When creating clusters, sending information to instances or even pulling extensions from GitHub, flambé needs to deal with user’s protected data.


Flambé will always rely on the default local configuration users have for all services flambé uses. This means that when using services like github or AWS, flambé will rely on the standard authentication mechanisms each service requires.

There is no need for users to configure special auth mechanisms for flambé.


As explained in Providing secrets, users have the posibility of providing secrets information to the Runnable objects that will be executed.

This is done via an ini file. For example:


PASSWORD = 0987654321

When calling:

flambe runnable.yaml --secrets secrets.ini [--cluster cluster.yaml]

Then the Runnable will have access to the secrets through its attribute config.


Some important items related to Security when dealing with clusters:

  • Flambé will use SSH for all communications with the instances. It will use only the key specified in the config.
  • All resources that need to be uploaded to the instances are done via rsync with the given key.
  • A copy of the secrets file will be sent to all instances using rsync with the given key.
  • The key provided in the config is never uploaded to the instances.
  • When loading the cluster, flambé will distribute a special key pair (created exclusively for the cluster) to all instances. This key will be used for internal communication (ie the communication betweeen the instances)


All flow between the local process and the instances is done in a secure way using SSH protocols.


Flambé won’t configure any instances security policies (eg firewalls, security groups, etc). The user is responsible for configuring this to ensure clusters work correctly. This involves:

  • Allowing private communication between the hosts created in the same subnet.
  • Opening port 22 for SSH connection in all hosts.
  • Opening ports 49556 and 49558 for the Report Site (in case of running an Experiment).


When using AWSCluster for creating an AWS EC2 cluster, flambé will rely on the local configuration for authentication (it uses boto3 under the hood). Users are going to be able to create clusters as long as they follow the AWS standards for storing credentials/tokens (for example, having ~/.aws/credentials file or having AWS_* environment variables defined).


As explained in Automatic extensions installation, flambé will install the extensions when -i is specified. For all extensions that are git based URLs (from GitHub or BitBucket for example), then flambé will try to clone/pull them using the local configuration. This means that if for example a user wants to use an extensions from its private GitHub account, then it needs to have local configuration that allows pulling from this GitHub account. Flambé will not provide any special SSH keys to authenticate with these services.


git URLs for extensions support both HTTPS/SSH protocols:

extensions: ssh://