod h1:IbckMUScFkM3pff0VJDNKRiT6TG/YpiHIM2yvyW5YoQ=
+github.com/containerd/log v0.1.0 h1:TCJt7ioM2cr/tfR8GPbGf9/VRAX8D2B4PjzCpfX540I=
+github.com/containerd/log v0.1.0/go.mod h1:VRRf09a7mHDIRezVKTRCrOq78v577GXq3bSa3EhrzVo=
+github.com/containerd/platforms v0.2.1 h1:zvwtM3rz2YHPQsF2CHYM8+KtB5dvhISiXh5ZpSBQv6A=
+github.com/containerd/platforms v0.2.1/go.mod h1:XHCb+2/hzowdiut9rkudds9bE5yJ7npe7dG/wG+uFPw=
 github.com/cpuguy83/go-md2man/v2 v2.0.2/go.mod h1:tgQtvFlXSQOSOSIRvRPT7W67SCa46tRHOmNcaadrF8o=
 github.com/cpuguy83/go-md2man/v2 v2.0.7 h1:zbFlGlXEAKlwXpmvle3d8Oe3YnkKIK4xSRTd3sHPnBo=
 github.com/cpuguy83/go-md2man/v2 v2.0.7/go.mod h1:oOW0eioCTA6cOiMLiUPZOpcVxMig6NIQQ7OS05n1F4g=

new.go

@@ -21,10 +21,10 @@ package umoci
 import (
 	"context"
 	"fmt"
-	"runtime"
 	"time"
 
 	"github.com/apex/log"
+	"github.com/containerd/platforms"
 	imeta "github.com/opencontainers/image-spec/specs-go"
 	ispec "github.com/opencontainers/image-spec/specs-go/v1"
 
@@ -46,13 +46,14 @@ func NewImage(engineExt casext.Engine, tagName string, sourceDateEpoch *time.Tim
 		createTime = *sourceDateEpoch
 	}
 
-	// Set all of the defaults we need.
 	g.SetCreated(createTime)
-	g.SetPlatformOS(runtime.GOOS)
-	g.SetPlatformArchitecture(runtime.GOARCH)
-	// TODO: Set the arm variant, if applicable.
 	g.ClearHistory()
 
+	hostPlatform := platforms.DefaultSpec()
+	g.SetPlatformOS(hostPlatform.OS)
+	g.SetPlatformArchitecture(hostPlatform.Architecture)
+	g.SetPlatformVariant(hostPlatform.Variant)
+
 	// Make sure we have no diffids.
 	g.SetRootfsType("layers")
 	g.ClearRootfsDiffIDs()