By default, CFEngine policy is published /var/cfengine/masterfiles on the policy server. It is recommended that this directory be backed by a version control system (VCS), such as Git or Subversion.

Repository synchronization

CFEngine Enterprise ships with masterfiles-stage, tooling to assist with deploying policy from a version control system.

Enterprise users can configure automatic publication of policy from Mission Portal as described in Policy Deployment or by using the VCS settings API. Community users can also install and use this tooling by following the installation instructions.

Commit hooks

Commit hooks are scripts that are run when a repository is updated. We can use a hook to notify a policy developer if an update causes a syntax error. While the agent on the policy server should not copy from /var/cfengine/masterfiles to /var/cfengine/inputs if the new policy does not pass validation, it can nevertheless be helpful to employ VCS commit hooks. A hook needs to be installed on the VCS server. Git and subversion store their hooks on the server, under directories .git/hooks and hooks, respectively.

Example Git update hook

We can use a Git update hook to prevent a change from being made unless it passes syntax checking. The idea is to check out the revision in a temporary directory and run cf-promises on it. Here is an example hook.

#!/bin/sh

# --- Command line
REF_NAME="$1"
OLD_REV="$2"
NEW_REV="$3"

GIT=/usr/bin/git
TAR=/bin/tar
CF_PROMISES=/home/a10021/Source/core/cf-promises/cf-promises
TMP_CHECKOUT_DIR=/tmp/cfengine-post-commit-syntax-check/
MAIN_POLICY_FILE=promises.cf

echo "Creating temporary checkout directory at ${TMP_CHECKOUT_DIR}"
mkdir -p ${TMP_CHECKOUT_DIR}

echo "Clearing potential data in temporary checkout directory"
rm -rf ${TMP_CHECKOUT_DIR}/*
rm -rf ${TMP_CHECKOUT_DIR}/.svn

echo "Checking out revision ${REV} from ${REPOS} to file://${TMP_CHECKOUT_DIR}"
${GIT} archive ${NEW_REV} | tar -x -C ${TMP_CHECKOUT_DIR}
if [ $? -ne 0 ]; then
    echo "Error checking out repository to temporary folder during post-commit syntax checking!" >&2
    return 1
fi

echo "Running cf-promises -cf on ${TMP_CHECKOUT_DIR}/${MAIN_POLICY_FILE}"
${CF_PROMISES} -cf ${TMP_CHECKOUT_DIR}/${MAIN_POLICY_FILE}

if [ $? -ne 0 ]; then
    echo "There were policy errors in pushed revision ${REV}" >&2
    return 1
else
    echo "Policy check completed successfully!"
    return 0
fi

Example subversion post-commit hook

For subversion, the principle is essentially the same. Note that for a post-commit hook the check is run after update, so the repository may be left with a syntax error, but the committer is notified.

#!/bin/sh

REPOS="$1"
REV="$2"

SVN=/usr/bin/svn
CF_PROMISES=/home/a10021/Source/core/cf-promises/cf-promises
TMP_CHECKOUT_DIR=/tmp/cfengine-post-commit-syntax-check/
MAIN_POLICY_FILE=trunk/promises.cf

echo "Creating temporary checkout directory at ${TMP_CHECKOUT_DIR}"
mkdir -p ${TMP_CHECKOUT_DIR}

echo "Clearing potential data in temporary checkout directory"
rm -rf ${TMP_CHECKOUT_DIR}/*
rm -rf ${TMP_CHECKOUT_DIR}/.svn

echo "Checking out revision ${REV} from ${REPOS} to file://${TMP_CHECKOUT_DIR}"
${SVN} co -r ${REV} file://${REPOS} ${TMP_CHECKOUT_DIR}
if [ $? -ne 0 ]; then
    echo "Error checking out repository to temporary folder during post-commit syntax checking!" >&2
    return 1
fi

echo "Running cf-promises -cf on ${TMP_CHECKOUT_DIR}/${MAIN_POLICY_FILE}"
${CF_PROMISES} -cf ${TMP_CHECKOUT_DIR}/${MAIN_POLICY_FILE}

if [ $? -ne 0 ]; then
    echo "There were policy errors in committed revision ${REV}" >&2
    return 1
else
    echo "Policy check completed successfully!"
    return 0
fi