podmanV2: implement pull

Implement pulling images for the v2 client.  What I _really_ don't like
is the fact that we are now having a near identical code clone among
`pkg/domain/infra/abi` and `pkg/api/handlers/libpod`.  Partly because we
don't yet have a higher-level pull function and partly because we have
redudancy among `pkg/domain` and `pkg/api`.  Pull might be a high
outlier but I am concerned already by the potential of introducing more
redundancy.  I'd love to `infra/abi` and `pkg/abi` to really use the
same code in the future.

Signed-off-by: Valentin Rothberg <rothberg@redhat.com>

1 files changed, 140 insertions, 0 deletions

diff --git a/cmd/podmanV2/images/pull.go b/cmd/podmanV2/images/pull.go
new file mode 100644
index 000000000..c7e325409
--- /dev/null
+++ b/cmd/podmanV2/images/pull.go
@@ -0,0 +1,140 @@
+package images
+
+import (
+	"fmt"
+
+	buildahcli "github.com/containers/buildah/pkg/cli"
+	"github.com/containers/image/v5/types"
+	"github.com/containers/libpod/cmd/podmanV2/registry"
+	"github.com/containers/libpod/pkg/domain/entities"
+	"github.com/opentracing/opentracing-go"
+	"github.com/pkg/errors"
+	"github.com/spf13/cobra"
+	"github.com/spf13/pflag"
+)
+
+// pullOptionsWrapper wraps entities.ImagePullOptions and prevents leaking
+// CLI-only fields into the API types.
+type pullOptionsWrapper struct {
+	entities.ImagePullOptions
+	TLSVerifyCLI bool // CLI only
+}
+
+var (
+	pullOptions     = pullOptionsWrapper{}
+	pullDescription = `Pulls an image from a registry and stores it locally.
+
+  An image can be pulled by tag or digest. If a tag is not specified, the image with the 'latest' tag is pulled.`
+
+	// Command: podman pull
+	pullCmd = &cobra.Command{
+		Use:     "pull [flags] IMAGE",
+		Short:   "Pull an image from a registry",
+		Long:    pullDescription,
+		PreRunE: preRunE,
+		RunE:    imagePull,
+		Example: `podman pull imageName
+  podman pull fedora:latest`,
+	}
+
+	// Command: podman image pull
+	// It's basically a clone of `pullCmd` with the exception of being a
+	// child of the images command.
+	imagesPullCmd = &cobra.Command{
+		Use:     pullCmd.Use,
+		Short:   pullCmd.Short,
+		Long:    pullCmd.Long,
+		PreRunE: pullCmd.PreRunE,
+		RunE:    pullCmd.RunE,
+		Example: `podman image pull imageName
+  podman image pull fedora:latest`,
+	}
+)
+
+func init() {
+	// pull
+	registry.Commands = append(registry.Commands, registry.CliCommand{
+		Mode:    []entities.EngineMode{entities.ABIMode, entities.TunnelMode},
+		Command: pullCmd,
+	})
+
+	pullCmd.SetHelpTemplate(registry.HelpTemplate())
+	pullCmd.SetUsageTemplate(registry.UsageTemplate())
+
+	flags := pullCmd.Flags()
+	pullFlags(flags)
+
+	// images pull
+	registry.Commands = append(registry.Commands, registry.CliCommand{
+		Mode:    []entities.EngineMode{entities.ABIMode, entities.TunnelMode},
+		Command: imagesPullCmd,
+		Parent:  imageCmd,
+	})
+
+	imagesPullCmd.SetHelpTemplate(registry.HelpTemplate())
+	imagesPullCmd.SetUsageTemplate(registry.UsageTemplate())
+	imagesPullFlags := imagesPullCmd.Flags()
+	pullFlags(imagesPullFlags)
+}
+
+// pullFlags set the flags for the pull command.
+func pullFlags(flags *pflag.FlagSet) {
+	flags.BoolVar(&pullOptions.AllTags, "all-tags", false, "All tagged images in the repository will be pulled")
+	flags.StringVar(&pullOptions.Authfile, "authfile", buildahcli.GetDefaultAuthFile(), "Path of the authentication file. Use REGISTRY_AUTH_FILE environment variable to override")
+	flags.StringVar(&pullOptions.CertDir, "cert-dir", "", "`Pathname` of a directory containing TLS certificates and keys")
+	flags.StringVar(&pullOptions.Credentials, "creds", "", "`Credentials` (USERNAME:PASSWORD) to use for authenticating to a registry")
+	flags.StringVar(&pullOptions.OverrideArch, "override-arch", "", "Use `ARCH` instead of the architecture of the machine for choosing images")
+	flags.StringVar(&pullOptions.OverrideOS, "override-os", "", "Use `OS` instead of the running OS for choosing images")
+	flags.BoolVarP(&pullOptions.Quiet, "quiet", "q", false, "Suppress output information when pulling images")
+	flags.StringVar(&pullOptions.SignaturePolicy, "signature-policy", "", "`Pathname` of signature policy file (not usually used)")
+	flags.BoolVar(&pullOptions.TLSVerifyCLI, "tls-verify", true, "Require HTTPS and verify certificates when contacting registries")
+
+	if registry.IsRemote() {
+		_ = flags.MarkHidden("authfile")
+		_ = flags.MarkHidden("cert-dir")
+		_ = flags.MarkHidden("signature-policy")
+		_ = flags.MarkHidden("tls-verify")
+	}
+}
+
+// imagePull is implement the command for pulling images.
+func imagePull(cmd *cobra.Command, args []string) error {
+	// Sanity check input.
+	if len(args) == 0 {
+		return errors.Errorf("an image name must be specified")
+	}
+	if len(args) > 1 {
+		return errors.Errorf("too many arguments. Requires exactly 1")
+	}
+
+	// Start tracing if requested.
+	if cmd.Flags().Changed("trace") {
+		span, _ := opentracing.StartSpanFromContext(registry.GetContext(), "pullCmd")
+		defer span.Finish()
+	}
+
+	pullOptsAPI := pullOptions.ImagePullOptions
+	// TLS verification in c/image is controlled via a `types.OptionalBool`
+	// which allows for distinguishing among set-true, set-false, unspecified
+	// which is important to implement a sane way of dealing with defaults of
+	// boolean CLI flags.
+	if cmd.Flags().Changed("tls-verify") {
+		pullOptsAPI.TLSVerify = types.NewOptionalBool(pullOptions.TLSVerifyCLI)
+	}
+
+	// Let's do all the remaining Yoga in the API to prevent us from
+	// scattering logic across (too) many parts of the code.
+	pullReport, err := registry.ImageEngine().Pull(registry.GetContext(), args[0], pullOptsAPI)
+	if err != nil {
+		return err
+	}
+
+	if len(pullReport.Images) > 1 {
+		fmt.Println("Pulled Images:")
+	}
+	for _, img := range pullReport.Images {
+		fmt.Println(img)
+	}
+
+	return nil
+}