ci: configure Renovate

.github/renovate.json5

@@ -0,0 +1,39 @@
+{
+  extends: [
+    "config:base",
+    ":dependencyDashboard",
+    ":prHourlyLimitNone",
+    ":prConcurrentLimitNone",
+    ":label(dependency-upgrade)",
+  ],
+  schedule: ["before 8am on thursday"],
+  branchPrefix: "renovate-",
+  commitMessagePrefix: "project: ",
+  commitMessageAction: "update",
+  commitMessageTopic: "{{depName}}",
+  commitMessageExtra: "to {{#if isSingleVersion}}v{{{newVersion}}}{{else}}{{{newValue}}}{{/if}}",
+  packageRules: [
+    // Ruby dependencies are managed by depfu
+    {
+      managers: ["bundler"],
+      enabled: false,
+    },
+    // Commit message formats
+    {
+      datasources: ["docker"],
+      commitMessagePrefix: "docker: ",
+    },
+    {
+      datasources: ["github-actions"],
+      commitMessagePrefix: "ci: ",
+    },
+  ],
+  regexManagers: [
+    {
+      fileMatch: ["\.rb$", "^Rakefile$"],
+      matchStrings: [
+        "renovate: datasource=(?<datasource>.*?) depName=(?<depName>.*?)\\s.*_version = '(?<currentValue>.*)'\\s"
+      ]
+    },
+  ],
+}

Rakefile

@@ -21,9 +21,12 @@ namespace :solargraph do
   end
 end
 
+# renovate: datasource=github-tags depName=hadolint/hadolint
+hadolint_version = 'v1.18.0'
+
 desc 'Run hadolint for Dockerfile linting'
 task :hadolint do
-  sh 'docker run --rm -i hadolint/hadolint:v1.18.0 hadolint --ignore DL3018 - < docker/Dockerfile'
+  sh "docker run --rm -i hadolint/hadolint:#{hadolint_version} hadolint --ignore DL3018 - < docker/Dockerfile"
 end
 
 task default: [:rubocop, :spec, 'bundle:audit', :solargraph]