Let's say I have a webapp where users can click a button that starts a long running task (eg. 3 days long). The user can also select options, for example the things it wants that task to do.
No matter what, the task will be the same script that runs when the instance starts. However, I would like it to somehow take arguments from the button click to change the function of the startup script.
Is there a way to do this with AWS EC2 instances?
So, you're saying that you want to pass certain parameters to some software that will be launched on an EC2 instance.
There are many ways to do this:
When the instance is launched, you can pass User Data. This is commonly used to run a startup script, but it can also be used just to pass information to the instance that can be accessed via http://169.254.169.254/latest/user-data/. So, either pass the configuration directly or pass it as part of the startup script.
Store it in tags on the instance when the instance is launched. Once the software starts up, it can retrieve the tags associated with the instance (itself) and act appropriately.
Store the configuration in a database and have the software access the database to determine what it should do.
Store the configuration in Amazon S3 and have the software retrieve the configuration file.
Personally, I like the idea of Tags. It's very Cloud.
This behaviour isn't directly related to EC2, although EC2 could host an application that does these long-running parameterised tasks. Whether EC2 is a good choice also depends on how your tasks react to underlying failures: if the EC2 instance fails or restarts, what happens to your task?
Depending on your use case, some managed options might be:
AWS Step Functions
AWS Simple Workflow Service
AWS Batch
Related
Bear with me, what I am requesting may be impossible. I am a AWS noob.
So I am going to describe to you the situation I am in...
I am doing a freelance gig and was essentially handed the keys to AWS. That is, I was handed the root user login credentials for the AWS account that powers this website.
Now there are 3 EC2 instances. One of the instances is a linux box that, from what I am being told, is running a Django Python backend.
My new "service" if you will must exist within this instance.
How do I introduce new source code into this instance? Is there a way to pull down the existing source code that lives within it?
I am not be helped by any existing/previous developers so I am kind of just handed the AWS credentials and have no idea where to start.
Is this even possible. That is, is it possible to pull the source code from an EC2 instance and/or modify the code? How do I do this?
EC2 instances are just virtual machines. So you can use SSH/SCP/SFTP files to and from. You can use the AWS CLI tools to copy stuff from S3. Dealers choice...
Now to get into this instance... If you look in the web console you can find its IP(s), what the security groups (firewall rules), and the key pair name. Hopefully they gave you the keys. You need these to SSH in.
You'll also want to check to make sure there's a security group applied that has SSH open. Hopefully only to your IP :)
If you don't have the keys you'll have to create an AMI image of the instance so you can create a new one with a key pair you do have.
Amazon has a set of tools for you in Amazon CodeSuite.
The tool used for "deploying" the code is Amazon CodeDeploy. By using this service you install an agent onto your host, then when triggered it will pull down an artifact of a code base and install it matching hosts. You can even specify additional commands through the hook system.
But you also want to trigger this to happen, maybe even automatically? CodeDeploy can be orchestrated using the CodePipeline tool.
I have few EC2 servers in AWS. Whenever the disk space exceeds a limit, i want to delete some files (may be logs folder) in EC2 instance automatically. I am planning to use Lambda and cloudwatch for this. Can i use Lambda to interact with EC2. If not possible, what is the alternate approach to achieve this functionality.
This is not an appropriate use-case for an AWS Lambda function.
AWS Lambda is suitable for tasks where compute is required in response to an event. Your use-case, however, is to manipulate information on an EC2 instance, which does not need cloud compute.
You could run a script on each each computer, triggered by a Scheduled Task.
Alternatively, you could use the Systems Manager Run Command (also known as the EC2 Run Command), which allows you to run commands on multiple Amazon EC2 instances and view the results. This could be used to trigger a local script, or it could pass the whole command to run (including the script). It is purpose-built for the type of task you describe.
AWS Lambda has access to your instances if they are available in the internet. If they are not available in the internet, it is possible to give access to AWS lambda using a NAT or instance Gateway in your VPC.
The problem is: access to your instance does not means access to the instances filesystems. To delete the files from Lambda you can use two alternatives:
Configure a network filesystem service in your instances an connect
to this services in your lambda function. Using windows you would
just "share" your disks, but in that case you would use some SMB
library in your lambda code, that "I think" did not have native SMB
support. Just keep in mind that your security guy will scream out
loud when you propose this alternative.
Create a "agent" in your EC2 instances and keep it running as a
Windows Service and call this agent from your lambda function. In
that case, the lambda will start the execution of the agent that
will be responsible for the file deletion.
Another option, is to follow Ramesh's suggestion and create a Powershell script and configure a cron job. To be easy, you can create a Image with this Powershell script and use the image to initialize each instance. The same solution would be applicable to "the agent" solution in the lambda alternantives.
I think that, in any case, you will need to change something in your 150 servers. Using a customized image can help you to simplify this a little bit, but you will not get a solution without some changes.
According to the following thread, you cannot access files inside a EC2 VM unless you are exposing files to the public using different methodology.
AWS Forum
Quoting from the forum
If you are talking about the underlying EC2 instance, answer is No, you cannot access those files.
However as a solution for your problem, you can used scheduled job to cleanup your files depending your usage. You can use a service or cron job.
I have an EC2 instance that is running a few processes. I also have a Lambda script that is triggered through various means. I would like this Lambda script to talk to my EC2 instance and get a list of running processes from it (Essentially run ps aux on the EC2 box, and read the output).
Now this is easy enough with just one instance and its instance-id. Just SSH in, run the command, get the output, and be on my way. However, I would like to scale this to multiple EC2 instances, for which only the instance-id is known and SSH keys may not be given.
Is such a configuration possible with Lambda and Boto (or other libraries)? Or do I just have to run a microserver on each of my instances that will reply with the given information (something I'm really trying to avoid)
You can do this easily with AWS Systems Manager - Run Command
AWS Systems Manager provides you safe, secure remote management of your instances at scale without logging into your servers, replacing the need for bastion hosts, SSH, or remote PowerShell.
Specifically:
Use the send-command API from Lambda function to get list of all processes on a group of instances. You can do this by providing a list of instances or even a tag query
You can also use CloudWatch Events to trigger a Run Command directly
I don't think there is something available out of the box for this scenario.
Instead of querying, try an alternate approach. Install an agent on all ec2 instances, which reports the required information to a central service or probably a DynamoDB table, with HashKey as InstanceId.
You may want to bake this script as a cron job, (executed probably hourly?) in the AMI itself.
With this implementation, you reduce the complexity of managing and running a separate web service on each EC2 instance.
Query the DynamoDB table on demand. There will be a lag, as data may not be real time, but you can always reduce the CRON interval per your needs.
Like Yeshodhan mentioned, There is no direct approach for this.
However, There is one more approach.
1) Save your private key file to an s3 bucket, Create a lambda function and use python fabric module to login to the remote machines from lambda function and execute commands.
The above-mentioned approach is possible but I highly recommend launching a separate machine and use a configuration management system (Preferably ansible) and get the results from remote machines.
While cloud-init is the optimal way to create users in an EC2 host at the time it gets instantiated I would like to hear how the community usually manages a dynamic group of users. I am planning to use Ansible to achieve the user config management but I am unsure how we can call the Ansible playbook from cloud-init script. Any pointers will be of help.
As you said, cloud-init by nature runs once and only once per instance, at creation time. If you expect your list of users to change over time and you want to keep an instance up to date, cloud-init isn't going to cover that use case.
The user module in ansible can be a good way to manage system users throughout the lifecycle of an instance.
I can't speak for the entire community but one possibility would be to maintain a list of users in ansible and then run your playbook targeting the instance or instances when there is a change to the user list.
Rather than cloud-init, these ansible-playbook runs could be manually run by an operator, run at a regular time interval, or triggered to run automatically with a combination of version control and continuous delivery.
We are discussing at a client how to boot strap auto scale AWS instances. Essentially, a instance comes up with hardly anything on it. It has a generic startup script that asks somewhere "what am I supposed to do next?"
I'm thinking we can use amazon tags, and have the instance itself ask AWS using awscli tool set to find out it's role. This could give puppet info, environment info (dev/stage/prod for example) and so on. This should be doable with just the DescribeTags privilege. I'm facing resistance however.
I am looking for suggestions on how a fresh AWS instance can find out about it's own purpose, whether from AWS or perhaps from a service broker of some sort.
EC2 instances offer a feature called User Data meant to solve this problem. User Data executes a shell script to perform provisioning functions on new instances. A typical pattern is to use the User Data to download or clone a configuration management source repository, such as Chef, Puppet, or Ansible, and run it locally on the box to perform more complete provisioning.
As #e-j-brennan states, it's also common to prebundle an AMI that has already been provisioned. This approach is faster since no provisioning needs to happen at boot time, but is perhaps less flexible since the instance isn't customized.
You may also be interested in instance metadata, which exposes some data such as network details and tags via a URL path accessible only to the instance itself.
An instance doesn't have to come up with 'hardly anything on it' though. You can/should build your own custom AMI (Amazon machine image), with any and all software you need to have running on it, and when you need to auto-scale an instance, you boot it from the AMI you previously created and saved.
http://docs.aws.amazon.com/gettingstarted/latest/wah-linux/getting-started-create-custom-ami.html
I would recommend to use AWS Beanstalk for creating specific instances, this makes it easier since it will create the AutoScaling groups and Launch Configurations (Bootup code) which you can edit later. Also you only pay for EC2 instances and you can manage most of the things from Beanstalk console.