.. _SOSW Layer:

========================
SOSW Layer
========================

A Lambda layer is a .zip file archive that contains supplementary code or data.
Layers usually contain library dependencies, a custom runtime, or configuration files.

You can find full documentation `here
<https://docs.aws.amazon.com/lambda/latest/dg/chapter-layers.html>`_.


The following diagram represents how does Lambda Layer work.

..   figure:: ../_static/images/lambda-layers-diagram.png
    :alt: Lambda Layer
    :align: center

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How to start
------------------

Create ``deploy.sh`` file by using
`deploy.sh
<https://link_to_file.com>`_.

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How to run
------------------

While in the same folder as your ``deploy.sh`` file just run:

..   code-block:: bash

    ./deploy.sh [-v branch] [-p profile]

Installs sosw from latest pip version, or from a specific branch if you use -v.
Use -p in case you have specific profile (not the default one) in your .aws/config with appropriate permissions.
It will create a folder with all dependencies. You only need to pack it into zip-archive.

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What's next?
------------------

You simply need to load layer zip file to your s3 bucket and deploy
Lambda Layer with CloudFormation or AWS SAM by using one of the following templates.

------------------
CloudFormation
------------------

To deploy a layer by CloudFormation you will need to create a ``.yaml`` file with `sosw-layer.yaml
<https://link_to_file.com>`_.

And after create a stack in AWS CloudFormation.
To create a stack you run the ``aws cloudformation create-stack`` command.
You must provide the stack name, the location of a valid template, and any input parameters.

..   code-block:: bash

    aws cloudformation create-stack \
      --stack-name myteststack \
      --template-body file:///home/testuser/mytemplate.json \
      --parameters ParameterKey=Parm1,ParameterValue=test1 ParameterKey=Parm2,ParameterValue=test2

Or upload it directly via GUI.

------------------
AWS SAM
------------------

To deploy Layer with AWS SAM you will simply need to create two files ``samconfig.toml`` and ``template.yaml``
which are represented below.

`samconfig.toml
<https://link_to_file.com>`_

`template.yaml
<https://link_to_file.com>`_

After you create these files you can run them just by entering ``sam build && sam deploy`` in your console.

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Versions
------------------

Lambda creates a new version of your function each time that you publish the function.
The new version is a copy of the unpublished version of the function.
The unpublished version is named ``$LATEST``.

You can use `layers_versions_changer.py
<https://link_to_file.com>`_ to change layer versions in your project.