» Cloud Auto-joining

As of Nomad 0.8.4, retry_join accepts a unified interface using the go-discover library for doing automatic cluster joining using cloud metadata. To use retry-join with a supported cloud provider, specify the configuration on the command line or configuration file as a key=value key=value ... string.

Values are taken literally and must not be URL encoded. If the values contain spaces, backslashes or double quotes then they need to be double quoted and the usual escaping rules apply.

{
  "retry_join": ["provider=my-cloud config=val config2=\"some other val\" ..."]
}

The cloud provider-specific configurations are detailed below. This can be combined with static IP or DNS addresses or even multiple configurations for different providers.

In order to use discovery behind a proxy, you will need to set HTTP_PROXY, HTTPS_PROXY and NO_PROXY environment variables per Golang net/http library.

The following sections give the options specific to a subset of supported cloud provider. For information on all providers, see further documentation in go-discover.

» Amazon EC2

This returns the first private IP address of all servers in the given region which have the given tag_key and tag_value.

{
  "retry_join": ["provider=aws tag_key=... tag_value=..."]
}
  • provider (required) - the name of the provider ("aws" in this case).
  • tag_key (required) - the key of the tag to auto-join on.
  • tag_value (required) - the value of the tag to auto-join on.
  • region (optional) - the AWS region to authenticate in.
  • addr_type (optional) - the type of address to discover: private_v4, public_v4, public_v6. Default is private_v4. (>= 1.0)
  • access_key_id (optional) - the AWS access key for authentication (see below for more information about authenticating).
  • secret_access_key (optional) - the AWS secret access key for authentication (see below for more information about authenticating).

» Authentication & Precedence

  • Static credentials access_key_id=... secret_access_key=...
  • Environment variables (AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY)
  • Shared credentials file (~/.aws/credentials or the path specified by AWS_SHARED_CREDENTIALS_FILE)
  • ECS task role metadata (container-specific).
  • EC2 instance role metadata.

The only required IAM permission is ec2:DescribeInstances, and it is recommended that you make a dedicated key used only for auto-joining. If the region is omitted it will be discovered through the local instance's EC2 metadata endpoint.

» Microsoft Azure

This returns the first private IP address of all servers in the given region which have the given tag_key and tag_value in the tenant and subscription, or in the given resource_group of a vm_scale_set for Virtual Machine Scale Sets.

{
  "retry_join": ["provider=azure tag_name=... tag_value=... tenant_id=... client_id=... subscription_id=... secret_access_key=..."]
}
  • provider (required) - the name of the provider ("azure" in this case).
  • tenant_id (required) - the tenant to join machines in.
  • client_id (required) - the client to authenticate with.
  • secret_access_key (required) - the secret client key.

Use these configuration parameters when using tags: - tag_name - the name of the tag to auto-join on. - tag_value - the value of the tag to auto-join on.

Use these configuration parameters when using Virtual Machine Scale Sets (Consul 1.0.3 and later): - resource_group - the name of the resource group to filter on. - vm_scale_set - the name of the virtual machine scale set to filter on.

When using tags the only permission needed is the `ListAll` method for `NetworkInterfaces`. When using
Virtual Machine Scale Sets the only role action needed is `Microsoft.Compute/virtualMachineScaleSets/*/read`.

» Google Compute Engine

This returns the first private IP address of all servers in the given project which have the given tag_value. ```

{
"retry_join": ["provider=gce project_name=... tag_value=..."]
}
  • provider (required) - the name of the provider ("gce" in this case).
  • tag_value (required) - the value of the tag to auto-join on.
  • project_name (optional) - the name of the project to auto-join on. Discovered if not set.
  • zone_pattern (optional) - the list of zones can be restricted through an RE2 compatible regular expression. If omitted, servers in all zones are returned.
  • credentials_file (optional) - the credentials file for authentication. See below for more information.

» Authentication & Precedence

  • Use credentials from credentials_file, if provided.
  • Use JSON file from GOOGLE_APPLICATION_CREDENTIALS environment variable.
  • Use JSON file in a location known to the gcloud command-line tool.
  • On Windows, this is %APPDATA%/gcloud/application_default_credentials.json.
  • On other systems, $HOME/.config/gcloud/application_default_credentials.json.
  • On Google Compute Engine, use credentials from the metadata server. In this final case any provided scopes are ignored.

Discovery requires a GCE Service Account. Credentials are searched using the following paths, in order of precedence.