age: optional caching of key command output#2247
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SOPS constructs one MasterKey per recipient and loads identities for each in turn, executing SOPS_AGE_KEY_CMD / SOPS_AGE_SSH_PRIVATE_KEY_CMD once per attempted recipient. With a slow command (e.g. a password manager CLI) a single decrypt multiplies into many seconds. Setting SOPS_AGE_KEY_CMD_CACHE=true executes each command at most once per process and reuses the output for every recipient. Opt-in because the command receives SOPS_AGE_RECIPIENT and may legitimately return a different key per recipient. Only successful outputs are cached, and the lock is not held while the command runs, so a failing or slow command cannot poison or serialise decrypts in long-lived processes such as the keyservice. Signed-off-by: Øivind Hoel <oivind.hoel@gmail.com>
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Since sops loads identities once per recipient it attempts, executing
SOPS_AGE_KEY_CMD/SOPS_AGE_SSH_PRIVATE_KEY_CMDeach time when set, using slow clients likebwis painful when files have many recipients. In my testing, a file with 7 recipients where the matching key is last takes ~20 seconds to finish decrypting.To fix this, add the opt-in
SOPS_AGE_KEY_CMD_CACHEto make the command run at most once per process and reuse the result for each recipient. If unset or false, no behaviour changes.Opt-in because a command may use
SOPS_AGE_RECIPIENTto return a different key per recipient; caching can break that (a command that exits non-zero for unknown recipients survives, since errors are not cached). The flag is only for commands that ignore the recipient.Tests cover once-per-process with the flag, once-per-recipient without, and errors not being cached.