I have an ec2 instance already running in AWS cloud. My objective is to execute a shell script on this running ec2 instance from my java program.
So far I have been not able to get much code examples or documentation for same. I understand that I first need to get hold of AmazonEC2Client as:
AWSCredentials credentials = new BasicAWSCredentials(accessKey,accessSecret);
AmazonEC2Client ec2 = new AmazonEC2Client(credentials);
What should be my further approach to achieve my objective?
I guess your EC2 will need to expose an endpoint API for this to happen.
You might want to write another script using a high-level language (Python or Node.js are excellent examples with great Web-Api support), where this new script listens to a certain port number, and executes your underlying shell script upon request.
This would give you some flexibility in securing your endpoint if you wish, externally monitoring your script, and having any sort of statistical analysis on the request.
Another option would be to extend your original shell script to act as a server itself.
Ex.
while { echo -en "Received Request"; } | nc -l "${1:-8080}"; do
However this is less flexible with more room for security vulnerabilities.
Related
I have a .sh script in Google Cloud Shell that automates my instance shutdown, backup, restart sequence.
How can I run a .sh script on Schedule (i.e. daily) in a simplest possible way?
I am not a professional and I've read all documentation about cron jobs, Cloud Scheduler, Cloud Tasks... but none of the examples in the documentation appear to detail a simple task that I need, and I do not have enough knowledge yet to understand these multiple services in details.... I just need a simple direction pointer to understand how to connect my Google Cloud Shell .sh script with any form of scheduler, as in:
Run a .sh script that I have in my virtual 5gb Cloud Sell Storage on schedule (daily at specific time), instead of manually opening Google Cloud Console and using a terminal to run the same script with "bash" command?
I just need to know what I need to learn/do to make this happen.
Thank you for your input.
That's not going to be possible. The Cloud Shell will turn off shortly after you close the tab. For this you'll need to use an actual VM. You can run one for free using the e2 micro instance.
https://cloud.google.com/free/docs/gcp-free-tier/#compute
Once you got this setup you can learn crontab to run your script on a schedule.
I've read multiple posts on running scripts on GCP VMs but unfortunately could not find an answer that would satisfy my needs.
I have a Go application and I'm looking for a way to run a bash script on a VM instance programatically.
I'm using a Google Cloud Golang SDK which allows me to fetch VM instance info. Unfortunately SDK does not contain a functionality that allows running a bash script on a specific instance(unlike an Azure Cloud SDK for example).
Options I've found:
Google Cloud Compute SDK has an option to set a startup script, that
will run every time an instance is restarted.
Add instance-level public SSH key. Establish an SSH connection and
run a script using Go SSH client.
Problems:
Obviously startup script will require an instance reboot and this is not possible in my use case.
SSH might be also problematic, in case instance is not running SSH
daemon or SSH port is not open. Also, SSH daemon config does not
permit root login by default(PermitRootLogin might be false), thus
script might be running on a non privileged user, making this option not
suitable either.
I should probably note that I am not authorised to change configuration of those VMs (for example change ssh daemon conf to permit root login), I can just use a token based authentication to access them, preferably through SDK, though other options are also possible as long as I am not exposing the instance to additional risks.
What options do I have? Is this even doable? Am I missing something?
Thanks!
As said by Kolban, there is no such API to trigger from outside a bash inside the VM. The best solution is to deploy a webserver (a REST API) that call the bash and to expose it (externally or internally).
But you can also cheat. You can create a daemon on your VM that you run with a startup script and that listen a custom metadata; let's say check it every seconds.
When the metadata is updated, the daemon can perform actions. You can imagine that the metadata contain the script to run with the parameters. At the end of the run, the metadata is cleaned by the daemon.
So now, to run your bash, call the setMetadata Api. It's not out of the box, but you can have something similar of what you expected.
Think of GCP as providing the virtual machine infrastructure such as compute, memory, disk and networking. What runs when the machine boots is between you and the machine image. I am hearing you say that you want to run a bash script within the VM. That is outside of the governance of GCP. GCP will only affect the operation and existence of the environment. If what you want to happen is run a script within the VM programatically you will need to run some form of demon inside the VM that can be signaled to run such a script. This could be a web server such as flask or express, it could be your SSH server or it could be some other technology you choose.
The core thing I think you were looking for was some GCP API that, when called, would run a script within the Compute Engine. I'm going to say that there is no such API.
I am looking for the best scripting option to automate process as below:
Every time an EC2 instance stands up, I'd like to add Centrify package into it, and run Centrify commands to connect to AD server so that EC2 user can be authenticated.
Give this scenario, which scripting language is the best option? I am thinking of Python or bash now.
Thanks!
Update:
The solution turns out to be a python script which is baked in the AMI, and triggered when an authentication request is initialized.
I'm creating an init.d script that will run a couple of tasks when the instance starts up.
it will create a new volume with our code repository and mount it if it doesn't exist already.
it will tag the instance
The tasks above being complete will be crucial for our site (i.e. without the code repository mounted the site won't work). How can I make sure that the server doesn't end up being publicly visible? Should I start my init.d script with de-registering the instance from the ELB (I'm not even sure if it will be registered at that point), and then register it again when all the tasks finished successfully?
What is the best practice?
Thanks!
You should have a health check on your ELB. So your server shouldn't get in unless it reports as happy. And it shouldn't report happy if the boot script errors out.
(Also, you should look into using cloud-init. That way you can change the boot script without making a new AMI.)
I suggest you use CloudFormation instead. You can bring up a full stack of your system by representing it in a JSON format template.
For example, you can create an autoscale group that has an instances with unique tags and the instances have another volume attached (which presumably has your code)
Here's a sample JSON template attaching an EBS volume to an instance:
https://s3.amazonaws.com/cloudformation-templates-us-east-1/EC2WithEBSSample.template
And here many other JSON templates that you can use for your guidance and deploy your specific Stack and Application.
http://aws.amazon.com/cloudformation/aws-cloudformation-templates/
Of course you can accomplish the same using init.d script or using the rc.local file in your instance but I believe CloudFormation is a cleaner solution from the outside (not inside your instance)
You can also write your own script that brings up your stack from the outside by why reinvent the wheel.
Hope this helps.
I want a single script that can lauch, and tag my instances which I can then use chef to configure them accordingly.
Say my service requires 10 instances, I want to be able to run 10 instances, then tag them according to their role (web, db, app server).
Then once I do that, I can use chef to connect to each one and configure them how i want.
But I'm confused, I know I can launch instances, but how do you wait for them to come online? Do you have to continously loop in some sort of a timer? That seems like a very hacky way to do it!
If you're going to do everything from the outside you do just have to poll to wait for the instance to be ready (which doesn't necessarily mean its ready to use - actual startup completed a little later)
You can also pass user data when you start an instance. Most amis support cloud init, and will interpret the data passed as a shell script if in the right format. That shell script could run chef or do other configuration tasks.