When creating ECS infrastructure we describe our Task Definitions with CloudFormation. We want to be able to dynamically pass environment variables as a parameter to the template. According to the docs, Environment has a KeyValuePair type, but CloudFormation parameters do not have this type.
We can not hardcode Environment variables to the template, because this template is used as a nested stack so environment variables will be dynamically passed inside it.
The only possible way I see so far is to pass all arguments as a CommaDelimitedList, and then somehow parse and map it using CloudFormation functions. I can Fn::Split every entity in key and value, but how to dynamically build an array of KeyValuePair in CloudFormation?
Or maybe there is an easier way, and I'm missing something? Thanks in advance for any ideas.
You may want to consider using the EC2 Parameter Store to create secured key/value pairs, which is supported in CloudFormation, and can be integrated with ECS environments.
AWS Systems Manager Parameter Store
AWS Systems Manager Parameter Store provides secure, hierarchical
storage for configuration data management and secrets management. You
can store data such as passwords, database strings, and license codes
as parameter values. You can store values as plain text or encrypted
data. You can then reference values by using the unique name that you
specified when you created the parameter. Highly scalable, available,
and durable, Parameter Store is backed by the AWS Cloud. Parameter
Store is offered at no additional charge.
While Parameter Store has great security features for storing application secrets, it can also be used to store nonsensitive application strings such as public keys, environment settings, license codes, etc.
And it is supported directly by CloudFormation, allowing you to easily capture, store and manage application configuration strings which can be accessed by ECS.
This template allows you provide the Parameter store key values at stack creation time via the console or CLI:
Description: Simple SSM parameter example
Parameters:
pSMTPServer:
Description: SMTP Server URL eg [email-smtp.us-east-1.amazonaws.com]:587
Type: String
NoEcho: false
SMTPServer:
Type: AWS::SSM::Parameter
Properties:
Name: my-smtp-server
Type: String
Value: !Ref pSMTPServer
Any AWS runtime environment (EC2, ECS, Lambda) can easily securely retrieve the values. From the console side, there is great Parameter manager interface that maintains parameter version history. Its intergated with IAM, so permissions are controlled with standard IAM policy syntax:
{
"Action": [
"ssm:GetParameterHistory",
"ssm:GetParameter",
"ssm:GetParameters",
"ssm:GetParametersByPath"
],
"Resource": [
"arn:aws:ssm:us-west-2:555513456471:parameter/smtp-server"
],
"Effect": "Allow"
},
{
"Action": [
"kms:Decrypt"
],
"Resource": [
"arn:aws:kms:us-west-2:555513456471:key/36235f94-19b5-4649-84e0-978f52242aa0a"
],
"Effect": "Allow"
}
Finally, this blog article shows a technique to read the permissions into a Dockerfile at runtime. They suggest a secure way to handle environment variables in Docker with AWS Parameter Store. For reference, I am including their Dockerfile here:
FROM grafana/grafana:master
RUN curl -L -o /bin/aws-env https://github.com/Droplr/aws-env/raw/master/bin/aws-env-linux-amd64 && \
chmod +x /bin/aws-env
ENTRYPOINT ["/bin/bash", "-c", "eval $(/bin/aws-env) && /run.sh"]
With that invocation, each of the parameters are available as an environment variable in the container. You app may or may not need a wrapper to read the parameters from the environment variables.
I was facing the same problem ,I needed to create a lambda resource with environment variables.
We decided to fix initial set of environment variable and keys name are also decided in advance.
So I added four parameters , and used Ref for values while keeping fixed keys name.
