Fix unsupported protocol schema "" errors with docker image tags provider

go.mod

@@ -1,6 +1,6 @@
 module github.com/variantdev/mod
 
-go 1.17
+go 1.25.3
 
 require (
 	github.com/Masterminds/semver v1.5.0
@@ -15,7 +15,6 @@ require (
 	github.com/hashicorp/go-cleanhttp v0.5.1 // indirect
 	github.com/hashicorp/go-getter v1.4.1
 	github.com/hashicorp/hcl/v2 v2.3.0
-	github.com/heroku/docker-registry-client v0.0.0-20190909225348-afc9e1acc3d5
 	github.com/iancoleman/strcase v0.0.0-20190422225806-e506e3ef7365 // indirect
 	github.com/imdario/mergo v0.3.8 // indirect
 	github.com/k-kinzal/aliases v0.5.1
@@ -42,8 +41,6 @@ require (
 	github.com/apparentlymart/go-textseg v1.0.0 // indirect
 	github.com/aws/aws-sdk-go v1.15.78 // indirect
 	github.com/bgentry/go-netrc v0.0.0-20140422174119-9fd32a8b3d3d // indirect
-	github.com/docker/distribution v0.0.0-20171011171712-7484e51bf6af // indirect
-	github.com/docker/libtrust v0.0.0-20160708172513-aabc10ec26b7 // indirect
 	github.com/fatih/color v1.7.0 // indirect
 	github.com/go-playground/locales v0.12.1 // indirect
 	github.com/go-playground/universal-translator v0.16.0 // indirect
@@ -58,7 +55,6 @@ require (
 	github.com/huandu/xstrings v1.3.0 // indirect
 	github.com/inconshreveable/mousetrap v1.0.0 // indirect
 	github.com/jmespath/go-jmespath v0.0.0-20160202185014-0b12d6b521d8 // indirect
-	github.com/konsorten/go-windows-terminal-sequences v1.0.1 // indirect
 	github.com/leodido/go-urn v1.1.0 // indirect
 	github.com/mattn/go-colorable v0.0.9 // indirect
 	github.com/mattn/go-isatty v0.0.4 // indirect
@@ -67,9 +63,8 @@ require (
 	github.com/mitchellh/go-testing-interface v1.0.0 // indirect
 	github.com/mitchellh/go-wordwrap v0.0.0-20150314170334-ad45545899c7 // indirect
 	github.com/mitchellh/reflectwalk v1.0.0 // indirect
-	github.com/opencontainers/go-digest v1.0.0-rc1 // indirect
 	github.com/pkg/errors v0.8.1 // indirect
-	github.com/sirupsen/logrus v1.4.2 // indirect
+	github.com/stretchr/testify v1.4.0 // indirect
 	github.com/ulikunitz/xz v0.5.5 // indirect
 	go.opencensus.io v0.22.0 // indirect
 	golang.org/x/crypto v0.0.0-20190605123033-f99c8df09eb5 // indirect

pkg/dockerregistry/client.go

@@ -0,0 +1,187 @@
+// Package dockerregistry provides a minimal Docker Registry API v2 client.
+//
+// This package exists because the heroku/docker-registry-client library is
+// broken when interacting with Docker Hub. Docker Hub now returns relative URL
+// paths in pagination Link headers instead of full URLs. This causes the
+// heroku library to fail with "unsupported protocol schema """ when fetching
+// tags that span multiple pages, because the request URL for the second page
+// lacks the protocol and host part (since the next link is relative).
+//
+// This client properly handles relative URLs by resolving them against the
+// base registry URL.
+//
+// Some code in this package is derived from heroku/docker-registry-client:
+// https://github.com/heroku/docker-registry-client
+// See transport.go for specific attributions.
+package dockerregistry
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"net/http"
+	"net/url"
+	"regexp"
+)
+
+var (
+	// ErrNoMorePages is returned when there are no more pages to fetch.
+	ErrNoMorePages = errors.New("no more pages")
+)
+
+// Client handles Docker Registry API v2 requests.
+type Client struct {
+	baseURL  *url.URL
+	username string
+	password string
+	client   *http.Client
+}
+
+// Option is a functional option for configuring the Client.
+type Option func(*Client)
+
+// WithHTTPClient sets a custom HTTP client for the registry client.
+// This is useful for testing or when custom transport settings are needed.
+func WithHTTPClient(client *http.Client) Option {
+	return func(c *Client) {
+		c.client = client
+	}
+}
+
+// New creates a new registry client for the given base URL.
+// If username and password are non-empty, they will be used for token authentication.
+func New(baseURL, username, password string, opts ...Option) (*Client, error) {
+	u, err := url.Parse(baseURL)
+	if err != nil {
+		return nil, fmt.Errorf("invalid base URL: %w", err)
+	}
+	c := &Client{
+		baseURL:  u,
+		username: username,
+		password: password,
+		client:   nil, // will be set below or by options
+	}
+	for _, opt := range opts {
+		opt(c)
+	}
+
+	// Wrap the transport with token auth support
+	if c.client == nil {
+		c.client = &http.Client{
+			Transport: WrapTransport(http.DefaultTransport, username, password),
+		}
+	} else {
+		// Wrap the custom client's transport with token auth
+		transport := c.client.Transport
+		if transport == nil {
+			transport = http.DefaultTransport
+		}
+		c.client = &http.Client{
+			Transport: WrapTransport(transport, username, password),
+		}
+	}
+	return c, nil
+}
+
+type tagsResponse struct {
+	Tags []string `json:"tags"`
+}
+
+// Tags fetches all tags for a repository, handling pagination.
+func (c *Client) Tags(repository string) ([]string, error) {
+	u := c.url("/v2/%s/tags/list", repository)
+
+	var tags []string
+	for {
+		var response tagsResponse
+		nextURL, err := c.getPaginatedJSON(u, &response)
+		switch err {
+		case ErrNoMorePages:
+			tags = append(tags, response.Tags...)
+			return tags, nil
+		case nil:
+			tags = append(tags, response.Tags...)
+			u = nextURL
+			continue
+		default:
+			return nil, err
+		}
+	}
+}
+
+// url constructs a full URL from the base URL and the given path format.
+func (c *Client) url(pathFormat string, args ...interface{}) string {
+	path := fmt.Sprintf(pathFormat, args...)
+	u := *c.baseURL
+	u.Path = path
+	return u.String()
+}
+
+// getPaginatedJSON fetches a URL and decodes the JSON response into the given
+// interface. It returns the next page URL if present in the Link header,
+// or ErrNoMorePages if there are no more pages.
+func (c *Client) getPaginatedJSON(urlStr string, response interface{}) (string, error) {
+	req, err := http.NewRequest(http.MethodGet, urlStr, nil)
+	if err != nil {
+		return "", err
+	}
+
+	resp, err := c.client.Do(req)
+	if err != nil {
+		return "", err
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		return "", fmt.Errorf("unexpected status code: %d", resp.StatusCode)
+	}
+
+	decoder := json.NewDecoder(resp.Body)
+	if err := decoder.Decode(response); err != nil {
+		return "", err
+	}
+
+	return c.getNextLink(resp, urlStr)
+}
+
+// nextLinkRE matches an RFC 5988 (https://tools.ietf.org/html/rfc5988#section-5)
+// Link header. For example,
+//
+//	<http://registry.example.com/v2/_catalog?n=5&last=tag5>; type="application/json"; rel="next"
+//
+// The URL is _supposed_ to be wrapped by angle brackets `< ... >`,
+// but e.g., quay.io does not include them. Similarly, params like
+// `rel="next"` may not have quoted values in the wild.
+//
+// Derived from: https://github.com/heroku/docker-registry-client/blob/master/registry/json.go
+var nextLinkRE = regexp.MustCompile(`^ *<?([^;>]+)>? *(?:;[^;]*)*; *rel="?next"?(?:;.*)?`)
+
+// getNextLink extracts the next page URL from the Link header.
+// It handles both absolute and relative URLs by resolving against the current request URL.
+func (c *Client) getNextLink(resp *http.Response, currentURL string) (string, error) {
+	for _, link := range resp.Header[http.CanonicalHeaderKey("Link")] {
+		parts := nextLinkRE.FindStringSubmatch(link)
+		if parts != nil {
+			nextURL := parts[1]
+
+			// Parse the next URL to check if it's relative or absolute
+			parsedNext, err := url.Parse(nextURL)
+			if err != nil {
+				return "", fmt.Errorf("invalid next link URL: %w", err)
+			}
+
+			// If the URL is relative (no scheme), resolve it against the current URL
+			if parsedNext.Scheme == "" {
+				parsedCurrent, err := url.Parse(currentURL)
+				if err != nil {
+					return "", fmt.Errorf("invalid current URL: %w", err)
+				}
+				resolved := parsedCurrent.ResolveReference(parsedNext)
+				return resolved.String(), nil
+			}
+
+			return nextURL, nil
+		}
+	}
+	return "", ErrNoMorePages
+}