Add extra config capabilities via a map

Dockerfile

@@ -31,6 +31,7 @@ RUN mv /etc/dd-agent/datadog.conf.example /etc/dd-agent/datadog.conf \
 # Add Docker check
 COPY conf.d/docker_daemon.yaml /etc/dd-agent/conf.d/docker_daemon.yaml
 
+COPY alpine/config_helper.py /config_helper.py
 COPY entrypoint.sh /entrypoint.sh
 
 # Extra conf.d and checks.d

alpine/Dockerfile

@@ -14,6 +14,7 @@ COPY conf.d/docker_daemon.yaml "$DD_HOME/agent/conf.d/docker_daemon.yaml"
 
 # Add install and config files
 ADD https://raw.githubusercontent.com/DataDog/dd-agent/master/packaging/datadog-agent/source/setup_agent.sh /tmp/setup_agent.sh
+COPY config_helper.py /config_helper.py
 COPY entrypoint.sh /entrypoint.sh
 
 # Expose supervisor and DogStatsD port

alpine/config_helper.py

@@ -0,0 +1,38 @@
+#!/opt/datadog-agent/embedded/bin/python
+'''
+This script is a helper to build additionnal config file options
+'''
+from argparse import ArgumentParser
+from os import getenv
+from json import loads
+
+def add_extra_datadog_conf(conf_string, conf_file):
+    '''
+    This function takes a json-formatted string as parameter and adds its
+    content at the end of the datadog.conf file given as parameter.
+
+    The json string defining the additionnal config HAS to be formatted as
+    follows:
+    '{"key1": "value1", "key2": "value2"}'
+    or: '{"histogram_percentiles": "0.75, 0.95, 0.99"}'
+    '''
+    try:
+        conf_data = loads(conf_string)
+        with open(conf_file, 'a') as f:
+            for data in conf_data:
+                f.write('{}: {}\n'.format(data, conf_data[data]))
+    except:
+        pass
+
+if __name__ == '__main__':
+    parser = ArgumentParser()
+    parser.add_argument('-c', '--config-file',
+                        default='/etc/dd-agent/datadog.conf',
+                        help='Full path of the config file to write the config to')
+    parser.add_argument('-j', '--json-env',
+                        default='DD_EXTRA_CONF',
+                        help='Name of the environment variable to retrieve the json string from')
+    args = parser.parse_args()
+
+    dd_extra_conf = getenv(args.json_env, '{}')
+    add_extra_datadog_conf(dd_extra_conf, args.config_file)

alpine/entrypoint.sh

@@ -115,6 +115,10 @@ if [[ $SD_BACKEND_PASSWORD ]]; then
     sed -i -e 's@^# sd_backend_password:.*$@sd_backend_password: '${SD_BACKEND_PASSWORD}'@' /opt/datadog-agent/agent/datadog.conf
 fi
 
+if [[ -n "$DD_EXTRA_CONF" ]]; then
+    PYTHONPATH=/opt/datadog-agent/agent /opt/datadog-agent/embedded/bin/python /config_helper.py -c /opt/datadog-agent/agent/datadog.conf
+fi
+
 ##### Integrations config #####
 
 if [[ -n "${KUBERNETES}" || -n "${MESOS_MASTER}" || -n "${MESOS_SLAVE}" ]]; then

entrypoint.sh

@@ -129,6 +129,10 @@ if [[ $SD_BACKEND_PASSWORD ]]; then
     sed -i -e 's@^# sd_backend_password:.*$@sd_backend_password: '${SD_BACKEND_PASSWORD}'@' /etc/dd-agent/datadog.conf
 fi
 
+if [[ -n "$DD_EXTRA_CONF" ]]; then
+  PYTHONPATH=/opt/datadog-agent/agent /opt/datadog-agent/embedded/bin/python /config_helper.py
+fi
+
 ##### Integrations config #####
 
 if [[ $KUBERNETES || $MESOS_MASTER || $MESOS_SLAVE ]]; then