awwan: SSH with steroid, infrastructure as files and history.

#awwan

#NAME

awwan - Configuration management software, infrastructure as file and directory layout.

#SYNOPSIS

awwan <command> <script> <line-start> [line-end | "-"]

#DESCRIPTION

awwan is command-line interface to execute multiple lines of command in the local or remote server using SSH.

#BACKGROUND

Do you have a collection of shell scripts to manage one more similar server? Do you ever want to execute only part of your script? Are you get tired with learning others syntax and tools for provisioning your own server, while you need is a handful of shell script?

If yes, awwan is the right tools for you.

#THE COMMAND

The awwan tool only need four arguments.

The first argument is mode: "local" or "play". The "local" mode execute the script in local environment, your own machine, without using SSH. The "play" mode execute the script in remote environment, your SSH server.

The second argument is the path to the awwan script file.

The third argument is line start number. Its define the line number in the script where awwan will start execution.

The fourth argument define the line number in the script where awwan will stop executing the script, or "-" to set to the last line. If not defined then it will be equal to the line start, which means awwan will execute only single line. Another value for this argument is "-", its means execute the script from line-start until the last line.

Here is some examples of how to execute script,

Execute only line 5 of "script.aww" on local system,

$ awwan local myserver/script.aww 5

Execute line 5 until line 10 of "script.aww" on remote server known as "myserver",

$ awwan play myserver/script.aww 5 10

Execute line 5 until last line of "script.aww" on remote server known as "myserver",

$ awwan play cloud/myserver/script.aww 5 -

#THE SCRIPT

The awwan script is similar to shell script. Each line started with '#' is a comment, except for special, magic words.

There are five magic words in the script: #require:, #get:, #get!, #put:, and #put!.

Magic word #require: will ensure that the next statement will always executed when its skipped with start number. For example, given following script with line number

1: #require:
2: echo a
3: echo b
4: #require:
5: echo c

executing awwan local script.aww 3, will always execute line number 2 echo a, but not line number 5 (because its before line start 3).

Magic word #get: will copy file from remote server to your local file system. Example,

#get: /etc/os-release os-release

Magic word #get! will copy file from remote server, that can be accessed only by using sudo, to your local file. Example,

#get! /etc/nginx/ssl/my.crt server.crt

Magic word #put: will copy file from your local to remote server. Example,

#put: /etc/locale.conf /tmp/locale.conf

Magic word #put! will copy file from your local system to remote server using sudo. Example,

#put! /etc/locale.conf /etc/locale.conf

One thing that script can't do is piping, for example "echo a > b" does not work, yet.

Here is an example of script that install Nginx on remote Arch Linux server using configuration from your local computer,

sudo pacman -Sy --noconfirm nginx
sudo systemctl enable nginx

#put! {{.ScriptDir}}/etc/nginx/nginx.conf /etc/nginx/

sudo systemctl restart nginx
sudo systemctl status nginx

#ENVIRONMENT FILE

The environment file is a file named awwan.env that contains variables using the form "key=value" that can be used for templating.

When executing the script, awwan will read environment files in the current directory, and in each sub-directory, until the script directory.

The environment file use the ini file format,

[section "subsection"]
key = value

We will explain how to use and get the environment variables below.

#TEMPLATING

Template file is any text or script files that dynamically generated using values from variables defined in environment files.

There are two global variables that shared to all template or script files,

.BaseDir contains the absolute path of current directory, and
.ScriptDir contains the relative path to script directory.

To get the value wrap the variable using '{{}}' for example,

#put! {{.BaseDir}}/templates/etc/hosts /etc/
#put! {{.ScriptDir}}/etc/hosts /etc/

To get the value of variable in environment file you put the string ".Val" followed by section, subsection and key names, each separated by colon ":". If no subsection exist you can leave it empty.

You can put the variable inside the script or in the file that you want to copy.

For example, given the following environment file,

[all]
user = arch

[whitelist "ip"]
alpha = 1.2.3.4/32
beta  = 2.3.4.5/32

{{.Val "all::user"}} will result to "arch" (without double quote), and
{{.Val "whitelist:ip:alpha"}} will result to "1.2.3.4/32" (without double quote)

#THE SSH CONFIG

After we learn about the command, script, variables, and templating; we need to explain some file and directory structure that required by awwan so it can connect to the SSH server.

To be able to connect to the remote SSH server, awwan need to know the remote host name, remote user, and location of private key file. All of this are derived from ssh_config(5) file in the current directory and in the user's home directory.

The remote host name is derived from directory name of the script file. It will be matched with Host or Match section in the ssh_config(5) file.

For example, given the following directory structure,

.
|
+-- .ssh/
|   |
|   --- config
+-- development
    |
    --- script.aww

If we execute the "development/script.aww", awwan will search for the Host that match with "development" in current ".ssh/config" or in "~/.ssh/config".

#EXAMPLE

To give you the taste of the idea, I will show you an example using the working directory $WORKDIR as our base directory.

Let say that we have the working remote server named "myserver" at IP address "1.2.3.4" using username "arch" on port "2222".

In the $WORKDIR, create directory ".ssh" and "config" file,

$ mkdir -p .ssh
$ cat > .ssh/config <<EOF
Host myserver
	Hostname 1.2.3.4
	User arch
	Port 2222
	IdentityFile .ssh/myserver
EOF

Still in the $WORKDIR, create the environment file "awwan.env"

$ cat > awwan.env <<EOF
[all]
user = arch
host = myserver

[whitelist "ip"]
alpha = 1.2.3.4/32
beta  = 2.3.4.5/32
EOF

Inside the $WORKDIR we create the directory that match with our server name and a script file "test.aww",

$ mkdir -p myserver
$ cat > myserver/test.aww <<EOF
echo {{.Val "all::host"}}`
#put: {{.ScriptDir}}/test /tmp/
cat /tmp/test
EOF

and a template file "test",

$ cat > myserver/test <<EOF
Hi {{.Val "all::user"}}!
EOF

When executed from start to end like these,

$ awwan play myserver/test.aww 1 -

it will print the following output to terminal,

>>> arch@1.2.3.4:2222: 1: echo myserver

myserver
test                                                  100%    9     0.4KB/s   00:00
>>> arch@1.2.3.4:2222: 3: cat /tmp/test

Hi arch!

That's it.

#FAQ

Since this software is working in progress, there are many things that we have in mind, but can't put it to code, yet.

#Workspace structure

Beside ".ssh" directory and directory as host name, awwan did not require any other special directory but we really recommend that you use sub directory to group several nodes on several cloud services. For example, if you use cloud services with several nodes inside it, we recommend the following directory structures,

<cloud-service>/<project-name>/<service-name>/<node-name>

The <cloud-service> is the name of your remote server, it could be "AWS", "GCP", "DO", and others. The <project-name> is your account ID in your cloud service or your project name. The <service-name> is a group of several nodes, for example "development", "staging", "production". The <node-name> is name of your node, each node should have one single directory.

Here is an example of directory structures,

.
├── commons
├── gcp
│   ├── development
│   │   └── vm
│   │       ├── www
│   │       │   └── etc
│   │       │       ├── my.cnf.d
│   │       │       ├── nginx
│   │       │       ├── php
│   │       │       │   └── php-fpm.d
│   │       │       └── systemd
│   │       │           └── system
│   │       │               └── mariadb.service.d
│   │       └── ci
│   └── production
│       └── vm
│           └── www
│               └── etc -> ../../../development/vm/www//etc
└── templates
    ├── etc
    │   ├── pacman.d
    │   └── ssh
    └── home

The commons directory contains common script that can be executed in any server.

The templates directory contains common templates that can be used by any scripts.

The gcp directory is cloud service with two accounts "development" and "production", and the rest are node names and templates used in that node.

#What happened if two variables declared inside two environment files?

When executing the script awwan will merge the variables from current directory with variable from script directory. Any keys that are duplicate will be merged and the last one will overwrite the previous one.

#Use case of magic command `#require:`

The magic command #require: is added to prevent running local command using different project or configuration.

The use case was derived from experience with gcloud and kubectl commands. When you have more than one projects in GCP, you need to make sure that the command that you run is using correct configuration.

Here is the example of deploying Cloud Functions using local awwan script,

1: #require:
2: gcloud config configurations activate {{.Val "gcloud::config"}}
3:
4: ## Create PubSub topic.
5:
6: gcloud pubsub topics create {{.Val "CloudFunctions:log2slack:pubsub_topic"}}
7:
8: ## Create Logger Sink to Route the log to PubSub topic.
9:
10: gcloud logging sinks create {{.Val "CloudFunctions:log2slack:pubsub_topic"}} \
11:	pubsub.googleapis.com/projects/{{.Val "gcloud::project"}}/topics/{{.Val "CloudFunctions:log2slack:pubsub_topic"}} \
12:	--log-filter=severity>=WARNING
13:
14: ## Create Cloud Functions to forward log to Slack.
15:
16: gcloud functions deploy Log2Slack \
17:	--source {{.ScriptDir}} \
18:	--entry-point Log2Slack \
19:	--runtime go113 \
20:	--trigger-topic {{.Val "CloudFunctions:log2slack:pubsub_topic"}} \
21:	--set-env-vars SLACK_WEBHOOK_URL={{.Val "slack::slack_webhook_url"}} \
22:	--ingress-settings internal-only \
23:	--max-instances=5
24:
25: ## Test the chains by publishing a message to Topic...
26:
27: gcloud pubsub topics \
28:	publish {{.Val "CloudFunctions:log2slack:pubsub_topic"}} \
29:	--message='Hello World!'

When executing statement at line number 6, 10, 16 or 27 we need to make sure that it always using the correct environment "gcloud::config",

$ awwan local awwan/playground/CloudFunctions/log2slack/local.deploy.aww 27
2020/06/04 01:48:38 >>> loading "/xxx//awwan.env" ...
2020/06/04 01:48:38 >>> loading "/xxx/awwan/dev/awwan.env" ...
2020/06/04 01:48:38 --- require 2: gcloud config configurations activate dev

Activated [dev].
2020/06/04 01:48:38 >>> local 29: gcloud pubsub topics publish logs
--message='Hello World!'

#BUGS

Shell pipe "|", "<", or ">" does not work in the script, yet.

#LINKS

The source codes for this software project can be viewed at https://sr.ht/~shulhan/awwan/ .

For request of features and/or bugs report please submitted through web at https://todo.sr.ht/~shulhan/awwan .

#LICENSE

Copyright (c) 2020 M. Shulhan (m.shulhan@gmail.com). All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are
met:

   * Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
   * Redistributions in binary form must reproduce the above
copyright notice, this list of conditions and the following disclaimer
in the documentation and/or other materials provided with the
distribution.
   * Neither the name of M. Shulhan, nor the names of its
contributors may be used to endorse or promote products derived from
this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

~shulhan/awwan