What Should a Docker Backup Include Besides the Media Library?
A Docker backup must preserve the deployment definition, application state, databases, credentials, and recovery procedureโnot only the replaceable media files.
Movies, music, and photos may be the largest dataset, but losing Compose files, app databases, metadata, user accounts, certificates, encryption keys, or mount mappings can make the library unusable or force weeks of rebuilding. A reliable backup starts from the question โWhat must exist to recreate the service on an empty host?โ and protects each required layer with an application-consistent method.
Back Up the Deployment Definition
Preserve every Compose file, override file, Dockerfile, build context, stack name, image tag, command, port mapping, network, volume declaration, health check, restart policy, and resource limit required to recreate the containers.
A self-hosting discussion describes keeping each applicationโs Compose and environment files together so the stack can be redeployed predictably. This makes the deployment configuration a first-class backup asset rather than relying on a running container as documentation.
Record exact image versions instead of only floating tags such as latest. Store configuration in version control where appropriate, but keep secrets out of public repositories and include a protected inventory of required external dependencies.
Protect Every Persistent Bind Mount and Named Volume
List the mounts attached to each service and classify them as replaceable cache, application configuration, metadata, database, uploaded content, generated thumbnails, or critical state. Back up all non-replaceable paths.
An OpenMediaVault discussion states that the important recovery set is the Compose definition plus persistent data, while container images can usually be downloaded again. That distinguishes durable state from replaceable container images.
Include hidden application directories and small metadata volumes, not only the large library mount. Verify bind-mount source paths are included by the host backup and that named volumes are exported through a method that preserves ownership and permissions.
Create Database-Consistent Backups
Identify PostgreSQL, MariaDB, MySQL, MongoDB, SQLite, Redis persistence, and embedded databases. Use the databaseโs supported dump, snapshot, or quiesced backup process instead of copying files while transactions are changing them.
A Stack Overflow Docker-volume backup discussion demonstrates mounting a volume into a temporary container for archive creation, but database files still require consistency awareness. A raw volume archive is not automatically a valid transactional database backup.
Record the engine version, database names, users, extensions, and restore order. Test a logical dump independently from the filesystem backup so one method can recover when the other is incomplete.
Preserve Secrets, Certificates, and Identity
Back up protected copies of environment secrets, API tokens, database passwords, OAuth client credentials, TLS certificates, private keys, SSH keys, encryption keys, and application recovery codes.
Secrets should be stored separately from ordinary Compose files and encrypted with a recovery method that does not depend on the failed Docker host. The backup must include enough context to know which service and variable each secret restores.
Do not omit encryption keys for encrypted databases or storage. A perfect copy of encrypted data is unrecoverable if the key, passphrase, or key-management configuration is lost.
Include Reverse Proxy, DNS, Jobs, and Host Assumptions
Preserve reverse-proxy routes, middleware, access controls, DNS records, DDNS configuration, scheduled jobs, update policies, firewall rules, GPU device mappings, UID and GID assignments, and storage mount units.
A backup product overview emphasizes that reliable volume protection also needs scheduling, retention, encryption, destination control, and visible execution history. These operational details turn a one-time archive into a repeatable backup workflow.
Document which host directories, networks, kernel features, and devices must exist before Compose starts. Without those assumptions, restored containers may create empty fallback directories, use wrong permissions, or start without hardware acceleration.
Prove the Backup With an Empty-Host Restore
Restore into an isolated test host or VM using only the backup and written instructions. Recreate storage paths, secrets, databases, proxy routes, and containers in the documented order.
The ZimaSpace guide to restoring one shared folder safely provides the same principle: a backup is trustworthy only after a controlled restore proves its scope.
Validate login, permissions, database integrity, metadata, thumbnails, playback, uploads, scheduled jobs, TLS, and a second restart. Record recovery time and update the backup checklist whenever the restore reveals a missing dependency.
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Why Does a Docker Volume Restore Recreate File Contents but Drop Extended Attributes?
A volume-restore diagnosis covering xattr inventory, tar and Rsync options, namespaces, destination support, privileges, labels, app metadata, and tests.
Why Does a Running Container Keep Its Old Memory Limit After the Compose File Changes?
A memory-limit diagnosis covering live cgroups, restart versus recreation, Compose fields, hard and soft limits, parent scopes, swap, and runtime heaps.
Why Does Restarting a Reverse Proxy Invalidate Every Session for One Self-Hosted App?
A session-loss diagnosis covering restart scope, cookie ownership, secret rotation, cache-backed sessions, sticky routing, auth gateways, and recovery.
