How to set an environment variable in Amazon EC2

Question

I created a tag on the AWS console for one of my EC2 instances.

However, when I look on the server, no such environment variable is set.

The same thing works with elastic beanstalk. env shows the tags I created on the console.

$ env
 [...]
 DB_PORT=5432

How can I set environment variables in Amazon EC2?

Answer 1

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

Answer 2

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 (marcello.desales@gmail.com)
# 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"

Answer 3

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

Answer 4

Following the instructions given by Guy , I wrote a small shell script. This script uses AWS CLI and jq . It lets you import your AWS instance and AMI tags as shell environment variables.

I hope it can help a few people.

https://github.com/12moons/ec2-tags-env

Answer 5

I normally load tags as environment variables on boot by running a UserData script. Depending on the instance, I change the --query and --filter parameters to the describe-instances call but otherwise the script stays the same. NOTE : The example below excludes the tag Name and tags containing : - change this behaviour to suit your needs.

#!/bin/bash -v
apt-get update
apt-get -y install awscli

# add boot script which loads environment variables
cat > /etc/profile.d/export_instance_tags.sh << 'EndOfMessage'
# fetch instance info
INSTANCE_ID=$(curl -s http://169.254.169.254/latest/meta-data/instance-id)
INSTANCE_AZ=$(curl -s http://169.254.169.254/latest/meta-data/placement/availability-zone)
INSTANCE_REGION="`echo \"$INSTANCE_AZ\" | sed -e 's:\([0-9][0-9]*\)[a-z]*\$:\\1:'`"

# export instance tags
export_statement=$(aws ec2 describe-tags --region "$INSTANCE_REGION" --filters "Name=resource-id,Values=$INSTANCE_ID" --query 'Tags[?!contains(Key, `Name`) && !contains(Key, `:`)].[Key,Value]' --output text | sed -E 's/^([^\s\t]+)[\s\t]+([^\n]+)$/export \1="\2"/g')
eval $export_statement

# export instance info
export INSTANCE_ID
export INSTANCE_AZ
export INSTANCE_REGION
EndOfMessage

It runs describe-tags to list all tags, reformats the output to a sequence of export statements with sed then runs the result using eval

Answer 6

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 

Answer 7

There are 2 ways to do this and this is more understandable to everyone.

===== 1. persistence way to store environment variables =====

After rebooting the EC2 instance also these environment variables will remain (persist).

Files with the .sh extension in the /etc/profile.d directory get executed whenever a bash login shell is entered (eg when logging in from the console or over ssh), as well as by the DisplayManager when the desktop session loads.

You can for instance create the file /etc/profile.d/my_env_vars.sh using below commands

1. cd / - go to the root directory

2. cd etc/profile.d/ - go to profile.d directory

3. sudo touch my_env_vars.sh - create your own file to store environment variables without sudo you can't create a file in this directory

4. sudo vi techflare_env.sh - edit file to open

   • Now press i key to enter INSERT mode
   • Paste your environment variable like below

   export MONGODB_URI=mongodb+srv://hello:easy.lqyny.mongodbnet/mydb
export PORT=5000

   • Now press Esc key and type :wq to save and exit
   • Finally press Enter to finish.

5. You can view file using cat my_env_vars.sh command.

6. To activate the environmental variable you need a Reboot(Restarting) instance.

7. After Rebooting(Restarting) you can view all environmental variables using printenv command.

===== 2. Temporary environmental variable using shell =====

• After rebooting Instance these are gone.
• Simply you can enter the terminal and export PORT=5000 press Enter .
• These environmental variables will be lost after Rebooting.

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