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Merge pull request #148164 from veehaitch/nixos-github-runner-148024-v2

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nixos/github-runner: refactor tokens handling
This commit is contained in:
Bobby Rong 2021-12-17 16:28:21 +08:00 committed by GitHub
commit 94144484c2
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1 changed files with 26 additions and 34 deletions
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60
nixos/modules/services/continuous-integration/github-runner.nix
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@ -10,6 +10,8 @@ let
stateDir = "%S/${systemdDir}";
# %L: Log directory root (usually /var/log); see systemd.unit(5)
logsDir = "%L/${systemdDir}";
# Name of file stored in service state directory
currentConfigTokenFilename = ".current-token";
in
{
options.services.github-runner = {
@ -144,13 +146,11 @@ in
ExecStart = "${cfg.package}/bin/runsvc.sh";
# Does the following, sequentially:
# - Copy the current and the previous `tokenFile` to the $RUNTIME_DIRECTORY
# and make it accessible to the service user to allow for a content
# comparison.
# - If the module configuration or the token has changed, clear the state directory.
# - Configure the runner.
# - Copy the configured `tokenFile` to the $STATE_DIRECTORY and make it
# inaccessible to the service user.
# - If the module configuration or the token has changed, purge the state directory,
# and create the current and the new token file with the contents of the configured
# token. While both files have the same content, only the later is accessible by
# the service user.
# - Configure the runner using the new token file. When finished, delete it.
# - Set up the directory structure by creating the necessary symlinks.
ExecStartPre =
let
@ -173,37 +173,20 @@ in
currentConfigPath = "$STATE_DIRECTORY/.nixos-current-config.json";
runnerRegistrationConfig = getAttrs [ "name" "tokenFile" "url" "runnerGroup" "extraLabels" ] cfg;
newConfigPath = builtins.toFile "${svcName}-config.json" (builtins.toJSON runnerRegistrationConfig);
currentConfigTokenFilename = ".current-token";
newConfigTokenFilename = ".new-token";
runnerCredFiles = [
".credentials"
".credentials_rsaparams"
".runner"
];
ownConfigTokens = writeScript "own-config-tokens" ''
# Copy current and new token file to runtime dir and make it accessible to the service user
cp ${escapeShellArg cfg.tokenFile} "$RUNTIME_DIRECTORY/${newConfigTokenFilename}"
chmod 600 "$RUNTIME_DIRECTORY/${newConfigTokenFilename}"
chown "$USER" "$RUNTIME_DIRECTORY/${newConfigTokenFilename}"
if [[ -e "$STATE_DIRECTORY/${currentConfigTokenFilename}" ]]; then
cp "$STATE_DIRECTORY/${currentConfigTokenFilename}" "$RUNTIME_DIRECTORY/${currentConfigTokenFilename}"
chmod 600 "$RUNTIME_DIRECTORY/${currentConfigTokenFilename}"
chown "$USER" "$RUNTIME_DIRECTORY/${currentConfigTokenFilename}"
fi
'';
disownConfigTokens = writeScript "disown-config-tokens" ''
# Make the token inaccessible to the runner service user
chmod 600 "$STATE_DIRECTORY/${currentConfigTokenFilename}"
chown root:root "$STATE_DIRECTORY/${currentConfigTokenFilename}"
'';
unconfigureRunner = writeScript "unconfigure" ''
differs=
# Set `differs = 1` if current and new runner config differ or if `currentConfigPath` does not exist
${pkgs.diffutils}/bin/diff -q '${newConfigPath}' "${currentConfigPath}" >/dev/null 2>&1 || differs=1
# Also trigger a registration if the token content changed
${pkgs.diffutils}/bin/diff -q \
"$RUNTIME_DIRECTORY"/{${currentConfigTokenFilename},${newConfigTokenFilename}} \
"$STATE_DIRECTORY"/${currentConfigTokenFilename} \
${escapeShellArg cfg.tokenFile} \
>/dev/null 2>&1 || differs=1
if [[ -n "$differs" ]]; then
@ -211,13 +194,18 @@ in
echo "The old runner will still appear in the GitHub Actions UI." \
"You have to remove it manually."
find "$STATE_DIRECTORY/" -mindepth 1 -delete
# Copy the configured token file to the state dir and allow the service user to read the file
install --mode=666 ${escapeShellArg cfg.tokenFile} "$STATE_DIRECTORY/${newConfigTokenFilename}"
# Also copy current file to allow for a diff on the next start
install --mode=600 ${escapeShellArg cfg.tokenFile} "$STATE_DIRECTORY/${currentConfigTokenFilename}"
fi
'';
configureRunner = writeScript "configure" ''
empty=$(ls -A "$STATE_DIRECTORY")
if [[ -z "$empty" ]]; then
if [[ -e "$STATE_DIRECTORY/${newConfigTokenFilename}" ]]; then
echo "Configuring GitHub Actions Runner"
token=$(< "$RUNTIME_DIRECTORY"/${newConfigTokenFilename})
token=$(< "$STATE_DIRECTORY"/${newConfigTokenFilename})
RUNNER_ROOT="$STATE_DIRECTORY" ${cfg.package}/bin/config.sh \
--unattended \
--work "$RUNTIME_DIRECTORY" \
@ -234,8 +222,7 @@ in
rm -rf "$STATE_DIRECTORY/_diag/"
# Cleanup token from config
rm -f "$RUNTIME_DIRECTORY"/${currentConfigTokenFilename}
mv "$RUNTIME_DIRECTORY"/${newConfigTokenFilename} "$STATE_DIRECTORY/${currentConfigTokenFilename}"
rm "$STATE_DIRECTORY/${newConfigTokenFilename}"
# Symlink to new config
ln -s '${newConfigPath}' "${currentConfigPath}"
@ -250,10 +237,8 @@ in
'';
in
map (x: "${x} ${escapeShellArgs [ stateDir runtimeDir logsDir ]}") [
"+${ownConfigTokens}" # runs as root
unconfigureRunner
"+${unconfigureRunner}" # runs as root
configureRunner
"+${disownConfigTokens}" # runs as root
setupRuntimeDir
];
@ -266,6 +251,13 @@ in
StateDirectoryMode = "0700";
WorkingDirectory = runtimeDir;
InaccessiblePaths = [
# Token file path given in the configuration
cfg.tokenFile
# Token file in the state directory
"${stateDir}/${currentConfigTokenFilename}"
];
# By default, use a dynamically allocated user
DynamicUser = true;