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3fd9726719
ugly hack with relativ URLs because relref is apparently broken when linking to section pages (_index.md) except for a few cases...
47 lines
1.7 KiB
Markdown
47 lines
1.7 KiB
Markdown
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title = "Implementation Overview"
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{{% alert theme="warning" %}}Under Construction{{% /alert %}}
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The following design aspects may convince you that `zrepl` is superior to a hacked-together shell script solution.
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## Language
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`zrepl` is written in Go, a real programming language with type safety,
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reasonable performance, testing infrastructure and an (opinionated) idea of
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software engineering.
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* key parts & algorithms of `zrepl` are covered by unit tests
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* zrepl is noticably faster than comparable shell scripts
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## RPC protocol
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While it is tempting to just issue a few `ssh remote 'zfs send ...' | zfs recv`, this has a number of drawbacks:
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* The snapshot streams need to be compatible.
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* Communication is still unidirectional. Thus, you will most likely
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* either not take advantage of features such as *compressed send & recv*
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* or issue additional `ssh` commands in advance to figure out what features are supported on the other side.
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* Advanced logic in shell scripts is ugly to read, poorly testable and a pain to maintain.
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`zrepl` takes a different approach:
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* Define an RPC protocol.
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* Establish an encrypted, authenticated, bidirectional communication channel...
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* ... with `zrepl` running at both ends of it.
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This has several obvious benefits:
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* No blank root shell access is given to the other side.
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* Instead, access control lists (ACLs) are used to grant permissions to *authenticated* peers.
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* The transport mechanism is decoupled from the remaining logic, keeping it extensible (e.g. TCP+TLS)
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{{% panel %}}
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Currently, the bidirectional communication channel is multiplexed on top of a single SSH connection.
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Local replication is of course handled efficiently via simple method calls
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See TODO for details.
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{{% / panel %}}
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