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https://github.com/retspen/webvirtcloud
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libvirt has no timeout for opening a connection. Measured in the test setup: an unreachable host blocked qemu+tcp for 135 s and qemu+ssh for 133 s; a daemon that accepts and never answers blocks forever. Gunicorn runs sync workers and the instance list connects to every compute, so one unreachable compute held a worker for minutes per page load. - A connection is opened in a helper thread, at most one per connection at a time. The request waits LIBVIRT_CONNECT_TIMEOUT (default 5 s). An open nobody waits for any more keeps running; until it ends, requests get its error at once, and if it succeeds later the connection is used. A failed open is not repeated for LIBVIRT_RETRY_AFTER (default 30 s). A stuck host holds one thread and does not keep other hosts from connecting. - qemu+ssh runs ssh through vrtManager/libvirt-ssh (the URI's command parameter), which adds ConnectTimeout=10 and BatchMode=yes, so an abandoned ssh process ends and no prompt can hang. The user's ssh configuration (aliases, ProxyJump, keys) still applies. - The close callback acts only for the connection it was registered for: a late callback of a replaced connection dropped its successor. The reason is reported as text. A connection that closed before it was published is an error. - Compute.status is a bool (it returned the exception object, so the "host is down" check in refresh_instance_database never fired); the message is Compute.connection_error. Unit tests cover the timeout, retry delay, late success, single open, a stuck host next to a healthy one and the close callback. Live tests (vrtManager/test_live_connection.py), for TCP and SSH computes of the test setup: an unreachable address (no ssh left after 10 s), an endpoint that never answers, a slow open completing later, a host that goes silent on an established connection (keepalive ends calls within 45 s, the next request reconnects), an ssh_config alias and a ProxyJump host.
12 lines
689 B
Bash
Executable file
12 lines
689 B
Bash
Executable file
#!/bin/sh
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# ssh for libvirt qemu+ssh connections (the URI's "command" parameter).
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# libvirt passes no connect timeout, so an unreachable host would keep this
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# ssh process waiting for the kernel's TCP timeout. BatchMode makes ssh fail
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# instead of waiting for a password or host key prompt nobody can answer.
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# The timeout is fixed: libvirt passes this script no environment or extra
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# arguments. It bounds only ssh's TCP connect; WebVirtCloud stops waiting
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# after LIBVIRT_CONNECT_TIMEOUT on its own, so an abandoned ssh lives at most
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# this long.
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# Everything else comes from the user's ssh configuration (aliases,
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# ProxyJump, keys).
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exec ssh -o ConnectTimeout=10 -o BatchMode=yes "$@"
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