https://github.com/grubernaut/cdsh

Consul DSH - Remote command execution on consul services
https://github.com/grubernaut/cdsh

Last synced: about 1 month ago
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Consul DSH - Remote command execution on consul services

• Host: GitHub
• URL: https://github.com/grubernaut/cdsh
• Owner: grubernaut
• Created: 2016-10-19T06:20:44.000Z (about 8 years ago)
• Default Branch: master
• Last Pushed: 2016-10-24T22:09:18.000Z (about 8 years ago)
• Last Synced: 2024-08-03T02:05:11.884Z (4 months ago)
• Language: Go
• Size: 2.58 MB
• Stars: 16
• Watchers: 4
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

Awesome Lists containing this project

• awesome-consul - cdsh: Distributed SSH

README

        
Consul DSH

==========

`go get -u github.com/grubernaut/cdsh`

The remote shell `exec` for consul services.

### Quick How-to

```

cdsh --server  --service  --user  ''

```

**Note:** 

Be sure that you're actually able to SSH to the target consul service. (SSH Keys, Host key verification, etc)

### Options

* `--server` / `-s`: Consul server to query against. Required. Can also use `CONSUL_SERVER`, but environment variable takes priority.

* `--service` / `-S`: Target service to run command against

* `--user` / `-u`: Remote user to connect as. If unspecified, defaults to current local user

More options are likely to come in the future, such as `--tag` `--token`, `--node`, etc...

If `--service` is left unspecified, `cdsh` will return a list of all available services. This will likely be changed

in the future to a separate flag entirely.

### Doesn't Consul have a native `exec` command?

While consul _does_ have a native `exec` command, there are a couple issues with using `consul exec`.

> Agents are informed about the new job using the event system, which propagates messages via the gossip protocol. As a 

> result, delivery is best-effort, and there is no guarantee of execution.

> ...

> While events are purely gossip driven, remote execution relies on the KV store as a message broker.  

Using Consul K/V as a message broker _definitely_ has it's benefits, but there are often times in daily operations work,

where a user might want to know immediately if they cannot connect to a service.

However, the main concern with using `consul exec` is as follows:

> Verbose output warning: use care to make sure that your command does not produce a large volume of output. Writes to

> the KV store for this output go through the Consul servers and the Raft consensus algorithm, so having a large number

> of nodes in the cluster flow a large amount of data through the KV store could make the cluster unavailable.

There are quite a few times where I've needed to fetch fairly verbose log output from N-servers, and pipe the output to

a file for further analysis. Using DSH completely abstracts the command output from Consul K/V, allowing the user to run

fairly verbose commands without worry.