A simple Mattermost notifier written in Go

A Go (golang) simple client for sending Mattermost posts via its REST API v4. This program makes use of the Go libraries http and url for interacting with a Mattermost server and Cobra coupled with Viper to implement the CLI interface.

Official Docker Image

A docker image is available in Docker Hub: madrisan/mattermost-notify

How to pull the Docker Image

docker pull madrisan/mattermost-notify

Build

Using go get

export GO111MODULE=on
[ "$GOPATH" ] || export GOPATH="$HOME/go"
go get -u github.com/madrisan/go-mattermost-notify

export PATH="$PATH:$GOPATH/bin"
$GOPATH/bin/go-mattermost-notify version

From the source code

git clone https://github.com/madrisan/go-mattermost-notify
cd go-mattermost-notify

make dev     # creates the binary for testing the application locally
make bin     # creates the binaries for all the supported OS and architectures

Create a container

podman build -t go-mattermost-notify:latest -f deploy/Containerfile .

or if you prefer, use docker or nerdctl instead of podman.

If you need to add an extra certificate that is signed by a custom CA (to fix the error message x509: certificate signed by unknown authority), do create a file named additional-ca-cert-bundle.crt at the root of the project sources and choose the docker file deploy/Containerfile.additional_ca instead.

podman build -t go-mattermost-notify:latest -f deploy/Containerfile.additional_ca .

Now you can load the image created by the previous command with the following command.

podman run --rm -it localhost/go-mattermost-notify:latest [add-the-required-options]

If you need to debug some issues, you can overwrite the entrypoint with the busybox shell:

podman run --entrypoint=sh --rm -it localhost/go-mattermost-notify:latest

Usage

Post Command

Use the post command of go-mattermost-notify to send a message to Mattermost.

$ go-mattermost-notify post --help
Post a message to a Mattermost channel or user using its REST APIv4 interface.

Example:
  post -c rybfbdi9ojy8xxxjjxc88kh3me -A CI -t "Job Status" -m "The job \#BEEF has failed :bug:" -l critical
  post -c @alice -A CI -t "Job Status" -m "The job \#BEEF ended successfully :tada:" -l success

Usage:
  go-mattermost-notify post [flags]

Flags:
  -A, --author string    author of the message
  -c, --channel string   Mattermost channel ID or username. Example: rybfbdi9ojy8xxxjjxc88kh3me or @alice
  -h, --help             help for post
  -l, --level string     criticity level. Can be info, success, warning, or critical (default "info")
  -m, --message string   the (markdown-formatted) message to send to the Mattermost channel
  -T, --team string      the Mattermost team
  -t, --title string     the title that will precede the text message

Global Flags:
  -a, --access-token string   Mattermost Access Token. The command-line value has precedence over the MATTERMOST_ACCESS_TOKEN environment variable.
      --config string         config file (default is $HOME/.go-mattermost-notify.yaml)
  -q, --quiet                 quiet mode
  -u, --url string            Mattermost URL. The command-line value has precedence over the MATTERMOST_URL environment variable.

The access token and the url can be set using different methods:

• At command-line (--access-token and --url respectively)
• By setting the environment variables MATTERMOST_ACCESS_TOKEN and MATTERMOST_URL
• By creating a yaml configuration file (by default ~/.go-mattermost-notify.yaml) containing the lines:

mattermost:
  access-token: <access-token>
  url: <base URL of the Mattermost server>

The precedence order is: flags > environment variables > configuration file.

Output in Mattermost

As an example we show a Mattermost message using some markdown features (text modifiers, emoticons, and a clickable URL):

Get Command

The get command of go-mattermost-notify is mainly intended for debugging or for getting Mattemost configuration information.

$ go-mattermost-notify get --help
Send a Get query to Mattermost using its REST APIv4 interface.

See the Mattermost API documentation:
  https://api.mattermost.com/

Example:
  get /bots
  get /channels
  get /users/me

Usage:
  go-mattermost-notify get [flags]

Flags:
  -h, --help   help for get
  -i, --insecure   ignore SSL/TLS certificate check

Global Flags:
  -a, --access-token string   Mattermost Access Token. The command-line value has precedence over the MATTERMOST_ACCESS_TOKEN environment variable.
      --config string         config file (default is $HOME/.go-mattermost-notify.yaml)
  -q, --quiet                 quiet mode
  -u, --url string            Mattermost URL. The command-line value has precedence over the MATTERMOST_URL environment variable.

Developers' corner

Some extra actions that may be usefull to project developers.

Run the Test Suite

Just run in the top source folder:

make test

or, if you like a more verbose output:

TESTARGS="-test.v" make test

Generate Test Coverage Statistics

Go to the top source folder and enter the command:

make cover

Style and Static Code Analyzers

GolangCI-Lint

Run the GolangCI-Lint linters aggregator:

make lint

You may need to run the following command before:

go install github.com/golangci/golangci-lint/cmd/golangci-lint@v1.45.2

to locally install the binary golangci-lint.

Go Vet

Run the Go source code static analysis tool vet to find any common errors:

make vet