Honor the host specified in current docker context

Big shoutout to Rajiv Kushwaha and his contribution in lazydocker (wagoodman#464)
 from where I have taken this code.

dive/image/docker/engine_resolver.go

@@ -5,9 +5,13 @@ import (
 	"io"
 	"net/http"
 	"os"
+	"runtime"
 	"strings"
 
+	cliconfig "github.com/docker/cli/cli/config"
 	"github.com/docker/cli/cli/connhelper"
+	ddocker "github.com/docker/cli/cli/context/docker"
+	ctxstore "github.com/docker/cli/cli/context/store"
 	"github.com/docker/docker/client"
 	"golang.org/x/net/context"
 
@@ -42,6 +46,77 @@ func (r *engineResolver) Build(args []string) (*image.Image, error) {
 	return r.Fetch(id)
 }
 
+// determineDockerHost tries to determine the docker host that we should connect to
+// in the following order of decreasing precedence:
+//   - value of the "DOCKER_HOST" environment variable
+//   - host retrieved from the current context (specified via DOCKER_CONTEXT)
+//   - "default docker host" for the host operating system, otherwise
+func determineDockerHost() (string, error) {
+	// if the docker host is explicitly set via the "DOCKER_HOST" environment variable,
+	// then it's a no-brainer :shrug:
+	if host := os.Getenv("DOCKER_HOST"); len(host) > 0 {
+		return host, nil
+	}
+
+	currentContext := os.Getenv("DOCKER_CONTEXT")
+	if len(currentContext) == 0 {
+		dockerConfigDir := cliconfig.Dir()
+		if _, err := os.Stat(dockerConfigDir); err != nil {
+			return "", err
+		}
+		cf, err := cliconfig.Load(dockerConfigDir)
+		if err != nil {
+			return "", err
+		}
+		currentContext = cf.CurrentContext
+	}
+	if len(currentContext) == 0 {
+		// if a docker context is neither specified via the "DOCKER_CONTEXT" environment variable nor via the
+		// $HOME/.docker/config file, then we fall back to connecting to the "default docker host" meant for
+		// the host operating system
+		if runtime.GOOS == "windows" {
+			return "npipe:////./pipe/docker_engine", nil
+		} else {
+			return "unix:///var/run/docker.sock", nil
+		}
+	}
+
+	storeConfig := ctxstore.NewConfig(
+		func() interface{} { return &ddocker.EndpointMeta{} },
+		ctxstore.EndpointTypeGetter(ddocker.DockerEndpoint, func() interface{} { return &ddocker.EndpointMeta{} }),
+	)
+
+	st := ctxstore.New(cliconfig.ContextStoreDir(), storeConfig)
+	md, err := st.GetMetadata(currentContext)
+	if err != nil {
+		return "", err
+	}
+	dockerEP, ok := md.Endpoints[ddocker.DockerEndpoint]
+	if !ok {
+		return "", err
+	}
+	dockerEPMeta, ok := dockerEP.(ddocker.EndpointMeta)
+	if !ok {
+		return "", fmt.Errorf("expected docker.EndpointMeta, got %T", dockerEP)
+	}
+
+	if dockerEPMeta.Host != "" {
+		return dockerEPMeta.Host, nil
+	}
+
+	// we might end up here if the context was created with the `host` set to an empty value (i.e. '')
+	// for example:
+	// ```sh
+	// docker context create foo --docker "host="
+	// ```
+	// in such a scenario, we mimic the `docker` cli and try to connect to the "default docker host"
+	if runtime.GOOS == "windows" {
+		return "npipe:////./pipe/docker_engine", nil
+	} else {
+		return "unix:///var/run/docker.sock", nil
+	}
+}
+
 func (r *engineResolver) fetchArchive(id string) (io.ReadCloser, error) {
 	var err error
 	var dockerClient *client.Client
@@ -70,15 +145,21 @@ func (r *engineResolver) fetchArchive(id string) (io.ReadCloser, error) {
 		clientOpts = append(clientOpts, client.WithDialContext(helper.Dialer))
 
 	default:
+		dockerHost, err := determineDockerHost()
+		if err != nil {
+			fmt.Printf("Could not determine host %v", err)
+		}
 
 		if os.Getenv("DOCKER_TLS_VERIFY") != "" && os.Getenv("DOCKER_CERT_PATH") == "" {
 			os.Setenv("DOCKER_CERT_PATH", "~/.docker")
 		}
 
 		clientOpts = append(clientOpts, client.FromEnv)
+		clientOpts = append(clientOpts, client.WithHost(dockerHost))
 	}
 
 	clientOpts = append(clientOpts, client.WithAPIVersionNegotiation())
+
 	dockerClient, err = client.NewClientWithOpts(clientOpts...)
 	if err != nil {
 		return nil, err

go.mod

@@ -6,56 +6,64 @@ require (
 	github.com/awesome-gocui/gocui v1.1.0
 	github.com/awesome-gocui/keybinding v1.0.1-0.20190805183143-864552bd36b7
 	github.com/cespare/xxhash v1.1.0
-	github.com/docker/cli v0.0.0-20190906153656-016a3232168d
-	github.com/docker/docker v24.0.2+incompatible
-	github.com/dustin/go-humanize v1.0.0
-	github.com/fatih/color v1.7.0
-	github.com/google/uuid v1.1.1
-	github.com/logrusorgru/aurora v0.0.0-20190803045625-94edacc10f9b
+	github.com/docker/cli v24.0.7+incompatible
+	github.com/docker/docker v24.0.7+incompatible
+	github.com/dustin/go-humanize v1.0.1
+	github.com/fatih/color v1.16.0
+	github.com/google/uuid v1.5.0
+	github.com/logrusorgru/aurora v2.0.3+incompatible
 	github.com/lunixbochs/vtclean v1.0.0
 	github.com/mitchellh/go-homedir v1.1.0
 	github.com/phayes/permbits v0.0.0-20190612203442-39d7c581d2ee
 	github.com/sergi/go-diff v1.0.0
-	github.com/sirupsen/logrus v1.4.2
-	github.com/spf13/afero v1.2.2
-	github.com/spf13/cobra v0.0.5
-	github.com/spf13/viper v1.4.0
-	golang.org/x/net v0.11.0
+	github.com/sirupsen/logrus v1.9.3
+	github.com/spf13/afero v1.11.0
+	github.com/spf13/cobra v1.8.0
+	github.com/spf13/viper v1.18.2
+	golang.org/x/net v0.19.0
 )
 
 require (
-	github.com/Microsoft/go-winio v0.4.14 // indirect
-	github.com/docker/distribution v2.8.2+incompatible // indirect
+	github.com/Microsoft/go-winio v0.6.1 // indirect
+	github.com/distribution/reference v0.5.0 // indirect
+	github.com/docker/distribution v2.8.3+incompatible // indirect
+	github.com/docker/docker-credential-helpers v0.8.0 // indirect
 	github.com/docker/go-connections v0.4.0 // indirect
-	github.com/docker/go-units v0.4.0 // indirect
-	github.com/fsnotify/fsnotify v1.4.7 // indirect
+	github.com/docker/go-units v0.5.0 // indirect
+	github.com/fsnotify/fsnotify v1.7.0 // indirect
+	github.com/fvbommel/sortorder v1.1.0 // indirect
 	github.com/gdamore/encoding v1.0.0 // indirect
-	github.com/gdamore/tcell/v2 v2.4.0 // indirect
+	github.com/gdamore/tcell/v2 v2.7.0 // indirect
 	github.com/gogo/protobuf v1.3.2 // indirect
 	github.com/hashicorp/hcl v1.0.0 // indirect
-	github.com/inconshreveable/mousetrap v1.0.0 // indirect
-	github.com/konsorten/go-windows-terminal-sequences v1.0.2 // indirect
-	github.com/lucasb-eyer/go-colorful v1.0.3 // indirect
-	github.com/magiconair/properties v1.8.1 // indirect
-	github.com/mattn/go-colorable v0.1.2 // indirect
-	github.com/mattn/go-isatty v0.0.9 // indirect
-	github.com/mattn/go-runewidth v0.0.10 // indirect
-	github.com/mitchellh/mapstructure v1.1.2 // indirect
+	github.com/inconshreveable/mousetrap v1.1.0 // indirect
+	github.com/lucasb-eyer/go-colorful v1.2.0 // indirect
+	github.com/magiconair/properties v1.8.7 // indirect
+	github.com/mattn/go-colorable v0.1.13 // indirect
+	github.com/mattn/go-isatty v0.0.20 // indirect
+	github.com/mattn/go-runewidth v0.0.15 // indirect
+	github.com/mitchellh/mapstructure v1.5.0 // indirect
 	github.com/moby/term v0.5.0 // indirect
 	github.com/morikuni/aec v1.0.0 // indirect
-	github.com/opencontainers/go-digest v1.0.0-rc1 // indirect
+	github.com/opencontainers/go-digest v1.0.0 // indirect
 	github.com/opencontainers/image-spec v1.0.2 // indirect
-	github.com/pelletier/go-toml v1.4.0 // indirect
+	github.com/pelletier/go-toml/v2 v2.1.1 // indirect
 	github.com/pkg/errors v0.9.1 // indirect
-	github.com/rivo/uniseg v0.1.0 // indirect
-	github.com/spf13/cast v1.3.0 // indirect
-	github.com/spf13/jwalterweatherman v1.1.0 // indirect
+	github.com/rivo/uniseg v0.4.4 // indirect
+	github.com/sagikazarmark/locafero v0.4.0 // indirect
+	github.com/sagikazarmark/slog-shim v0.1.0 // indirect
+	github.com/sourcegraph/conc v0.3.0 // indirect
+	github.com/spf13/cast v1.6.0 // indirect
 	github.com/spf13/pflag v1.0.5 // indirect
-	github.com/stretchr/testify v1.4.0 // indirect
-	golang.org/x/sys v0.9.0 // indirect
-	golang.org/x/term v0.9.0 // indirect
-	golang.org/x/text v0.10.0 // indirect
-	gopkg.in/yaml.v2 v2.2.8 // indirect
-	gotest.tools v2.2.0+incompatible // indirect
+	github.com/subosito/gotenv v1.6.0 // indirect
+	go.uber.org/multierr v1.11.0 // indirect
+	golang.org/x/exp v0.0.0-20231219180239-dc181d75b848 // indirect
+	golang.org/x/mod v0.14.0 // indirect
+	golang.org/x/sys v0.15.0 // indirect
+	golang.org/x/term v0.15.0 // indirect
+	golang.org/x/text v0.14.0 // indirect
+	golang.org/x/tools v0.16.1 // indirect
+	gopkg.in/ini.v1 v1.67.0 // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
 	gotest.tools/v3 v3.5.0 // indirect
 )