fix: Add support for entrypoint and command (#122)

* fix: Add support for entrypoint and command

https://www.docker.com/blog/docker-best-practices-choosing-between-run-cmd-and-entrypoint/

https://docs.podman.io/en/v5.0.1/markdown/podman-run.1.html#entrypoint-command-command-arg1

Podman is happy to take in a list for entrypoint, whereas Docker only wants the executable, with the rest being held within cmd.

---------

Co-authored-by: Sitansh Rajput <me@lostpolaris>

Author: lostpolaris

compose.go

@@ -495,7 +495,21 @@ func (g *Generator) buildNixContainer(service types.ServiceConfig, networkMap ma
 		c.Command = service.Command
 	}
 	if entrypoint := service.Entrypoint; !entrypoint.IsZero() {
-		c.ExtraOptions = append(c.ExtraOptions, fmt.Sprintf("--entrypoint=%s", sliceToStringArray(entrypoint)))
+		// Docker's --entrypoint takes a single executable
+		// Any extra argv after the executable belongs to CMD, so we prepend
+		// it to the container's command, matching compose semantics.
+		if g.Runtime == ContainerRuntimeDocker {
+			if len(entrypoint) == 0 {
+				c.ExtraOptions = append(c.ExtraOptions, "--entrypoint=")
+			} else {
+				c.ExtraOptions = append(c.ExtraOptions, "--entrypoint="+entrypoint[0])
+				if len(entrypoint) > 1 {
+					c.Command = slices.Concat(entrypoint[1:], c.Command)
+				}
+			}
+		} else if g.Runtime == ContainerRuntimePodman {
+			c.ExtraOptions = append(c.ExtraOptions, fmt.Sprintf("--entrypoint=%s", sliceToStringArray(entrypoint)))
+		}
 	}
 
 	// Figure out explicit dependencies for this container.

testdata/TestCommandAndEntrypoint.docker.nix

@@ -13,11 +13,11 @@
   # Containers
   virtualisation.oci-containers.containers."test-both" = {
     image = "nginx:latest";
-    cmd = [ "ls" "-la" "\"escape me please\"" ];
+    cmd = [ "-g" "daemon off;" "-c" "/etc/config/nginx/conf/nginx.conf" "ls" "-la" "\"escape me please\"" ];
     log-driver = "journald";
     autoStart = false;
     extraOptions = [
-      "--entrypoint=[\"nginx\", \"-g\", \"daemon off;\", \"-c\", \"/etc/config/nginx/conf/nginx.conf\"]"
+      "--entrypoint=nginx"
       "--network-alias=both"
       "--network=test_default"
     ];
@@ -39,7 +39,7 @@
     log-driver = "journald";
     autoStart = false;
     extraOptions = [
-      "--entrypoint=[]"
+      "--entrypoint="
       "--network-alias=empty-command-and-entrypoint"
       "--network=test_default"
     ];
@@ -77,10 +77,11 @@
   };
   virtualisation.oci-containers.containers."test-string" = {
     image = "nginx:latest";
+    cmd = [ "bash" "/abc.sh" ];
     log-driver = "journald";
     autoStart = false;
     extraOptions = [
-      "--entrypoint=[\"ENV_VAR=\${ABC}\", \"bash\", \"/abc.sh\"]"
+      "--entrypoint=ENV_VAR=\${ABC}"
       "--network-alias=string"
       "--network=test_default"
     ];