Add env variable option for experimental

[seemethere]

Signed-off-by: Eli Uriegas eli.uriegas@docker.com

- What I did
Added an option to enable the experimental cli options with an environment variable

- How to verify it

Proof of work

~/go/src/github.com/docker/cli env_experimental eli@castlerock
❯ DOCKER_CLI_EXPERIMENTAL=enabled ./build/docker manifest

Usage:  docker manifest COMMAND

Manage Docker image manifests and manifest lists

Options:
      --orchestrator string   Orchestrator to use (swarm|kubernetes|all)

Commands:
  annotate    Add additional information to a local image manifest
  create      Create a local manifest list for annotating and pushing to a registry
  inspect     Display an image manifest, or manifest list
  push        Push a manifest list to a repository

Run 'docker manifest COMMAND --help' for more information on a command.

~/go/src/github.com/docker/cli env_experimental eli@castlerock
❯ DOCKER_CLI_EXPERIMENTAL=disabled ./build/docker manifest
docker manifest is only supported on a Docker cli with experimental cli features enabled

~/go/src/github.com/docker/cli env_experimental eli@castlerock
❯ ./build/docker manifest
docker manifest is only supported on a Docker cli with experimental cli features enabled

- Description for the changelog

* Added the option to enable experimental cli features through the `DOCKER_CLI_EXPERIMENTAL environment variable

- A picture of a cute animal (not mandatory but encouraged)

[thaJeztah]

Can you update the documentation, and add this env-var to the list in https://github.com/docker/cli/blob/master/docs/reference/commandline/cli.md#environment-variables ?

[silvin-lubecki]

So this means that DOCKER_CLI_EXPERIMENTAL=false docker manifest will be valid? Maybe we should match the configuration file values instead of just checking the existence of the environment variable?

[mat007]

This does not seem very consistent at the moment, for instance there is

func contentTrustEnabled() bool {
	if e := os.Getenv("DOCKER_CONTENT_TRUST"); e != "" {
		if t, err := strconv.ParseBool(e); t || err != nil {
			// treat any other value as true
			return true
		}
	}
	return false
}

but

func hide(cmd *cobra.Command) *cobra.Command {
	// If the environment variable with name "DOCKER_HIDE_LEGACY_COMMANDS" is not empty,
	// these legacy commands (such as `docker ps`, `docker exec`, etc)
	// will not be shown in output console.
	if os.Getenv("DOCKER_HIDE_LEGACY_COMMANDS") == "" {
		return cmd
	}
…

[silvin-lubecki]

Oh right...

[seemethere]

Yeah for it to be uniform with what the value in the config is, it would need to be either enabled or disabled. Should I change it to that?

[seemethere]

Here's what the diff would look like for that:

diff --git a/cli/command/cli.go b/cli/command/cli.go
index 37e3e10e..0597341d 100644
--- a/cli/command/cli.go
+++ b/cli/command/cli.go
@@ -182,7 +182,7 @@ func (cli *DockerCli) Initialize(opts *cliflags.ClientOptions) error {
 func isEnabled(value string) (bool, error) {
        // Environment variable always overrides configuration
        if os.Getenv("DOCKER_CLI_EXPERIMENTAL") != "" {
-               return true, nil
+               value = os.Getenv("DOCKER_CLI_EXPERIMENTAL")
        }
        switch value {
        case "enabled":

[silvin-lubecki]

Thank you for this PR @seemethere ! At first we wanted the user to explicitly enable the experimental features only by adding a value in the config file. But maybe with env var it is also explicit enough? WDYT @vdemeester ?

[silvin-lubecki]

So this means that DOCKER_CLI_EXPERIMENTAL=false docker manifest will be valid? Maybe we should match the configuration file values instead of just checking the existence of the environment variable?

[seemethere]

Updated to environment variable to only accept enabled or disabled per @silvin-lubecki's suggestion, and added a mention in the docs per @thaJeztah's suggestion.

[silvin-lubecki]

Thank you @seemethere , LGTM !

[vdemeester]

LGTM 🐸

[thaJeztah]

LGTM