Bugfix: /etc/hostname is not guaranteed, sane default to random string

chaturanga50 · Jan 30, 2023 · fb6fdfa · fb6fdfa
1 parent 8b5cafc
commit fb6fdfa
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Showing 2 changed files with 7 additions and 2 deletions.
diff --git a/README.md b/README.md
@@ -55,7 +55,7 @@ These containers are built via Github actions that [copy the dockerfile](https:/
 | --- | --- |
 | `RUN_AS_ROOT` | Boolean to run as root. If `true`: will run as root. If `True` and the user is overridden it will error. If any other value it will run as the `runner` user and allow an optional override. Default is `true` |
 | `RUNNER_NAME` | The name of the runner to use. Supercedes (overrides) `RUNNER_NAME_PREFIX` |
-| `RUNNER_NAME_PREFIX` | A prefix for runner name (followed by docker container id). You must not also provide `RUNNER_NAME`. Defaults to `github-runner`                                                                                                                                                              |
+| `RUNNER_NAME_PREFIX` | A prefix for runner name (followed by docker container id if /etc/hostname if exists, else a random 13 digit string). You must not also provide `RUNNER_NAME`. Defaults to `github-runner`                                                                                                                                                              |
 | `ACCESS_TOKEN` | A [github PAT](https://docs.github.com/en/github/authenticating-to-github/creating-a-personal-access-token) to use to generate `RUNNER_TOKEN` dynamically at container start. Not using this requires a valid `RUNNER_TOKEN` |
 | `APP_ID` | The github application ID. Must be paired with `APP_PRIVATE_KEY` and should not be used with `ACCESS_TOKEN` or `RUNNER_TOKEN` |
 | `APP_PRIVATE_KEY` | The github application private key. Must be paired with `APP_ID` and should not be used with `ACCESS_TOKEN` or `RUNNER_TOKEN` |

diff --git a/entrypoint.sh b/entrypoint.sh
@@ -23,7 +23,12 @@ deregister_runner() {
 
 _DISABLE_AUTOMATIC_DEREGISTRATION=${DISABLE_AUTOMATIC_DEREGISTRATION:-false}
 
-_RUNNER_NAME=${RUNNER_NAME:-${RUNNER_NAME_PREFIX:-github-runner}-$(cat /etc/hostname)}
+_RUNNER_NAME=${RUNNER_NAME:-${RUNNER_NAME_PREFIX:-github-runner}-$(head /dev/urandom | tr -dc A-Za-z0-9 | head -c 13 ; echo '')}
+if [[ -f "/etc/hostname" ]]; then
+  # In some cases this file does not exist
+  _RUNNER_NAME=${RUNNER_NAME:-${RUNNER_NAME_PREFIX:-github-runner}-$(cat /etc/hostname)}
+fi
+
 _RUNNER_WORKDIR=${RUNNER_WORKDIR:-/_work-${_RUNNER_NAME}}
 _LABELS=${LABELS:-default}
 _RUNNER_GROUP=${RUNNER_GROUP:-Default}