Add support for pre-start hook script

Author: vbem

README.md

@@ -27,7 +27,8 @@ Environment variables:
   MR_GITHUB_API_BASEURL=https://api.github.com
   MR_RELEASE_URL=<latest on github.com/actions/runner/releases>
   MR_USER_BASE=<default in /etc/default/useradd>
-  MR_GITHUB_PAT=***
+  MR_USER_PREFIX=runner-
+  MR_GITHUB_PAT=ghp_***
 
 Sub-commands:
   add       Add one self-hosted runner on this host
@@ -185,3 +186,24 @@ TZ=Asia/Shanghai
 PATH=$PATH:/mybin
 all_proxy=socks5h://localhost:1080
 ```
+
+### Inject hook script before starting the runner service
+
+This application also supports to inject a hook script before starting the [runner service](https://docs.github.com/en/actions/hosting-your-own-runners/managing-self-hosted-runners/configuring-the-self-hosted-runner-application-as-a-service) via `MR_CMD_SVC_PRE_START` environment variable.
+
+For example, you can limit the CPU and RAM usage of the runner service by modifying the unit file of the runner service. Add the following lines to the `.env` file under the directory of this application. Then this script will be executed just before starting the runner service - `./svc.sh start`.
+
+```bash
+MR_CMD_SVC_PRE_START="$(cat <<-'__HEREDOC__'
+echo "🚀 Running custom commands before starting runner service."
+name="$(<mr.d/name)"
+echo "🚀 Runner: $name | User: $USER | Dir: $PWD"
+source <( sed -n "1,$(grep -n '^UNIT_PATH=' svc.sh | cut -d: -f1)p" svc.sh )
+echo "🚀 UNIT_PATH: $UNIT_PATH"
+sudo sed -i -e '/^\[Service\]/a CPUQuota=50%' -e '/^\[Service\]/a MemoryMax=512M' "$UNIT_PATH"
+sudo systemctl daemon-reload
+echo "🚀 Updated unit file:"
+cat "$UNIT_PATH"
+__HEREDOC__
+)"
+```

mr.bash

@@ -16,20 +16,22 @@ declare -rg DIR_THIS FILE_THIS
 [[ -r "$DIR_THIS/.env" ]] && source "$DIR_THIS/.env"
 
 # environment variables for customization
-# Github personal access token
-declare -rg MR_GITHUB_PAT
-# download URL of actions runner release, defaults to latest release on GitHub.com
-declare -rg MR_RELEASE_URL
-# baseurl of GitHub API, defaults to https://api.github.com
-declare -rg MR_GITHUB_API_BASEURL="${MR_GITHUB_API_BASEURL:-https://api.github.com}"
+# URL of this application
+declare -rg MR_URL='https://github.com/vbem/multi-runners'
 # baseurl of GitHub service, defaults to https://github.com
 declare -rg MR_GITHUB_BASEURL="${MR_GITHUB_BASEURL:-https://github.com}"
-# runners' local username prefix, defaults to `runner-`
-declare -rg MR_USER_PREFIX="${MR_USER_PREFIX:-runner-}"
+# baseurl of GitHub API, defaults to https://api.github.com
+declare -rg MR_GITHUB_API_BASEURL="${MR_GITHUB_API_BASEURL:-https://api.github.com}"
+# download URL of actions runner release, defaults to latest release on GitHub.com
+declare -rg MR_RELEASE_URL
 # runners' local users base directory, overrides the `HOME` setting in `/etc/default/useradd`
 declare -rg MR_USER_BASE
-# URL of this application
-declare -rg MR_URL='https://github.com/vbem/multi-runners'
+# runners' local username prefix, defaults to `runner-`
+declare -rg MR_USER_PREFIX="${MR_USER_PREFIX:-runner-}"
+# custom commands to run before starting the runner service
+declare -rg MR_CMD_SVC_PRE_START
+# Github personal access token
+declare -rg MR_GITHUB_PAT
 
 # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # #
 # stdlib
@@ -305,6 +307,7 @@ function mr::addRunner {
             if [[ "$(getenforce 2>/dev/null)" == "Enforcing" ]]; then
                 chcon -t bin_t ./runsvc.sh # https://github.com/vbem/multi-runners/issues/9
             fi
+            $MR_CMD_SVC_PRE_START # https://github.com/vbem/multi-runners/issues/23
             sudo ./svc.sh start
 __
         log::failed $? "Failed installing runner $i in local user '$user' for $url!" || return $?
@@ -393,6 +396,7 @@ Environment variables:
   MR_GITHUB_API_BASEURL=$MR_GITHUB_API_BASEURL
   MR_RELEASE_URL=${MR_RELEASE_URL:-<latest on github.com/actions/runner/releases>}
   MR_USER_BASE=${MR_USER_BASE:-<default in /etc/default/useradd>}
+  MR_USER_PREFIX=${MR_USER_PREFIX}
   MR_GITHUB_PAT=${MR_GITHUB_PAT::11}${MR_GITHUB_PAT:+***}
 
 Sub-commands: