validate media type of manifest descendants #341
Conversation
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On Fri, Sep 23, 2016 at 01:09:39AM -0700, xiekeyang wrote:
Descriptors can stand on their own (e.g. as ref payloads), -so-this- |
schema/config-descriptor.json
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| "properties": { | ||
| "mediaType": { | ||
| "type": "string", | ||
| "pattern": "^application/vnd[.]oci[.]image[.]config[.]v1[+]json$" |
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Ah, descriptors can point at anything in general, but this is a descriptor that points at a config file. That makes sense to me.
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On Fri, Sep 23, 2016 at 01:09:39AM -0700, xiekeyang wrote:
I don't think we can handle this in JSON Schema. With 7cb3a30 this |
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PTAL |
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On Fri, Sep 23, 2016 at 08:16:00AM -0700, W. Trevor King wrote:
#304 landed a few days ago 1, so the approach you're taking here |
I suppose that you are meaning to modify func (v Validator) Validate(src io.Reader) error {
...
if v==MediaTypeManifest{ //or switch-case here
err:=validateDescendants(src)
if err!=nil{
return err
}
}
...
}If I am right? cc @stevvooe |
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On Thu, Sep 29, 2016 at 11:25:37PM -0700, xiekeyang wrote:
I'm not convinced that the maintainer consensus is to keep more
I've mocked up a callback-based validation approach in that commit. |
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@wking |
| "mediaType": "application/vnd.docker.distribution.manifest.v2+json", | ||
| "config": { | ||
| "mediaType": "application/octet-stream", | ||
| "mediaType": "application/vnd.docker.container.image.v1+json", |
| // https://registry-1.docker.io/v2/library/docker/manifests/sha256:888206c77cd2811ec47e752ba291e5b7734e3ef137dfd222daadaca39a9f17bc | ||
| { | ||
| digest: "sha256:888206c77cd2811ec47e752ba291e5b7734e3ef137dfd222daadaca39a9f17bc", | ||
| digest: "sha256:d901d5244c94db8151415bf3a1d3a0b10e7468e4997786b01c287cbcbaeca446", |
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I don't think we want to bump this, but if we do we should probably bump the comment above or explain why the hashes are now different.
schema/schema.go
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| MediaTypeDockerImageConfig = "application/vnd.docker.container.image.v1+json" | ||
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| // MediaTypeNonDistributable specifies the non-distributable layer's mediaType. | ||
| MediaTypeNonDistributable = "application/vnd.oci.image.layer.nondistributable.v1.tar+gzip" |
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I still don't think we want to export these as part of our public API (discussion in #320).
schema/validator.go
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| return errors.Wrap(err, "unable to read the document file") | ||
| } | ||
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| if f := mapValidateDescendants[v]; f != nil { |
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I think the idiomatic way to handle this is with:
f, ok := mapValidateDescendants[v]
if ok {
…validate descendant…
}
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@wking ,
In the case of setting nil to some key, the checking by ok will have risk.
For that f is nil when ok is true, the next calling f will lead to panic.
So I think it is safe to check f is not nil.
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I'm fine panicking if somebody inserts a nil value in mapValidateDescendants. I would be happier if Go's typing was strict enough to error with cannot convert nil to type validateDescendantsFunc when they attempted the insertion, but I don't see a way to do that if the zero value for function types is nil. To be extra safe and clear, I'd recommend handling the three cases explicitly:
f, ok := mapValidateDescendents[v]
if ok {
if f == nil {
…internal error: shame on you for putting a nil value in mapValidateDescendents…
}
…validate descendants…
}
schema/validator.go
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| func init() { | ||
| mapValidateDescendants[MediaTypeManifest] = validateManifestDescendants | ||
| } |
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No need for init(), you can declare a package-level constant.
schema/validator.go
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| if layer.MediaType != string(v1.MediaTypeImageLayer) && | ||
| layer.MediaType != MediaTypeDockerImageLayer && | ||
| layer.MediaType != MediaTypeNonDistributable { | ||
| return fmt.Errorf("illegal layer mediaType: %s", layer.MediaType) |
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This is still too strong. You want to warn if the type is not an OCI type, but it's not an error.
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@wking, here I've 2 questions:
- Do you think we should emit warn for all string not equal to OCI type, even for buzz words? It seems too loose.
- Current logger have no
warnlevel. Do you agree that we importlogrushere, to print different levels log?
Thanks so much.
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On Wed, Oct 05, 2016 at 07:10:01PM -0700, xiekeyang wrote:
- Do you think we should emit warn for all string not equal to OCI type, even for buzz words? It seems too loose.
We're warning them, and they would be wise to take the warning seriously. I don't think we can do anything stronger by default; how do we know that the strange type they're using isn't handled by their tooling? But I think image-tools should have a --strict flag (for “error on any features not required in compliant unpackers”) and/or an --unpackable flag (for “error on any features I don't recognize”).
- Current logger have no
warnlevel. Do you agree that we importlogrushere, to print different levels log?
I think logging is orthogonal. These tests are the primary output of validation, so I think a validator should be printing the validation results (including warnings like this) to stdout (or some sort of writer). In my callback-based mock-up, I'm using tap.go, and in that case warnings would look like:
ok 7 # skip sha256-a… layers[2] has an unknown media type: image/png
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@wking |
schema/validator.go
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| return errors.Wrap(err, "unable to read the document file") | ||
| } | ||
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| if f, ok := mapValidateDescendants[v]; ok && f != nil { |
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There's no reason to check both ok and nil if you're silently ignoring the nil case. I think you should either skip the nil check and pacnic if someone stuck a nil value in mapValidateDescendants or explicitly check for and error out if someone stuck a nil value in mapValidateDescendants
schema/validator.go
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| } | ||
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| if header.Config.MediaType != string(v1.MediaTypeImageConfig) { | ||
| fmt.Printf("warning: config %s has a non OCI media type: %s\n", header.Config.Digest, header.Config.MediaType) |
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The problem isn't that it has a non-OCI type (application/vnd.oci.image.manifest.list.v1+json is an OCI type, and it deserves this warning). My suggested wording is:
{blobDigest} {property} has an unknown media type: {type}
That's a bit complicated with your APIs, because you take a reader and not a descriptor or digest. In my mock-up, the validator takes a digest and CAS engine, so it's easy to make messages like that. But it makes sense to want a way to validate a reader without having to inject it into a CAS engine, and for that initial reader-based validation I think the message should just be:
{blobDigest} {property} has an unknown media type: {type}
For this line here, that's:
fmt.Println("warning: config has an unknown media type: %s", header.Config.MediaType)
schema/validator.go
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| } | ||
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| for _, layer := range header.Layers { | ||
| if layer.MediaType != string(v1.MediaTypeImageLayer) { |
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These can also be MediaTypeImageLayerNonDistributable.
| type validateDescendantsFunc func(r io.Reader) error | ||
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| var mapValidateDescendants = map[Validator]validateDescendantsFunc{ | ||
| MediaTypeManifest: validateManifestDescendants, |
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This is currently just looking at the types of the descriptors. It doesn't follow those references to actually validate the descendants (e.g. “the manifest claims sha256:a… is a application/vnd.oci.image.config.v1+json. Does it validate as such?). I think we eventually want this callback-based validation to handle that, but I don't see an easy way to do it without a CAS-engine API (once you have that it is pretty easy), so I'm fine punting on that for this PR and only doing these local checks.
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@wking
At beginning I work this in image-tool project, but seems improper.
In schema package, validateManifestDescendants acting as the validator.Validate child is what I think the nice way.
Callback handler must impact on up-layer calling in image-tool project, to which I worry maintainers not fully agree.
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I agree that you wouldn't want all of recursive validation, all recursive validation code in image-spec, and CAS-engine code in image-tools. My personal preference there is to do non-recursive JSON Schema validation here and to handle recursive validation and the CAS-engine in image-tools. @stevvooe seems to prefer keeping more than just JSON Schema validation in image-spec, but @philips has moved a fair bit of stuff to image-tools, so I'm not sure there's a clear maintainer position on this yet. Once there is a clear position, it should be fairly straightforward to put this logic in the approved location.
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This code is simply validating mediatypes. It doesn't actually validate the descendent objects. This style of validation clearly belongs within the image-spec repo.
The maintainer position is clear and we have discussed on the call multiple times, without dissent.
Please stop fomenting disagreement where there is none.
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Please stop fomenting disagreement where there is none.
The maintainer position has been clear on this since the 2016-10-12 meeting. I don't think it was particular clear when I made these comments on 2016-10-05.
schema/validator.go
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| if f, ok := mapValidateDescendants[v]; ok { | ||
| if f == nil { | ||
| return fmt.Errorf("internal error: shame on you for putting a nil value in mapValidateDescendents") |
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This is taking me too literally ;). How about:
return fmt.Errorf("internal error: mapValidateDescendents[%q] is nil", v)
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Oh, the message was rough. Fix it.
Signed-off-by: xiekeyang <[email protected]>
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@opencontainers/image-spec-maintainers |
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So, the objective here is to descend into a manifest to validate the other objects, right? Are we in agreement up to this point? |
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On Thu, Oct 06, 2016 at 07:09:05AM -0700, Vincent Batts wrote:
This PR doesn't descend into children, because you can't do that
That would be nice, but currently this PR just checks to see if the
We're not validating the children yet, known media type or not. But |
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@vbatts I've tried to understand maintainers proposal, and improve this PR. Now hopefully it can be accepted. |
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@stevvooe If this is the implementation way what you want? |
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@xiekeyang This seems sufficient. It is just making sure the media types are valid. It is too bad that json schema can't do this. LGTM |
With image-tools split off into its own repository, the plan seems to
be to keep all intra-blob JSON validation in this repository and to
move all other validation (e.g. for layers or for walking Merkle
trees) in image-tools [1]. All the non-validation logic currently in
image/ is moving into image-tools as well [2].
Some requirements (e.g. multi-parameter checks like allowed OS/arch
pairs [3]) are difficult to handle in JSON Schema but easy to handle
in Go. And callers won't care if we're using JSON Schema or not; they
just want to know if their blob is valid.
This commit restructures intra-blob validation to ease the path going
forward (although it doesn't actually change the current validation
significantly). The old method:
func (v Validator) Validate(src io.Reader) error
is now a new Validator type:
type Validator(blob io.Reader, descriptor *v1.Descriptor, strict bool) (err error)
and instead of instantiating an old Validator instance:
schema.MediaTypeImageConfig.Validate(reader)
there's a Validators registry mapping from the media type strings to
the appropriate Validator instance (which may or may not use JSON
Schema under the hood). And there's a Validate function (with the
same Validator interface) that looks up the appropriate entry in
Validators for you so you have:
schema.Validate(reader, descriptor, true)
By using a Validators map, we make it easy for library consumers to
register (or override) intra-blob validators for a particular type.
Locations that call Validate(...) will automatically pick up the new
validators without needing local changes.
All of the old validation was based on JSON Schema, so currently all
Validators values are ValidateJSONSchema. As the schema package grows
non-JSON-Schema validation, entries will start to look like:
var Validators = map[string]Validator{
v1.MediaTypeImageConfig: ValidateConfig,
...
}
although ValidateConfig will probably use ValidateJSONSchema
internally.
By passing through a descriptor, we get a chance to validate the
digest and size (which we were not doing before). Digest and size
validation for a byte array are also exposed directly (as
ValidateByteDigest and ValidateByteSize) for use in validators that
are not based on ValidateJSONSchema. Access to the digest also gives
us a way to print specific error messages on failures. In situations
where you don't know the blob digest, the new DigestByte will help you
calculate it (for a byte array).
There is also a new 'strict' parameter to distinguish between
compliant images (which should only pass when strict is false) and
images that only use features which the spec requires implementations
to support (which should pass regardless of strict). The current JSON
Schemas are not strict, and I expect we'll soon gain Go code to handle
the distinction (e.g. [4]). So the presence of 'strict' in the
Validator type is future-proofing our API and not exposing a
currently-implemented feature.
I've made the minimal sane changes to cmd/ and image/, because we're
dropping them from this repository [2] (and continuing them in
runtime-tools).
[1]: http://ircbot.wl.linuxfoundation.org/meetings/opencontainers/2016/opencontainers.2016-10-12-21.01.log.html#l-71
[2]: opencontainers#337
[3]: https://tools.ietf.org/html/draft-fge-json-schema-validation-00#section-5.5.5
[4]: opencontainers#341
Signed-off-by: W. Trevor King <[email protected]>
With image-tools split off into its own repository, the plan seems to
be to keep all intra-blob JSON validation in this repository and to
move all other validation (e.g. for layers or for walking Merkle
trees) in image-tools [1]. All the non-validation logic currently in
image/ is moving into image-tools as well [2].
Some requirements (e.g. multi-parameter checks like allowed OS/arch
pairs [3]) are difficult to handle in JSON Schema but easy to handle
in Go. And callers won't care if we're using JSON Schema or not; they
just want to know if their blob is valid.
This commit restructures intra-blob validation to ease the path going
forward (although it doesn't actually change the current validation
significantly). The old method:
func (v Validator) Validate(src io.Reader) error
is now a new Validator type:
type Validator(blob io.Reader, descriptor *v1.Descriptor, strict bool) (err error)
and instead of instantiating an old Validator instance:
schema.MediaTypeImageConfig.Validate(reader)
there's a Validators registry mapping from the media type strings to
the appropriate Validator instance (which may or may not use JSON
Schema under the hood). And there's a Validate function (with the
same Validator interface) that looks up the appropriate entry in
Validators for you so you have:
schema.Validate(reader, descriptor, true)
By using a Validators map, we make it easy for library consumers to
register (or override) intra-blob validators for a particular type.
Locations that call Validate(...) will automatically pick up the new
validators without needing local changes.
All of the old validation was based on JSON Schema, so currently all
Validators values are ValidateJSONSchema. As the schema package grows
non-JSON-Schema validation, entries will start to look like:
var Validators = map[string]Validator{
v1.MediaTypeImageConfig: ValidateConfig,
...
}
although ValidateConfig will probably use ValidateJSONSchema
internally.
By passing through a descriptor, we get a chance to validate the
digest and size (which we were not doing before). Digest and size
validation for a byte array are also exposed directly (as
ValidateByteDigest and ValidateByteSize) for use in validators that
are not based on ValidateJSONSchema. Access to the digest also gives
us a way to print specific error messages on failures. In situations
where you don't know the blob digest, the new DigestByte will help you
calculate it (for a byte array).
There is also a new 'strict' parameter to distinguish between
compliant images (which should only pass when strict is false) and
images that only use features which the spec requires implementations
to support (which should pass regardless of strict). The current JSON
Schemas are not strict, and I expect we'll soon gain Go code to handle
the distinction (e.g. [4]). So the presence of 'strict' in the
Validator type is future-proofing our API and not exposing a
currently-implemented feature.
I've made the minimal sane changes to cmd/ and image/, because we're
dropping them from this repository [2] (and continuing them in
runtime-tools).
[1]: http://ircbot.wl.linuxfoundation.org/meetings/opencontainers/2016/opencontainers.2016-10-12-21.01.log.html#l-71
[2]: opencontainers#337
[3]: https://tools.ietf.org/html/draft-fge-json-schema-validation-00#section-5.5.5
[4]: opencontainers#341
Signed-off-by: W. Trevor King <[email protected]>
With image-tools split off into its own repository, the plan seems to
be to keep all intra-blob JSON validation in this repository and to
move all other validation (e.g. for layers or for walking Merkle
trees) in image-tools [1]. All the non-validation logic currently in
image/ is moving into image-tools as well [2].
Some requirements (e.g. multi-parameter checks like allowed OS/arch
pairs [3]) are difficult to handle in JSON Schema but easy to handle
in Go. And callers won't care if we're using JSON Schema or not; they
just want to know if their blob is valid.
This commit restructures intra-blob validation to ease the path going
forward (although it doesn't actually change the current validation
significantly). The old method:
func (v Validator) Validate(src io.Reader) error
is now a new Validator type:
type Validator(blob io.Reader, descriptor *v1.Descriptor, strict bool) (err error)
and instead of instantiating an old Validator instance:
schema.MediaTypeImageConfig.Validate(reader)
there's a Validators registry mapping from the media type strings to
the appropriate Validator instance (which may or may not use JSON
Schema under the hood). And there's a Validate function (with the
same Validator interface) that looks up the appropriate entry in
Validators for you so you have:
schema.Validate(reader, descriptor, true)
By using a Validators map, we make it easy for library consumers to
register (or override) intra-blob validators for a particular type.
Locations that call Validate(...) will automatically pick up the new
validators without needing local changes.
All of the old validation was based on JSON Schema, so currently all
Validators values are ValidateJSONSchema. As the schema package grows
non-JSON-Schema validation, entries will start to look like:
var Validators = map[string]Validator{
v1.MediaTypeImageConfig: ValidateConfig,
...
}
although ValidateConfig will probably use ValidateJSONSchema
internally.
By passing through a descriptor, we get a chance to validate the
digest and size (which we were not doing before). Digest and size
validation for a byte array are also exposed directly (as
ValidateByteDigest and ValidateByteSize) for use in validators that
are not based on ValidateJSONSchema. Access to the digest also gives
us a way to print specific error messages on failures. In situations
where you don't know the blob digest, the new DigestByte will help you
calculate it (for a byte array).
There is also a new 'strict' parameter to distinguish between
compliant images (which should only pass when strict is false) and
images that only use features which the spec requires implementations
to support (which should pass regardless of strict). The current JSON
Schemas are not strict, and I expect we'll soon gain Go code to handle
the distinction (e.g. [4]). So the presence of 'strict' in the
Validator type is future-proofing our API and not exposing a
currently-implemented feature.
I've made the minimal sane changes to cmd/ and image/, because we're
dropping them from this repository [2] (and continuing them in
runtime-tools).
[1]: http://ircbot.wl.linuxfoundation.org/meetings/opencontainers/2016/opencontainers.2016-10-12-21.01.log.html#l-71
[2]: opencontainers#337
[3]: https://tools.ietf.org/html/draft-fge-json-schema-validation-00#section-5.5.5
[4]: opencontainers#341
Signed-off-by: W. Trevor King <[email protected]>
With image-tools split off into its own repository, the plan seems to
be to keep all intra-blob JSON validation in this repository and to
move all other validation (e.g. for layers or for walking Merkle
trees) in image-tools [1]. All the non-validation logic currently in
image/ is moving into image-tools as well [2].
Some requirements (e.g. multi-parameter checks like allowed OS/arch
pairs [3]) are difficult to handle in JSON Schema but easy to handle
in Go. And callers won't care if we're using JSON Schema or not; they
just want to know if their blob is valid.
This commit restructures intra-blob validation to ease the path going
forward (although it doesn't actually change the current validation
significantly). The old method:
func (v Validator) Validate(src io.Reader) error
is now a new Validator type:
type Validator(blob io.Reader, descriptor *v1.Descriptor, strict bool) (err error)
and instead of instantiating an old Validator instance:
schema.MediaTypeImageConfig.Validate(reader)
there's a Validators registry mapping from the media type strings to
the appropriate Validator instance (which may or may not use JSON
Schema under the hood). And there's a Validate function (with the
same Validator interface) that looks up the appropriate entry in
Validators for you so you have:
schema.Validate(reader, descriptor, true)
By using a Validators map, we make it easy for library consumers to
register (or override) intra-blob validators for a particular type.
Locations that call Validate(...) will automatically pick up the new
validators without needing local changes.
All of the old validation was based on JSON Schema, so currently all
Validators values are ValidateJSONSchema. As the schema package grows
non-JSON-Schema validation, entries will start to look like:
var Validators = map[string]Validator{
v1.MediaTypeImageConfig: ValidateConfig,
...
}
although ValidateConfig will probably use ValidateJSONSchema
internally.
By passing through a descriptor, we get a chance to validate the
digest and size (which we were not doing before). Digest and size
validation for a byte array are also exposed directly (as
ValidateByteDigest and ValidateByteSize) for use in validators that
are not based on ValidateJSONSchema. Access to the digest also gives
us a way to print specific error messages on failures. In situations
where you don't know the blob digest, the new DigestByte will help you
calculate it (for a byte array).
There is also a new 'strict' parameter to distinguish between
compliant images (which should only pass when strict is false) and
images that only use features which the spec requires implementations
to support (which should pass regardless of strict). The current JSON
Schemas are not strict, and I expect we'll soon gain Go code to handle
the distinction (e.g. [4]). So the presence of 'strict' in the
Validator type is future-proofing our API and not exposing a
currently-implemented feature.
[1]: http://ircbot.wl.linuxfoundation.org/meetings/opencontainers/2016/opencontainers.2016-10-12-21.01.log.html#l-71
[2]: opencontainers#337
[3]: https://tools.ietf.org/html/draft-fge-json-schema-validation-00#section-5.5.5
[4]: opencontainers#341
Signed-off-by: W. Trevor King <[email protected]>
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LGTM |
With image-tools split off into its own repository, the plan seems to
be to keep all intra-blob JSON validation in this repository and to
move all other validation (e.g. for layers or for walking Merkle
trees) in image-tools [1]. All the non-validation logic currently in
image/ is moving into image-tools as well [2].
Some requirements (e.g. multi-parameter checks like allowed OS/arch
pairs [3]) are difficult to handle in JSON Schema but easy to handle
in Go. And callers won't care if we're using JSON Schema or not; they
just want to know if their blob is valid.
This commit restructures intra-blob validation to ease the path going
forward (although it doesn't actually change the current validation
significantly). The old method:
func (v Validator) Validate(src io.Reader) error
is now a new Validator type:
type Validator(blob io.Reader, descriptor *v1.Descriptor, strict bool) (err error)
and instead of instantiating an old Validator instance:
schema.MediaTypeImageConfig.Validate(reader)
there's a Validators registry mapping from the media type strings to
the appropriate Validator instance (which may or may not use JSON
Schema under the hood). And there's a Validate function (with the
same Validator interface) that looks up the appropriate entry in
Validators for you so you have:
schema.Validate(reader, descriptor, true)
By using a Validators map, we make it easy for library consumers to
register (or override) intra-blob validators for a particular type.
Locations that call Validate(...) will automatically pick up the new
validators without needing local changes.
All of the old validation was based on JSON Schema, so currently all
Validators values are ValidateJSONSchema. As the schema package grows
non-JSON-Schema validation, entries will start to look like:
var Validators = map[string]Validator{
v1.MediaTypeImageConfig: ValidateConfig,
...
}
although ValidateConfig will probably use ValidateJSONSchema
internally.
By passing through a descriptor, we get a chance to validate the
digest and size (which we were not doing before). Digest and size
validation for a byte array are also exposed directly (as
ValidateByteDigest and ValidateByteSize) for use in validators that
are not based on ValidateJSONSchema. Access to the digest also gives
us a way to print specific error messages on failures. In situations
where you don't know the blob digest, the new DigestByte will help you
calculate it (for a byte array).
There is also a new 'strict' parameter to distinguish between
compliant images (which should always pass when strict is false) and
images that only use features which the spec requires implementations
to support (which should only pass if strict is true). The current
JSON Schemas are not strict, but the config/layer media type checks in
ValidateManifest exercise this distinction.
[1]: http://ircbot.wl.linuxfoundation.org/meetings/opencontainers/2016/opencontainers.2016-10-12-21.01.log.html#l-71
[2]: opencontainers#337
[3]: https://tools.ietf.org/html/draft-fge-json-schema-validation-00#section-5.5.5
[4]: opencontainers#341
Signed-off-by: W. Trevor King <[email protected]>
With image-tools split off into its own repository, the plan seems to
be to keep all intra-blob JSON validation in this repository and to
move all other validation (e.g. for layers or for walking Merkle
trees) in image-tools [1]. All the non-validation logic currently in
image/ is moving into image-tools as well [2].
Some requirements (e.g. multi-parameter checks like allowed OS/arch
pairs [3]) are difficult to handle in JSON Schema but easy to handle
in Go. And callers won't care if we're using JSON Schema or not; they
just want to know if their blob is valid.
This commit restructures intra-blob validation to ease the path going
forward (although it doesn't actually change the current validation
significantly). The old method:
func (v Validator) Validate(src io.Reader) error
is now a new Validator type:
type Validator(blob io.Reader, descriptor *v1.Descriptor, strict bool) (err error)
and instead of instantiating an old Validator instance:
schema.MediaTypeImageConfig.Validate(reader)
there's a Validators registry mapping from the media type strings to
the appropriate Validator instance (which may or may not use JSON
Schema under the hood). And there's a Validate function (with the
same Validator interface) that looks up the appropriate entry in
Validators for you so you have:
schema.Validate(reader, descriptor, true)
By using a Validators map, we make it easy for library consumers to
register (or override) intra-blob validators for a particular type.
Locations that call Validate(...) will automatically pick up the new
validators without needing local changes.
All of the old validation was based on JSON Schema, so currently all
Validators values are ValidateJSONSchema. As the schema package grows
non-JSON-Schema validation, entries will start to look like:
var Validators = map[string]Validator{
v1.MediaTypeImageConfig: ValidateConfig,
...
}
although ValidateConfig will probably use ValidateJSONSchema
internally.
By passing through a descriptor, we get a chance to validate the
digest and size (which we were not doing before). Digest and size
validation for a byte array are also exposed directly (as
ValidateByteDigest and ValidateByteSize) for use in validators that
are not based on ValidateJSONSchema. Access to the digest also gives
us a way to print specific error messages on failures.
There is also a new 'strict' parameter to distinguish between
compliant images (which should always pass when strict is false) and
images that only use features which the spec requires implementations
to support (which should only pass if strict is true). The current
JSON Schemas are not strict, but the config/layer media type checks in
ValidateManifest exercise this distinction.
Also use go-digest for local hashing now that we're vendoring it.
[1]: http://ircbot.wl.linuxfoundation.org/meetings/opencontainers/2016/opencontainers.2016-10-12-21.01.log.html#l-71
[2]: opencontainers#337
[3]: https://tools.ietf.org/html/draft-fge-json-schema-validation-00#section-5.5.5
[4]: opencontainers#341
Signed-off-by: W. Trevor King <[email protected]>
With image-tools split off into its own repository, the plan seems to
be to keep all intra-blob JSON validation in this repository and to
move all other validation (e.g. for layers or for walking Merkle
trees) in image-tools [1]. All the non-validation logic currently in
image/ is moving into image-tools as well [2].
Some requirements (e.g. multi-parameter checks like allowed OS/arch
pairs [3]) are difficult to handle in JSON Schema but easy to handle
in Go. And callers won't care if we're using JSON Schema or not; they
just want to know if their blob is valid.
This commit restructures intra-blob validation to ease the path going
forward (although it doesn't actually change the current validation
significantly). The old method:
func (v Validator) Validate(src io.Reader) error
is now a new Validator type:
type Validator(blob io.Reader, descriptor *v1.Descriptor, strict bool) (err error)
and instead of instantiating an old Validator instance:
schema.MediaTypeImageConfig.Validate(reader)
there's a Validators registry mapping from the media type strings to
the appropriate Validator instance (which may or may not use JSON
Schema under the hood). And there's a Validate function (with the
same Validator interface) that looks up the appropriate entry in
Validators for you so you have:
schema.Validate(reader, descriptor, true)
By using a Validators map, we make it easy for library consumers to
register (or override) intra-blob validators for a particular type.
Locations that call Validate(...) will automatically pick up the new
validators without needing local changes.
All of the old validation was based on JSON Schema, so currently all
Validators values are ValidateJSONSchema. As the schema package grows
non-JSON-Schema validation, entries will start to look like:
var Validators = map[string]Validator{
v1.MediaTypeImageConfig: ValidateConfig,
...
}
although ValidateConfig will probably use ValidateJSONSchema
internally.
By passing through a descriptor, we get a chance to validate the
digest and size (which we were not doing before). Digest and size
validation for a byte array are also exposed directly (as
ValidateByteDigest and ValidateByteSize) for use in validators that
are not based on ValidateJSONSchema. Access to the digest also gives
us a way to print specific error messages on failures.
There is also a new 'strict' parameter to distinguish between
compliant images (which should always pass when strict is false) and
images that only use features which the spec requires implementations
to support (which should only pass if strict is true). The current
JSON Schemas are not strict, but the config/layer media type checks in
ValidateManifest exercise this distinction.
Also use go-digest for local hashing now that we're vendoring it.
[1]: http://ircbot.wl.linuxfoundation.org/meetings/opencontainers/2016/opencontainers.2016-10-12-21.01.log.html#l-71
[2]: opencontainers#337
[3]: https://tools.ietf.org/html/draft-fge-json-schema-validation-00#section-5.5.5
[4]: opencontainers#341
Signed-off-by: W. Trevor King <[email protected]>
4 participants
This PR is alternate of opencontainers/image-tools#10.
As we have some suggestion that descendants media type should be checked by JSON schema, I put up this PR.
JSON schema constrains config and layer fields type in manifest file. If this is acceptable, we should then update the vendor to this in #image-tools.
Signed-off-by: xiekeyang [email protected]