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Refactor platforms.Only with a "platformVector" helper

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This improves the hard-coded list of ARM fallbacks in the `platform.Only` implementation (by doing a descending loop over variant numbers instead, which is all the hard-coded list was doing).

Making this a separate function can then more easily be recursive later for handling an `arm64`->`arm` fallback (or similar), but I think it makes the code a lot more clear too (so we're calculating a vector of platforms separately from building a matcher object).

This also makes a minor adjustment in `TestImagePullWithDistSourceLabel` which had an implicit assumption that `platforms.Only` would only ever result in a single suitable manifest, which isn't strictly true (and is likely failing as-is when run on any 32bit `arm` system that's `v6` or higher, which this fixes 😅).

Signed-off-by: Tianon Gravi <admwiggin@gmail.com>
This commit is contained in:
Tianon Gravi 2020-12-28 14:07:55 -08:00
parent 7a2720f5e0
commit 9072b09145
2 changed files with 34 additions and 103 deletions
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2
image_test.go
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@ -113,7 +113,7 @@ func TestImagePullWithDistSourceLabel(t *testing.T) {
key := fmt.Sprintf("containerd.io/distribution.source.%s", source)
// only check the target platform
childrenHandler := images.FilterPlatforms(images.ChildrenHandler(cs), pMatcher)
childrenHandler := images.LimitManifests(images.ChildrenHandler(cs), pMatcher, 1)
checkLabelHandler := func(ctx context.Context, desc ocispec.Descriptor) ([]ocispec.Descriptor, error) {
children, err := childrenHandler(ctx, desc)

135
platforms/compare.go
View File

@ -16,7 +16,12 @@
package platforms
import specs "github.com/opencontainers/image-spec/specs-go/v1"
import (
"strconv"
"strings"
specs "github.com/opencontainers/image-spec/specs-go/v1"
)
// MatchComparer is able to match and compare platforms to
// filter and sort platforms.
@ -26,103 +31,37 @@ type MatchComparer interface {
Less(specs.Platform, specs.Platform) bool
}
// Only returns a match comparer for a single platform
// using default resolution logic for the platform.
//
// For ARMv8, will also match ARMv7, ARMv6 and ARMv5 (for 32bit runtimes)
// For ARMv7, will also match ARMv6 and ARMv5
// For ARMv6, will also match ARMv5
func Only(platform specs.Platform) MatchComparer {
platform = Normalize(platform)
if platform.Architecture == "arm" {
if platform.Variant == "v8" {
return orderedPlatformComparer{
matchers: []Matcher{
&matcher{
Platform: platform,
},
&matcher{
Platform: specs.Platform{
Architecture: platform.Architecture,
OS: platform.OS,
OSVersion: platform.OSVersion,
OSFeatures: platform.OSFeatures,
Variant: "v7",
},
},
&matcher{
Platform: specs.Platform{
Architecture: platform.Architecture,
OS: platform.OS,
OSVersion: platform.OSVersion,
OSFeatures: platform.OSFeatures,
Variant: "v6",
},
},
&matcher{
Platform: specs.Platform{
Architecture: platform.Architecture,
OS: platform.OS,
OSVersion: platform.OSVersion,
OSFeatures: platform.OSFeatures,
Variant: "v5",
},
},
},
}
}
if platform.Variant == "v7" {
return orderedPlatformComparer{
matchers: []Matcher{
&matcher{
Platform: platform,
},
&matcher{
Platform: specs.Platform{
Architecture: platform.Architecture,
OS: platform.OS,
OSVersion: platform.OSVersion,
OSFeatures: platform.OSFeatures,
Variant: "v6",
},
},
&matcher{
Platform: specs.Platform{
Architecture: platform.Architecture,
OS: platform.OS,
OSVersion: platform.OSVersion,
OSFeatures: platform.OSFeatures,
Variant: "v5",
},
},
},
}
}
if platform.Variant == "v6" {
return orderedPlatformComparer{
matchers: []Matcher{
&matcher{
Platform: platform,
},
&matcher{
Platform: specs.Platform{
Architecture: platform.Architecture,
OS: platform.OS,
OSVersion: platform.OSVersion,
OSFeatures: platform.OSFeatures,
Variant: "v5",
},
},
},
// platformVector returns an (ordered) vector of appropriate specs.Platform
// objects to try matching for the given platform object (see platforms.Only).
func platformVector(platform specs.Platform) []specs.Platform {
vector := []specs.Platform{platform}
switch platform.Architecture {
case "arm":
if armVersion, err := strconv.Atoi(strings.TrimPrefix(platform.Variant, "v")); err == nil && armVersion > 5 {
for armVersion--; armVersion >= 5; armVersion-- {
vector = append(vector, specs.Platform{
Architecture: platform.Architecture,
OS: platform.OS,
OSVersion: platform.OSVersion,
OSFeatures: platform.OSFeatures,
Variant: "v" + strconv.Itoa(armVersion),
})
}
}
}
return singlePlatformComparer{
Matcher: &matcher{
Platform: platform,
},
}
return vector
}
// Only returns a match comparer for a single platform
// using default resolution logic for the platform.
//
// For arm/v8, will also match arm/v7, arm/v6 and arm/v5
// For arm/v7, will also match arm/v6 and arm/v5
// For arm/v6, will also match arm/v5
func Only(platform specs.Platform) MatchComparer {
return Ordered(platformVector(Normalize(platform))...)
}
// Ordered returns a platform MatchComparer which matches any of the platforms
@ -153,14 +92,6 @@ func Any(platforms ...specs.Platform) MatchComparer {
// with preference for ordering.
var All MatchComparer = allPlatformComparer{}
type singlePlatformComparer struct {
Matcher
}
func (c singlePlatformComparer) Less(p1, p2 specs.Platform) bool {
return c.Match(p1) && !c.Match(p2)
}
type orderedPlatformComparer struct {
matchers []Matcher
}