start of work to add DOCKER_HOST environment

this seems to be the basic to add support for a custom docker host as
an envar or command line option. Some questions I have:
1. how/where to test
2. should the default value be set to something instead of empty string?

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

CHANGELOG.md

@@ -21,6 +21,7 @@
   specified instance, running within a cgroup.
 - Add `--sparse` flag to `overlay create` command to allow generation of a
   sparse ext3 overlay image.
+- Support for `DOCKER_HOST` parsing when using `docker-daemon://`
 
 ### Bug Fixes
 

cmd/internal/cli/action_flags.go

@@ -861,6 +861,7 @@ func init() {
 		cmdManager.RegisterFlagForCmd(&commonNoHTTPSFlag, actionsInstanceCmd...)
 		cmdManager.RegisterFlagForCmd(&commonOldNoHTTPSFlag, actionsInstanceCmd...)
 		cmdManager.RegisterFlagForCmd(&dockerLoginFlag, actionsInstanceCmd...)
+		cmdManager.RegisterFlagForCmd(&dockerHostFlag, actionsInstanceCmd...)
 		cmdManager.RegisterFlagForCmd(&dockerPasswordFlag, actionsInstanceCmd...)
 		cmdManager.RegisterFlagForCmd(&dockerUsernameFlag, actionsInstanceCmd...)
 		cmdManager.RegisterFlagForCmd(&actionEnvFlag, actionsInstanceCmd...)

cmd/internal/cli/build.go

@@ -300,6 +300,7 @@ func init() {
 		cmdManager.RegisterFlagForCmd(&commonNoHTTPSFlag, buildCmd)
 		cmdManager.RegisterFlagForCmd(&commonTmpDirFlag, buildCmd)
 
+		cmdManager.RegisterFlagForCmd(&dockerHostFlag, buildCmd)
 		cmdManager.RegisterFlagForCmd(&dockerUsernameFlag, buildCmd)
 		cmdManager.RegisterFlagForCmd(&dockerPasswordFlag, buildCmd)
 		cmdManager.RegisterFlagForCmd(&dockerLoginFlag, buildCmd)

cmd/internal/cli/pull.go

@@ -141,6 +141,7 @@ func init() {
 		cmdManager.RegisterFlagForCmd(&pullDisableCacheFlag, PullCmd)
 		cmdManager.RegisterFlagForCmd(&pullDirFlag, PullCmd)
 
+		cmdManager.RegisterFlagForCmd(&dockerHostFlag, PullCmd)
 		cmdManager.RegisterFlagForCmd(&dockerUsernameFlag, PullCmd)
 		cmdManager.RegisterFlagForCmd(&dockerPasswordFlag, PullCmd)
 		cmdManager.RegisterFlagForCmd(&dockerLoginFlag, PullCmd)

cmd/internal/cli/push.go

@@ -69,6 +69,7 @@ func init() {
 		cmdManager.RegisterFlagForCmd(&pushAllowUnsignedFlag, PushCmd)
 		cmdManager.RegisterFlagForCmd(&pushDescriptionFlag, PushCmd)
 
+		cmdManager.RegisterFlagForCmd(&dockerHostFlag, PushCmd)
 		cmdManager.RegisterFlagForCmd(&dockerUsernameFlag, PushCmd)
 		cmdManager.RegisterFlagForCmd(&dockerPasswordFlag, PushCmd)
 	})

cmd/internal/cli/singularity.go

@@ -50,6 +50,7 @@ var currentRemoteEndpoint *endpoint.Config
 var (
 	dockerAuthConfig ocitypes.DockerAuthConfig
 	dockerLogin      bool
+	dockerHost       string
 
 	encryptionPEMPath   string
 	promptForPassphrase bool
@@ -154,6 +155,16 @@ var dockerLoginFlag = cmdline.Flag{
 	EnvKeys:      []string{"DOCKER_LOGIN"},
 }
 
+// --docker-host
+var dockerHostFlag = cmdline.Flag{
+	ID:           "dockerHostFlag",
+	Value:        &dockerHost,
+	DefaultValue: "",
+	Name:         "docker-host",
+	Usage:        "specify a custom Docker daemon host",
+	EnvKeys:      []string{"DOCKER_HOST"},
+}
+
 // --passphrase
 var commonPromptForPassphraseFlag = cmdline.Flag{
 	ID:           "commonPromptForPassphraseFlag",

internal/pkg/build/sources/conveyorPacker_oci.go

@@ -144,11 +144,13 @@ func (cp *OCIConveyorPacker) Get(ctx context.Context, b *sytypes.Bundle) (err er
 	cp.sysCtx = &types.SystemContext{
 		OCIInsecureSkipTLSVerify: cp.b.Opts.NoHTTPS,
 		DockerAuthConfig:         cp.b.Opts.DockerAuthConfig,
+		DockerDaemonHost:         cp.b.Opts.DockerDaemonHost,
 		OSChoice:                 "linux",
 		AuthFilePath:             syfs.DockerConf(),
 		DockerRegistryUserAgent:  useragent.Value(),
 		BigFilesTemporaryDir:     b.TmpDir,
 	}
+
 	if cp.b.Opts.NoHTTPS {
 		cp.sysCtx.DockerInsecureSkipTLSVerify = types.NewOptionalBool(true)
 	}

pkg/build/types/bundle.go

@@ -49,6 +49,8 @@ type Options struct {
 	KeyServerOpts []scskeyclient.Option
 	// contains docker credentials if specified.
 	DockerAuthConfig *ocitypes.DockerAuthConfig
+	// Custom docker Daemon host
+	DockerDaemonHost string
 	// EncryptionKeyInfo specifies the key used for filesystem
 	// encryption if applicable.
 	// A nil value indicates encryption should not occur.