Poseidon

Setup

If you haven't installed Go on your system yet, follow the golang installation guide.

To get your local setup going, run make bootstrap. It will install all required dependencies as well as setting up our git hooks. Run make help to get an overview of available make targets.

The project can be compiled using make build. This should create a binary which can then be executed.

Alternatively, the go run . command can be used to automatically compile and run the project.

Docker

The CI builds a Docker image and pushes it to our Docker registry at drp.codemoon.xopic.de. In order to pull an image from the registry you have to login with sudo docker login drp.codemoon.xopic.de. Execute sudo docker run -p 7200:7200 drp.codemoon.xopic.de/<image name> to run the image locally. You can find the image name in the dockerimage CI job. You can then interact with the webserver on your local port 7200.

You can also build the Docker image locally by executing make docker in the root directory of this project. It builds the binary first and a container with the tag poseidon:latest afterwards. You can then start a Docker container with sudo docker run --rm -p 7200:7200 poseidon:latest.

Linter

To lint our source code and ensure a common code style amongst our codebase we use Golang CI Lint as a linter. Use make lint to execute it.

Git hooks

The repository contains a git pre-commit hook which runs the go formatting tool gofmt to ensure the code is formatted properly before committing. To enable them, run make git-hooks.

Configuration

The file config/config.go contains a configuration struct containing all possible configuration options for Poseidon. The file also defines default values for most of the configuration options.
The options can be overridden with a yaml configuration file whose path can be configured with the flag -config. By default, Poseidon searches for configuration.yaml in the project root. configuration.example.yaml is an example for a configuration file and contains explanations for all options.
The options can also be overridden by environment variables. Currently, only the Go types string, int, bool and struct (nested) are implemented. The name of the environment variable is constructed as follows: POSEIDON_(<name of nested struct>_)*<name of field> (all letters are uppercase).

The precedence of configuration possibilities is:

1. Environment variables
2. Configuration file
3. Default values

If a value is not specified, the value of the subsequent possibility is used.

Example

• The default value for the Port (type int) field in the Server field (type struct) of the configuration is 7200.

• This can be overwritten with the following configuration.yaml:

  server:
    port: 4000
  

• This can again be overwritten by the environment variable POSEIDON_SERVER_PORT. This can be done with export POSEIDON_SERVER_PORT=5000.

Documentation

For the OpenAPI 3.0 definition of the API Poseidon provides, see swagger.yaml.

Authentication

⚠️ Don't use authentication without TLS enabled, as otherwise the token will be transmitted in clear text.

⚠ We encourage you to enable authentication for this API. If disabled, everyone with access to your API has also indirectly access to your Nomad cluster as this API uses it.

The API supports authentication via an HTTP header. To enable it, specify the server.token value in the configuration.yaml or the corresponding environment variable POSEIDON_SERVER_TOKEN.

Once configured, all requests to the API, except the health route require the configured token in the X-Poseidon-Token header.

An example curl command with the configured token being SECRET looks as follows:

$ curl -H "X-Poseidon-Token: SECRET" http://localhost:7200/api/v1/some-protected-route

TLS

We highly encourage the use of TLS in this API to increase the security. To enable TLS, set server.tls or the corresponding environment variable to true and specify the server.certfile and server.keyfile options.

You can create a self-signed certificate to use with this API using the following command.

$ openssl req -x509 -nodes -newkey rsa:2048 -keyout server.rsa.key -out server.rsa.crt -days 3650

Tests

As testing framework we use the testify toolkit.

Run make test to run the unit tests.

E2E

For e2e tests we provide a separate package. E2e tests require the connection to a Nomad cluster. Run make e2e-tests to run the e2e tests. This requires Poseidon to be already running. Instead, you can run make e2e-docker to run the API in a Docker container, and the e2e tests afterwards. You can use the DOCKER_OPTS variable to add additional arguments to the Docker run command that runs the API. By default, it is set to -v $(shell pwd)/configuraton.yaml:/configuration.yaml, which means, your local configuration file is mapped to the container. If you don't want this, use the following command.

$ make e2e-docker DOCKER_OPTS=""

Mocks

For mocks we use mockery. You can create a mock for the interface of your choice by running

make mock name=INTERFACE_NAME pkg=./PATH/TO/PKG

on a specific interface.

For example, for an interface called ExecutorApi in the package nomad, you might run

make mock name=ExecutorApi pkg=./nomad

If the interface changes, you can rerun this command (deleting the mock file first to avoid errors may be necessary).

Mocks can also be generated by using mockery directly on a specific interface. To do this, first navigate to the package the interface is defined in. Then run

mockery \
  --name=<<interface_name>> \
  --structname=<<interface_name>>Mock \
  --filename=<<interface_name>>Mock.go \
  --inpackage

For example, for an interface called ExecutorApi in the package nomad, you might run

mockery \
--name=ExecutorApi \
--structname=ExecutorAPIMock \
--filename=ExecutorAPIMock.go \
--inpackage

Note that per default, the mocks are created in a mocks sub-folder. However, in some cases (if the mock implements private interface methods), it needs to be in the same package as the interface it is mocking. The --inpackage flag can be used to avoid creating it in a subdirectory.