CI: drop Ubuntu 21.10, EOL 2022-07-14

.cirrus.yml

@@ -208,13 +208,6 @@ ubuntu22_task:
     << : *RESOURCES_TEMPLATE
   << : *CI_TEMPLATE
 
-ubuntu21_task:
-  container:
-    # Ubuntu 21.10 EOL: July 2022
-    dockerfile: ci/ubuntu-21.10/Dockerfile
-    << : *RESOURCES_TEMPLATE
-  << : *CI_TEMPLATE
-
 ubuntu20_task:
   container:
     # Ubuntu 20.04 EOL: April 2025

ci/ubuntu-21.10/Dockerfile

@@ -1,39 +0,0 @@
-FROM ubuntu:21.10
-
-ENV DEBIAN_FRONTEND="noninteractive" TZ="America/Los_Angeles"
-
-# A version field to invalide Cirrus's build cache when needed, as suggested in
-# https://github.com/cirruslabs/cirrus-ci-docs/issues/544#issuecomment-566066822
-ENV DOCKERFILE_VERSION 20220519
-
-RUN apt-get update && apt-get -y install \
-    bc \
-    bison \
-    bsdmainutils \
-    ccache \
-    cmake \
-    curl \
-    flex \
-    g++ \
-    gcc \
-    git \
-    lcov \
-    libkrb5-dev \
-    libmaxminddb-dev \
-    libpcap-dev \
-    libssl-dev \
-    make \
-    python3 \
-    python3-dev \
-    python3-pip\
-    ruby \
-    sqlite3 \
-    swig \
-    unzip \
-    wget \
-    zlib1g-dev \
-  && apt autoclean \
-  && rm -rf /var/lib/apt/lists/*
-
-RUN pip3 install websockets junit2html
-RUN gem install coveralls-lcov