feat: Restart salt-master on config changes

Automatically restart salt-master when config changes are detected.

.github/workflows/build-and-test.yml

@@ -130,6 +130,9 @@ jobs:
           chmod 644 "${GITFS_KEYS_DIR}"/gitfs_ssh.pub
           tests/gitfs/test.sh
 
+      - name: Execute config-reloader tests
+        run: tests/config-reloader/test.sh
+
       - name: Cleanup
         run: |
           docker stop registry

CHANGELOG.md

@@ -4,6 +4,10 @@ This file only reflects the changes that are made in this image.
 Please refer to the [Salt 3004 Release Notes](https://docs.saltstack.com/en/latest/topics/releases/3004.html)
 for the list of changes in SaltStack.
 
+**3004_2**
+
+- Support for automatically restart `salt-master` after config changes
+
 **3004_1**
 
 - Install `libssh2 1.10.0` from source

Dockerfile

@@ -7,7 +7,7 @@ ARG VCS_REF
 ENV SALT_VERSION="3004" \
     PYTHON_VERSION="3.9"
 
-ENV IMAGE_VERSION="${SALT_VERSION}_1"
+ENV IMAGE_VERSION="${SALT_VERSION}_2"
 
 ENV SALT_DOCKER_DIR="/etc/docker-salt" \
     SALT_ROOT_DIR="/etc/salt" \
@@ -35,7 +35,7 @@ RUN apt-get update \
     sudo ca-certificates openssl apt-transport-https wget locales openssh-client \
     python${PYTHON_VERSION} python3-dev libpython3-dev \
     python3-pip python3-setuptools python3-wheel \
-    supervisor logrotate git gettext-base tzdata \
+    supervisor logrotate git gettext-base tzdata inotify-tools \
  && DEBIAN_FRONTEND=noninteractive update-locale LANG=C.UTF-8 LC_MESSAGES=POSIX \
     locale-gen en_US.UTF-8 \
     dpkg-reconfigure locales \

README.md

@@ -133,6 +133,10 @@ docker run --name salt_master -d \
     cdalvaro/docker-salt-master:latest
 ```
 
+This image provides support for automatically restart `salt-master` when configuration files change.
+This support is disabled by default, but it can be enabled by setting the
+`SALT_RESTART_MASTER_ON_CONFIG_CHANGE` environment variable to `true`.
+
 ### Custom States
 
 In order to provide salt with your custom states you must mount the volume `/home/salt/data/srv/` with your `roots` directory inside it.
@@ -503,9 +507,10 @@ Please refer the docker run command options for the `--env-file` flag where you
 Below you can find a list with the available options that can be used to customize your `docker-salt-master` installation.
 
 | Parameter                              | Description                                                                                                                                                                                                                |
-| :--------------------------------- | :------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
+| :------------------------------------- | :------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
 | `DEBUG`                                | Set this to `true` to enable entrypoint debugging.                                                                                                                                                                         |
 | `TIMEZONE`                             | Set the container timezone. Defaults to `UTC`. Values are expected to be in Canonical format. Example: `Europe/Madrid`. See the list of [acceptable values](https://en.wikipedia.org/wiki/List_of_tz_database_time_zones). |
+| `SALT_RESTART_MASTER_ON_CONFIG_CHANGE` | Set this to `true` to restart `salt-master` service when configuration files change. Default: `false`                                                                                                                      |
 | `SALT_LOG_LEVEL`                       | The level of messages to send to the console. One of 'garbage', 'trace', 'debug', info', 'warning', 'error', 'critical'. Default: `warning`                                                                                |
 | `SALT_LOG_ROTATE_FREQUENCY`            | Logrotate frequency for salt logs. Available options are 'daily', 'weekly', 'monthly', and 'yearly'. Default: `weekly`                                                                                                     |
 | `SALT_LOG_ROTATE_RETENTION`            | Keep x files before deleting old log files. Defaults: `52`                                                                                                                                                                 |

assets/runtime/env-defaults.sh

@@ -11,6 +11,7 @@ SALT_LOG_ROTATE_FREQUENCY=${SALT_LOG_ROTATE_FREQUENCY:-weekly}
 SALT_LOG_ROTATE_RETENTION=${SALT_LOG_ROTATE_RETENTION:-52}
 
 # https://docs.saltstack.com/en/latest/ref/configuration/master.html
+SALT_RESTART_MASTER_ON_CONFIG_CHANGE=${SALT_RESTART_MASTER_ON_CONFIG_CHANGE:-false}
 
 #####         Logging settings       #####
 # https://docs.saltstack.com/en/latest/ref/configuration/master.html#master-logging-settings

assets/runtime/functions.sh

@@ -432,6 +432,27 @@ EOF
 
 }
 
+function configure_config_reloader()
+{
+  rm -f /etc/supervisor/conf.d/config-reloader.conf
+  [ "${SALT_RESTART_MASTER_ON_CONFIG_CHANGE}" == true ] || return 0
+
+  echo "Configuring config reloader ..."
+
+  # configure supervisord to start config-reloader
+  cat > /etc/supervisor/conf.d/config-reloader.conf <<EOF
+[program:config-reloader]
+priority=20
+directory=/tmp
+command=/usr/local/sbin/config-reloader
+user=root
+autostart=true
+autorestart=true
+stdout_logfile=${SALT_LOGS_DIR}/supervisor/%(program_name)s.log
+stderr_logfile=${SALT_LOGS_DIR}/supervisor/%(program_name)s.log
+EOF
+}
+
 #---  FUNCTION  -------------------------------------------------------------------------------------------------------
 #          NAME:  initialize_system
 #   DESCRIPTION:  Initialize the system.
@@ -445,6 +466,7 @@ function initialize_system()
   configure_salt_master
   configure_salt_api
   configure_salt_formulas
+  configure_config_reloader
   setup_salt_keys
   setup_ssh_keys
   rm -rf /var/run/supervisor.sock

assets/sbin/config-reloader

@@ -0,0 +1,17 @@
+#!/bin/bash
+
+# shellcheck source=assets/runtime/functions.sh
+FUNCTIONS_FILE="${SALT_RUNTIME_DIR}/functions.sh"
+source "${FUNCTIONS_FILE}"
+
+function check_for_config_changes()
+{
+  inotifywait -qq --recursive \
+    --event modify,move,create,delete \
+    "${SALT_CONFS_DIR}"
+}
+
+while check_for_config_changes; do
+  log_info "Configuration changes detected. Reloading salt-master ..."
+  supervisorctl restart salt-master
+done

tests/config-reloader/README.md

@@ -0,0 +1,5 @@
+# Config Reloader Tests
+
+Checks:
+
+  - `salt-master` is reloaded after config changes

tests/config-reloader/config/fileserver.conf

@@ -0,0 +1,2 @@
+# The buffer size in the file server can be adjusted here:
+file_buffer_size: 1048576

tests/config-reloader/test.sh

@@ -0,0 +1,54 @@
+#!/usr/bin/env bash
+
+set -e
+[ "${DEBUG}" == true ] && set -vx
+
+echo "🧪 Running config-reloader tests ..."
+
+# https://stackoverflow.com/a/4774063/3398062
+SCRIPT_PATH="$( cd -- "$(dirname "$0")" >/dev/null 2>&1 ; pwd -P )"
+
+# shellcheck source=assets/build/functions.sh
+COMMON_FILE="${SCRIPT_PATH}/../lib/common.sh"
+source "${COMMON_FILE}"
+trap cleanup EXIT
+
+# Run test instance
+echo "==> Starting docker-salt-master (${PLATFORM}) ..."
+start_container_and_wait \
+  --env SALT_RESTART_MASTER_ON_CONFIG_CHANGE=true \
+  --volume "${SCRIPT_PATH}/config":/home/salt/data/config:ro \
+|| error "container started"
+ok "container started"
+
+# Get initial configuration values
+echo "==> Checking initial configuration values ..."
+FILE_BUFFER_SIZE="$(salt-run config.get file_buffer_size)"
+YAML_UTF8="$(salt-run config.get yaml_utf8)"
+
+FILE_BUFFER_SIZE_EXPECTED=1048576
+YAML_UTF8_EXPECTED=
+
+check_equal "${FILE_BUFFER_SIZE}" "${FILE_BUFFER_SIZE_EXPECTED}" "file_buffer_size"
+check_equal "${YAML_UTF8}" "${YAML_UTF8_EXPECTED}" "yaml_utf8"
+
+# Update fileserver config
+echo "==> Updating file_buffer_size config ..."
+FILE_BUFFER_SIZE_EXPECTED=2097152
+sed -i "s/file_buffer_size:.*/file_buffer_size: ${FILE_BUFFER_SIZE_EXPECTED}/" "${SCRIPT_PATH}/config/fileserver.conf"
+sleep 30 # Wait for the config to be reloaded
+
+FILE_BUFFER_SIZE="$(salt-run config.get file_buffer_size)"
+check_equal "${FILE_BUFFER_SIZE}" "${FILE_BUFFER_SIZE_EXPECTED}" "file_buffer_size"
+
+# Create yaml_utf8 config
+echo "==> Creating yaml_utf8 config ..."
+YAML_UTF8_EXPECTED=True
+cat > "${SCRIPT_PATH}/config/yaml_utf8.conf" <<EOF
+# Enable extra routines for YAML renderer used states containing UTF characters.
+yaml_utf8: ${YAML_UTF8_EXPECTED}
+EOF
+sleep 30 # Wait for the config to be reloaded
+
+YAML_UTF8="$(salt-run config.get yaml_utf8)"
+check_equal "${YAML_UTF8}" "${YAML_UTF8_EXPECTED}" "yaml_utf8"

tests/lib/common.sh

@@ -43,6 +43,15 @@ function docker-exec()
   docker exec "${CONTAINER_NAME}" "$@"
 }
 
+#---  FUNCTION  -------------------------------------------------------------------------------------------------------
+#          NAME:  docker-logs
+#   DESCRIPTION:  Get the logs of the container.
+#----------------------------------------------------------------------------------------------------------------------
+function docker-logs()
+{
+  docker logs "${CONTAINER_NAME}"
+}
+
 #---  FUNCTION  -------------------------------------------------------------------------------------------------------
 #          NAME:  salt-run
 #   DESCRIPTION:  Execute the salt-run command inside the container.
@@ -107,3 +116,27 @@ function error()
   master_log
   return 1
 }
+
+#---  FUNCTION  -------------------------------------------------------------------------------------------------------
+#          NAME:  check_equal
+#   DESCRIPTION:  Check if the given value is equal to the expected value.
+#----------------------------------------------------------------------------------------------------------------------
+function check_equal()
+{
+  local actual="$1"
+  local expected="$2"
+  local message="$3"
+
+  output=$(cat <<EOF
+${message}
+  Expected: ${expected}
+    Actual: ${actual}
+EOF
+)
+
+  if [[ "${actual}" == "${expected}" ]]; then
+    ok "${output}"
+  else
+    error "${output}"
+  fi
+}