Fleet Server

Fleet server is the control server to manage a fleet of elastic-agents.

For production deployments the fleet-server is supervised and bootstrapped by an elastic-agent.

Compatibility and upgrades

Fleet-server communicates with Elasticsearch. Elasticsearch must be on the same version or newer. Fleet server is always on the exact same version as the Elastic Agent running fleet-server. Any Elastic Agent enrolling into a fleet-server must be the same version or older. For Kibana it is assumed it is on the same version as Elasticsearch. With this the compatibility looks as following:

Elastic Agent <= Elastic Agent with fleet-server <= Elasticsearch / Kibana

There might be differences on the bugfix version.

For upgrades Elasticsearch/Kibana must be upgraded first, then the Elastic Agent with fleet-server followed by any other Elastic Agents.

MacOSX Version

The golang-crossbuild produces images used for testing/building. The golang-crossbuild:1.16.X-darwin-debian10 images expects the minimum MacOSX version to be 10.14+.

Development

The following are notes to help developers onboarding to the project to quickly get running. These notes might change at any time.

Development build

To compile the fleet-server in development mode set the env var DEV=true. When compiled in development mode the fleet-server will support debugging. i.e.:

SNAPSHOT=true DEV=true make release-darwin/amd64
GOOS=darwin GOARCH=amd64 go build -tags="dev" -gcflags="all=-N -l" -ldflags="-X main.Version=8.7.0 -X main.Commit=31668e0 -X main.BuildTime=2022-12-23T20:06:20Z" -buildmode=pie -o build/binaries/fleet-server-8.7.0-darwin-x86_64/fleet-server .

Change release-darwin/amd64 to release-YOUR_OS/platform. Run make list-platforms to check out the possible values.

The SNAPSHOT flag sets the snapshot version flag.

Docker build

You can build a fleet-server docker image with make build-docker. This image includes the default fleet-server.yml configuration file and can be customized with the available environment variables.

This image includes only fleet-server and is intended for stand alone mode, see the section about stand alone Fleet Server to know more.

You can run this image with the included configuration file with the following command:

docker run -it --rm \
  -e ELASTICSEARCH_HOSTS="https://elasticsearch:9200" \
  -e ELASTICSEARCH_SERVICE_TOKEN="someservicetoken" \
  -e ELASTICSEARCH_CA_TRUSTED_FINGERPRINT="somefingerprint" \
  docker.elastic.co/fleet-server/fleet-server:8.8.0

You can replace the included configuration by mounting your configuration file as a volume in /etc/fleet-server.yml.

docker run -it --rm \
  -e ELASTICSEARCH_HOSTS="https://elasticsearch:9200" \
  -e ELASTICSEARCH_SERVICE_TOKEN="someservicetoken" \
  -e ELASTICSEARCH_CA_TRUSTED_FINGERPRINT="somefingerprint" \
  -v "/path/to/your/fleet-server.yml:/etc/fleet-server.yml:ro" \
  docker.elastic.co/fleet-server/fleet-server:8.8.0

Running a development build

ES and Kibana from SNAPSHOTS API on host

Download SNAPSHOT builds for Elasticsearch and Kibana from the snapshots API: Edit the version and OS/arch to suit your system, or check the API (change the version if needed) if the ones below does not suit you.

• 8.7.0-SNAPSHOT-linux-x86_64.tar.gz
• 8.7.0-SNAPSHOT-darwin-aarch64.tar.gz
• 8.7.0-SNAPSHOT-windows-x86_64.zip

TODO: parse the JSON to get the URL

wget https://snapshots.elastic.co/8.7.0-19f30181/downloads/elasticsearch/elasticsearch-8.7.0-SNAPSHOT-linux-x86_64.tar.gz
wget https://snapshots.elastic.co/8.7.0-19f30181/downloads/kibana/kibana-8.7.0-SNAPSHOT-linux-x86_64.tar.gz

Generally you will need to unarchive and run the binaries:

tar -xzf elasticsearch-8.7.0-SNAPSHOT-linux-x86_64.tar.gz
cd elasticsearch-8.7.0-SNAPSHOT
./bin/elasticsearch

The elasticsearch output will output the elastic user's password and a Kibana configuration string.

tar -xzf kibana-8.7.0-SNAPSHOT-linux-x86_64.tar.gz
cd kibana-8.7.0-SNAPSHOT
./bin/kibana

The kibana output will show a URL that will need to be visted in order to configure Kibana with the string elasticsearch provides.

More instructions for setup can be found in the Elastic Stack Installation Guide.

fleet-server stand alone

Fleet UI requires a managed Fleet Server, to be able to use stand alone Fleet server, you need to enroll a managed Fleet Server or disable this requirement. You can disable this requirement since Kibana 8.8.0, starting it with xpack.fleet.enableExperimental: ['fleetServerStandalone']. This is only supported internally and is not intended for end-users at this time.

Access the Fleet UI on Kibana and generate a fleet-server policy. Set the following env vars with the information from Kibana:

• ELASTICSEARCH_CA_TRUSTED_FINGERPRINT
• ELASTICSEARCH_SERVICE_TOKEN
• FLEET_SERVER_POLICY_ID

Create a self-signed TLS CA and cert+key for the fleet-server instance, you can use elasticsearch-certutil for this:

# Create a CA
../elasticsearch/bin/elasticsearch-certutil ca --pem --out stack.zip
unzip stack.zip
# Create a cert+key
../elasticsearch/bin/elasticsearch-certutil cert --pem --ca-cert ca/ca.crt --ca-key ca/ca.key --ip $HOST_IP_ADDR --out cert.zip
unzip cert.zip

Ensure that server.ssl.enabled: true is set as well as the server.ssl.certificate and server.ssl.key attributes in fleet-server.yml

Then run the fleet-server:

./build/binaries/fleet-server-8.7.0-darwin-x86_64/fleet-server -c fleet-server.yml

By default the fleet-server will attempt to connect to Elasticsearch on https://localhost:9200, if this needs to be changed set it with ELASTICSEARCH_HOSTS The fleet-server should appear as an agent with the ID dev-fleet-server.

Any additional agents will need the ca/ca.crt file to enroll (or will need to use the --insecure flag).

fleet-server+agent on a Vagrant VM

The development Vagrant machine assumes the elastic-agent, beats, and fleet-server repos are in the same folder. Thus, it mounts ../ to /vagrant on the Vagrant machine. The vagrant machine IP address is 192.168.56.43. Use https://192.168.56.43:8220 as fleet-server host.

vagrant up
vagrant ssh

Build the elastic-agent

Once in the Vagrant VM, and assuming that the repos are correctly mounted in /vagrant. Build the agent by running:

cd /vagrant/elastic-agent
SNAPSHOT=true EXTERNAL=true PLATFORMS="linux/amd64" PACKAGES="tar.gz" mage -v dev:package # adjust PLATFORMS and PACKAGES to your system and needs.

For detailed instructions, check the Elastic-Agent repo.

Run the elastic-agent+fleet-server in Vagrant

Copy and unpack the elastic-agent .tar.gz file and replace the fleet-server binary in elastic-agent-8.Y.Z-SNAPSHOT-OS-ARCH/data/elastic-agent-*/components/ with the snapshot from the fleet-server repo.

Then go to Kibana > Managment > Fleet and follow the instructions there.

The vagrant machine IP address is 192.168.56.43. Use https://192.168.56.43:8220 as fleet-server host.

tl;dr/example:

cp /vagrant/elastic-agent/build/distributions/elastic-agent-8.7.0-SNAPSHOT-linux-x86_64.tar.gz* ./
tar -xzf elastic-agent-8.7.0-SNAPSHOT-linux-x86_64.tar.gz
cd elastic-agent-8.7.0-SNAPSHOT-linux-x86_64
cp build/binaries/fleet-server-8.7.0-SNAPSHOT-linux-x86_64/fleet-server ./data/elastic-agent-494b79/components/
./elastic-agent install ...

Running go test and benchmarks

When developing new features as you write code you would want to make sure your changes are not breaking any pre-existing functionality. For this reason as you make changes you might want to run a subset of tests or the full tests before you create a pull request.

Running go tests

To execute the full unit tests from your local environment you can do the following

make test-unit

This make target will execute the go unit tests and should normally pass without an issue.

Running go benchmark tests

It's a good practice before you start your changes to establish the current baseline of the benchmarks in your machine. To establish the baseline benchmark report you can follow the following workflow

Establish a baseline

BENCH_BASE=base.out make benchmark

This will execute all the go benchmark test and write the output into the file build/base.out. If you omit the BENCH_BASE variable it will automatically select the name build/benchmark-{git_head_sha1}.out.

Re-running benchmark after changes

After applying your changes into the code you can reuse the same command but with different output file.

BENCH_BASE=next.out make benchmark

At this point you can compare the 2 reports using benchstat.

Comparing the 2 results

BENCH_BASE=base.out BENCH_NEXT=next.out make benchstat

And this will print the difference between the baseline and next results.

You can read more on the benchstat official site.

There are some additional parameters that you can use with the benchmark target.

• BENCHMARK_FILTER: you can define the test filter so that you only run a subset of tests (Default: Bench, only run the test BenchmarkXXXX and not unit tests)
• BENCHMARK_COUNT: you can define the number of iterations go test will run. Having larger number helps remove run-to-run variations (Default: 8)