Add a core-version command.

README.md

@@ -75,6 +75,14 @@ Override any environment variable value from [.ddev/config.contrib.yaml](config.
 
 ### Changing the Drupal core version
 
+Use the `ddev core-version` command to set the core version environment variable and update the code, for example:
+
+```shell
+ddev core-version ^11
+```
+
+You can also do this manually:
+
 In `.ddev/config.local.yaml` set the Drupal core version:
 
 ```yaml

commands/host/core-version

@@ -0,0 +1,25 @@
+#!/usr/bin/env bash
+
+#ddev-generated
+## Command provided by https://github.com/ddev/ddev-drupal-contrib
+## Description: Switch the core version and rebuild.
+## Usage: core-version [version]
+## Example: "ddev core-version ^11" or "ddev core-version ~11.1.0"
+
+set -eu -o pipefail
+
+# Handle when config.local.yaml doesn't exist, or has no web_environment key.
+if [[ ! -f .ddev/config.local.yaml || ! `grep '^web_environment:' .ddev/config.local.yaml` ]]; then
+  echo -e "web_environment:\n  - DRUPAL_CORE=$1" >> .ddev/config.local.yaml
+# Handle when we have a DRUPAL_CORE env var already.
+elif [[ `grep 'DRUPAL_CORE=' .ddev/config.local.yaml` ]]; then
+  sed -ri "s/^(\s+)- DRUPAL_CORE=.*/\1- DRUPAL_CORE=$1/" .ddev/config.local.yaml
+# Handle when we do not have a DRUPAL_CORE env var already.
+else
+  # Additionally handle if web_environment is set to an empty array.
+  sed -ri "s/web_environment:\s+\[\s*\]/web_environment:/" .ddev/config.local.yaml
+  sed -i "/web_environment:/a \ \ - DRUPAL_CORE=$1" .ddev/config.local.yaml
+fi
+
+ddev restart
+ddev poser

install.yaml

@@ -1,6 +1,7 @@
 name: ddev-drupal-contrib
 
 project_files:
+  - commands/host/core-version
   - commands/web/eslint
   - commands/web/expand-composer-json
   - commands/web/nightwatch