Merge #1032

1032: Allow disabling buildkit for engines lacking support. r=Emilgardis a=Alexhuszagh



Co-authored-by: Alex Huszagh <ahuszagh@gmail.com>

Author: bors[bot]

.changes/1032.json

@@ -0,0 +1,4 @@
+{
+    "description": "allow disabling buildkit for container engines lacking buildkit support.",
+    "type": "added"
+}

src/config.rs

@@ -186,6 +186,8 @@ fn split_to_cloned_by_ws(string: &str) -> Vec<String> {
     string.split_whitespace().map(String::from).collect()
 }
 
+/// this takes the value of the environment variable,
+/// so you should call `bool_from_envvar(env::var("FOO"))`
 pub fn bool_from_envvar(envvar: &str) -> bool {
     if let Ok(value) = bool::from_str(envvar) {
         value

src/docker/custom.rs

@@ -71,8 +71,11 @@ impl<'a> Dockerfile<'a> {
         msg_info: &mut MessageInfo,
     ) -> Result<String> {
         let uses_zig = options.cargo_variant.uses_zig();
-        let mut docker_build = docker::subcommand(&options.engine, "buildx");
-        docker_build.arg("build");
+        let mut docker_build = docker::command(&options.engine);
+        match docker::Engine::has_buildkit() {
+            true => docker_build.args(["buildx", "build"]),
+            false => docker_build.arg("build"),
+        };
         docker_build.env("DOCKER_SCAN_SUGGEST", "false");
         self.runs_with()
             .specify_platform(&options.engine, &mut docker_build);

src/docker/engine.rs

@@ -108,6 +108,13 @@ impl Engine {
             .map(|s| bool_from_envvar(&s))
             .unwrap_or_default()
     }
+
+    #[must_use]
+    pub fn has_buildkit() -> bool {
+        !env::var("CROSS_CONTAINER_ENGINE_NO_BUILDKIT")
+            .map(|x| bool_from_envvar(&x))
+            .unwrap_or_default()
+    }
 }
 
 // determine if the container engine is docker. this fixes issues with

xtask/src/build_docker_image.rs

@@ -176,7 +176,11 @@ pub fn build_docker_image(
             msg_info.note(format_args!("Build {target} for {}", platform.target))?;
         }
         let mut docker_build = docker::command(engine);
-        docker_build.args(["buildx", "build"]);
+        let has_buildkit = docker::Engine::has_buildkit();
+        match has_buildkit {
+            true => docker_build.args(["buildx", "build"]),
+            false => docker_build.arg("build"),
+        };
         docker_build.current_dir(&docker_root);
 
         docker_build.args(["--platform", &platform.docker_platform()]);
@@ -185,7 +189,7 @@ pub fn build_docker_image(
             docker_build.arg("--push");
         } else if engine.kind.is_docker() && no_output {
             docker_build.args(["--output", "type=tar,dest=/dev/null"]);
-        } else {
+        } else if has_buildkit {
             docker_build.arg("--load");
         }