Add support for Docker

.travis.yml

@@ -7,7 +7,10 @@ rvm:
   - ruby-2.5
   - ruby-2.6
   - ruby-2.7
+services:
+  - docker
 script:
   - bundle exec bundler-audit
   - bundle exec rubocop
   - bundle exec rspec
+  - docker build .

Dockerfile

@@ -0,0 +1,7 @@
+FROM ruby:2.6.5-alpine
+
+USER nobody
+
+RUN gem install aws_public_ips
+
+CMD aws_public_ips

README.md

@@ -46,6 +46,14 @@ $ AWS_PROFILE=production aws_public_ips
 52.84.11.159
 ```
 
+The gem can also be run from Docker:
+```
+$ docker pull arkadiyt/aws_public_ips
+
+# For credentials, ensure the appropriate environment variables are defined in the host environment:
+$ docker run -e AWS_REGION -e AWS_ACCESS_KEY_ID -e AWS_SECRET_ACCESS_KEY -e AWS_SESSION_TOKEN arkadiyt/aws_public_ips
+```
+
 ### CLI reference
 
 ```