10c3bad652
Fixes #2522 Skip embedding client.alloc_dir when building chroot. If a user configures a Nomad client agent so that the chroot_env will embed the client.alloc_dir, Nomad will happily infinitely recurse while building the chroot until something horrible happens. The best case scenario is the filesystem's path length limit is hit. The worst case scenario is disk space is exhausted. A bad agent configuration will look something like this: ```hcl data_dir = "/tmp/nomad-badagent" client { enabled = true chroot_env { # Note that the source matches the data_dir "/tmp/nomad-badagent" = "/ohno" # ... } } ``` Note that `/ohno/client` (the state_dir) will still be created but not `/ohno/alloc` (the alloc_dir). While I cannot think of a good reason why someone would want to embed Nomad's client (and possibly server) directories in chroots, there should be no cause for harm. chroots are only built when Nomad runs as root, and Nomad disables running exec jobs as root by default. Therefore even if client state is copied into chroots, it will be inaccessible to tasks. Skipping the `data_dir` and `{client,server}.state_dir` is possible, but this PR attempts to implement the minimum viable solution to reduce risk of unintended side effects or bugs. When running tests as root in a vm without the fix, the following error occurs: ``` === RUN TestAllocDir_SkipAllocDir alloc_dir_test.go:520: Error Trace: alloc_dir_test.go:520 Error: Received unexpected error: Couldn't create destination file /tmp/TestAllocDir_SkipAllocDir1457747331/001/nomad/test/testtask/nomad/test/testtask/.../nomad/test/testtask/secrets/.nomad-mount: open /tmp/TestAllocDir_SkipAllocDir1457747331/001/nomad/test/.../testtask/secrets/.nomad-mount: file name too long Test: TestAllocDir_SkipAllocDir --- FAIL: TestAllocDir_SkipAllocDir (22.76s) ``` Also removed unused Copy methods on AllocDir and TaskDir structs. Thanks to @eveld for not letting me forget about this! |
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