Docker in docker

Cargo.toml

@@ -21,6 +21,7 @@ semver = "0.9"
 toml = "0.5"
 which = { version = "3.1.0", default_features = false }
 shell-escape = "0.1.4"
+serde_json = "1.0.48"
 
 [target.'cfg(not(windows))'.dependencies]
 nix = "0.15"

README.md

@@ -123,6 +123,49 @@ RUN dpkg --add-architecture arm64 && \
 $ docker build -t my/image:tag path/to/where/the/Dockerfile/resides
 ```
 
+### Docker in Docker
+
+When running `cross` from inside a docker container, `cross` needs access to
+the hosts docker daemon itself. This is normally achieved by mounting the
+docker daemons socket `/var/run/docker.sock`. For example:
+
+```
+$ docker run -v /var/run/docker.sock:/var/run/docker.sock -v .:/project \
+  -w /project my/development-image:tag cross build --target mips64-unknown-linux-gnuabi64
+```
+
+The image running `cross` requires the rust development tools to be installed.
+
+With this setup `cross` must find and mount the correct host paths into the
+container used for cross compilation. This includes the original project directory as
+well as the root path of the parent container to give access to the rust build
+tools.
+
+To inform `cross` that it is running inside a container set `CROSS_DOCKER_IN_DOCKER=true`.
+
+A development or CI container can be created like this:
+
+```
+FROM rust:1
+
+# set CROSS_DOCKER_IN_DOCKER to inform `cross` that it is executed from within a container
+ENV CROSS_DOCKER_IN_DOCKER=true
+
+# install `cross`
+RUN cargo install cross
+
+...
+
+```
+
+**Limitations**: Finding the mount point for the containers root directory is
+currently only available for the overlayfs2 storage driver. In order to access
+the parent containers rust setup, the child container mounts the parents
+overlayfs. The parent must not be stopped before the child container, as the
+overlayfs can not be unmounted correctly by Docker if the child container still
+accesses it.
+
+
 ### Passing environment variables into the build environment
 
 By default, `cross` does not pass any environment variables into the build

azure-pipelines.yml

@@ -79,6 +79,9 @@ jobs:
       - bash: echo "##vso[task.setvariable variable=TAG]${BUILD_SOURCEBRANCH##refs/tags/}"
         displayName: Set TAG Variable
         condition: startsWith(variables['Build.SourceBranch'], 'refs/tags/')
+      - bash: cargo test 
+        displayName: Run unit tests
+        timeoutInMinutes: 5
       - bash: ./build-docker-image.sh "${TARGET}"
         displayName: Build Docker Image
         timeoutInMinutes: 360

src/cli.rs

@@ -1,14 +1,16 @@
+use std::str::FromStr;
 use std::{env, path::PathBuf};
 
-use crate::Target;
 use crate::cargo::Subcommand;
 use crate::rustc::TargetList;
+use crate::Target;
 
 pub struct Args {
     pub all: Vec<String>,
     pub subcommand: Option<Subcommand>,
     pub target: Option<Target>,
     pub target_dir: Option<PathBuf>,
+    pub docker_in_docker: bool,
 }
 
 pub fn parse(target_list: &TargetList) -> Args {
@@ -27,7 +29,10 @@ pub fn parse(target_list: &TargetList) -> Args {
                     all.push(t);
                 }
             } else if arg.starts_with("--target=") {
-                target = arg.splitn(2, '=').nth(1).map(|s| Target::from(&*s, target_list));
+                target = arg
+                    .splitn(2, '=')
+                    .nth(1)
+                    .map(|s| Target::from(&*s, target_list));
                 all.push(arg);
             } else if arg == "--target-dir" {
                 all.push(arg);
@@ -41,19 +46,24 @@ pub fn parse(target_list: &TargetList) -> Args {
                     all.push(format!("--target-dir=/target"));
                 }
             } else {
-              if !arg.starts_with('-') && sc.is_none() {
-                  sc = Some(Subcommand::from(arg.as_ref()));
-              }
+                if !arg.starts_with('-') && sc.is_none() {
+                    sc = Some(Subcommand::from(arg.as_ref()));
+                }
 
-              all.push(arg.to_string());
+                all.push(arg.to_string());
             }
         }
     }
 
+    let docker_in_docker = env::var("CROSS_DOCKER_IN_DOCKER")
+        .map(|s| bool::from_str(&s).unwrap_or_default())
+        .unwrap_or_default();
+
     Args {
         all,
         subcommand: sc,
         target,
         target_dir,
+        docker_in_docker,
     }
 }