228 lines
8.2 KiB
Plaintext
228 lines
8.2 KiB
Plaintext
---
|
|
layout: docs
|
|
page_title: server_join Stanza - Agent Configuration
|
|
description: >-
|
|
The "server_join" stanza specifies how the Nomad agent will discover and
|
|
connect to Nomad servers.
|
|
---
|
|
|
|
# `server_join` Stanza
|
|
|
|
<Placement
|
|
groups={[
|
|
['server', 'server_join'],
|
|
['client', 'server_join'],
|
|
]}
|
|
/>
|
|
|
|
The `server_join` stanza specifies how the Nomad agent will discover and connect
|
|
to Nomad servers.
|
|
|
|
```hcl
|
|
server_join {
|
|
retry_join = [ "1.1.1.1", "2.2.2.2" ]
|
|
retry_max = 3
|
|
retry_interval = "15s"
|
|
}
|
|
```
|
|
|
|
## `server_join` Parameters
|
|
|
|
- `retry_join` `(array<string>: [])` - Specifies a list of server addresses to
|
|
join. This is similar to [`start_join`](#start_join), but will continue to
|
|
be attempted even if the initial join attempt fails, up to
|
|
[retry_max](#retry_max). Further, `retry_join` is available to
|
|
both Nomad servers and clients, while `start_join` is only defined for Nomad
|
|
servers. This is useful for cases where we know the address will become
|
|
available eventually. Use `retry_join` with an array as a replacement for
|
|
`start_join`, **do not use both options**.
|
|
|
|
Address format includes both using IP addresses as well as an interface to the
|
|
[go-discover](https://github.com/hashicorp/go-discover) library for doing
|
|
automated cluster joining using cloud metadata. See the [Cloud Auto-join](#cloud-auto-join)
|
|
section below for more information.
|
|
|
|
```
|
|
server_join {
|
|
retry_join = [ "1.1.1.1", "2.2.2.2" ]
|
|
}
|
|
```
|
|
|
|
Using the `go-discover` interface, this can be defined both in a client or
|
|
server configuration as well as provided as a command-line argument.
|
|
|
|
```
|
|
server_join {
|
|
retry_join = [ "provider=aws tag_key=..." ]
|
|
}
|
|
```
|
|
|
|
See the [server address format](#server-address-format) for more information about expected
|
|
server address formats.
|
|
|
|
- `retry_interval` `(string: "30s")` - Specifies the time to wait between retry
|
|
join attempts.
|
|
|
|
- `retry_max` `(int: 0)` - Specifies the maximum number of join attempts to be
|
|
made before exiting with a return code of 1. By default, this is set to 0
|
|
which is interpreted as infinite retries.
|
|
|
|
- `start_join` `(array<string>: [])` - Specifies a list of server addresses to
|
|
join on startup. If Nomad is unable to join with any of the specified
|
|
addresses, agent startup will fail. See the
|
|
[server address format](#server-address-format) section for more information
|
|
on the format of the string. This field is defined only for Nomad servers and
|
|
will result in a configuration parse error if included in a client
|
|
configuration.
|
|
|
|
## Server Address Format
|
|
|
|
This section describes the acceptable syntax and format for describing the
|
|
location of a Nomad server. There are many ways to reference a Nomad server,
|
|
including directly by IP address and resolving through DNS.
|
|
|
|
### Directly via IP Address
|
|
|
|
It is possible to address another Nomad server using its IP address. This is
|
|
done in the `ip:port` format, such as:
|
|
|
|
```
|
|
1.2.3.4:5678
|
|
```
|
|
|
|
If the port option is omitted, it defaults to the Serf port, which is 4648
|
|
unless configured otherwise:
|
|
|
|
```
|
|
1.2.3.4 => 1.2.3.4:4648
|
|
```
|
|
|
|
### Via Domains or DNS
|
|
|
|
It is possible to address another Nomad server using its DNS address. This is
|
|
done in the `address:port` format, such as:
|
|
|
|
```
|
|
nomad-01.company.local:5678
|
|
```
|
|
|
|
If the port option is omitted, it defaults to the Serf port, which is 4648
|
|
unless configured otherwise:
|
|
|
|
```
|
|
nomad-01.company.local => nomad-01.company.local:4648
|
|
```
|
|
|
|
### Via the go-discover interface
|
|
|
|
As of Nomad 0.8.4, `retry_join` accepts a unified interface using the
|
|
[go-discover](https://github.com/hashicorp/go-discover) library for doing
|
|
automated cluster joining using cloud metadata. See [Cloud
|
|
Auto-join](#cloud-auto-join) for more information.
|
|
|
|
```
|
|
"provider=aws tag_key=..." => 1.2.3.4:4648
|
|
```
|
|
|
|
## Cloud Auto-join
|
|
|
|
The following sections describe the Cloud Auto-join `retry_join` options that are specific
|
|
to a subset of supported cloud providers. For information on all providers, see further
|
|
documentation in [go-discover](https://github.com/hashicorp/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`.
|
|
|
|
```json
|
|
{
|
|
"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](http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/instance-identity-documents.html).
|
|
|
|
### 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.
|
|
|
|
```json
|
|
{
|
|
"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`.
|
|
|
|
```json
|
|
{
|
|
"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](https://cloud.google.com/compute/docs/access/service-accounts).
|
|
Credentials are searched using the following paths, in order of precedence.
|