IT Support » DMZ-WEB Infrastructure

*Chapter 5 of the dmz-web documentation · headings are numbered like the cheat sheets · index: [[Wiki]]*

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## 5.1 Services

```bash

systemctl --user daemon-reload                        # after editing any Quadlet file

systemctl --user list-units 'db-*' 'site-*' 'net-*' 'nginx-proxy-manager*'

systemctl --user status  db-<name>.service site-<name>.service

systemctl --user restart db-<name>.service site-<name>.service

journalctl --user -u site-<name>.service -e

/usr/libexec/podman/quadlet -dryrun -user             # validate Quadlet syntax

```

## 5.2 Listing / inspecting

```bash

podman ps -a

podman network ls ; podman volume ls ; podman secret ls

podman inspect <ctr> --format '{{.ImageName}}'

podman inspect <ctr> --format '{{range .Mounts}}{{.Name}} -> {{.Destination}}{{"\n"}}{{end}}'

podman inspect <ctr> | jq '.[0].Config.Env'

podman logs -f <ctr>

podman exec -it <ctr> bash                            # root shell inside, no password

```

## 5.3 Environment variables inside a container

```bash

podman exec <ctr> printenv

podman exec <ctr> printenv | grep -iE 'ROOT|PASSWORD|KEY'

podman exec <ctr> printenv MYSQL_ROOT_PASSWORD | od -c | tail -3   # reveals a stray trailing \n

```

## 5.4 Secrets

Injected as env at container start (`Secret=<secret>,type=env,target=VAR`).

MariaDB/PostgreSQL only read their `*_PASSWORD` env on **first**

initialisation of an empty data dir; afterwards the env var is inert and the

real password is whatever is in the DB.

```bash

podman secret inspect --showsecret <secret>

podman secret inspect --showsecret --format '{{.SecretData}}' <secret>

# always create WITHOUT a trailing newline

printf '%s' 'VALUE' | podman secret create <secret> -

printf '%s' "$(openssl rand -base64 32)" | podman secret create <secret> -

# replace: rm + create, then restart the consumers

podman secret rm <secret> && printf '%s' 'VALUE' | podman secret create <secret> -

```

## 5.5 Fixing a secret that has a trailing `\n` (legacy WordPress sites)

```bash

cat > ~/tmp/fixpw.sh <<'EOF'

ROOTPW="$(printf '%s' "$MYSQL_ROOT_PASSWORD")"   # $(...) strips the trailing \n

WPPW="$(printf '%s' "$MYSQL_PASSWORD")"

mariadb -uroot -p"$MYSQL_ROOT_PASSWORD" <<SQL

ALTER USER 'root'@'localhost' IDENTIFIED BY '$ROOTPW';

ALTER USER 'root'@'%'         IDENTIFIED BY '$ROOTPW';

ALTER USER 'wordpress'@'%'    IDENTIFIED BY '$WPPW';

FLUSH PRIVILEGES;

SQL

EOF

podman exec -i db-<name> sh < ~/tmp/fixpw.sh

for s in <name>-db-root-password <name>-db-password; do

  v="$(podman secret inspect --showsecret --format '{{.SecretData}}' "$s")"

  podman secret rm "$s"; printf '%s' "$v" | podman secret create "$s" -

done

systemctl --user restart db-<name>.service site-<name>.service   # run back to back with the SQL half

```

## 5.6 Database engines and version upgrades

Every stack has its own DB container; the engine and version are in the DB unit (`Image=`). Rule

for all of them: **dump first, change one `Image=` line in the repo copy, commit, copy the unit,

daemon-reload, restart, check** (§3.1.7 and §3.1.6, same procedure as the Snipe-IT image upgrade in §4.3). Which

of the two cases applies depends on the kind of jump.

| Engine | Patch / minor (same major) | Major jump |

|--------|----------------------------|------------|

| MariaDB (WordPress, Snipe-IT) | Change the tag or digest, restart. The data directory is kept; schema upgrades are applied by the server. Dump beforehand. | Never straight on the live volume. 1. Dump all databases. 2. Start the new version as a **scratch** container with an empty volume and restore the dump there. 3. Check the application against it (staging first). 4. Only then switch the real unit. Do not rely on `MARIADB_AUTO_UPGRADE` as the only safety net: it upgrades the system tables on start, but a failed or half-done upgrade cannot be undone without the dump. If you do keep the volume, run `mariadb-upgrade` inside the container once after the start and read its output. |

| PostgreSQL (Redmine) | Change the minor tag (e.g. `16.4` → `16.6`), restart. | The data directory format changes: **dump and restore** (`pg_dumpall` or `pg_dump -Fc` per database into a new empty volume under the new major version). Do not just change the tag; the container would refuse to start or, worse, you would be tempted to delete the volume. |

| TimescaleDB on PG 16 (PF) | The `timescaledb:<x.y.z>-pg16` tag can move to a newer extension version; after the restart run `ALTER EXTENSION timescaledb UPDATE;` in the PF database (in a fresh session) and check `\dx`. Dump first. | A PostgreSQL major (`-pg16` → `-pg17`) is the dump-and-restore case above, with the Timescale restore steps from `pf-mgmt-cheatsheet.md` (`timescaledb_pre_restore()` / `timescaledb_post_restore()`). |

A dump that was never restored is not a backup: restore it once into a scratch container and look

at the data before you depend on it. Keep the old image tag and the old volume until the new

version has run for a few days; then remove them.

---

_Source: `dmz-web-podman-cheatsheet.md` v1.8 in the `dmz-web-deploy` repo ([[Releases]]). Edit the wiki and the repo copy together._