Separate stdout/stderr streams for one-off commands #1101
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This refactors the internal `empire.Empire.Run` method to support separate I/O streams for stdout and stderr. Previously, stdout and stderr from the attached container would be merged together. This comment does not change the Heroku API to include support for multiplexing the streams, so stdout/stderr will still be merged from the clients perspective.
phobologic
approved these changes
Aug 10, 2017
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Closes #1044
This separates stdout from stderr in
emp run, so thatemp runcan be used with existing UNIX tools more easily.Implementation wise, the endpoint for running one-offs now multiplexes stdout/stderr over the same TCP connection, and the client de-multiplexes it before writing it to the terminal's stdout/stderr. The multiplex/de-multiplex is done using the stdcopy, which is pulled from Docker's internals.
This is 100% backwards compatible. Older clients will receive the combined stream, while newer clients (those that send
X-Multiplex: 1in the headers), will get a multiplexed stream. And inversely, new clients talking with an older daemon will continue to handle the combined stream.