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lix/tests/read-only-store.sh
Ben Radford 6ae35534b7
Support opening local store with database on read-only filesystem ()
Previously it was not possible to open a local store when its database is on a read-only filesystem. Obviously a store on a read-only filesystem cannot be modified, but it would still be useful to be able to query it.

This change adds a new read-only setting to LocalStore. When set to true, Nix will skip operations that fail when the database is on a read-only filesystem (acquiring big-lock, schema migration, etc), and the store database will be opened in immutable mode.

Co-authored-by: Ben Radford <benradf@users.noreply.github.com>
Co-authored-by: cidkidnix <cidkidnix@protonmail.com>
Co-authored-by: Dylan Green <67574902+cidkidnix@users.noreply.github.com>
Co-authored-by: John Ericson <git@JohnEricson.me>
Co-authored-by: Valentin Gagarin <valentin.gagarin@tweag.io>
2023-06-20 11:34:09 +02:00

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source common.sh
enableFeatures "read-only-local-store"
needLocalStore "cannot open store read-only when daemon has already opened it writeable"
clearStore
happy () {
# We can do a read-only query just fine with a read-only store
nix --store local?read-only=true path-info $dummyPath
# We can "write" an already-present store-path a read-only store, because no IO is actually required
nix-store --store local?read-only=true --add dummy
}
## Testing read-only mode without forcing the underlying store to actually be read-only
# Make sure the command fails when the store doesn't already have a database
expectStderr 1 nix-store --store local?read-only=true --add dummy | grepQuiet "database does not exist, and cannot be created in read-only mode"
# Make sure the store actually has a current-database, with at least one store object
dummyPath=$(nix-store --add dummy)
# Try again and make sure we fail when adding a item not already in the store
expectStderr 1 nix-store --store local?read-only=true --add eval.nix | grepQuiet "attempt to write a readonly database"
# Test a few operations that should work with the read-only store in its current state
happy
## Testing read-only mode with an underlying store that is actually read-only
# Ensure store is actually read-only
chmod -R -w $TEST_ROOT/store
chmod -R -w $TEST_ROOT/var
# Make sure we fail on add operations on the read-only store
# This is only for adding files that are not *already* in the store
expectStderr 1 nix-store --add eval.nix | grepQuiet "error: opening lock file '$(readlink -e $TEST_ROOT)/var/nix/db/big-lock'"
expectStderr 1 nix-store --store local?read-only=true --add eval.nix | grepQuiet "Permission denied"
# Test the same operations from before should again succeed
happy