wan
78c8e79726
Per https://www.postgresql.org/download/linux/debian/ (manual configuration): GPG key + deb822 sources (codename-pgdg) + postgresql-18. Skip-check now requires an 18 cluster. Down also removes the PGDG repo.
55 lines
2.1 KiB
Markdown
55 lines
2.1 KiB
Markdown
# sysmig
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Lightweight tool that manages host state in DB-migration (Flyway) style.
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Started for a 1GB VM (`ocrt-postgres`), but deployable to any machine
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via cloud-init.
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## Usage
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```bash
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sudo bash /opt/sysmig/sysmig up # apply all pending migrations (idempotent)
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sudo bash /opt/sysmig/sysmig down # roll back the last migration
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sudo bash /opt/sysmig/sysmig down all # roll back everything (reverse order)
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bash /opt/sysmig/sysmig status # show status (no root required)
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```
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- Migrations: `migrations/NNN-name.sh`, receiving `up`/`down` as `$1`
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- Applied history: `/var/lib/sysmig/applied` - applied entries never re-run
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- On failure the run aborts at that step; earlier steps stay applied
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## Adding a new migration
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1. Create `migrations/NNN-name.sh` (number higher than existing; leave gaps)
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2. Implement both `up` and `down` cases - both must actually work
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3. Commit & push, then on the server: `git pull && sudo bash sysmig/sysmig up`
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## cloud-init integration
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```yaml
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#cloud-config
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runcmd:
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- [ git, clone, <REPO_URL>, /opt/sysmig ]
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- [ bash, /opt/sysmig/sysmig, up ]
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```
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For a private repo you need an auth strategy:
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- **deploy key** (existing machines): register a read-only key on the repo
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- **fleet rollout**: make the repo public, or embed a read-only token in
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the https URL
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## Current migrations
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| # | name | effect |
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|----|----------------------------|-----------------------------------------------|
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| 001 | create-swap | 2GB swap + fstab + vm.swappiness=10 |
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| 002 | disable-networkd-dispatcher| reclaim ~27MB RAM |
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| 003 | purge-exim4 | reclaim ~21MB RAM (package removed) |
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| 004 | purge-haveged | reclaim ~8MB RAM (package removed) |
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| 005 | mount-pgdata | /dev/sdb (20G) -> /var/lib/postgresql, fstab |
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| 006 | install-postgres | PG 18 via PGDG repo, cluster on the disk |
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## Roadmap
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- `010-tune-postgres` - 1GB tuning (shared_buffers=128MB, work_mem=4MB,
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max_connections=30, ...)
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