[cache] Rename cache copy, add single package functionality (#1943)

## Summary

Renames `devbox cache copy` to `devbox cache upload`. Also changes the
interface to use `--to` flag for cache URI. This allows easier use if
cache is provided by jetpack API.

e.g.

```
# upload project packages to jetpack provided cache
devbox cache upload

# upload installable to jetpack provided cache
devbox cache upload <installable>
```

If user wishes to specify cache URI, they can do:

```
# upload project
devbox cache upload --to 's3://mike-test-nix-cache?region=us-west-2'

# upload single installable
devbox cache upload --to 's3://mike-test-nix-cache?region=us-west-2' nixpkgs#php
```

## How was it tested?

```
devbox cache upload --to 's3://mike-test-nix-cache?region=us-west-2'
devbox cache upload --to 's3://mike-test-nix-cache?region=us-west-2' nixpkgs#php
```

Inspected cache on aws.

Author: mikeland73

internal/boxcli/cache.go

@@ -4,6 +4,7 @@
 package boxcli
 
 import (
+	"github.com/MakeNowJust/heredoc/v2"
 	"github.com/pkg/errors"
 	"github.com/spf13/cobra"
 	"go.jetpack.io/devbox/internal/devbox"
@@ -12,6 +13,7 @@ import (
 
 type cacheFlags struct {
 	pathFlag
+	to string
 }
 
 func cacheCmd() *cobra.Command {
@@ -22,25 +24,40 @@ func cacheCmd() *cobra.Command {
 		PersistentPreRunE: ensureNixInstalled,
 	}
 
-	copyCommand := &cobra.Command{
-		Use:   "copy <uri>",
-		Short: "Copies all nix packages in current project to the cache at <uri>",
-		Args:  cobra.ExactArgs(1),
+	uploadCommand := &cobra.Command{
+		Use:     "upload [installable]",
+		Aliases: []string{"copy"}, // This mimics the nix command
+		Short:   "upload specified or nix packages in current project to cache",
+		Long: heredoc.Doc(`
+			Upload specified nix installable or nix packages in current project to cache.
+			If [installable] is provided, only that installable will be uploaded. 
+			Otherwise, all packages in the project will be uploaded.
+			To upload to specific cache, use --to flag. Otherwise, a cache from 
+			the cache provider will be used, if available.
+		`),
+		Args: cobra.MaximumNArgs(1),
 		RunE: func(cmd *cobra.Command, args []string) error {
+			if len(args) > 0 {
+				return devbox.UploadInstallableToCache(
+					cmd.Context(), cmd.ErrOrStderr(), flags.to, args[0],
+				)
+			}
 			box, err := devbox.Open(&devopt.Opts{
 				Dir:    flags.path,
 				Stderr: cmd.ErrOrStderr(),
 			})
 			if err != nil {
 				return errors.WithStack(err)
 			}
-			return box.CacheCopy(cmd.Context(), args[0])
+			return box.UploadProjectToCache(cmd.Context(), flags.to)
 		},
 	}
 
-	flags.pathFlag.register(copyCommand)
+	flags.pathFlag.register(uploadCommand)
+	uploadCommand.Flags().StringVar(
+		&flags.to, "to", "", "URI of the cache to copy to")
 
-	cacheCommand.AddCommand(copyCommand)
+	cacheCommand.AddCommand(uploadCommand)
 	cacheCommand.Hidden = true
 
 	return cacheCommand

internal/devbox/cache.go

@@ -2,12 +2,16 @@ package devbox
 
 import (
 	"context"
+	"io"
 
 	"go.jetpack.io/devbox/internal/devbox/providers/nixcache"
 	"go.jetpack.io/devbox/internal/nix"
 )
 
-func (d *Devbox) CacheCopy(ctx context.Context, cacheURI string) error {
+func (d *Devbox) UploadProjectToCache(
+	ctx context.Context,
+	cacheURI string,
+) error {
 	var err error
 	cacheConfig := nixcache.NixCacheConfig{URI: cacheURI}
 	if cacheConfig.URI == "" {
@@ -23,3 +27,19 @@ func (d *Devbox) CacheCopy(ctx context.Context, cacheURI string) error {
 
 	return nix.CopyInstallableToCache(ctx, d.stderr, cacheConfig.URI, profilePath)
 }
+
+func UploadInstallableToCache(
+	ctx context.Context,
+	stderr io.Writer,
+	cacheURI, installable string,
+) error {
+	var err error
+	cacheConfig := nixcache.NixCacheConfig{URI: cacheURI}
+	if cacheConfig.URI == "" {
+		cacheConfig, err = nixcache.Get().Config(ctx)
+		if err != nil {
+			return err
+		}
+	}
+	return nix.CopyInstallableToCache(ctx, stderr, cacheConfig.URI, installable)
+}