define MSRV and check for it in CI

.cirrus.yml

@@ -224,30 +224,18 @@ meta_task:
     clone_script: &noop mkdir -p $CIRRUS_WORKING_DIR  # source not needed
     script: /usr/local/bin/entrypoint.sh
 
-ubuntu20_build_task:
-    alias: ubuntu20_build
+msrv_build_task:
+    alias: msrv_build
     depends_on:
       - "build"
     gce_instance: *standard_gce_x86_64
     container:
         cpu: 2 # Do not increase, will result in scheduling delays
         memory: "8Gb"
-        image: quay.io/libpod/ubuntu20rust
+        # When bumping the image always remember to update the README MSRV as well.
+        image: quay.io/libpod/nv-rust:1.76
     script:
-        - cargo build
-
-
-centos9_build_task:
-    alias: centos9_build
-    depends_on:
-      - "build"
-    gce_instance: *standard_gce_x86_64
-    container:
-        cpu: 2 # Do not increase, will result in scheduling delays
-        memory: "8Gb"
-        image: quay.io/libpod/centos9rust
-    script:
-        - cargo build
+        - make build
 
 
 success_task:
@@ -263,8 +251,7 @@ success_task:
     - "integration"
     - "integration_aarch64"
     - "meta"
-    - "ubuntu20_build"
-    - "centos9_build"
+    - "msrv_build"
   gce_instance: *standard_gce_x86_64
   env:
     API_URL_BASE: "https://api.cirrus-ci.com/v1/artifact/build/${CIRRUS_BUILD_ID}"

README.md

@@ -22,6 +22,15 @@ Netavark is a tool for configuring networking for Linux containers. Its features
 - [Podman](https://podman.io/docs) 4.0+
 - [protoc](https://grpc.io/docs/protoc-installation/)
 
+## MSRV (Minimum Supported Rust Version)
+
+v1.76
+
+We test that Netavark can be build on this Rust version and on some newer versions.
+All newer versions should also build, and if they do not, the issue should be
+reported and will be fixed. Older versions are not guaranteed to build and issues
+will not be fixed.
+
 ## Build
 
 ```console

contrib/container_images/Dockerfile.Rust

@@ -0,0 +1,4 @@
+# Source for quay.io/libpod/nv-rust
+# This version should always match the MSRV, when you update this also update the version in the root README.md.
+FROM docker.io/library/rust:1.76
+RUN apt-get update && apt-get -y install protobuf-compiler libprotobuf-dev

contrib/container_images/README.md

@@ -0,0 +1,9 @@
+# Rust image
+
+The point of this image is to verify the MSRV in CI so we can catch if a code or dependency change bumped the MSRV.
+If this is acceptable then update the version in the Dockerfile.Rust FROM line then build the new image see below.
+
+# Build and publish rust image
+
+Make sure you have valid `quay.io/libpod` credentials in order to push the image there.
+Then run the script `build_and_publish_rust_image.sh` to build and push it.

contrib/container_images/build_and_publish_rust_image.sh

@@ -0,0 +1,19 @@
+#!/bin/bash
+
+set -e
+
+PODMAN=${PODMAN:-podman}
+SCRIPT_DIR=$(dirname "${BASH_SOURCE[0]}")
+DOCKERFILE="$(dirname "${BASH_SOURCE[0]}")/Dockerfile.Rust"
+
+# get the tag from the Dockerfile so we do not duplicate it
+TAG=$(awk -F':' '/FROM/{print $NF}' $DOCKERFILE)
+if [[ -z "$TAG" ]]; then
+    echo "Empty tag in $DOCKERFILE; the tag must specify the rust version to use" >&2
+    exit 1
+fi
+
+FULL_IMAGE_NAME="quay.io/libpod/nv-rust:$TAG"
+
+$PODMAN build -t $FULL_IMAGE_NAME -f $DOCKERFILE
+$PODMAN push $FULL_IMAGE_NAME