Shift a couple of stages from Jenkinsfile into Dockerfile

The Jenkins job on our new deployment is running Docker containers with
the option `-u 1000:1000` instead of `-u 0:0` which results in
permissions issues when doing administrative things such as using
`apt-get` to install stuff.

So this commit moves the install stages of the test run into a
Dockerfile, so that the image which is all nicely configured can then be
used to run the tests.

Relates to NGC-1447.

Dockerfile.CI

@@ -0,0 +1,37 @@
+# syntax = docker/dockerfile:1
+
+################################################################################
+# Copyright (c) 2024, National Research Foundation (SARAO)
+#
+# Licensed under the BSD 3-Clause License (the "License"); you may not use
+# this file except in compliance with the License. You may obtain a copy
+# of the License at
+#
+#   https://opensource.org/licenses/BSD-3-Clause
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+################################################################################
+
+FROM ubuntu:24.04
+
+COPY . .
+
+# Install dependencies
+# jq and iproute2 are used to find the interface IPv4 address
+RUN apt-get update && apt-get -y --no-install-recommends install libpython3-dev python3-venv jq iproute2
+RUN python3 -m venv /venv
+RUN .ci/install-sys-pkgs.sh
+RUN PATH="/venv/bin:$PATH" .ci/py-requirements.sh
+
+# Install Python package
+RUN PATH="/venv/bin:$PATH" pip install -v \
+    --config-settings=setup-args=--native-file=ci.ini \
+    --config-settings=setup-args=-Dibv=enabled \
+    --config-settings=setup-args=-Dibv_hw_rate_limit=enabled \
+    --config-settings=setup-args=-Dmlx5dv=enabled \
+    .
+

Jenkinsfile

@@ -23,10 +23,10 @@
 
 pipeline {
   agent {
-    docker {
+    dockerfile {
       label 'spead2'
+      filename 'Dockerfile.CI'
       registryCredentialsId 'dockerhub'  // Supply credentials to avoid rate limit
-      image 'ubuntu:24.04'
       // These arguments allow direct access to the NVIDIA NIC with ibverbs
       args '--network=host --ulimit=memlock=-1 -e NVIDIA_MOFED=enabled -e NVIDIA_VISIBLE_DEVICES=all --runtime=nvidia'
     }
@@ -42,26 +42,6 @@ pipeline {
   }
 
   stages {
-    stage('Install dependencies') {
-      steps {
-        // jq and iproute2 are used to find the interface IPv4 address
-        sh 'apt-get update && apt-get -y --no-install-recommends install libpython3-dev python3-venv jq iproute2'
-        sh 'python3 -m venv /venv'
-        sh '.ci/install-sys-pkgs.sh'
-        sh 'PATH="/venv/bin:$PATH" .ci/py-requirements.sh'
-      }
-    }
-
-    stage('Install Python package') {
-      steps {
-        sh '''PATH="/venv/bin:$PATH" pip install -v \
-          --config-settings=setup-args=--native-file=ci.ini \
-          --config-settings=setup-args=-Dibv=enabled \
-          --config-settings=setup-args=-Dibv_hw_rate_limit=enabled \
-          --config-settings=setup-args=-Dmlx5dv=enabled \
-          .'''
-      }
-    }
 
     stage('Run tests') {
       steps {