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Install Docker Desktop for MacOS

Refer to Installation

SC4S Initial Configuration

SC4S can be run with docker-compose or directly from the CLI with the simple docker run command. Both options are outlined below.

  • Create a directory on the server for local configurations and disk buffering. This should be available to all administrators, for example: /opt/sc4s/

  • (Optional for docker-compose) Create a docker-compose.yml file in the directory created above, based on the template below:

  • IMPORTANT: Always use the latest compose file (below) with the current release. By default, the latest container is automatically downloaded at each restart. Therefore, make it a habit to check back here regularly to be sure any changes that may have been made to the compose template file below (e.g. suggested mount points) are incorporated in production prior to relaunching via compose.

version: "3.7"
      replicas: 2
        condition: on-failure
       - target: 514
         published: 514
         protocol: tcp
       - target: 514
         published: 514
         protocol: udp
       - target: 601
         published: 601
         protocol: tcp
       - target: 6514
         published: 6514
         protocol: tcp
      - /opt/sc4s/env_file
      - /opt/sc4s/local:/etc/syslog-ng/conf.d/local:z
      - splunk-sc4s-var:/var/lib/syslog-ng
# Uncomment the following line if local disk archiving is desired
#     - /opt/sc4s/archive:/var/lib/syslog-ng/archive:z
# Map location of TLS custom TLS
#     - /opt/sc4s/tls:/etc/syslog-ng/tls:z

  • Set /opt/sc4s folder as shared in Docker (Settings -> Resources -> File Sharing)
  • Execute the following command to create a local volume that will contain the disk buffer files in the event of a communication failure to the upstream destination(s). This will also be used to keep track of the state of syslog-ng between restarts, and in particular the state of the disk buffer. This is a required step.
sudo docker volume create splunk-sc4s-var
  • NOTE: Be sure to account for disk space requirements for the docker volume created above. This volume is located in /var/lib/docker/volumes/ and could grow significantly if there is an extended outage to the SC4S destinations (typically HEC endpoints). See the “SC4S Disk Buffer Configuration” section on the Configuration page for more info.

  • IMPORTANT: When creating the directories below, ensure the directories created match the volume mounts specified in the docker-compose.yml file (if used). Failure to do this will cause SC4S to abort at startup.

  • Create subdirectories /opt/sc4s/local /opt/sc4s/archive /opt/sc4s/tls

  • Create a file named /opt/sc4s/env_file and add the following environment variables and values:

#Uncomment the following line if using untrusted SSL certificates
  • Update SC4S_DEST_SPLUNK_HEC_DEFAULT_URL and SC4S_DEST_SPLUNK_HEC_DEFAULT_TOKEN to reflect the correct values for your environment. Do not configure HEC Acknowledgement when deploying the HEC token on the Splunk side; the underlying syslog-ng http destination does not support this feature. Moreover, HEC Ack would significantly degrade performance for streaming data such as syslog.

  • The default number of SC4S_DEST_SPLUNK_HEC_WORKERS is 10. Consult the community if you feel the number of workers (threads) should deviate from this.

  • NOTE: Splunk Connect for Syslog defaults to secure configurations. If you are not using trusted SSL certificates, be sure to uncomment the last line in the example above.

Dedicated (Unique) Listening Ports

  • NOTE: Container networking differs on MacOS compared to that for linux. On Docker Desktop, there is no “host” networking driver, so NAT networking must be used. For this reason, each listening port on the container must be mapped to a listening port on the host. These port mappings are configured in the docker-compose.yml file or directly as a runtime option when run out of the CLI. Be sure to update the docker-compose.yml file or CLI arguments when adding listening ports for new data sources.

Follow these steps to configure unique ports:

  • Modify the /opt/sc4s/env_file file to include the port-specific environment variable(s). Refer to the “Sources” documentation to identify the specific environment variables that are mapped to each data source vendor/technology.
  • (Optional for docker-compose) The docker compose file used to start the SC4S container needs to be modified as well to reflect the additional listening ports configured by the environment variable(s) added above. The docker compose file can be amended with additional target stanzas in the ports section of the file (after the default ports). For example, the following additional target and published lines provide for 21 additional technology-specific UDP and TCP ports:
       - target: 5000-5020
         published: 5000-5020
         protocol: tcp
       - target: 5000-5020
         published: 5000-5020
         protocol: udp

Start/Restart SC4S

You can use the following command to directly start SC4S if you are not using docker-compose. Be sure to map the listening ports (-p arguments) according to your needs:

/usr/bin/podman run -p 514:514 -p 514:514/udp -p 6514:6514 -p 5000-5020:5000-5020 -p 5000-5020:5000-5020/udp \
    --env-file=/opt/sc4s/env_file \
    --name SC4S \
    --rm splunk/scs:latest

If you are using docker-compose, from the catalog where you created compose file execute:

docker-compose up

Otherwise use docker-compose with -f flag pointing to the compose file

docker-compose up -f /path/to/compose/file/docker-compose.yml

Stop SC4S

If the container is run directly from the CLI, simply stop the container using the docker stop <containerID> command.

If using docker-compose, execute:

docker-compose down 


docker-compose down -f /path/to/compose/file/docker-compose.yml

Verify Proper Operation

SC4S has a number of “preflight” checks to ensure that the container starts properly and that the syntax of the underlying syslog-ng configuration is correct. After this step completes, to verify SC4S is properly communicating with Splunk, execute the following search in Splunk:

index=* sourcetype=sc4s:events "starting up"

This should yield an event similar to the following:

syslog-ng starting up; version='3.28.1'

When the startup process proceeds normally (without syntax errors). If you do not see this, follow the steps below before proceeding to deeper-level troubleshooting:

  • Check to see that the URL, token, and TLS/SSL settings are correct, and that the appropriate firewall ports are open (8088 or 443).
  • Check to see that the proper indexes are created in Splunk, and that the token has access to them.
  • Ensure the proper operation of the load balancer if used.
  • Lastly, execute the following command to check the sc4s startup process running in the container.
docker logs SC4S

You should see events similar to those below in the output:

syslog-ng checking config
sc4s version=v1.36.0
starting goss
starting syslog-ng

If you do not see the output above, proceed to the “Troubleshoot sc4s server” and “Troubleshoot resources” sections for more detailed information.