first shot at adding ability to use docker dist api to get image conf…

…ig (#47)

* first shot at adding ability to use docker dist api to get image config

Signed-off-by: vsoch <vsoch@users.noreply.github.com>

* missing file

Signed-off-by: vsoch <vsoch@users.noreply.github.com>

* finishing up looking up containers in cache

Signed-off-by: vsoch <vsoch@users.noreply.github.com>

Co-authored-by: vsoch <vsoch@users.noreply.github.com>

cli/dockerbuild.go

@@ -13,8 +13,9 @@ type DockerBuildArgs struct {
 }
 
 type DockerBuildFlags struct {
-	Changes bool   `long:"changes" desc:"Only consider changed uptodate files"`
-	Branch  string `long:"branch" desc:"Branch to compare HEAD against, defaults to main"`
+	Registry string `long:"registry" desc:"A registry is required to look up changes from previous builds."`
+	Changes  bool   `long:"changes" desc:"Only consider changed uptodate files"`
+	Branch   string `long:"branch" desc:"Branch to compare HEAD against, defaults to main"`
 }
 
 // Dockerfile updates one or more Dockerfile
@@ -52,6 +53,6 @@ func RunDockerBuild(r *cmd.Root, c *cmd.Sub) {
 
 	// Update the dockerfiles with a Dockerfile parser
 	parser := docker.DockerBuildParser{}
-	parser.Parse(args.Root[0], flags.Changes, flags.Branch)
+	parser.Parse(args.Root[0], flags.Changes, flags.Branch, flags.Registry)
 
 }

docs/docs/user-guide/user-guide.md

@@ -407,9 +407,17 @@ And to only include changed uptodate.yaml files:
 ```bash
 $ uptodate dockerbuild --changes
 ```
+And finally, if you want the most functionality (not just to look for changes to files but
+also check previous images and rebuild those that have detailed changes in build args) then you
+need to provide uptodate with the registry that the images are intended for (and this also
+assumes you use the build names that are generated).
 
-We could add support for changed associated Dockerfile too - please [open an issue](https://github.com/vsoch/uptodate/issues)
-is this is interesting to you.
+```bash
+$ uptodate dockerbuild --registry ghcr.io/rse-radiuss
+```
+
+Note that the registry flag is enough to indicate that you want to look for changes of
+this type.
 
 ### Git
 

parsers/common.go

@@ -88,7 +88,12 @@ func GetVersions(contenders []string, filters []string, startAtVersion string, e
 
 	// Do we have semantic versions? If so, this is the better sort
 	if HasSemanticVersions(contenders) {
-		contenders = SortVersions(contenders)
+		newContenders := SortVersions(contenders)
+
+		// But only use if it doesn't remove everything!
+		if len(newContenders) > 0 {
+			contenders = newContenders
+		}
 	}
 
 	// We look for tags based on filters (this is an OR between them)