diff --git a/Dockerfile b/Dockerfile
index 898c674cc5..f4b611cd10 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,36 +1,41 @@
 ARG version=22.04
+# version is passed through by Docker.
 # shellcheck disable=SC2154
 FROM ubuntu:"${version}"
 ARG DEBIAN_FRONTEND=noninteractive
 
+# We don't want to manually pin versions, happy to use whatever
+# Ubuntu thinks is best.
 # hadolint ignore=DL3008
-# shellcheck disable=SC2292
+
+# /etc/lsb-release is checked inside the container and sets DISTRIB_RELEASE.
+# shellcheck disable=SC1091,SC2154
 RUN apt-get update \
   && apt-get install -y --no-install-recommends software-properties-common gnupg-agent \
   && add-apt-repository -y ppa:git-core/ppa \
   && apt-get update \
   && apt-get install -y --no-install-recommends \
-    acl \
-    bzip2 \
-    ca-certificates \
-    curl \
-    file \
-    fonts-dejavu-core \
-    g++ \
-    gawk \
-    git \
-    less \
-    libz-dev \
-    locales \
-    make \
-    netbase \
-    openssh-client \
-    patch \
-    sudo \
-    uuid-runtime \
-    tzdata \
-    jq \
-  && if [ "$(. /etc/lsb-release; echo "${DISTRIB_RELEASE}" | cut -d. -f1)" -ge 18 ]; then apt-get install gpg; fi \
+  acl \
+  bzip2 \
+  ca-certificates \
+  curl \
+  file \
+  fonts-dejavu-core \
+  g++ \
+  gawk \
+  git \
+  less \
+  libz-dev \
+  locales \
+  make \
+  netbase \
+  openssh-client \
+  patch \
+  sudo \
+  uuid-runtime \
+  tzdata \
+  jq \
+  && if [[ "$(. /etc/lsb-release; echo "${DISTRIB_RELEASE}" | cut -d. -f1)" -ge 18 ]]; then apt-get install gpg; fi \
   && apt-get remove --purge -y software-properties-common \
   && apt-get autoremove --purge -y \
   && rm -rf /var/lib/apt/lists/* \
@@ -45,15 +50,15 @@ ENV PATH="/home/linuxbrew/.linuxbrew/bin:/home/linuxbrew/.linuxbrew/sbin:${PATH}
 WORKDIR /home/linuxbrew
 
 RUN mkdir -p \
-     .linuxbrew/bin \
-     .linuxbrew/etc \
-     .linuxbrew/include \
-     .linuxbrew/lib \
-     .linuxbrew/opt \
-     .linuxbrew/sbin \
-     .linuxbrew/share \
-     .linuxbrew/var/homebrew/linked \
-     .linuxbrew/Cellar \
+  .linuxbrew/bin \
+  .linuxbrew/etc \
+  .linuxbrew/include \
+  .linuxbrew/lib \
+  .linuxbrew/opt \
+  .linuxbrew/sbin \
+  .linuxbrew/share \
+  .linuxbrew/var/homebrew/linked \
+  .linuxbrew/Cellar \
   && ln -s ../Homebrew/bin/brew .linuxbrew/bin/brew \
   && git -C .linuxbrew/Homebrew remote set-url origin https://github.com/Homebrew/brew \
   && git -C .linuxbrew/Homebrew fetch origin \