mirror of
https://github.com/docker/compose.git
synced 2026-10-12 02:13:08 +00:00
Nicolas De Loof
5bc5b864fc
Providers opt into image distribution by declaring a pull block in their metadata — the presence of the command block is the declaration of support, generalizing the stop precedent. During its pull command a provider can request the service image from the local daemon with a get-image message (optionally platform-narrowed); compose answers on stdin with one image-stream JSON line then the tar as HTTP/1.1 chunked data (RFC 9112): length-prefixed blocks need no in-band delimiter in binary data, the zero-length chunk marks a COMPLETE transfer, and any stock chunked reader consumes it. There is deliberately no trailer nor final CRLF after the zero chunk — a stock reader stops there without consuming further bytes, so the next stdin answer starts clean for a provider requesting several images. An export failure is announced in-band through the error field so the provider is never left waiting; a failure after the announce closes the answer channel so the truncation is observable as EOF mid-chunk instead of a stream nobody will finish. The stream is exclusive on stdin for its whole duration — the framing invariant behind the lock. get-image is scoped to the pull command: emitted during up, down or stop it is a protocol error rather than served, so an image export can never stall another lifecycle command. Message dispatch moves out of executePlugin into handlePluginMessage, which also keeps the function under the complexity threshold. Signed-off-by: Nicolas De Loof <[email protected]>