contrib: Add script to bump docker image version.

contrib/devtools/README.md

@@ -39,3 +39,10 @@ add every module.
 Do note, however, that workspaces are local, so final submissions to the
 repository will still require the appropriate changes to the relevant `go.mod`
 files to ensure resolution outside of the workspace.
+
+### Docker Image Version Bump Script
+
+The [bump_docker.sh](./bump_docker.sh) script creates a `git` commit on a new
+branch that updates the [Dockerfile](../docker/Dockerfile) to the provided image
+and digest.  The commit description includes the relevant details and
+instructions for others to verify the digest.

contrib/devtools/bump_docker.sh

@@ -0,0 +1,88 @@
+#!/usr/bin/env bash
+#
+# Copyright (c) 2024 The Decred developers
+# Use of this source code is governed by an ISC
+# license that can be found in the LICENSE file.
+#
+# Script to update the image in the Dockerfile to a given image name and
+# associated hash.
+
+set -e
+
+display_usage() {
+  echo "Usage: $0 <docker_image> <image_hash>"
+  echo " Switches:"
+  echo "  -h    help"
+}
+
+# Parse option flags.
+while getopts "h" arg; do
+  case $arg in
+    h)
+      display_usage
+      exit 0
+      ;;
+    *)
+      display_usage
+      exit 1
+      ;;
+  esac
+done
+shift $((OPTIND-1))
+
+# Check arguments and set vars with them.
+if [ $# -ne 2 ]; then
+  display_usage
+  exit 1
+fi
+DOCKER_IMAGE=$1
+GO_VER=${DOCKER_IMAGE##golang:}
+GO_VER=${GO_VER%%-*}
+DOCKER_IMAGE_HASH=$2
+
+# Ensure the script is run from either the root of the repo or the devtools dir.
+DOCKER_FILE=contrib/docker/Dockerfile
+if [ -f "../../$DOCKER_FILE" ]; then
+  cd ../..
+fi
+if [ ! -f "$DOCKER_FILE" ]; then
+  echo "$DOCKER_FILE does not exist"
+  exit 1
+fi
+
+# Ensure git is available.
+if ! command -v git &> /dev/null; then
+  echo "git could not be found"
+  exit 1
+fi
+
+# Ensure the branch does not already exist.
+BRANCH_NAME="contrib_docker_go${GO_VER//\./_}"
+if $(git show-ref --verify --quiet refs/heads/${BRANCH_NAME}); then
+  echo "$BRANCH_NAME already exists"
+  exit 1
+fi
+
+# Create the branch.
+git checkout -b "$BRANCH_NAME" master
+
+# Modify the Dockerfile with the updated image details.
+sed -Eie "s/golang:[0-9]\.[0-9]+\.[0-9]+\-alpine[0-9]+\.[0-9]+/${DOCKER_IMAGE}/" "$DOCKER_FILE"
+sed -Eie "s/golang@sha256:[0-9a-f]{64}/golang@sha256:${DOCKER_IMAGE_HASH}/" "$DOCKER_FILE"
+
+# Commit the changes with the appropriate message.
+git add "$DOCKER_FILE"
+git commit -m "docker: Update image to $DOCKER_IMAGE.
+
+This updates the docker image to $DOCKER_IMAGE.
+
+To confirm the new digest:
+
+\`\`\`
+$ docker pull $DOCKER_IMAGE
+${DOCKER_IMAGE##golang:}: Pulling from library/golang
+...
+Digest: sha256:${DOCKER_IMAGE_HASH}
+...
+\`\`\`
+"