Docker Network CIDR Planner
Predict which subnet Docker's default-address-pools allocator will hand out next, and which one to pin.
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How it works
This computes address arithmetic only — it does not talk to a Docker daemon, read your routing table, or know what containers or networks actually exist. The example uses Docker Engine's documented built-in local-scope pools. Given aligned address pools (base CIDR + block size, one per line) and ranges already in use, it walks the pools in order and skips overlapping candidates. A base with host bits is rejected because daemon address-pool bases are CIDR networks. Actual allocation also depends on daemon history, so treat the result as a plan, not a guarantee.