Add a --meta-data-ec2 flag

[toolmantim]

This adds a --meta-data-ec2 option to automatically populate the agent's meta-data with EC2 meta-data such as aws:ami-id, aws:instance-id and aws:instance-type. This will mean that buildkite/elastic-ci-stack-for-aws#67 and the like can just use --meta-data-ec2.

$ buildkite-agent start --token xxx --meta-data-ec2

  _           _ _     _ _    _ _                                _
 | |         (_) |   | | |  (_) |                              | |
 | |__  _   _ _| | __| | | ___| |_ ___    __ _  __ _  ___ _ __ | |_
 | '_ \| | | | | |/ _` | |/ / | __/ _ \  / _` |/ _` |/ _ \ '_ \| __|
 | |_) | |_| | | | (_| |   <| | ||  __/ | (_| | (_| |  __/ | | | |_
 |_.__/ \__,_|_|_|\__,_|_|\_\_|\__\___|  \__,_|\__, |\___|_| |_|\__|
                                                __/ |
 http://buildkite.com/agent                    |___/

2016-05-15 13:32:51 NOTICE Starting buildkite-agent v3.0-beta.1 with PID: 2558
2016-05-15 13:32:51 NOTICE The agent source code can be found here: https://github.com/buildkite/agent
2016-05-15 13:32:51 NOTICE For questions and support, email us at: hello@buildkite.com
2016-05-15 13:32:51 INFO   Registering agent with Buildkite...
2016-05-15 13:32:51 INFO   Successfully registered agent "ip-172-31-60-230" with meta-data [aws:instance-id=i-575f61ca aws:instance-type=t2.nano aws:ami-id=ami-f5f41398]
2016-05-15 13:32:51 INFO   Connecting to Buildkite...
2016-05-15 13:32:51 INFO   Agent successfully connected
2016-05-15 13:32:51 INFO   You can press Ctrl-C to stop the agent
2016-05-15 13:32:51 INFO   Waiting for work...

If you try to use the flag on a non-EC2 machine you just get some errors in the log:

$ buildkite-agent start --token xxx --meta-data-ec2

  _           _ _     _ _    _ _                                _
 | |         (_) |   | | |  (_) |                              | |
 | |__  _   _ _| | __| | | ___| |_ ___    __ _  __ _  ___ _ __ | |_
 | '_ \| | | | | |/ _` | |/ / | __/ _ \  / _` |/ _` |/ _ \ '_ \| __|
 | |_) | |_| | | | (_| |   <| | ||  __/ | (_| | (_| |  __/ | | | |_
 |_.__/ \__,_|_|_|\__,_|_|\_\_|\__\___|  \__,_|\__, |\___|_| |_|\__|
                                                __/ |
 http://buildkite.com/agent                    |___/

2016-05-15 23:35:30 NOTICE Starting buildkite-agent v3.0-beta.1 with PID: 54918
2016-05-15 23:35:30 NOTICE The agent source code can be found here: https://github.com/buildkite/agent
2016-05-15 23:35:30 NOTICE For questions and support, email us at: hello@buildkite.com
2016-05-15 23:35:32 ERROR Failed to fetch EC2 meta-data: Get http://169.254.169.254/latest/meta-data/instance-id: dial tcp 169.254.169.254:80: i/o timeout
2016-05-15 23:35:36 INFO   Registering agent with Buildkite...
2016-05-15 23:35:38 INFO   Successfully registered agent "tim.local-1" with meta-data []
2016-05-15 23:35:38 INFO   Connecting to Buildkite...
2016-05-15 23:35:39 INFO   Agent successfully connected
2016-05-15 23:35:39 INFO   You can press Ctrl-C to stop the agent
2016-05-15 23:35:39 INFO   Waiting for work...

[toolmantim]

This is ready to roll!

[keithpitt]

typo

[toolmantim]

@keithpitt all fixed!

[keithpitt]

Perfect! 🚀