containers: add a standard container for running cargo fmt

The "cargo fmt" code style checking tool is something we wish to run on all
Rust code, so it is useful to have a common container that can be used by
all relevant projects.

Reviewed-by: Andrea Bolognani <abologna@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>

3 files changed, 52 insertions, 0 deletions

diff --git a/containers/cargo-fmt/Dockerfile b/containers/cargo-fmt/Dockerfile
new file mode 100644
index 0000000..66621eb
--- /dev/null
+++ b/containers/cargo-fmt/Dockerfile
@@ -0,0 +1,10 @@
+FROM rust:1.43
+
+RUN export DEBIAN_FRONTEND=noninteractive && \
+    apt-get update && \
+    apt-get install --no-install-recommends -y \
+            diffstat && \
+    apt-get autoclean -y && \
+    rustup component add rustfmt
+
+COPY cargo-fmt.sh /cargo-fmt
diff --git a/containers/cargo-fmt/README.rst b/containers/cargo-fmt/README.rst
new file mode 100644
index 0000000..00f50a2
--- /dev/null
+++ b/containers/cargo-fmt/README.rst
@@ -0,0 +1,20 @@
+================================================
+Container for running cargo fmt code style check
+================================================
+
+This container provides a simple way to invoke ``cargo fmt`` to validate code
+style across a Rust codebase. It should be integrated into CI by adding
+the following snippet to ``.gitlab-ci.yml``
+
+::
+
+   cargo-fmt:
+     stage: prebuild
+     image: registry.gitlab.com/libvirt/libvirt-ci/cargo-fmt:master
+     script:
+       - /cargo-fmt
+     artifacts:
+       paths:
+         - cargo-fmt.patch
+       expire_in: 1 week
+       when: on_failure
diff --git a/containers/cargo-fmt/cargo-fmt.sh b/containers/cargo-fmt/cargo-fmt.sh
new file mode 100755
index 0000000..53fb0df
--- /dev/null
+++ b/containers/cargo-fmt/cargo-fmt.sh
@@ -0,0 +1,22 @@
+#!/bin/sh
+
+cargo fmt -v -- --check > cargo-fmt.patch
+
+if test -s cargo-fmt.patch
+then
+    echo
+    echo "❌ ERROR: some files failed cargo fmt code style check"
+    echo
+    diffstat cargo-fmt.patch
+    echo
+    echo "See the cargo-fmt patch artifact for full details of mistakes."
+    echo
+    echo "For guidance on how to configure Emacs or Vim to automatically"
+    echo "run cargo fmt when saving files read"
+    echo
+    echo "     https://github.com/rust-lang/rustfmt"
+    echo
+    exit 1
+fi
+
+echo "✔ OK: all files passed cargo fmt code style check"