How to set an environment variable in Amazon EC2

If you are using linux or mac os for your ec2 instance then,

Go to your root directory and write command:

vim .bash_profile

You can see your bash_profile file and now press 'i' for inserting a lines, then add

export DB_PORT="5432"

After adding this line you need to save file, so press 'Esc' button then press ':' and after colon write 'w' it will save the file without exiting.

For exit, again press ':' after that write 'quit' and now you are exit from the file. To check that your environment variable is set or not write below commands:

python
>>>import os
>>>os.environ.get('DB_PORT')
>>>5432 

You can retrieve this information from the meta data and then run your own set environment commands.

You can get the instance-id from the meta data (see here for details: http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/ec2-instance-metadata.html#instancedata-data-retrieval)

curl http://169.254.169.254/latest/meta-data/instance-id

Then you can call the describe-tags using the pre-installed AWS CLI (or install it on your AMI)

aws ec2 describe-tags --filters "Name=resource-id,Values=i-5f4e3d2a" "Name=Value,Values=DB_PORT"

Then you can use OS set environment variable command

export DB_PORT=/what/you/got/from/the/previous/call

You can run all that in your user-data script. See here for details: http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/user-data.html

Lately, it seems AWS Parameter Store is a better solution.

Now there is even a secrets manager which auto manages sensitive configurations as database keys and such..

See this script using SSM Parameter Store based of the previous solutions by Guy and PJ Bergeron.

https://github.com/lezavala/ec2-ssm-env

I used a combination of the following tools:

• Install jq library (sudo apt-get install -y jq)
• Install the EC2 Instance Metadata Query Tool

Here's the gist of the code below in case I update it in the future: https://gist.github.com/marcellodesales/a890b8ca240403187269

######
# Author: Marcello de Sales ([email protected])
# Description: Create Create Environment Variables in EC2 Hosts from EC2 Host Tags
# 
### Requirements:  
# * Install jq library (sudo apt-get install -y jq)
# * Install the EC2 Instance Metadata Query Tool (http://aws.amazon.com/code/1825)
#
### Installation:
# * Add the Policy EC2:DescribeTags to a User
# * aws configure
# * Souce it to the user's ~/.profile that has permissions
#### 
# REboot and verify the result of $(env).

# Loads the Tags from the current instance
getInstanceTags () {
  # http://aws.amazon.com/code/1825 EC2 Instance Metadata Query Tool
  INSTANCE_ID=$(./ec2-metadata | grep instance-id | awk '{print $2}')

  # Describe the tags of this instance
  aws ec2 describe-tags --region sa-east-1 --filters "Name=resource-id,Values=$INSTANCE_ID"
}

# Convert the tags to environment variables.
# Based on https://github.com/berpj/ec2-tags-env/pull/1
tags_to_env () {
    tags=$1

    for key in $(echo $tags | /usr/bin/jq -r ".[][].Key"); do
        value=$(echo $tags | /usr/bin/jq -r ".[][] | select(.Key==\"$key\") | .Value")
        key=$(echo $key | /usr/bin/tr '-' '_' | /usr/bin/tr '[:lower:]' '[:upper:]')
        echo "Exporting $key=$value"
        export $key="$value"
    done
}

# Execute the commands
instanceTags=$(getInstanceTags)
tags_to_env "$instanceTags"