I want to send commands to a ecs/FARGATE container using python/boto3. I can successfully open a session using execute_command.
But how can I get output of the command? And wait until its done?
I find a a lot about the aws cli and the session-manager-plugin. So one way would be to run the aws cli from python. But is there also a way to get the output of the command from native python?
You can re-implement the same procedure that aws execute-command uses internally:
# making an execute-command call to connect to an
# active session on a container would require
# session-manager-plugin to be installed on the client machine.
# Hence, making this empty session-manager-plugin call
# before calling execute-command to ensure that
# session-manager-plugin is installed
# before execute-command-command is made
check_call(["session-manager-plugin"])
client = self._session.create_client(
...
response = client.execute_command(**parameters)
...
ssm_request_params = build_ssm_request_paramaters(response, client)
# ignore_user_entered_signals ignores these signals
# because if signals which kills the process are not
# captured would kill the foreground process but not the
# background one. Capturing these would prevents process
# from getting killed and these signals are input to plugin
# and handling in there
with ignore_user_entered_signals():
# call executable with necessary input
check_call(["session-manager-plugin",
...
The commit message by the author of this code summarizes the approach:
https://github.com/aws/aws-cli/commit/ba4163d46969a8aba0e4712852aba9ad5a3f3667
CLI CUSTOMIZATION FOR ECS EXECUTE-COMMAND API
- ECS execute-command API returns a streamUrl and a token-value using a user can connect to a session inside a running container by calling session-manager-plugin with those values.
- This CLI customization makes this call for the user, thus internally making two calls.