Enable renovatebot for the project

.github/renovate.json

@@ -0,0 +1,47 @@
+{
+  "$schema": "https://docs.renovatebot.com/renovate-schema.json",
+  "description": "Runs Renovate with solrbot, see dev-docs/dependency-upgrades.adoc for more",
+  "enabled": true,
+  "dependencyDashboard": false,
+  "enabledManagers": ["gradle"],
+  "includePaths": ["versions.*", "build.gradle"],
+  "postUpgradeTasks": {
+    "commands": ["./gradlew updateLicenses"],
+    "fileFilters": ["solr/licenses/*.sha1"],
+    "executionMode": "branch"
+  },
+  "packageRules": [
+    {
+      "description": "Fix for non-semantic versions for older artifacts",
+      "matchDatasources": ["maven"],
+      "matchPackageNames": ["commons-collections:commons-collections", "commons-io:commons-io", "commons-lang:commons-lang"],
+      "versioning": "regex:^(?<major>\\d{1,4})\\.(?<minor>\\d+)(\\.(?<patch>\\d+))?$"
+    },
+    {
+      "description": "Group these together in same PR",
+      "matchPackagePatterns": ["org.apache.httpcomponents"],
+      "groupName": "org.apache.httpcomponents"
+    },
+    {
+      "description": "Test-dependencies are checked less often than the shipped deps",
+      "matchDepTypes": ["test"],
+      "extends": ["schedule:monthly"]
+    },
+    {
+      "description": "Noisy, frequently updated dependencies checked less often",
+      "matchPackagePrefixes": ["software.amazon.awssdk"],
+      "extends": ["schedule:monthly"]
+    },
+    {
+      "description": "Workaround for https://github.com/renovatebot/renovate/issues/19226",
+      "matchPackageNames": ["solr:modules", "HH:mm"],
+      "enabled": false
+    }
+  ],
+  "schedule": [
+    "* 8-20 * * *"
+  ],
+  "prConcurrentLimit": 5,
+  "prHourlyLimit": 5,
+  "stabilityDays": 5
+}

dev-docs/dependency-upgrades.adoc

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+= Dependency upgrades
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// 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.
+
+Solr has lots of 3rd party dependencies, defined mainly in `versions.props`.
+Keeping them up-to-date is crucial for a number of reasons:
+
+* minimizing the risk of critical CVE vulnerabilities by staying on a recent and supported version
+* avoiding "dependency hell", that can arise from falling too far behind
+
+Read the `help/dependencies.txt` file for an in-depth explanation of how gradle is deployed in Solr, using
+https://github.com/palantir/gradle-consistent-versions[Gradle consistent-versions] plugin.
+
+== Manual dependency upgrades
+In order to upgrade a dependency, you need to run through a number of steps:
+
+1. Identify the available versions from e.g. https://search.maven.org[Maven Central]
+2. Update the version in `versions.props` file
+3. Run `./gradlew --write-locks` to re-generate `versions.lock`. Note that this may cause a cascading effect where
+   the locked version of other dependencies also change.
+4. Run `./gradlew updateLicenses` to re-generate SHA1 checksums of the new jar files.
+5. Once in a while, a new version of a dependency will transitively bring in brand-new dependencies.
+   You'll need to decide whether to keep or exclude them. See `help/dependencies.txt` for details.
+
+== Renovate bot Pull Requests
+A member of the Solr community operates a Github bot running https://github.com/renovatebot/renovate[Renovate], which
+files Pull Requests to Solr with dependency upgrade proposals. The PRs are labeled `dependencies` and do include
+changes resulting from `gradle --write-locks` and `updateLicenses`.
+
+Community members and committers can then review, and if manual changes are needed, help bring the PR to completion.
+For many dependencies, a changelog is included in the PR text, which may help guide the upgrade decision.
+
+The scans are run on a schedule. New PRs are filed every Sunday, and only dependency versions that are at least
+5 days old are suggested, to guard against bad apples. If a new *major* version of a dependency is available,
+that will get its own separate Pull Request, so you can choose.
+
+If an upgrade is decided, simply merge (and backport) the PR. To skip an upgrade, close the PR. If a PR is left open,
+it will be re-used and auto updated whenever a newer patch- or minor version gets available. Thus, one can reduce
+churn from frequently-updated dependencies by delaying merge until a few weeks before a new release. One can also
+choose to change to a less frequent schedule or disable the bot, by editing `renovate.json`
+
+=== Configuring renovate.json
+While the bot runs on a https://github.com/solrbot/renovate-github-action[GitHub repo external to the project],
+the bot behavior can be tailored by editing `.github/renovate.json` in this project.
+See https://docs.renovatebot.com[Renovatebot docs] for available options.