Add support for tcp:// DOCKER_HOST

The Docker daemon that I am using is running remotely, and I connect to
it via Tailscale tunnel, which means that my DOCKER_HOST is set to
tcp://100.113.182.91:2375

This change makes Dagger work with my setup. It's been running well for
me for a few weeks now, this started as https://github.com/thechangelog/changelog.com/pull/395

I think there is an opportunity to add support for ssh:// & file://,
but I am keeping this first addition small on purpose.

Signed-off-by: Gerhard Lazu <gerhard@lazu.co.uk>
Signed-off-by: Sam Alba <samalba@users.noreply.github.com>

stdlib/docker/command.cue

@@ -30,6 +30,10 @@ import (
 		keyPassphrase?: dagger.#Secret @dagger(input)
 	}
 
+	// Connect via DOCKER_HOST, supports tcp://
+	// TODO: Consider refactoring to support ssh:// & even file://
+	host?: string @dagger(input)
+
 	// Command to execute
 	command: string
 
@@ -203,6 +207,9 @@ import (
 						FINGERPRINT: ssh.fingerprint
 					}
 				}
+				if host != _|_ && ssh == _|_ {
+					DOCKER_HOST: host
+				}
 			}
 			"mount": {
 				if ssh != _|_ {

stdlib/docker/docker.cue

@@ -124,6 +124,10 @@ import (
 		keyPassphrase?: dagger.#Input & {dagger.#Secret}
 	}
 
+	// Connect via DOCKER_HOST, supports tcp://
+	// TODO: Consider refactoring to support ssh:// & even file://
+	host?: string @dagger(input)
+
 	// Mount local docker socket
 	socket?: dagger.#Stream & dagger.#Input
 
@@ -146,6 +150,9 @@ import (
 		if ssh != _|_ {
 			"ssh": ssh
 		}
+		if host != _|_ && ssh == _|_ {
+			"host": host
+		}
 		if socket != _|_ {
 			"socket": socket
 		}
@@ -194,6 +201,10 @@ import (
 		keyPassphrase?: dagger.#Input & {dagger.#Secret}
 	}
 
+	// Connect via DOCKER_HOST, supports tcp://
+	// TODO: Consider refactoring to support ssh:// & even file://
+	host?: string @dagger(input)
+
 	// Mount local docker socket
 	socket?: dagger.#Stream & dagger.#Input
 
@@ -246,6 +257,9 @@ import (
 		if ssh != _|_ {
 			"ssh": ssh
 		}
+		if host != _|_ && ssh == _|_ {
+			"host": host
+		}
 		if socket != _|_ {
 			"socket": socket
 		}

stdlib/docker/tests/command-host/command.cue

@@ -0,0 +1,17 @@
+package docker
+
+import (
+	"alpha.dagger.io/dagger"
+)
+
+TestConfig: {
+	host: string @dagger(input)
+}
+
+TestHost: client: #Command & {
+	command: #"""
+			docker $CMD
+		"""#
+	host: TestConfig.host
+	env: CMD: "version"
+}

stdlib/docker/tests/run-host/simple.cue

@@ -0,0 +1,22 @@
+package docker
+
+import (
+	"alpha.dagger.io/dagger"
+	"alpha.dagger.io/random"
+)
+
+TestConfig: {
+	host: string @dagger(input)
+}
+
+TestHost: {
+	suffix: random.#String & {
+		seed: ""
+	}
+
+	run: #Run & {
+		name: "daggerci-test-ssh-\(suffix.out)"
+		ref:  "hello-world"
+		host: TestConfig.host
+	}
+}