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nixos/github-runner: fix bugs related to InaccessiblePaths=

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This commit fixes two bugs:

1) When starting a github-runner for the very first time, the
   unconfigure script did not copy the `tokenFile` to the state
   directory. This case just was not handled so far. As a result, the
   runner could not configure. The unit did, however, fail even before
   as the state token file is configured as inaccessible for the service
   through `InaccessiblePaths=`. As the given path did not exist in the
   described case, setting up the unit's namespacing failed.

2) Similarly, the `tokenFile` is also marked as not accessible to the
   service user. There are, however, cases where other namespacing
   options make the files inaccessible even before `InaccessiblePaths=`
   kicks in; thus, they appear as non existing and cause the namespacing
   to fail yet again. Prefixing the entry with a `-` causes Systemd to
   ignore the entry if it cannot find it. This is the behavior we want.

I also took fixing those bugs as a chance to refactor the unconfigure
script to make it easier to follow.
This commit is contained in:
Vincent Haupert 2022-10-08 01:32:55 +02:00
parent bcf071d514
commit 941c79b620
1 changed files with 50 additions and 31 deletions
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81
nixos/modules/services/continuous-integration/github-runner.nix
View file

@ -200,46 +200,65 @@ in
${lines}
'';
currentConfigPath = "$STATE_DIRECTORY/.nixos-current-config.json";
runnerRegistrationConfig = getAttrs [ "name" "tokenFile" "url" "runnerGroup" "extraLabels" "ephemeral" ] cfg;
newConfigPath = builtins.toFile "${svcName}-config.json" (builtins.toJSON runnerRegistrationConfig);
newConfigTokenFilename = ".new-token";
currentConfigPath = "$STATE_DIRECTORY/.nixos-current-config.json";
newConfigTokenPath= "$STATE_DIRECTORY/.new-token";
currentConfigTokenPath = "$STATE_DIRECTORY/${currentConfigTokenFilename}";
runnerCredFiles = [
".credentials"
".credentials_rsaparams"
".runner"
];
unconfigureRunner = writeScript "unconfigure" ''
differs=
if [[ "$(ls -A "$STATE_DIRECTORY")" ]]; then
# State directory is not empty
# 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
${pkgs.diffutils}/bin/diff -q \
"$STATE_DIRECTORY"/${currentConfigTokenFilename} \
${escapeShellArg cfg.tokenFile} \
>/dev/null 2>&1 || differs=1
# If .credentials does not exist, assume a previous run de-registered the runner on stop (ephemeral mode)
[[ ! -f "$STATE_DIRECTORY/.credentials" ]] && differs=1
fi
if [[ -n "$differs" ]]; then
echo "Config has changed, removing old runner state."
# In ephemeral mode, the runner deletes the `.credentials` file after de-registering it with GitHub
[[ -f "$STATE_DIRECTORY/.credentials" ]] && 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_tokens() {
# 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}"
install --mode=666 ${escapeShellArg cfg.tokenFile} "${newConfigTokenPath}"
# Also copy current file to allow for a diff on the next start
install --mode=600 ${escapeShellArg cfg.tokenFile} "$STATE_DIRECTORY/${currentConfigTokenFilename}"
install --mode=600 ${escapeShellArg cfg.tokenFile} "${currentConfigTokenPath}"
}
clean_state() {
find "$STATE_DIRECTORY/" -mindepth 1 -delete
copy_tokens
}
diff_config() {
changed=0
# Check for module config changes
[[ -f "${currentConfigPath}" ]] \
&& ${pkgs.diffutils}/bin/diff -q '${newConfigPath}' "${currentConfigPath}" >/dev/null 2>&1 \
|| changed=1
# Also check the content of the token file
[[ -f "${currentConfigTokenPath}" ]] \
&& ${pkgs.diffutils}/bin/diff -q "${currentConfigTokenPath}" ${escapeShellArg cfg.tokenFile} >/dev/null 2>&1 \
|| changed=1
# If the config has changed, remove old state and copy tokens
if [[ "$changed" -eq 1 ]]; then
echo "Config has changed, removing old runner state."
echo "The old runner will still appear in the GitHub Actions UI." \
"You have to remove it manually."
clean_state
fi
}
if [[ "${optionalString cfg.ephemeral "1"}" ]]; then
# In ephemeral mode, we always want to start with a clean state
clean_state
elif [[ "$(ls -A "$STATE_DIRECTORY")" ]]; then
# There are state files from a previous run; diff them to decide if we need a new registration
diff_config
else
# The state directory is entirely empty which indicates a first start
copy_tokens
fi
'';
configureRunner = writeScript "configure" ''
if [[ -e "$STATE_DIRECTORY/${newConfigTokenFilename}" ]]; then
if [[ -e "${newConfigTokenPath}" ]]; then
echo "Configuring GitHub Actions Runner"
args=(
@ -256,7 +275,7 @@ in
# If the token file contains a PAT (i.e., it starts with "ghp_"), we have to use the --pat option,
# if it is not a PAT, we assume it contains a registration token and use the --token option
token=$(<"$STATE_DIRECTORY/${newConfigTokenFilename}")
token=$(<"${newConfigTokenPath}")
if [[ "$token" =~ ^ghp_* ]]; then
args+=(--pat "$token")
else
@ -271,7 +290,7 @@ in
rm -rf "$STATE_DIRECTORY/_diag/"
# Cleanup token from config
rm "$STATE_DIRECTORY/${newConfigTokenFilename}"
rm "${newConfigTokenPath}"
# Symlink to new config
ln -s '${newConfigPath}' "${currentConfigPath}"
@ -305,8 +324,8 @@ in
WorkingDirectory = runtimeDir;
InaccessiblePaths = [
# Token file path given in the configuration
cfg.tokenFile
# Token file path given in the configuration, if visible to the service
"-${cfg.tokenFile}"
# Token file in the state directory
"${stateDir}/${currentConfigTokenFilename}"
];