gungnir

(pronounced “GUNG-neer”)

Summary

Gungnir provides an API to get information about a device, based upon events found in the database. It can also return the events themselves, which are WRP Messages. For more information on how Gungnir fits into codex, check out the codex README.

Table of Contents

• Code of Conduct
• Details
• Build
• Deploy
• Contributing

Code of Conduct

This project and everyone participating in it are governed by the XMiDT Code Of Conduct. By participating, you agree to this Code.

Details

Gungnir has two endpoints currently:

• /device/{deviceID}/events provides a list of events for the specified device id, ordered in descending order by record birth date. The list of events are a list of WRP messages extended to also include the BirthDate of the record.
• /device/{deviceID}/status provides the status of the device according to the most recent birth date. The values it returns are:
  • the device id
  • the state
  • the record's birth date
  • the current time
  • the reason the device went offline most recently

When Gungnir received a request to either endpoint, it first validates that the request is authorized. This authorization is configurable. Then, Gungnir gets records for that device id, limited by a configurable max number of records but sorted in descending order by birth date. Gungnir checks how the record is encrypted, if at all, and decrypts it. Then it decodes the message into a struct so that it can parse the information as necessary before returning the information the consumer asked for.

The events are stored in the database as MsgPack, and gungnir uses ugorji's implementation to decode them.

Build

Source

In order to build from the source, you need a working Go environment with version 1.11 or greater. Find more information on the Go website.

You can directly use go get to put the Gungnir binary into your GOPATH:

GO111MODULE=on go get github.com/xmidt-org/gungnir

You can also clone the repository yourself and build using make:

mkdir -p $GOPATH/src/github.com/xmidt-org
cd $GOPATH/src/github.com/xmidt-org
git clone git@github.com:xmidt-org/gungnir.git
cd gungnir
make build

Makefile

The Makefile has the following options you may find helpful:

• make build: builds the Gungnir binary
• make docker: builds a docker image for Gungnir, making sure to get all dependencies
• make local-docker: builds a docker image for Gungnir with the assumption that the dependencies can be found already
• make it: runs make docker, then deploys Gungnir and a cockroachdb database into docker.
• make test: runs unit tests with coverage for Gungnir
• make clean: deletes previously-built binaries and object files

RPM

First have a local clone of the source and go into the root directory of the repository. Then use rpkg to build the rpm:

rpkg srpm --spec <repo location>/<spec file location in repo>
rpkg -C <repo location>/.config/rpkg.conf sources --outdir <repo location>'

Docker

The docker image can be built either with the Makefile or by running a docker command. Either option requires first getting the source code.

See Makefile on specifics of how to build the image that way.

For running a command, either you can run docker build after getting all dependencies, or make the command fetch the dependencies. If you don't want to get the dependencies, run the following command:

docker build -t gungnir:local -f deploy/Dockerfile .

If you want to get the dependencies then build, run the following commands:

GO111MODULE=on go mod vendor
docker build -t gungnir:local -f deploy/Dockerfile.local .

For either command, if you want the tag to be a version instead of local, then replace local in the docker build command.

Kubernetes

WIP. TODO: add info

Deploy

For deploying on Docker or in Kubernetes, refer to the deploy README.

For running locally, ensure you have the binary built. If it's in your GOPATH, run:

gungnir

If the binary is in your current folder, run:

./gungnir

Contributing

Refer to CONTRIBUTING.md.