Support specifying images using sha256 digests

[boazberman]

You can run docker images by specifying the sha256 digest of the designated image instead of using a specific version.

Using sha256 is somewhat more secure as it pins the exact image, thus not allowing possible overriding of a tag by a malicious actor.

Usage can be something along:

impl Image for SomeImage {
    type Args = ();

    fn name(&self) -> String {
        "some name"
    }

    fn sha256(&self) -> String {
       "a826cb8a6a0023..."
    }
}

[boazberman]

I intend on implementing it (as this can be useful for us), and it will be nice if the project can take part of the current hacktoberfest. Thanks!

[thomaseizinger]

I am liking this idea. It would be well in line with the "Reliable" principle in our upcoming "Design principles" draft: #420

We would probably have to make it an Option.

I intend on implementing it (as this can be useful for us), and it will be nice if the project can take part of the current hacktoberfest. Thanks!

I am sorry for getting back to you too late for this to make any sense.

[boazberman]

I am liking this idea. It would be well in line with the "Reliable" principle in our upcoming "Design principles" draft: #420

We would probably have to make it an Option.

I intend on implementing it (as this can be useful for us), and it will be nice if the project can take part of the current hacktoberfest. Thanks!

I am sorry for getting back to you too late for this to make any sense.

Cool, just now saw your comment, will try to implement that tomorrow!

[boazberman]

I had created a PR: #446