PHP Configuration¶

PHP settings are templated from a single file — /etc/php84/conf.d/custom.ini.tpl — which the entrypoint runs through envsubst and writes to /etc/php84/conf.d/custom.ini. FPM pool settings (/etc/php84/php-fpm.d/www.conf) get the same treatment.

Concretely, anything you can change via a documented env var is already wired up. You don't need to mount a custom php.ini for the vast majority of settings.

Core runtime knobs¶

Variable	Default	Purpose
`memory_limit`	`128M`	Per-request memory ceiling. Raise for Composer, Moosh, large imports. `-1` = unlimited.
`max_execution_time`	`0`	Max seconds a script can run. `0` = unlimited.
`max_input_time`	`-1`	Max seconds parsing input (POST, GET, uploads). `-1` = unlimited.
`max_input_vars`	`1000`	Max POST/GET variables per request. Raise for Moodle-style admin forms.
`post_max_size`	`8M`	Max POST body size. Must exceed `upload_max_filesize`.
`upload_max_filesize`	`2M`	Max individual file upload size.
`file_uploads`	`On`	Enable HTTP uploads.
`display_errors`	`Off`	Render errors in responses. Leave off in production.
`allow_url_fopen`	`On`	Enable URL-aware fopen wrappers.
`allow_url_include`	`Off`	Allow `include()` from URLs. Leave off.
`zlib_output_compression`	`On`	Transparent output compression.
`clear_env`	`no`	Keep env vars available to FPM workers.

Locale and timezone¶

Variable	Default	Purpose
`date_timezone`	`UTC`	`date.timezone` in `custom.ini`. Use PHP timezone identifiers — `Europe/Madrid`, `America/New_York`, etc.
`intl_default_locale`	`en_US`	`intl.default_locale` in `custom.ini`. Used by the `intl` extension and `Locale::getDefault()`.

environment:
  date_timezone: Europe/Madrid
  intl_default_locale: es_ES

OPcache¶

OPcache is installed but disabled by default so that development mounts reflect changes immediately. Turn it on for production:

environment:
  opcache_enable: "1"
  opcache_memory_consumption: "256"
  opcache_max_accelerated_files: "20000"
  opcache_validate_timestamps: "0"

Variable	Default	Purpose
`opcache_enable`	`0`	`1` = enable OPcache.
`opcache_memory_consumption`	`256`	MB reserved for the opcode cache.
`opcache_max_accelerated_files`	`20000`	Max number of cached files (keep above your script count).
`opcache_validate_timestamps`	`0`	`0` = skip mtime checks (prod); `1` = revalidate each request (dev).
`opcache_preload`	(empty)	Path to a preload script.
`realpath_cache_size`	`4096K`	Realpath cache size.
`realpath_cache_ttl`	`600`	Realpath cache TTL in seconds.

opcache_validate_timestamps=0 + live mounts

With opcache_validate_timestamps=0, PHP will not re-read files on the fly. In production that is what you want (rebuild the image or restart the container on every deploy). In development, keep it at 1 or OPcache disabled.

Preloading¶

environment:
  opcache_enable: "1"
  opcache_preload: /var/www/html/config/preload.php

Preload runs at FPM worker startup, so any error in the script will keep workers from booting. Start with a small preload file and grow it.

Bundled extensions¶

The image ships with a curated set of PHP 8.4 extensions — enough for most frameworks out of the box:

Core: ctype, curl, dom, exif, fileinfo, iconv, intl, json, mbstring, openssl, session, simplexml, soap, sodium, tokenizer, xml, xmlreader, zip, zlib, phar
Image: gd
Databases: mysqli, pdo, pdo_mysql, pgsql, sqlite3
Performance: opcache, pecl-apcu

Need something else (e.g. ldap, redis, imagick)? Build a thin image on top — see Composer & Building:

FROM erseco/alpine-php-webserver:latest
USER root
RUN apk add --no-cache php84-ldap php84-pecl-redis
USER nobody

Mounting your own `php.ini` snippet¶

The entrypoint only manages custom.ini. You can drop additional .ini files into /etc/php84/conf.d/ and PHP will pick them up:

docker run --rm -p 8080:8080 \
  -v "$PWD/90-my-app.ini:/etc/php84/conf.d/90-my-app.ini:ro" \
  erseco/alpine-php-webserver

Filename convention: NN-name.ini where NN controls load order. Use a number ≥ 90 to override the image defaults.

Verifying the running configuration¶

# Effective settings (merged)
docker compose exec web php -i | head -60

# Just one setting
docker compose exec web php -r 'echo ini_get("memory_limit"), PHP_EOL;'

# Check which modules are loaded
docker compose exec web php -m