# Finish the 2026-04-23 DB-off-NFS migration by removing pfi-postgres's
# residual dependency on ana-nas's /mnt/db NFS export.
#
# Postgres on pfi-postgres is already running from local disk
# (/var/lib/postgresql/13/main); /mnt/db is still mounted but
# nothing writes to it. This playbook pulls the fstab line, unmounts,
# and removes the empty mountpoint — eliminating ana-nas from
# pfi-postgres's fault domain entirely.
#
# The old pre-migration data directories on ana-nas (pfi-mongo/,
# pfi-postgres/) are NOT touched. They remain as a cold archive of
# the pre-migration state and cost nothing to keep.
#
# Usage:
#   scripts/elway pfi-postgres --playbook playbooks/decouple-pfi-postgres-from-ana-nas.yaml
#
# Safe to re-run: every mutation is creates-gated or when-gated, so a
# second invocation is a no-op.

vars:
  fstab: /etc/fstab
  mount_point: /mnt/db
  nfs_source: "10.250.50.50:/mnt/db"

steps:
  # ── pre-flight confirmations ────────────────────────────────────────

  - name: Confirm Postgres IS running off local disk (not /mnt/db)
    # changed_when: false — we're attesting, not changing. Fails hard
    # if Postgres somehow ended up on the NFS path we're about to
    # unmount.
    shell: ps -ef | grep -v grep | grep 'postgres.*-D' | grep -q '/var/lib/postgresql'
    changed_when: "false"

  - name: Confirm /mnt/db has no open files (nothing writing to it)
    # lsof exits non-zero if no matches found — that's what we want.
    # Invert with `!`. If the mount point IS in use we want the
    # playbook to halt so the user can investigate.
    shell: "! sudo lsof +D {{ mount_point }} 2>/dev/null | grep -v '^COMMAND'"
    sudo: true
    changed_when: "false"

  # ── unmount + fstab ────────────────────────────────────────────────

  - name: Remove fstab entry for {{ nfs_source }}
    shell: sed -i "\\|^{{ nfs_source }}[[:space:]]|d" {{ fstab }}
    sudo: true
    # Idempotency: if the line is already absent, the sed is a no-op
    # but still reports "changed" since sed always rewrites the file.
    # `when:` gate below makes it truly idempotent.
    when: "grep -qE '^{{ nfs_source }}[[:space:]]' {{ fstab }}"

  - name: Unmount {{ mount_point }}
    shell: umount {{ mount_point }}
    sudo: true
    # Only run if currently mounted.
    when: "mountpoint -q {{ mount_point }}"

  - name: Remove empty mountpoint dir
    shell: rmdir {{ mount_point }}
    sudo: true
    # Only if the dir exists AND is empty (rmdir fails on non-empty,
    # which is the safety we want). The `creates: null` pattern
    # doesn't apply here; we use a when: that checks both conditions.
    when: "[ -d {{ mount_point }} ] && [ -z \"$(ls -A {{ mount_point }} 2>/dev/null)\" ]"

  # ── tell systemd to forget the old mount unit ──────────────────────

  - name: Reload systemd so the synthesized mnt-db.mount unit clears
    shell: systemctl daemon-reload
    sudo: true
    changed_when: "false"

verify:
  - name: fstab no longer references /mnt/db
    shell: "! grep -qE '^{{ nfs_source }}[[:space:]]' {{ fstab }}"
    changed_when: "false"

  - name: /mnt/db is not a mountpoint
    shell: "! mountpoint -q {{ mount_point }}"
    changed_when: "false"

  - name: No systemd mnt-db.mount unit remains active
    # Don't grep for "active" — "inactive" contains it as a substring.
    # `is-active` returns 0 only when the unit is truly active; invert.
    shell: "! systemctl is-active mnt-db.mount >/dev/null 2>&1"
    changed_when: "false"

  - name: Postgres is still running (we didn't accidentally break it)
    shell: systemctl is-active postgresql
    changed_when: "false"

  - name: Postgres still listening on :5432
    shell: "ss -tln | grep -q ':5432'"
    changed_when: "false"