discover

README

Go Discover Nodes for Cloud Providers

go-discover is a Go (golang) library and command line tool to discover ip addresses of nodes in cloud environments based on meta information like tags provided by the environment.

The configuration for the providers is provided as a list of key=val key=val ... tuples. If either the key or the value contains a space ( ), a backslash (\) or double quotes (") then it needs to be quoted with double quotes. Within a quoted string you can use the backslash to escape double quotes or the backslash itself, e.g. key=val "some key"="some value"

Duplicate keys are reported as error and the provider is determined through the provider key.

Supported Providers

The following cloud providers have implementations in the go-discover/provider sub packages. Additional providers can be added through the Register function.

• Aliyun (Alibaba) Cloud Config options
• Amazon AWS Config options
• DigitalOcean Config options
• Google Cloud Config options
• Hetzner Cloud Config options
• Linode Config options
• mDNS Config options
• Microsoft Azure Config options
• Openstack Config options
• Scaleway Config options
• SoftLayer Config options
• TencentCloud Config options
• Triton Config options
• vSphere Config options
• Packet Config options

The following providers are implemented in the go-discover/provider subdirectory but aren't automatically registered. If you want to support these providers, register them manually:

• Kubernetes Config options

HashiCorp maintains acceptance tests that regularly allocate and run tests with real resources to verify the behavior of several of these providers. Those currently are: Amazon AWS, Microsoft Azure, Google Cloud, DigitalOcean, Triton, Scaleway, AliBaba Cloud, vSphere, and Packet.net.

Config Example

# Aliyun (Alibaba) Cloud
provider=aliyun region=... tag_key=consul tag_value=... access_key_id=... access_key_secret=...

# Amazon AWS
provider=aws region=eu-west-1 tag_key=consul tag_value=... access_key_id=... secret_access_key=...

# DigitalOcean
provider=digitalocean region=... tag_name=... api_token=...

# Google Cloud
provider=gce project_name=... zone_pattern=eu-west-* tag_value=consul credentials_file=...

# Hetzner Cloud
provider=hcloud location=... label_selector=... address_type=... api_token=...

# Linode
provider=linode tag_name=... region=us-east address_type=private_v4 api_token=...

# mDNS
provider=mdns service=consul domain=local

# Microsoft Azure
provider=azure tag_name=consul tag_value=... tenant_id=... client_id=... subscription_id=... secret_access_key=...

# Openstack
provider=os tag_key=consul tag_value=server username=... password=... auth_url=...

# Scaleway
provider=scaleway organization=my-org tag_name=consul-server token=... region=...

# SoftLayer
provider=softlayer datacenter=dal06 tag_value=consul username=... api_key=...

# TencentCloud
provider=tencentcloud region=ap-guangzhou tag_key=consul tag_value=... access_key_id=... access_key_secret=...

# Triton
provider=triton account=testaccount url=https://us-sw-1.api.joyentcloud.com key_id=... tag_key=consul-role tag_value=server

# vSphere
provider=vsphere category_name=consul-role tag_name=consul-server host=... user=... password=... insecure_ssl=[true|false]

# Packet
provider=packet auth_token=token project=uuid url=... address_type=...

# Kubernetes
provider=k8s label_selector="app = consul-server"

Command Line Tool Usage

Install the command line tool with:

go get -u github.com/rossrochford/go-discover/cmd/discover

Then run it with:

$ discover addrs provider=aws region=eu-west-1 ...

Library Usage

Install the library with:

go get -u github.com/rossrochford/go-discover

You can then either support discovery for all available providers or only for some of them.

// support discovery for all supported providers
d := discover.Discover{}

// support discovery for AWS and GCE only
d := discover.Discover{
	Providers : map[string]discover.Provider{
		"aws": discover.Providers["aws"],
		"gce": discover.Providers["gce"],
	}
}

// use ioutil.Discard for no log output
l := log.New(os.Stderr, "", log.LstdFlags)

cfg := "provider=aws region=eu-west-1 ..."
addrs, err := d.Addrs(cfg, l)

You can also add support for providers that aren't registered by default:

// Imports at top of file
import "github.com/rossrochford/go-discover/provider/k8s"

// support discovery for all supported providers
d := discover.Discover{}

// support discovery for AWS and GCE only
d := discover.Discover{
	Providers : map[string]discover.Provider{
		"k8s": &k8s.Provider{},
	}
}

// ...

For complete API documentation, see GoDoc. The configuration for the supported providers is documented in the providers sub-package.

Testing

Note: Due to the go.sum checksum errors referenced in #68, you will need Go 1.11.4+ to build/test go-discover.

Configuration tests can be run with Go:

$ go test ./...

By default tests that communicate with providers do not run unless credentials are set for that provider. To run provider tests you must set the necessary environment variables.

Note: This will make real API calls to the account provided by the credentials.

$ AWS_ACCESS_KEY_ID=... AWS_ACCESS_KEY_SECRET=... AWS_REGION=... go test -v ./provider/aws

This requires resources to exist that match those specified in tests (eg instance tags in the case of AWS). To create these resources, there are sets of Terraform configuration in the test/tf directory for supported providers.

You must use the same account and access credentials above. The same environment variables should be applicable and read by Terraform.

$ cd test/tf/aws
$ export AWS_ACCESS_KEY_ID=... AWS_ACCESS_KEY_SECRET=... AWS_REGION=...
$ terraform init
...
$ terraform apply
...

After Terraform successfully runs, you should be able to successfully run the tests, assuming you have exported credentials into your environment:

$ go test -v ./provider/aws

To destroy the resources you need to use Terraform again:

$ cd test/tf/aws
$ terraform destroy
...

Note: There should be no requirements to create and test these resources other than credentials and Terraform. This is to ensure tests can run in development and CI environments consistently across all providers.

Retrieving Test Credentials

Below are instructions for retrieving credentials in order to run tests for some of the providers.

Google Cloud

1. Go to https://console.cloud.google.com/
2. IAM & Admin / Settings:
   • Create Project, e.g. discover
   • Write down the Project ID, e.g. discover-xxx
3. Billing: Ensure that the project is linked to a billing account
4. API Manager / Dashboard: Enable the following APIs
   • Google Compute Engine API
5. IAM & Admin / Service Accounts: Create Service Account
   • Service account name: admin
   • Roles:
     • Project/Service Account Actor
     • Compute Engine/Compute Instance Admin (v1)
     • Compute Engine/Compute Security Admin
   • Furnish a new private key: yes
   • Key type: JSON
6. The credentials file discover-xxx.json will have been downloaded automatically to your machine
7. Source the contents of the credentials file into the GOOGLE_CREDENTIALS environment variable

Azure

See also the [Terraform provider documentation](https://www.terraform.io/docs/providers/azurerm/index.html#creating-credentials).

# Install Azure CLI (https://github.com/Azure/azure-cli)
curl -L https://aka.ms/InstallAzureCli | bash

# 1. Login
$ az login

# 2. Get SubscriptionID
$ az account list
[
  {
    "cloudName": "AzureCloud",
    "id": "subscription_id",
    "isDefault": true,
    "name": "Gratis versie",
    "state": "Enabled",
    "tenantId": "tenant_id",
    "user": {
      "name": "user@email.com",
      "type": "user"
    }
  }
]

# 3. Switch to subscription
$ az account set --subscription="subscription_id"

# 4. Create ClientID and Secret
$ az ad sp create-for-rbac --role="Contributor" --scopes="/subscriptions/subscription_id"
{
  "appId": "client_id",
  "displayName": "azure-cli-2017-07-18-16-51-43",
  "name": "http://azure-cli-2017-07-18-16-51-43",
  "password": "client_secret",
  "tenant": "tenant_id"
}

# 5. Export the Credentials for the client
export ARM_CLIENT_ID=client_id
export ARM_CLIENT_SECRET=client_secret
export ARM_TENANT_ID=tenant_id
export ARM_SUBSCRIPTION_ID=subscription_id

# 6. Test the credentials
$ az vm list-sizes --location 'West Europe'

Documentation

Overview

Package discover provides functions to get metadata for different cloud environments.

Index

• Variables
• type Config
  • func Parse(s string) (Config, error)
  • func (c Config) String() string
• type Discover
  • func New(opts ...Option) (*Discover, error)
  • func (d *Discover) Addrs(cfg string, l *log.Logger) ([]string, error)
  • func (d *Discover) Help() string
  • func (d *Discover) Names() []string
• type Option
  • func WithProviders(m map[string]Provider) Option
  • func WithUserAgent(agent string) Option
• type Provider
• type ProviderWithUserAgent

Variables

var Providers = map[string]Provider{
	"aliyun":       &aliyun.Provider{},
	"aws":          &aws.Provider{},
	"azure":        &azure.Provider{},
	"digitalocean": &digitalocean.Provider{},
	"gce":          &gce.Provider{},
	"hcloud":       &hcloud.Provider{},
	"linode":       &linode.Provider{},
	"mdns":         &mdns.Provider{},
	"os":           &os.Provider{},
	"scaleway":     &scaleway.Provider{},
	"softlayer":    &softlayer.Provider{},
	"tencentcloud": &tencentcloud.Provider{},
	"triton":       &triton.Provider{},
	"vsphere":      &vsphere.Provider{},
	"packet":       &packet.Provider{},
}

Providers contains all available providers.

Types

type Config

type Config map[string]string

Config stores key/value pairs for the discovery functions to use.

func Parse

func Parse(s string) (Config, error)

Parse parses a "key=val key=val ..." string into a config map. Keys and values which contain spaces, backslashes or double-quotes must be quoted with double quotes. Use the backslash to escape special characters within quoted strings, e.g. "some key"="some \"value\"".

func (Config) String

func (c Config) String() string

String formats a config map into the "key=val key=val ..." understood by Parse. The order of the keys is stable.

type Discover

type Discover struct {
	// Providers is the list of address lookup providers.
	// If nil, the default list of providers is used.
	Providers map[string]Provider
	// contains filtered or unexported fields
}

Discover looks up metadata in different cloud environments.

func New

func New(opts ...Option) (*Discover, error)

New creates a new discover client with the given options.

func (*Discover) Addrs

func (d *Discover) Addrs(cfg string, l *log.Logger) ([]string, error)

Addrs discovers ip addresses of nodes that match the given filter criteria. The config string must have the format 'provider=xxx key=val key=val ...' where the keys and values are provider specific. The values are URL encoded.

func (*Discover) Help

func (d *Discover) Help() string

Help describes the format of the configuration string for address discovery and the various provider specific options.

func (*Discover) Names

func (d *Discover) Names() []string

Names returns the names of the configured providers.

type Option

type Option func(*Discover) error

Option is used as an initialization option/

func WithProviders

func WithProviders(m map[string]Provider) Option

WithProviders allows specifying your own set of providers.

func WithUserAgent

func WithUserAgent(agent string) Option

WithUserAgent allows specifying a custom user agent option to send with requests when the underlying client library supports it.

type Provider

type Provider interface {
	// Addrs looks up addresses in the cloud environment according to the
	// configuration provided in args.
	Addrs(args map[string]string, l *log.Logger) ([]string, error)

	// Help provides the configuration help for the command line client.
	Help() string
}

Provider has lookup functions for meta data in a cloud environment.

type ProviderWithUserAgent

type ProviderWithUserAgent interface {
	// SetUserAgent sets the user agent on the provider to the provided string.
	SetUserAgent(s string)
}

ProviderWithUserAgent is a provider that declares it's user agent. Not all providers support this.