LocalStack provides an easy-to-use test/mocking framework for developing Cloud applications. In today's post, we're going to have a quick look at setting up LocalStack locally to work with their free tier AWS emulated products.
In particular, today's post will have a quick look at emulating S3 buckets for local development.
Prerequisites
Before getting started, it is required that you have the following on your machine:
- Python (both Python 2.x and 3.x supported)
- pip (python package manager)
- Docker
- AWS CLI (for interacting with LocalStack after installation)
Installing LocalStack
Following the instructions on their README, we can use pip
to install the package.
# if you are using pip
pip install localstack
# or if using pip3
pip3 install localstack
In my case, I installed using pip3
.
Running LocalStack
Once installed, we can get everything up by running localstack start
. You will get feedback in the terminal that a number of services are started and finally get the service list with the ports they are running on. By default, these services will start on port 4566. Easy peasy!
Creating our first S3 bucket with LocalStack
Now that things are running, we can run some basic tests using the AWS CLI. I am not going to go into the installation process for the CLI, so follow the link above and use those installation instructions if you have not yet installed the CLI.
We will use the aws s3api [command] --endpoint-url http://localhost:4566
pattern to interact and use the local endpoint to list and create buckets.
To show what we currently have, we can run aws s3api list-buckets --endpoint-url http://localhost:4566
and we will get something like the following:
{
"Buckets": [],
"Owner": {
"DisplayName": "webfile",
"ID": "<some-id>"
}
}
This proves that we currently have no buckets in our LocalStack setup.
We can create a bucket my-bucket
by running aws s3api create-bucket --bucket my-bucket --endpoint-url http://localhost:4566
.
To confirm it has been made, we can run aws s3api list-buckets --endpoint-url http://localhost:4566
once again:
{
"Buckets": [
{
"Name": "my-bucket",
"CreationDate": "2021-01-12T05:46:28+00:00"
}
],
"Owner": {
"DisplayName": "webfile",
"ID": "bcaf1ffd86f41161ca5fb16fd081034f"
}
}
Success!
Adding and removing objects locally
Create a new temp.txt
and add some content. In my case, I added Hello, world!
.
Once this is done, we can put the file temp.txt
into bucket my-bucket
by running aws s3api put-object --bucket my-bucket --key temp.txt --body temp.txt --endpoint-url http://localhost:4566
. You will have an object returned with an ETag
value if successful.
To confirm our object is now in the bucket, run aws s3api list-objects-v2 --bucket my-bucket --endpoint-url http://localhost:4566
.
{
"Contents": [
{
"Key": "temp.txt",
"LastModified": "2021-01-12T05:51:38+00:00",
"ETag": "\"746308829575e17c3331bbcb00c0898b\"",
"Size": 14,
"StorageClass": "STANDARD"
}
]
}
If we remove our temp.txt
file locally using rm temp.txt
, we can retrieve the bucket version by running aws s3api get-object --bucket my-bucket --key temp.txt --endpoint-url http://localhost:4566 temp2.txt
.
{
"AcceptRanges": "bytes",
"LastModified": "2021-01-12T05:51:38+00:00",
"ContentLength": 14,
"ETag": "\"746308829575e17c3331bbcb00c0898b\"",
"CacheControl": "no-cache",
"ContentEncoding": "identity",
"ContentLanguage": "en-US",
"ContentType": "binary/octet-stream",
"Metadata": {}
}
Once successful, you can run cat temp2.txt
to see that we installed the bucket's temp.txt
file into temp2.txt
locally.
Now that we have proven how to develop and test the S3 service locally, we can terminate our localstack
instance in the terminal to tear down the local infrastructure.
Conclusion
In summary, we installed LocalStack to our local machine and explored one of the free-tier services in S3.
I am working locally with interacting with some AWS services through some language APIs, and the capability to do so locally with LocalStack has been a real time-saver for putting together some infrastructure solutions for my personal projects.
I highly recommend giving it a go for your own infrastructure development. There may be some issues that I am yet to run into, but as far as a lightweight approach to quickly interacting with files locally and not expending costs, it has been great for introductions into some of the AWS products.
Resources and further reading
Image credit: REVOLT
Originally posted on my blog. Follow me on Twitter for more hidden gems @dennisokeeffe92.
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