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A shell for AWS

Project description

Nephele: a shell for aws.


I wasn't happy with the AWS web console, because the UI felt
disjointed and was slow to navigate. So I slapped this together:
a very simple interactive cli shell in python.

I'm actively using it for work, so it supports the things that
I'm doing, rather than being an exhaustive system. I invite
pull requests for missing features, bugfixes, etc.


This tool is incredibly immature. It WILL be changing considerably as
long as I'm using it, because I will be viewing the things it does (or
doesn't do), and the manner in which it does (or doesn't do) them as
impediments to my workflow.

It is not even "alpha" level code yet, so expect things to be broken
or buggy. Also expect syntax to be in a fairly constant state of flux.


.. code-block::

pip install nephele


.. code-block:: bash

$ nephele
(aws)/: help


Nephele reads `~/.nephele/config.yaml` during startup. Its format looks like this:

.. code-block::

profile: {profile-name}

awsProfile: {aws profile name}
ssh-jump-host: {jump host name or ip}
ssh-jump-user: {jump host username}
awsProfile: {aws profile name}
ssh-jump-host: {jump host name or ip}
ssh-jump-user: {jump host username}

{macro-name}: {remote command}

SSH support

If you've set up your `~/.nephele/config.yaml` with a correct
`profiles.{profile}.ssh-jump-host` entry, then this is probably the best
part of `nephele`.

nephele can ssh to an instance without you having to figure out its
ip, modify /etc/host, or know anything other than its aws instance id:

.. code:: bash
(aws)/: ssh {instance-id}
/usr/bin/ssh {first private ip}
Last login: {sometime} from {somewhere}

__| __|_ )
_| ( / Amazon Linux AMI

If you've navigated to an autoscaling group, you don't even need to
know the instance id. You can ssh by the instance's index in the
autoscaling group's list of instances:

.. code-block:: bash

(aws)/stack:{stack}/stack:{substack}/: asg 0
loading auto scaling group 0
loading stack resource arn:{arn}
AutoScaling Group:{name}
=== Instances ===
0 Healthy az-2a {instance-id}
1 Healthy az-2b {instance-id}
2 Healthy az-2c {instance-id}
(aws)/stack:{stack}/stack:{substack}/asg:{asg}/: ssh 2
/usr/bin/ssh {first private ip}
Last login: {sometime} from {somewhere}

__| __|_ )
_| ( / Amazon Linux AMI

It also supports port forwarding!

.. code-block:: bash

(aws)/stack:{stack}/stack:{substack}/asg:{asg}/: ssh 2 -L 8888:localhost:8888
/usr/bin/ssh {first private ip}
Last login: {sometime} from {somewhere}

__| __|_ )
_| ( / Amazon Linux AMI
$ exit
(aws)/stack:{stack}/stack:{substack}/asg:{asg}/: ssh 2 -L 8888 # <-- useful shorthand!

So how do you set up your `~/.nephele/config.yaml` for this? It helps if your
AWS admins have set things up so that using ssh from a command line is
fairly straightforward. If you need a `-J` option to ssh to connect to
a host, specify the jump host user and password using
`profiles.{profile}.ssh-jump-host` and
`profiles.{profile}.ssh-jump-user`, respectively.

SSH also supports selecting an ssh key based upon instance tags (or
other instance metadata). To use this, implement an ssh plug-in, and
place it in `~/.nephele/plugins` to accomplish this. Here's an

.. code-block:: python

import os
class sshPlugin:
def getUserName(self, instance, profile):
Given a description of an AWS instance and a nephele profile,
determine the user name to use when ssh-ing to that instance.
return "ec2-user"

def getIdentityFile(self, instance, profile):
Given a description of an AWS instance and a nephele profile,
determine the name of the ssh identity file to use when ssh-ing to
that instance.
return os.path.join(os.path.expanduser("~"),".ssh","keys","prod",'somekey.pem')

Command Reference

We use the excellent argparse module to specify how commands are
used. This reference contains descriptions only; for details on
syntax, use any command's `-h` option.

Globally Available Commands


Deal with configuration. Available subcommands:

* config print - print the current configuration
* config reload - reload the current configuration from disk
* config set - change a setting in the configuration
* config save - save the configuration to disk


Enter a 6-digit MFA token. Nephele will execute the
appropriate `aws` command line to authenticate that token.


Navigate to an instance. This is different from `ssh` in that it isn't
_connecting_ to the instance; just navigating the shell there for
detailed inspection.


Select nephele profile


Exit nephele


SSH to an instance.

Note: This command is extended in more specific contexts, for example
inside Autoscaling Groups.


Navigate back to the root level.

For example, if you are in `(aws)/stack:.../asg:.../`, executing
`slash` will place you in `(aws)/`.


Navigate up by one level.

For example, if you are in `(aws)/stack:.../asg:.../`, executing `up`
will place you in `(aws)/stack:.../`.

New Features

_Most Recent Last._

Doesn't include bug fixes, or any features I forgot to list. Maybe
that last bit was obvious :-D

Yes, you could figure this all out by looking at commit logs. Why would
I make you go through that?

* You can now input an MFA token by running `mfa {token}`. It's
rudimentary support at this point, and likely broken if you've never
used [aws-mfa]( before.

* You can now ssh with shorthanded port forwarding. Basically, if you
want to forward a port on the remote server via the same local port,
you no longer have to use the `-L {port}:localhost:{port}`
syntax. Instead, just say `-L {port}`. You can still use the server
as a tunnel to yet another server, or choose different local/remote
port numbers with the old syntax though.

* When launching, nephele automatically runs "stacks" for you.

* --profile (short: -p) selects a specific AWS profile. This is
helpful when other processes require that your default profile be
one other than the one you would like nephele to use.

* nephele now knows how to get your aws device info. I also tried to
make it file-compatible with aws-mfa, so you should in theory not
need the separate aws-mfa tool any longer - just use nephele to
manage your .aws/{mfa-related-files}, and you should be good to
go. Of course, my wife always says she wants to move to Theory,
because everything works... in Theory.

* --mfa (short: -m) provide your mfa command at launch. If you *know*
your cached mfa credentials are expired, this saves the step of
waiting for nephele to get access denied.

* there is now a `profile` command to change profiles after you've
started nephele.

* `stacks` now adds `-e` and `-i` parameters so you can exclude or
include new stack states in the filter.

* `~/.nephele/config.yaml` is the new config file. It has one setting for now,
`profile`. Example:

.. code-block:: config

profile: {aws profile name}

* `ssh` commands now have a `-R`/`--replace-key` option. It is quite
possible in AWS for IP addresses to get recycled, especially if you
are creating/tearing-down cloudformation stacks while iterating on
their templates. When this happens, you don't want to have to go
hack on `~/.ssh/known_hosts` in order to ssh in to the host. This
option will run the appropriate command (`ssh-keygen -R {host}`) to
remove the entry before running ssh.

* auto-scaling groups now support the `terminateInstance` command.

* AwsStack now prints stack events and outputs as if they were normal
stack resources.

* Added ability to glob when listing stacks. E.g., `stacks *cass*`
will list all stacks with "cass" as a substring.

* Renamed from aws-shell to nephele (after the mythological cloud
nymph), and got the tool to be installable via pip.

* You can now run a command across the instances in an auto scaling
group. Navigate to the group and use the `run` command.

* Cloudwatch logging support has commenced. It's very rudimentary
so far - you can see log groups inside stacks, select them
using the `logGroup` command, and see that there are streams present.
The output is not beautified yet, and you can't actually see
the content of those streams yet. Soon.

* IAM role support has commenced, too. It's also very rudimentary so
far. You can see roles inside cloudformation stacks, down to the
policy document level using the `role`. The output is not beautified yet
and it's purely read-only. I don't anticipate beautifying it, because
pprint() is good enough for me, but I certainly welcome patches if
it matters to you.

* Cloudwatch logging support continues with the addition of the
`logStream` command, which is available from inside a `logGroup`.
Right now you can tail the logs, and they aren't beautified.
As I get more comfortable with the log-scanning API, I plan to add
some cross-stream log viewing at the `logGroup` level, probably
in the form of a grep-like capability. No promises, of course,
just logging where my head's at.

* In an autoscaling group, the `printInstances` command has two new
options: `-t` to print the list of tags, and `-d` to print all the
node's details.

* In a stack, the `copy` command now knows how to copy an asg's id
to the clipboard.

* ASG's now support the `printActivities` and `printActivity` commands
to assist in debugging changes initiated by autoscaling.

* ASG's now support showing scaling policies via the `printPolicy`

* ASG `run` command supports `-s` option to skip _n_ hosts

* Stacks now display their parameters. These are escaped and "elipsified"
in order to fit. Will be adding a command to print a full parameter
value at some point.

* stdplus.elipsifyMiddle is now a thing.

* ssh commands no longer depend on `~/.ssh/config` working, instead
supporting `~/.nephele/config.yaml`

* ssh now supports the fantastic -J option (you'll need a recent ssh
client for this to work)

* ssh has a very limited macro capability. While it does not yet have
a way to do variable substitution, you can do something like this:

.. code-block:: config

cassandrapid: pgrep -f CassandraDaemon

(aws)/stack:.../asg:.../: ssh -m 0 cassandrapid
/usr/bin/ssh -q -J pgrep -f CassandraDaemon

* You can now reload your config using the `config reload` command.

* Started adding a command reference to this doc.

* There is now a mechanism for determining which user and identity
files to use when ssh-ing, based on instance metadata.

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