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# Podman CLI
The following is an example of how to add a new primary command (`manifest`) and a sub-command (`inspect`) to the Podman CLI.
This is example code, the production code has additional error checking and the business logic provided.
See items below for details on building, installing, contributing to Podman:
- [Readme](README.md)
- [Contributing](CONTRIBUTING.md)
- [Podman Usage](transfer.md)
- [Trouble Shooting](troubleshooting.md)
- [Code Of Conduct](CODE-OF-CONDUCT.md)
## Adding a new command `podman manifest`
```shell script
$ mkdir -p $GOPATH/src/github.com/containers/podman/cmd/podmanV2/manifests
```
Create the file ```$GOPATH/src/github.com/containers/podman/cmd/podmanV2/manifests/manifest.go```
```go
package manifests
import (
"github.com/containers/podman/cmd/podman/registry"
"github.com/containers/podman/cmd/podman/validate"
"github.com/containers/podman/pkg/domain/entities"
"github.com/spf13/cobra"
)
var (
// podman _manifests_
manifestCmd = &cobra.Command{
Use: "manifest",
Short: "Manage manifests",
Args: cobra.ExactArgs(1),
Long: "Manage manifests",
Example: "podman manifest IMAGE",
TraverseChildren: true,
RunE: validate.SubCommandExists, // Report error if there is no sub command given
}
)
func init() {
// Subscribe command to podman
registry.Commands = append(registry.Commands, registry.CliCommand{
Command: manifestCmd,
})
}
```
To "wire" in the `manifest` command, edit the file ```$GOPATH/src/github.com/containers/podman/cmd/podmanV2/main.go``` to add:
```go
package main
import _ "github.com/containers/podman/cmd/podman/manifests"
```
## Adding a new sub command `podman manifests list`
Create the file ```$GOPATH/src/github.com/containers/podman/cmd/podmanV2/manifests/inspect.go```
```go
package manifests
import (
"github.com/containers/podman/cmd/podman/registry"
"github.com/containers/podman/pkg/domain/entities"
"github.com/spf13/cobra"
)
var (
// podman manifests _inspect_
inspectCmd = &cobra.Command{
Use: "inspect IMAGE",
Short: "Display manifest from image",
Long: "Displays the low-level information on a manifest identified by image name or ID",
RunE: inspect,
Annotations: map[string]string{
// Add this annotation if this command cannot be run rootless
// registry.ParentNSRequired: "",
},
Example: "podman manifest inspect DEADBEEF",
}
)
func init() {
// Subscribe inspect sub command to manifest command
registry.Commands = append(registry.Commands, registry.CliCommand{
Command: inspectCmd,
// The parent command to proceed this command on the CLI
Parent: manifestCmd,
})
// This is where you would configure the cobra flags using inspectCmd.Flags()
}
// Business logic: cmd is inspectCmd, args is the positional arguments from os.Args
func inspect(cmd *cobra.Command, args []string) error {
// Business logic using registry.ImageEngine()
// Do not pull from libpod directly use the domain objects and types
return nil
}
```
## Helper functions
The complete set can be found in the `validate` package, here are some examples:
- `cobra.Command{ Args: validate.NoArgs }` used when the command does not accept errors
- `cobra.Command{ Args: validate.IdOrLatestArgs }` used to ensure either a list of ids given or the --latest flag
- `cobra.Command{ RunE: validate.SubCommandExists }` used to validate a subcommand given to a command
- `validate.ChoiceValue` used to create a `pflag.Value` that validate user input against a provided slice of values. For example:
```go
flags := cobraCommand.Flags()
created := validate.ChoiceValue(&opts.Sort, "command", "created", "id", "image", "names", "runningfor", "size", "status")
flags.Var(created, "sort", "Sort output by: "+created.Choices())
```
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